The following article explains a very simple yet effective 48v automatic battery charger circuit, utilizing very ordinary components. The circuit is highly accurate with its over charge cut off features.
Circuit Description:
As shown in the figure, the main element in the circuit is the opamp IC 741, which has been arranged as a comparator.
Pin#3 which is the inverting input of the IC is referenced with a fixed voltage of 4.7V through the respective zener/resistor network.
The other input is applied with the sensing voltage which is actually the voltage merged from the supply and the from the battery, in other words the charging voltage which is applied to the battery for charging.
The resistor network at pin#2 along with the preset forms a voltage divider network which is initially adjusted such that the voltage at this pin stays below the voltage level at pin3, which is the reference voltage set at 4.7v by the zener diode.
The preset is set in such a way that the voltage at pin#2 rises above the 4.7 mark as soon as the battery voltage rises above 50V or the fill charge threshold level of the battery.
The moment this happens, the output of the op amp goes low switching OFF the mosfet, and cutting off the voltage to the battery.
Initially as ling as the battery voltage and the over all voltage from the 48V supply remains below the full charge threshold level of the battery, the output of the opamp stays high and the mosfet us kept switched ON.
This allows the voltage to the battery for charging, until the above explained threshold is reached which automatically inhibits the battery from further charging.
The mosfet can be selected as per the AH rating of the battery.
Current Controlled Version of the above Design
NOTE: The above diagrams mistakenly shows 48V as the input, the correct value is 56V.
The above circuit can be upgraded into an over charge cut off, as well as low charge restoring battery charger system, for charging 48V batteries.
The modifications enables the circuit to switch OFF the battery charging process at the set over charge threshold and restore back the process when the battery voltage falls below the low threshold value.
The 10k preset must be adjusted to set the full charge level while the 22k preset for detecting the lower threshold of the battery.
The above design appears to have one problem, it won't be able to detect low battery thresholds, the design should be rather configured in the following manner:
How to Set up the above Circuit:
For setting up procedure, the sample power supply should be connected across the points where the battery is connected, the mosfet does not require any attention initially. DO NOT connect the battery while carrying out this procedure.
Also keep the 22k preset link disconnected initially.
Apply the higher threshold level across the above mentioned points and adjust the 10K preset such that the RED LED just switches ON. Seal the adjusted preset with some glue.
Now reconnect the 22k preset link back into position.
Next, reduce the sample voltage to the lower threshold value and adjust the 22k preset such that now the green LED just lights up, while switching OFF the RED LED.
If you find no response from the circuit try using a 100K preset instead of the 22k preset.
Seal the adjusted preset as above.
The setting up of the circuit is over and done.
Please note that during actual operations, the above circuit will remain functional only as long as a battery stays connected at the shown points, without a battery the circuit will not detect or respond.
Feedback from Mr. Rohit
Hello Swagatam,
I have a 50-52v solar panel setup which is charging a 48v 78ah battery. What I want is when my battery is fully charged that is it reaches to 54v the battery charging stops and the supply which is coming from the solar panels is directed to another port from which we can charge any other device connected to the port. This charging should only continue till the battery is above 48v. Once it reaches 48v the battery again starts charging on solar panels and the supply to the other port is stopped.
Hoping you will reply soon.
Thanking you in advance
Rohit Pandey
My Response to the above Circuit Request
Hi Rohit,
you can try the last circuit from the following artcilehttps://www.homemade-circuits.
Regards
Have questions? We love answering questions, Please feel free to post them through comments and get guaranteed replies within 5 hours. (Please Share and Bookmark us)
Yusuf abdulazeez says
Thank you very much for helping people. God bless you.
marvin says
sir can this circuit be used as a BMS for lithium ion batteries and can it be wired in series or parallel the way BMS is usually wire sir
Swag says
Marvin, yes it can used, but the cells cannot be monitored individually for series connected modules, same for the parallel connected modules, however the entire module can be monitored as a whole
विपिन वर्मा says
24vdc बैटरी को चार्ज करने के लिए क्या चेंज करना होगा डिज़ाइन में 150 w 12 vdc के 2 पैनल हैं
Swag says
use the second circuit from top, replace all 22k resistors with 10K, and optimize Rx as per your battery’s Ah rating
yashvardhan says
Sir, we want to design 48V battery level indicator. As after full charge battery voltage reaches to 54V. Our team is manufacturing a solar car with a battery of 48v. Our problem is when ever driver press throttle the battery voltage in battery level indicator fluctuate very much and then the car is stationary it doesn’t. So we want such battery level indicator which do not fluctuate when throttle is applied and show battery percentage while driving the vehicle.
Hope you reply soon.
Thank you Sir
Swag says
Yashvardhan, if your battery level indicator is fluctuating due to an actual drop in battery voltage while throttling then that cannot be corrected, because if the battery voltage drops suddenly and rises then the indicator will also show corresponding sudden drop and rise in its reading….so first yu will have to investigate why the indicator is fluctuating, is it due to actual battery voltage drop or due to some other reason such as RF disturbance or noise spikes?
abdulnoni says
Gud day sir, I av 2000watt stabilizer transformer, I want to use the transformer for 1kva inverter, when I calculated it d primary currently is 4.5amp while d secondary current us 83amp but I dnt no size of copper Guage to use
Swag says
Hi Abdul, you can use the trafo for inverter purpose, but for inverter the mentioned specs for primary will become for the secondary and vice vers….wire size is not important, the measured are enough for the verification
abdulnoni says
I did get u sir, what I mean is Dat I want design a 1kva inverter using 2000watt stabilizer transformer. And I want to wind it myself. So hw can I get d number of turns and size of wire to be used. Sir I nid ur help
Swag says
sorry, my knowledge about rewinding trafos is very low, so can’t help you in this regard
Dayo says
Good day sir, please how can I modify it to charge 24v of 200ah battery
Swag says
Dayo you can try the second circuit from top, and use it for your 24V/200AH battery.
use IRF540 on heatsink for the mosfet.
dimension the current sensing resistor for limiting 20 amp current
feed 28V/20amp to the circuit
Dayo says
Thanks for the response, but the second circuit does not have overcharge cutoff and low level feature. How will that be possible sir.
Swag says
Why is the opamp used, according to you? It is used as a full charge cut off. This charger will start charging as soon as the battery level falls below the full charge level, and cut-off as soon as it crosses the full charge level…the difference between these thresholds will be hardly 0.2V
If you want it to stop untill a much lower threshold, then you can add a calculated resistor across pin#6 and pin#2
segun says
Hi Mr Swag,
I constructed the last circuit today(for 12v battery)though without the current control bcos I could not found appropriate RX.
With high threshold the red led came up but became brighter when I adjusted he 10k preset ok.
But with low threshold, I adjusted the/22k/100k preset yet the red LED did not go off. Both LEDs came on. What did you think I did wrong?
Do I need the 12v zener diode across gate and source of p channel bcos am using 12v supply.
Thanks
Swag says
Connect a 3V zener diode at pin#6, such that the signal from pin#6 passes through this zener to reach the other connected parts. cathode will go to pin#6
Swag says
the 12v zener is required otherwise your mosfet will burn
segun says
Thanks so much
Swag says
You are welcome!
YILDIRIM KAYA says
Dear Swagatam,
How is possible to limiting to charging current with 3 amper.
I want to charge 4 x 50 Amper battery set with 7 Amper transformer but I want to limit charging current with 3 Amper with this circuit.
Swag says
Dear Yildirim,
in the second circuit use Rx = 0.6/3 = 0.2 ohms, wattage = 0.6 x 3 = 1.8 watts
therefore replacing Rx with a 0.2 ohm/2 watt resistor will do the job
segun says
Hi swag
Using the last circuit from top, pls where is the Rx resistor? Is it the resistor connected to emitter of BC 546 to gate of MOSFET.
Thanks
Swag says
Hi Segun,
Rx is near the battery in the last diagram 🙂
segun says
I still don’t get it. Is the 22k connected to 10k preset or 22k connected to zener diode 4v7 at the inverting input of op amp from 4th diagram from top.
Swag says
for a 12V battery you can remove all the 22K resistors except the 22K preset. and also remove the 10k and zener at pin#7…all these resistors were used to safeguard the IC from the high 48V source. pin#7 can be directly connected to the positive line.
and please do it only after proper understanding of each and every steps and stages…otherwise you may fail to get things working for you.
segun says
I still don’t get it. Is Rx resistor the 22k connected to 10k preset at non-inverting side or 22k resistor connected to zener diode 4v7 at the inverting input of op amp for 4th diagram from top.
Swag says
I think you should try the second circuit first which is much simpler, the low voltage restoration can be added by adding a feedback link from pin#6 to pin#2
segun says
Thanks Swag
So, P-channel MOSFET what part Not can I use if I am to convert the circuit to 12V up to 200AH battery charger with current limit = 30A
Swag says
Hi Segun, I have already explained which parts should be removed, please check my previous comments.
the mosfet s not P-channel, it is N-channel IRF540
segun says
I really commend you for your great work and interest.
Straight to the point.
I am using the last circuit from the top (i.e 4th circuit) for 12V upto 200ah batt with xformer 15v/50A. I want to limit the current to battery to 30amp.
Now(1) how do I calculate the current 30A limit
(2) you told me to remove all 22k resistors with links and 15v zener and use N channel irf540 MOSFET right?
Swag says
Segun, you can calculate 30A limit by calculating Rx…see Rx formula in the 2nd diagram…
segun says
Hi pls how can we adapt this circuit to charge any battery of 12v upto 200AH
(1) what will the zener diode volts would be
(2) wattage of resistors and preset resistor and ohm size
(3) can it limit the current drawn from battery to 20A
Swag says
for a 12V battery you can remove all the 22K resistors and replace them with a link.
also remove the 15V zener, and the 4k7 resistor.
rest all be as given , all resistor are 1/4 watt.
pin#3 zener can be any zener between 4V and 9V rated at 1/2 watt
Tim says
I need to charge a 48V lithium Ion battery pack. It needs to have a current limiter installed. Can you tell me how to modify your circuit to control current? Then constant voltage after bulk charging?
Thank you!
Tim
Swag says
I have modified and updated the first diagram, please check out the second one from top.
Abdulnoni says
Gud day sir, I av a project am working on title inverter type arc welding machine. I av finish constructing it. And is 48v system. When I tested it is working properly after a week later later I tested is jst starting but no melting the electrode as before. My question is wat can be d problem, bcos am thinking maybe the battery is low. Can u giv me ur opinion. Thanks.
Swag says
Hi Abdul, yes most probably it could be due to low batt, because a welding inverter is supposed to draw heavy current and in the process the battery may drain relatively quickly…you can verify it with a voltmeter and possibly keep a voltmeter permanently connected with the system.
Jai Arora says
Hello Sir,
Request
Sir can you refer a circuit for the following situation
I have two battery packs, Let us assume one of them is charged. Now there are two parts one is the generator which charges the empty battery pack and the other part is the motor which uses the charged battery pack. Now what i want is when the motor has used the battery to the fullest i want a automatic battery switching circuit which switches the connection with this battery with the other one(being charged by generator till now). So that now newly charged battery from generator is used by motor and the other one starts charging.
Please help.
Swag says
Jai, you can try the following concepts and customize them as per your battery specifications:
https://homemade-circuits.com/?s=twin+battery
https://homemade-circuits.com/automatic-dual-battery-charger-with/
Abdulnoni says
Thanks sir, I we try it n see.
But sir i av 48v 100ah battery and I want connect dc fan rated 12v, 0.13amp to my inverter to b fan d mosfet .i nid a circuit diagram to limit d current. Bcos it as damage 2 dc fan. Pls I nid ur help sir
Swag says
Abdul, only voltage will need to be controlled, not current.
you can use the following configuration for your fan
https://homemade-circuits.com/2012/08/simplest-dc-cell-phone-charger-circuit.html
the input will be your 48V input, resistor should be replaced with a 10K, and zener with a 15V zener.
transistor must be a TIP122C
Abdulnoni says
Gud day sir, I av issue with the charging circuit setting , after complete the circuit via third circuit, I disconnected the 22k,then I vary the 10k the red led turn on, so I connected the 22k back, the green light turn off and the red light good off. But the question is the green light always on even I vary the 22k.pls I nid ur help about the setup
Swag says
Abdulnoni, disconnect the positive side of the green LED from the existing position and connect it with pin#7 of the IC..this will solve the issue but the illumination might decrease….to correct this decrease the pin#7 resistor to 4k7, and also decrease the LED resistor to 4k7….do this and check the response…
and also remember that the 22k feedback preset is arbitrarily selected…you can try other values such 100k preset or 220K preset for getting the correct lower threshold restoration adjustment of the circuit.
Abdulnoni says
Could not get irfp9540,can I use irfp9240 for replacement
Swag says
please check the datasheet of the device, if the current and voltage specs suit your application then you can use it….
Abdulnoni says
Thanks sir, I we try it n see
Abdulnoni says
Sorry sir, is a mistake the battery is 12v 100ah x 4 to in series to give 48volt 100ah. What type of mosfet will I use via third circuit
Swag says
OK, in that case you can use a IRF9540 mosfet
Abdulnoni says
Hello sir, I want to construct a 48v automatic battery charger and my battery rating is 12v 100ah via ur third circuit what type of mosfet will I use
Swag says
Hello Abdulnoni, why do you need a 48V charger for a 12V battery?
Richards Samson says
I have a circuit ,where I am getting the 52v 700mA output at my power supply but the problem is about the current. I require 5-7A to charge my battery pack because its is 19A pack.
Please Kindly help me sir.
Please suggest me a design to get 5-7A 52V supply to charge my battery pack using 1st or 3rd circuit diagram
Swag says
To get higher current you will have to use a higher current power supply, there’s no way to increase 52V 700mA to 52V 5 amps, that’s just not possible.
you can buy a 48V 7amp transformer and use a bridge rectifier and a 2200uF/100V filter capacitor for rectifying its output, this will provide you the required 56V/5 amp.
Richards Samson says
Thank you so much
But I want to make the charger with my own hands not to buy
Swag says
For making a charger you must have the power supply first, for that you will have to buy a 48V / 7 amp transformer.
Richards Samson says
please kindly refer me a best one
Swag says
you can use the first design
Richards Samson says
I tried the first circuit in that the LED is goes on during charging and when the battery is fully charged the LED goes off!
Is I mentioned in the above statement is right? or not?
Swag says
that’s perfect, If the green LED i getting OFF it means the opamp is correctly responding to the fully charge level, and the mosfet must also switch OFF in this state.
Richards Samson says
I had set the #pin 2 as 4.7v without connecting the batteries and then i connected the battery pack.
After the battery pack is fully charged up-to 48v but the circuit doesn’t cutoff
Swag says
sorry, that’s not the correct way to set.
you must feed 48V to the circuit without battery connected, then adjust the preset until the green LED just shuts down. That’s all, your circuit is now set.
By the way for a 48V battery the full charge level should be 56V.
Richards Samson says
The circuit doesn’t cutoff even after the battery pack is reaches to 48v. Please help me
Swag says
how did you set the preset??
Richards Samson says
i had seted the preset without connecting battery pack
Swag says
OK, please tell me how you implemented the procedure?
Richards Samson says
I need 53v li ion battery charger. I have 73v DC supply with 5amp. Can you please help me
Swag says
you can try the first concept for your application
Richards Samson says
This is very help full article. Thanks for your great support for beginners like me.
Can i use the first circuit for 48v 7amps supply, which is going to be charge the 18650 Li Ion batteries of 48v 19amps.
Swag says
Thanks Richards, yes you can use the first design for charging and cutting off the mentioned battery automatically
Durgasankar sahs says
please tell me the mosfet no of n type
Swag says
use IRF540 for n channel
Carl Corbeau says
Do you have a parts list for this circuit?
thank you
Carl
Swagatam says
Parts are all standard, the resistors are 1/4 watt CFR, the zeners are 1/2 watt
Carl Corbeau says
Thanks Swagatam………
Would it be hard to set this design up for 12 volts?
Could the self regulating design be tweaked to shut off high and turn on low?
Carl
BTW where are you located?
Swagatam says
Hi Carl, there are plenty of similar circuits published in this website which you you can refer and customize as per your preferences…all of these employ opamps are self regulating type and the distance between the full charge and low charge can be adjusted as desired.
you can check out the top sidebar section for getting all the links related to automatic battery chargers…
Swagatam says
…I am in India…
Unknown says
Hello good sir, can you recommend trans other than BC546 and BC556? Thank you in advance!
-Ru
Shakil Ahmmed says
Same circuit if I use 48 volt & 10Amp current then what will be the output voltage?
Swagatam says
same as explained in the article
mark kim blando says
Hi hello mr swagatam. I'm back again ask you again..let me ask you sir.. is this capable to charge 48V with 365AH? IF not what components to be replaced?thanks in advance sir
Swagatam says
Hi Mark, yes you can use the designs for charging a 48V/365AH battery, but make sure that the input source has a current not more than 40 amps.
and also make sure the mosfet is mounted over a large heatsink
Swagatam says
Hi Mark, you can use the circuits which are explained in the above article for charging any battery from 12V to 48V, simply by adjusting the indicated 10k preset accordingly
mark kim blando says
Hi hello mr swagatam..im back again..let me ask you sir.. do you have a circuit that will be able to charge 12v, 24v, and 48v,.. I really need it mr sir swagatam.. thanks again
olufade oladayo says
Engineer Swagatam, thanks i ve gotten the capacitor thanks God bless u
Swagatam says
OK thanks!
olufade oladayo says
Sir pls i have not seen the answer to that pin 14 and pin 10, that capacitor is it the one of polarity which pin is negative and positive please sir help me/. the first question that i asked before about the value of the CT and RT u have answered me that i should try any value but the pin 14 and 10 i did not know its polarity please help me sir or i should try any polarity? u know u are our lecturer thanks.
Swagatam says
Please comment under the article to which your question is related, I will check it and answer you….
olufade oladayo says
…And pls Engineer Swag, this circuit of IRS2453 the capacitor in pin no 14 and pin no 10 is it ceramic or micro-farad with polarity?
Swagatam says
please comment under the referred article…
olufade oladayo says
pls Swag, help me with 280vdc to 48vdc circuit to charge my 4 batteries
Swagatam says
Olufade, I have already answered to this question in your earlier comment posted under a different article
olufade oladayo says
please Swag, my own request is still 280vdc in and 48vdc out for charging 4 batteries pls help me. and its like there are many John in this site may be i will change my name to Dayo thanks
Anonymous says
How to set the first circuit (the simple one) in order to have 28v when the battery is full charged. I need your support. Thank You!!
Unknown says
will this circuit works for 72v 50ah battery
Swagatam says
yes it will, after suitably adjusting the perset
Anonymous says
Swagatam Majumdar I need your help im trying to simulate your 48v circuit on MULTISIM however I cant run it, apperently im not using the right mosfet could you give me a couple of names of different mosfets that I can use for that circuit?
Swagatam says
all mosfets work in an identical manner, so any mosfet matching the N/P and V/I specs will work here.
you can try the ones which are rated to work with 60V or above
It's better to build and check it practically instead of checking on a simulator.
Anonymous says
I Did what you said , I build it and it still didnt work is there any way you can build it on multisim and upload a screen shot or pictura of the actual circuit build in multisim ?
Anonymous says
Is it suitable the first circuit to charge a nicd battery that has maximum load voltage 29v when is full charged? I want to charge a battery nicd up to 29v. Thank you!
Swagatam says
yes you can use it for the purpose….
Anonymous says
Hello
Been following your posts with great interest. I have some questions please. But first I’ll explain what I’m trying to do.
Attach a 12V 100 Watt solar panel to a 12 to 60 volt converter. Converter attaches to your 48 Volt battery charger. Attached is a diagram. There have been revisions on your charger so I’m confused regarding to components.
The value of the 3 Zeners, which Mosfet to use and the value of the resistor connected to the base of the BC546.
Many Thanks,
Jim
Swagatam says
thank you, the first circuit is the easiest and the best one, although it is designed only for full charge cut off.
the 3V zener can be a 1 watt type….all resistors are 1/4 watt
the mosfet can be a IRF9540 for P channel, and IRF540 for N channel
BC546 base resistor is a 10K
Amit Seth says
I need a 60 volts auto cut charger circuit for 12*5 (=60 Volts) and 24 AH batteries for my e bike. Please suggest. amitrajseth@gmail.com
soufiane amestak says
Hello every body ,Please if you have any PCB of battery charger on 24V and Imin=10A,don't hesitate to help me and thank you in advance
nikhil ms says
Will u please send the link where I can get automatic charging circuit.
nikhil ms says
Sir where can I get that automatic charging circuit and cost of it.we are from karnataka.
Swagatam says
sorry, I have no idea regarding readymade units
nikhil ms says
Sir can we provide 5 amps so that we can reduce the charging time
Swagatam says
5amp is OK, but as you increase the charging current, the battery gets more prone to an early damage, and vice versa
nikhil ms says
Sir I need battery charging circuit of 48v (12 *4)v and each battery capacity is 26 ah. I need automatic charging circuit.so will u please suggest which one I can use.
Swagatam says
Nikhil, you can use the first circuit from the above article…make sure the DC input is 56V DC and with 3 ampere current
Shayan Firoozi says
Mr Swagatam Majumdar
thank you for helping and directing me to the right path !
in other post you told me to use the first circuit of this article
i just wanna know is first circuit could detect low batter voltage ?
i other word can i use first circuit for a battery backup which is standby ?
when battery falls below 13.6 or 13.5 or less will it charge it automatically to the full level ?
thank you again
Swagatam says
yes it can, in the first circuit from the above article, the circuit will rapidly switch ON/OF when battery voltage reaches the set full charge threshold say 14V and drops to 13.9V….this gap can be increased to any desired value simply by adding a calculated resistor across the pin6 and pin2 of the IC
Ajay Sharma says
i want to build a cutoff circuit for 48v battery charger of battery 400ah please give me the component list
Swagatam says
you can use one of the above designs, it will work
Unknown says
Hello sir, pls I need an auto-cut off car battery charger circuit diagram to charge my 96volts/600amps battery bank for my inverter,pls my mail:eureka.deg911@gmail.com, tnx alot!
Swagatam says
you can try this concept
https://homemade-circuits.com/2016/01/high-voltage-360v-battery-charger.html
labh Singh says
I require 48v 30amps solar current controller circuit diagram of 12*4–150ah batteries
Swagatam says
presently I do not have, will try to update it soon.
Bandi Szasz says
Hello.
I want to build the last circuit. I don't have 741 but i have some other op-amp's left from other projects, they are : TLC271,LM358,LM318N can i use any of them instead of the 741 ?
Thx.
Swagatam says
Hello, yes you can use any of those opamps for making the above explained circuits.
elhart says
Hello Swagatam i am a great fun of you and have been following your work. please can i use the above circuit to charge 36 v battery and can i replace the mosfet with relay, if yes please can you make the change for me ?
Swagatam says
Thanks elhart, yes you can use the above circuit with a 36V battery, without changing anything in the design.
relay can be used in place of the relay, you can refer to the second circuit from this article in order to know how the relay needs to be connected:
https://homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html
klemen fikon says
Does it work at 72v, for 72v battery pack? (Charging at 83v)
Swagatam says
yes it will work, but the NPN, PNP and the fet will need to be upgraded at over 80V.
Saiq Hussain says
Hi Swagatam Majumdar ,
I have gone through your blog and I appreciate your efforts ! I wanna try the third circuit to cutoff charging at 56.8 v and reconnect charging at 44 v . Means if battery voltage reaches 56.8 v it should cutoff charging and wait till battery drained to 44 v . Will this ckt work for this purpose ??
Thanks in advance 🙂
Swagatam says
Thanks Saiq,
yes, I have simulated the design in my mind thoroughly and I feel it would work perfectly if assembled and set correctly.
Gary Whitney says
I need a charger about 15 amps for 6 8volt(48v) trojan golf cart batteries is this circuit feasible for my application? thanks
Swagatam says
You could probably build the following design and modify its turns in the following manner for achieving the desired output:
https://homemade-circuits.com/2014/03/12v-5-amp-transformerless-battery.html
use 20 turns for the secondary winding of the trafo and use 50V zener in place of the 12V zener, also make sure the primary is wound with two or three 0.4mm wires in parallel for allowing more current in to the trafo….similarly use two or more 0.6mm wires in parallel for the secondary winding.
Swagatam says
….the circuit presented in the above article is for enabling auto cut to the battery it's not a power supply circuit….you could probably use it in conjunction with the linked circuit in the above comment.
Gary Whitney says
I need a charger about 15 amps for 6 8volt batteries(48v) in a golf cart is this circuit feasible for my application? thanks
john carter says
Hi Swagatam,
thx for the fast response, i really love this site,
yes, second curcuit, i'm trying, i guess,there is a therotical misunderstanding or i did not understand properly, when i apply 52Vdc and PİN number3 must be just lower than PİN number 2(Zener) of the OPAMP. this is setting up the upper cut of level. till here fine.
then connect the link and reduce the voltage to 49VDC and play with the 22K Pot to make PIN number 3 higher than PIN number 2 of the OPAMP. this setting up the lower treshold value.(On sunday i could not manage but ill try again),
But, here is the therotical problem, when you connect the supply voltage(on second curcuit, where, it is printed as 52VDC) and battery(Where it is printed as per shematic), since supply voltage side is the sensing side, means, if my supply is, let's say 53VDC curcuit is just cut-off because supply is 53VDC and treshold was setted up 52VDC anything above 52VDC will trigger curcuit to OFF state, and if i reduce supply voltage to 51,5V then upper cut-off will never be utulize since supply voltage 51,5 always less than that of upper cut-off level 52VDC.
could you kindly enlight me.
regards
Swagatam says
Hi John, thanks!
I am sorry there was indeed a mistake in the last two diagrams, I have corrected them now with PNPs as the relay driver, however with the present diagram please follow the new setup procedure, that is now pin3 should be higher than pin2 at 52V and vice versa…I hope now everything will fall into place and you won't have to go through all those previous weird results:)
Swagatam says
…oops:p it should be mosfet driver not relay driver….
john carter says
Hi Swagatam,
yesterday, i had time to test charger curcuit, i could not figure out, how does overcharge cut of feature works, Could you enlight me pls. here below what i have done,
i have applied the 52Vdc sample voltage, where battery shown, and play with the 10K pot where mosfet just switched OFF. i have double checked at 51,9V curcuit does conduct and 52V curcuit cut-off(mosfet off) so over charge cut off setted up?
i connected 22K link and applied 49Vdc where battery printed and play with 22K pot, do not respond, 100K do not respond, 470K do not respond. do you think more higher value pot will respond? or am i doing wrong set-up procedure.
Then i connect the battery for charging purpose, but when i aplly 53Vdc where input shown, voltage level of battery claimed to 52,5V suddenly, but actually level of battery is 48V, start flickiring. mosfet start ON and OFF continuously. i could not fix hysteresis.
Could you advise me pls, where is my mistake?
regards
Swagatam says
Hi John,
Assuming you have used the second circuit,
You must do the setting up procedures by checking the voltages across input pins of the opamp.
After you have set the upper limit, connect the multimeter in DC V range across the preset pin of the opamp (pin3) and ground.
Now in this position reduce the input to 49V and starting varying the feedback preset until the pin3 voltage just falls below the pin2 reference. You can add a 1N4148 diode in series with the feedback link to avoid any sort of leakages from the opamp output.
A 470k preset would be more than enough.
a diode may also be added in series with the base of the lower BC546 transistor for a better response.
If you are connecting the battery as the load you must connect it first before applying the input voltage, also the input amp must be 1/10th of the battery AH for proper functioning of the circuit. For example if the battery AH is 20AH, the input must not be more than 3amps,
Please confirm the above and see how it fairs.
john carter says
Hi Swagatam;
regarding to your question, İ have managed to cut off at 43V and re-connect at 47V, if i be more spesific.
1-)i constructed to curcuit except mosfet part, and sample voltage suplied, where battery is printed. i aplly sample voltage 48V(where battery printed), i check PİN number2, it was 3.6V due to zener reference voltage. PIN number3, i adjusted to 3.7V(By the help of 10K pot). then i connect to hysteresis link 100K and reduced to sample voltage 43V . i played with 100K pot till, where output of the OPAMP just switch to low logic.
2-) then i experimented the curcuit at 43V, it was cutting output of the OPAMP, to low logic and at 47V, it was again reconnecting(making high logic output). then i replaced the PİN2 to PİN3 to see output of the opamp at 43V high logic and at 47V low logic. comparator part working superbly.there is no problem at all.
3-) my trouble strated, when i try to switch OFF and ON the mossfet, first, i thought due to P-channel N-channel mosfet diffrence, but later, i realize that, its always ON regardless of the OPAMP condition(Low logic or High logic no difference,always ON due to same supply line of the source, meaning at 43V supply voltage, gate of the mossfet low logic, but Source of the mosfet 43V and drain also 43V and mosfett ON, at 47V gate is high logic 12V at the gate, source 47V and drain 47V,what ever the supply voltage mosfett is ON), when i try to increase output of the OPAMP to full suplly voltage,by this way gate would also receive full voltage (cancelling PİN7 limitation) then mosfett started to act but not perfomed well as well.in order not danger curcuit, i asked you, you said, dont do it(but i did not check thoroughly increasing the output of the OPAMP, you said bad idea).
my question is, can i do, with this circuit 48V battery disconnect? ill constructed battery, where battery is printed and where you placed to 52V DC input, ill construct to load, and switch ON and OFF the load, by the help of this curcuit? if i manage to OFF and ON the mosfett then load also would be ON and OFF at desired level of battery since comparator part is working superbly.
Could you advise pls?
Swagatam says
Thanks John, It's great to hear that you have succeeded in making the circuit work as per the explanation.
You are right, the second circuit can be used for connecting or disconnecting a particular load in response to the set battery thresholds, it could be a battery or any other load whatsoever.
You may go ahead and make the second design for the intended operations, in fact you could even try the first circuit for the same, using an N channel would make the design much easier to configure as could be witnessed by comparing the above schematics.
john carter says
Hi Swagatam;
i was bussy, just today had some time to experiment on circuit, evetually failed to switch off mosfet.
Actually; i was worried both the case, about 2.2V during low logic of the curcuit and not switching off the mosfet(you said that drain and source voltage doesnt matter and PİN7 have nothing to do), as per your suggestion 3.3 zener solved the 2.2V problem, i mean low logic,i get 0v instead 2,2v. but mosfet, from the moment, curcuit is energized, become on, and never becoming off. it is very strange.
i gave up on mosfet, i dont know, why, it is not becoming off, damn thing, always on, regardless of the low logic or high logic condition.
Could you advise me about BJT, i shall connect base to zener 3.3 (PİN6), collector to positive supply and emiter to load, right? and how many pcs would be enough? no need to make some darlington pair etc right? simple 1 transistor instead of mosfet right?
Swagatam says
Hi John,
I think we are missing something here….the circuit uses a p-channel mosfet which will switch OFF with a positive that must be at least 5V more than its source voltage.
It means we need to supply at least 5 + 48 = 53V in order to switch OFF this mosfet.
oh that's a big blunder!!
The BJT will also face the same issues, it will require at least 48 + 1 = 49V in order to switch OFF completely.
And our opamo is helpless, it's not able to supply anything above 12V.
So that's the problem we are facing presently.
I would rather suggest that we switch to a N-channel device instead of the P-channel.
All connections remain as is.
we just need to put the N-channel in series with the negative supply instead of the positive, and swap the input pins of the op amp with one another.
Swagatam says
Hi John, I have corrected the diagrams with respect to the above discussion, please check them out.
Swagatam says
…by the way the p mosfet would require just 48V in order to switch OFF in your case and not 48 + 5 as wrongly mentioned in my previous comment:)
Swagatam says
John, I was just going through your first comment and it made me realize that perhaps the last circuit will need to be modified differently for your application.
The above circuits are all configured for charging the battery and not for connecting or disconnecting a load with the mosfet.
So I am a little confused here with your following statement:
"What im trying to set up is; at 43VDC battery should dissconnect the load and when battery level reach 46VDC or 47VDC battery should re-connect to load. is it possible with third circuit above?:"
I would like to have a little more clarification on this.
john carter says
Hi Swagatam;
İf, i remove the opamp suply voltage component(PIN number7) what i mean is, removing 15V zener and 10K resistor, by this way output of the opamp voltage will be the same suplly voltage available in the battery.
right now, output of the opamp is limited to zener voltage, which is max 14,6V(in high logic case). do you think, ill put the circuit in danger? by removing zener and 10K resistor at PIN number 7. the circuit can also operate without zener and 10K resistor at PIN number 7 ?
regards
Swagatam says
Hi John, I would have never put the zener at the IC supply if it could tolerate anything above 40 volts.
The IC and the mosfet would get instantly damaged if the protection zener was removed.
Moreover any mosfet would nicely work at around 12V, irrespective of their S/D specifications, so 14V is quite optimal, I thought you were worried about the leaking 2.2V which was not allowing the fet to switch OFF at full charge levels.
john carter says
Hello Swagatam;
your site is really informative, thanks for the response.
i have established the curcuit, without the mosfet part, operating just fine, i manage the trip at 45V and re-trip the 48V. but mosfet do not trip the load.
Since by placing 15V zener at opam supply,you fix the output of the opam at 14,6V(High logic case), gate of the mosfet is receiving 14,6v at 48,49,50,51,52,53,54V supply voltage. At 45V sample voltage mosfett gate is receving 2.2V(Low logic) but mosfett do not make any cut out for the load. pls note that at 45V sample voltage, drain and source of the mosfett is 45V. gate is only 2.2V. how will mosfett will trip, when gate is receiving only 2,2V in low logic case and 14,6V at high logic case,in the other hand drain and source receiving 45V. i have try N-channel and P-channel both.
Could you pls advise for the mosfett part.
Swagatam says
Thank you John,
In order to block the 2.2V and make it zero you can try adding a 3V zener in series with the gate of the mosfet. (anode to gate)
Alternatively you could quit using fets and try BJT such as TIP142 for making things much easier.
In any case the 3.3V zener would be required at the output of the IC.
This should hopefully solve the problem.
john carter says
Hi Swagatam;
İm a new bee in electronics,thx for the response, here below what i have seen, when, i try to build third circuit.
1-)Since im observing battery discharge cut off side, i have feed 52Vdc sample voltage to battery end,(not mossfet side) .
2-) i saw green LED lighted but not the red LED(red led never lighted actually,green led always lighted).
3-)İ checked with the help of multimeter voltage at PIN number2 of IC and saw 3,6V
4-)İ checked PIN number 3 of IC and voltage was 3,1. with the 10K preset i increase the level 3,8V.
5-)İ checked voltage at the output of PIN number 6 , 2V low logic.
6-) İ inserted 22K preset and feed the sample voltage 43V, nothing change, then i change to 22k to 100K preset, output of the İC became 14V, high logic.
7-)i remove the sample voltage source and connected the actual 48V battery and connect the load at mossfet side, battery level reduced to 43V but mossfet did not cut off the load.
😎 gate voltage for mosfet is maximum 14V when İC is high logic level and 2V when IC is low logic. but mossfet drain and source voltage is 42V. mossfet did not cut out out the load.
do you think, did i do correct? if i did correct, then when battery level falls to at 43V i should have seen the load cut out from the battery suplly.
Could you advise pls.
regards
Swagatam says
Hi John,
Yes your procedures look OK, I think the IC could be duplicate or faulty.
I would recommend you to make the following basic set up as shown in the first circuit from this link:
https://homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html
Use 12V, and check if the LED toggles ON/OFF at a particular point on the preset. If it doesn't work with your IC you can be sure the IC to be faulty.
You could try swapping the input pins of the IC for a reverse effect from the same.
john carter says
Hello Swagatam;
i build third circuit, when i aplly the 52VDC, as per the cicuit set up procedure, while playing 10K preset, red led supposed to lit or off but strangely from the moment apllyinng 52VDC greed led lit, and do not switched off what ever i try and red led do not light at all. so actually i could not setup circuit.
Could you kindly tell what is the procedure to setup. pls note that, i follow your circuit set up procedure, with some trial and error also i could not fix. here below your comment which i have tried as well.
don't bother about the LEDs remove them for the time being or use 10K resistors.
Just check the output voltage while adjusting the preset. Do it in the following manner:
Initially keep the 22K feedback preset link disconnected.
feed approximately 52V DC to the circuit, with some trial and error adjust the 10K preset to make the output (where the battery would be connected) switch OFF. Flip the preset to and fro to confirm the adjustment….now glue the preset tight.
Now reconnect the 22k preset link back into position.
next apply a 46V DC input and adjust the 22k preset to restore back power at the output, if it gives problems increase the preset value to 100K.
the circuit is all set now
What im trying to set up is; at 43VDC battery should dissconnect the load and when battery level reach 46VDC or 47VDC battery should re-connect to load. is it possible with third circuit above?
you kind response will be highly appreciated.
regards
john
Swagatam says
Hello John,
It will definitely work if you do as per the abve stated instructions.
It has to work.
The idea is (with a 46/47V input) to make the pin3 voltage of the IC just higher than the pin2 voltage of the IC by tweaking the pin3 preset so that the output of the IC is forced to go high (RED LED ON), until this happens meaning as long as pin2 V is higher than pin3 V, the output stays low (green LED ON)
You'll have to implement this by connecting the sample power supply input at the battery end….not at the mosfet end.
You can check the proceedings as explained above with a multimeter.
And as mentioned in the earlier explanation the feedback link should disconnected while setting the 46V threshold and must be reconnected and brought to use while
setting up the lower threshold cut off
john carter says
Hello Mr. Swagatam;
how about battery over discharge cut-off curcuit for 48V battery. assume that, when battery level reduced to 43V, curcuit should cut-off the load, and when battery level reach to 46V curcuit should supply the load. do you think it is possible to make using op-amp 741 such a circuit? i think it is easy when battery level at 43V cut-off is easy, but re-conducting at 46V will be difficult?
Could you pls advise?
Swagatam says
Hello John, yes it's possible, the above circuits are all designed to cut off and switch ON at the any desired high and low thresholds within the reange, so it's already there in the above shown design
prince godson says
Pleas I need a circuit that can charge 12v 100Ah battery for 2kva inverter
Swagatam says
automatic or ordinary, pls specify.
chin long cham says
Hi Swagatam, I simulated circuits 2 and circuits 3 with TINA and I found out that the currents flowed through the battery were both more than 30A. The cause of these were found to be the very high gate source voltage across the p-mostfet (i simulated with IRFP9140). can you comment on this?
thanks
Cham
Swagatam says
Hi Cham,
You are right, we need to add 12V zener diodes across the gates of the shown p-channel mosfets for correct operations.
Thanks.
chin long cham says
the 12V zener is to be connected between the gate and the drain of pMOS? what is the role of the OpAmp in this case? it doesnt seem to be helping in ensuring constant current does it?
Swagatam says
the opamp cuts off the mosfet gate voltage when the battery is fully charged by applying a high logic at pin#6. this happens as per the setting of the preset a its pin3
the opamp is for controlling over charge of the battery, not the current.
KAILASH says
Dear Sir
I have al-ready request the plz send to me 12vx4(48v ) Circuit when the battery discharge the battery bank to get 46v around . relay cut off with circuit diagram and install the parts in detail plz sir……
Swagatam says
Dear Kailash,
Try the second circuit in the above article.
replace the mosfet with BC546 transistor. Connect its emitter to negative line of the circuit and connect a relay across its collector and positive, relay should be 48V rated.
kingy says
Just a quick thought before I make myself sound stupid by saying I can solder but thats about it lol could I get a permanent magnet wind turbine generator the 48v version and boltbthat to the engine and run it through a wind turbine regulator I could be realy wrong but just thought the only diference is its my engine driving the motor rather than the wind. But no idea about wats amps snd volts calculations lol with me having 4x 12v 75 ah batteries what sort of wattage or amp or even voltage for it to work. Like I say just a thought lol i can repair most electronic or electrical things but dont realy understand the ohms law thing i like working on circuit boards but wouldnt know where to get a circuit board from like you have in your pics with nothing soldered onto it to start with. What I do have here dont know if it might be the same as what is on your pics, I hav 2x kemo m102n accumulator chargers these are ment to charge 2x 12v batteries up so I bought 2 of them a while ago thinking it would do the job but like I say when I looked at the wire diagram I would have ended up with a strait positive to negative short with the batteries still connected up.
Swagatam says
Considering your limitations, I think the last design in the following article would be the best for your application:
https://homemade-circuits.com/2013/08/connecting-batteries-in-parallel.html
The lamps are 24V truck head lamp bulbs….as long as the lamps stay illuminated would mean the charging of those particular bats are in progress,once the glow fades off would indicate a fully charged battery.
The arrangement is the safes according to me without much electronics.
kingy says
So how much in gbp would it cost if you could make something for me to save blowing myself up lol
Swagatam says
shipment could be a big hassle…so may be not a feasible idea to get it done from India
lol you wont blow up anything believe me, i'll show you how to do it step wise.
could you please procure the IC LM196 or LM396 one for each battery in the meantime??
As soon as you get them we can proceed with the construction, of course i am assuming that you know all the basics such as soldering, resistor color codes, mounting parts on pcb etc.
kingy says
Not sure I will get notifications through this butbif not my email address is babyboyk@aol.com
Swagatam says
according to me, you will have to make the circuit that's given at the bottom of this article:
https://homemade-circuits.com/2012/05/make-this-voltage-stabilizer-circuit.html
you will need 4 of these with a common input….the individual 4 outputs will connect with the positives of the 4 batts.
all the negatives should be made into a common rail and connected with the alternator negative.
however the above set up would not give you an automatic cut, for that you will have to modify each individual circuit with additional parts as done in the following design:
https://homemade-circuits.com/2012/02/how-to-build-automatic-6-volt-12-volt.html
kingy says
Wow lol way to complicated for me the thing is if you look at how 4x12v batteries are wired up to get 48v if you joined something up to all the positive wires then used the earth surely at some point on the batteries you would be running positive strait to negative somewhere along the battery cables. Ive done a drawing of it and dont think it would work, the only other thing I could do is add another alternator to the engine wich is possible and have it rewound to give out 48v and isolate the earth and just go strait to the batteries, someone said a car alternator is actualy 3 phase and generates 110v its the regulator and rectifier that trims it down so isnt there a way to change the regulator myself to give out 48v and isolate the earth then some how work out what amps that would give me
Swagatam says
My suggestions are lengthy but not complicated,moreover the idea is technically correct and extremely safe…it will take care of your batteries for years to come.
Your idea could be quick but hazardous and non-friendly to the batteries.
Modding an alternator?? do you think it would be an easy job? Even a slightest mistake could mean fire and explosions.
Charging batteries by connecting them in parallel without appropriate isolation is never recommended.
kingy says
Hi mate thought id ask to see if you could help me atvall as no one else seems to be able to, I need to charge 4x12v 75ah lead acid batteries from a 12v input. This is going to go into my van so will be charging from van alternator, looked at the alternator and it says 120a is there anything you could suggest and is that possible. It would need to cut out when it had fully charged the batteries and could do with being quite a good amp setup to charge that bit quicker than say a 3a system. Thank you in advance
Anonymous says
dear sir,
how to check IRF9540 p-channel mosfet and n-channel mosfet in multimeter
Swagatam says
It's a lengthy and confusing procedure, better to check it practically by attaching a 1k resistor across it's gate and positive, and confirming a lamp activation across its drain and ground by touching its gate to ground.
Subramaniam Vijayakumar says
dear sir,
please modify the 3rd circuit in led resister value and ic pin 6 to mosfet gate resister value and 22k preset value
Swagatam says
Dear Subramanyam,
led resistor value is OK.
pin6 voltage will be equal to the zener voltage at pin7 of the IC…use a 15v zener here.
chamcl says
Hi Swagatam, may I know how is the charging current being controlled in this circuit?
Swagatam says
Hi Chamcl,
the above circuit does not have a current control feature, it can be added though.
chamcl says
So I'm actually going to need an Op-Amp and implement something like a voltage follower to have current control? Thanks in advance
wilson slva says
How can I charge 24v battery
Swagatam says
you can use the last circuit as is shown, or alternatively try this one:
https://homemade-circuits.com/2012/02/how-to-build-automatic-6-volt-12-volt.html
Anonymous says
Sir,
Can i use a IRF9Z34 P channel MOSFET for 48v 100AH
Swagatam says
check the current and voltage rating of the mosfet in its datasheet, if it's more than 60V and 20amps, then you can use it.
wilson slva says
Sir … How can I used it to charge 24v battery … And what I change in the circuit
Anonymous says
heello swagatam sir,
will this work for 12v 150ah battery charging,
if yes what should be the changes
Swagatam says
you can try the last circuit, replace the 22k resistors at pin3/2 of the IC with 1k resistors, and remove the 22k at pin7 with a direct link, also remove the zener at pin7.
ধ্রুবজ্যোতি দে says
Hi Swagatam, Ami battery byke charger toiri korchi, 12volt 20amp battery ache 4te. total voltage 48. ami ei page er 1st diagram ta toiri korbo thik korechi, etay to Hi voltage cut off ache, kintu 12 volt er battery te full charge hole 14.2 volt hoy, se karon e mot voltage hobe 56.8 volt ba pray 57 volt, ei circuit daigram e sei voltage e cut off kor jabe to ? ar ei prothom diagram tate ami ki mosfet use korbo seta ektu janao. tomar ei blog amader moto electronics premi manusher onek upokar e lagche. onek dhanyobad tomay, ei blog din e dine aro onek somriddhyo hok ei asha rakhi. – Dhrubajyoti
Swagatam says
Hi Drubajyoti, thanks very much!
yes you can use the first diagram in the above article, and use a supply of 56V approximately as the input.
Without connecting the battery adjust the preset such that the LED just shuts off at 56V input.
After this switch OFF power, connect the discharged battery and then switch ON power again for the required charging until the supply cuts off automatically.
You can use a transistor TIP122 in place of the mosfet, use a large heatsink for it.
The input current should be 1/10th of the battery AH, that is around 20/10 = 2amps
ধ্রুবজ্যোতি দে says
Swagatam, tomake onek dhanyodab eto sojoj kore bujhie debar jonyo..Amar kache MJE 13007 transistor ache, ami ki TIP122 er bodole seta lagate pari ?
Swagatam says
sorry Dhruba, MJE13007 will not work properly, you will have to use a TIP122 only.
E RICK says
we need digital smps based chargers for 100ah @ 48v. we need them e-rickshaws. Kindly suggest the output power of the charger – should it be 10amp or 15amp. can you please help in with the circuit design for the same.
Swagatam says
Designing would be difficult because the circuit would involve complex inductors, it would be better to procure a readymade sample and copy it.
the current will depend on the vehicle HP requirement, so it would be better to test it practically.
Anonymous says
And sir please tell me whether i need to include a fuse in the circuit of 48v, 40amp circuit.
Swagatam says
It will depend on the battery AH, so please mention the battery AH
Anonymous says
Sir i'm building a charge controller for 48v, 14A SPV output which will charge a 48v, 200ah battery bank for my village house.
Today i built the circuit. it works fine. But a prblm i faced that i can not set the voltage cut-out by adjusting the preset. Battery voltage was 50.5 and SPV system voltage was around 51.5-52.6V.
And also i could not understand how to set the low-cut out. I was trying to discharge the battery bank to get 45V around. but till now i'm getting 48.3V(lowest).
Please suggest a way sir.
Thank you sir for providing this circuit.
Swagatam says
When the voltage reaches 50 and above, adjust the given preset such that the output just cuts off and the green LED shuts off.
the circuit does not include a low voltage detection system, I'll update the diagram soon to make it more suitable for the needs.
Anonymous says
thank you sir for your reply
Anonymous says
Thank you very much sir for updating the circuit. Thank you very very much 🙂
Swagatam says
you are welcome.
Anonymous says
Sir the updated circuit is not working. 1k Resistor across the RED LED burnt out. I tried with a 4.7k resistor. Same problem. I used P55NF p-channel mosfet. Please suggest a way to overcome this problem sir.
Swagatam says
don't bother about the LEDs remove them for the time being or use 10K resistors.
Just check the output voltage while adjusting the preset. Do it in the following manner:
Initially keep the 22K feedback preset link disconnected.
feed approximately 52V DC to the circuit, with some trial and error adjust the 10K preset to make the output (where the battery would be connected) switch OFF. Flip the preset to and fro to confirm the adjustment….now glue the preset tight.
Now reconnect the 22k preset link back into position.
next apply a 46V DC input and adjust the 22k preset to restore back power at the output, if it gives problems increase the preset value to 100K.
the circuit is all set now
Swagatam says
are you sure P55NF mosfet is P-channel?? pls confirm it accurately first
Swagatam says
I think the present configuration will not detect the lower threshold automatically, it will only work for high threshold…i'll modify it soon.
Anonymous says
The earlier circuit worked ok. I just tested now the 1st ckt and do as you mentioned in the comment. Everything went ok sir. I think for such huge system a lower cut off may not be necessary. because today i was discharging the battery-bank and the system voltage decreased to 47.9 VDC(the lowest).
So, sir now i'm worried about the protection of the charger, Should i need to add 6 Amp blocking-diodes to the charger as my system is generating near about 21-24 Amps DC in a full sun-light? Or should i go for a Fuse instead? And sir if you suggest a proper method for protection of the charger, it'll be a great help for me.
Swagatam says
OK, no problem!
adding diodes will not control amps, it will only protect from accidental reverse polarity.
Current protection will require an additional transistor stage with the circuit, or simply you may put a high watt resistor in series with the solar panel output.
By the way, the last circuit is the best one according to me and it also includes a low voltage switch ON feature.
Anonymous says
In the last circuit i'm little bit confused. Sir did you alter the i/p, o/p by mistake? and i'm going to use irf 4905 p-channel mosfet.today i bought them. I'll try the last circuit tomorrow and gave you the result.
Swagatam says
Yes it's done deliberately for making the configuration easier and suitable for both the operations.
Anonymous says
Sir today i tested the both circuits-1st and the 3rd one. 1st one operating superbly. the 3rd circuit-that is the modified one-worked.but LEDs not working.and also the the 10k preset not functioning in the circuit. I think the the op-amp pins-2 and 3-should be like the 1st circuit.will it help?
And sir i have a doubt.that is if i dont use any low threshold cut-off for charging the battery, will it affect the battery life?
And one more thing :p
sir please provide a 850va pure sine inverter circuit. I'm trying to build the electronics part myself. I found it's very interesting to make things to use for myself.It's helping me to know many many things which i've never imagined.
Swagatam says
I have updated the last diagram with more information regarding its setting up procedure, you may refer to it and proceed as per the given instructions.
If the battery is frequently used below its lower thershold, it will get damaged very soon.
For the inverter you can try the following design:
https://homemade-circuits.com/2012/05/make-this-1kva-1000-watts-pure-sine.html
Anonymous says
sorry sir for late reply.sir the last circuit worked superbly.thanks sir for such great help.
now sir i'm facing another problem while setting up my solar power system.that is i need to cut the panel output once my battery bank(48v,200Ah)is fully charged. i need it because i observed my system for the last week very carefully and noticed that by over charging the batteries after the full charge is done, causing the battery-health badly. to get rid of it, i applied a full-charge protection circuit within it, which became a complete failure. then i again built the circuit you provided here.
Sir please help me.
Swagatam says
The last circuit also includes an over charge cut off facility, please read the set-up section once again carefully
Anonymous says
i want to build a 48v, 30amp charge controller for my solar power system.which mosfet should i use?
Sir you helped me before. Please help this time.
Trinh Trung says
I charger ?
to boost charger should i do?
Anonymous says
if i need a 48V,60A charger, what MOSFET should I use 16*200AH batteries
Swagatam says
you can try IRF3205
prashanth N says
i need to charge a 48v 20Ah battery with a variable Dc voltage (20v-60V DC keeping on changing), how to regulate the following voltage to charge the battery with a volt of 53v,is there regulator IC or any circuit….pls help its very urgent for my project
Swagatam says
if you are looking for a variable option you may try the following circuit:
https://homemade-circuits.com/2012/01/how-to-make-versatile-variable-voltage.html
it will work upto 60V
Yuvaraj V says
sir i need 59v with 3A rating charger (4*12= 48v battery pack of electric bike)and single 12v battery use to charge 59V with 3A converter charger circuit.
Swagatam says
Provide me with full details, what's the AH of the 12V source and what's the AH of the 59V battery pack.
Subramaniam Vijayakumar says
48v,20ah(4 nos,12v*20ah battery series total volt 48v full charge 52v) escooter charger 48v 3a charger) and gate volt how much?
Subramaniam Vijayakumar says
48v,20ah(4 nos,12v*20ah battery series total volt 48v full charge 52v) escooter charger 48v 3a charger) and gate volt how much?
Gbenga Oyeb says
You said the mosfet can be selected as per the AH rating of the battery, what channel is the mosfet required for the subject. Thanks
Swagatam says
you can see it in the diagram, it's an N-channel mosfet
Anonymous says
whole 741 section can be replaced with a simple Tl431 based setup
Anonymous says
Hi, can I charge a 48V battery with 12V input using similar approach?
Swagatam says
Hi, the above circuit is a voltage cut of circuit, your application will need a voltage booster circuit, it is possible but the source voltage will need to be at least 5 times higher than the battery AH rating.
Anonymous says
How did you come to get the values of the components
Anonymous says
Could you please provide component/part list as you have done for your earlier circuit diagram post. Thanks in advance for your help. I am planning for a charger which would go upto 55v, its for my electric bike.
Swagatam says
Here's the parts list:
22K, 1/4W – 3
4K7, 1/4w – 1
10K, 1/4w – 1
10K preset – 1
4.7V zener,1/2w – 2
15W zener,1w – 1
IC – 741
LED – green or red,5mm
Mosfet – 10amp, 100W….example 2SK1058
Anonymous says
hallo, can i use the same circuit for a 36V charger (output 42V)? which components needs to be changed? thank you
Swagatam says
Yes you may use the same circuit…nothing's required to be changed.
Mohammed Maiyaki says
What of for 24v do I have to change it?
Swagatam says
remove all the 22k resistors, remove the 15V zener and replace the 741 IC with LM321 IC
Unknown says
How does the voltage at pin#2 rise above the 4.7 mark as soon as the battery voltage rises above 50V or the fill charge threshold level of the battery?
Swagatam says
The preset is adjusted such that the voltage at pin#2 becomes just above 4.7V when the battery voltage reaches 50V…..the input voltage is wrongly shown as 48V, it should be 50V.