Circuit Description
Looking at the shown 100 to 200 amp high current battery charger circuit, we can understand the circuit idea through the following simple points:There are basically three stages in the shown configuration viz: the power supply stage consisting of a transformer and a bridge rectifier network.
A filter capacitor after the bridge network has been ignored for the sake of simplicity, however for better DC output to the battery one can add a 1000uF/25V capacitor across the bridge positive and negative.
The output from the power supply is directly applied to the battery which requires to be charged.
The next stage consists of an opamp 741 IC voltage comparator, which is configured to sense the battery voltage while it is being charged and switch its output at pin #6 with the relevant response.
Pin #3of the IC is rigged with the battery or the supply positive of the circuit via a 10K preset.
The preset is adjusted such that the IC reverts its output at pin #6 when the battery becomes fully charged and reaches about 14 volts which happens to be the transformer voltage at normal conditions.
Pin #2 of the IC is clamped with a fixed reference via a voltage divider network consisting of a 10K resistor and a 6 volt zener diode.
The output from the IC is fed to a relay driver stage where the transistor BC557 forms the main controlling component.
Initially, power to the circuit is initiated by pressing the "start" switch. On doing this, the switch bypasses the contacts of the relay and powers the circuit momentarily.
The IC senses the battery voltage and since it will be low during that stage, the output of the IC responds with a logic low output.
This switches ON the transistor and the relay, the relay instantly latches the power via its relevant contacts such that now even if the "start" switch is released, the circuit remains switched ON and begins charging the connected battery.
Now as the battery charge reaches about 14 volts, the IC senses this and instantly reverts its output to a high logic level.
The transistor BC557 responds to this high pulse and switches OFF the relay which in turn switches of the power to the circuit, breaking the latch.
The circuit gets completely switched OFF until the start button is pressed once again and the connected battery has a charge that's under the set 14 volt mark.
How to set up the proposed high current battery charger circuit.
It's very easy.
Do not connect any battery to the circuit.
Switch ON power by pressing the start button and keep it depressed manually, simultaneously adjust the preset such that the relay just trips or switches OFF at the given rated transformer voltage which should be around 14 volts.
The setting is complete, now connect a semi discharged battery to the shown points in the circuit and press the "start" switch.
Due to the discharged battery, now the voltage to the circuit will drop under 14 volts and the circuit will instantly latch, initiating the procedure as explained in the above section.
High Current 100 to 200 Amp Automatic Lead Acid Battery Circuit Diagram is shown below
High Current Automatic Charger using two opamps:
An alternative way of achieving an automatic high current battery charging for a lead acid battery can be observed in the following diagram, using a couple of opamps:
At low battery level, the lower opamp output remains high disabling the upper transistor relay driver, which allows the battery to initiate its charging process through the N/C contact of the relay.
As the charging voltage rises, the potential at (-) input pin of the lower opamp exceeds its (+) input level, which switches OFF the lower BC547, however the upper opamp output being still at logic zero the relay sustains its N/C relay position and carries on charging the battery.
At the full charge level when the potential at (+) input pin of the upper opamps tends to exceed its (-) input pin, the output of the upper opamp goes high, switching ON the relay and toggling its contacts to N/O.
This action switches OFF the charging current for the battery.
In this condition, a positive feed back from the 1K/10K resistive divider is applied to the (+) input pin of the upper opamp, which latches the opamp hard, and this in turn latches the relay in the N/O position.
Now, if any intended load is operated through this battery, and as it goes through a discharging process....after a period of time the battery voltage tends to drop to a point wherein the potential at (-) input of the lower opamp gets lower than its (+) input pin....this instantly causes its output to go high, switching ON the lower BC547.
The BC547 grounds and breaks the feedback latching potential and also the base triggering voltage of the relay driver transistor.
The action switches OFF the upper relay driver transistor allowing the relay contacts to revert to its N/C position, yet again initiating an automatic charging of the attached battery.
Hello Sir,
I am a fan of your work. I am having a little problem. I need a circuit that will automatically cutoff supply from a charger to 3pieces of 200ah battery charging in parallel. I was thinking of using a comparator but I have not found anything useful. The maximum charge voltage for the batteries must not be above 14volts and I definitely would love one that works with MOSFETs or any other transistor you may prescribe. Thanks a lot sir
Thanks Kelly, appreciate your feelings!
A conparator circuit is the most useful and the ultimate thing that should be used for any voltage cut off related circuit…so you must employ only an opamp based circuit for your application too!
you can try try the first circuit from the following article:
https://www.homemade-circuits.com/2014/04/48v-solar-battery-charger-circuit-with.html
if your battery is 12V you can remove the 22K resistors and the the pin#7 components, pin#7 can be directly connected with the positive line.
I am sorry I have provided the wrong link, the correct one can be seen here
https://www.homemade-circuits.com/2012/08/make-this-48v-automatic-battery-charger.html
please sir i have great challenge i need design a battery in the the battery capacity is 3.7V and overall battery capacity is 20A and a need a rechargeble circuit for that
That’s not difficult,
you can use the second design from this article:
http://www.homemade-circuits.com/2013/12/usb-automatic-li-ion-battery-charger.html
replace the 2N2907 with an IRF9540, and calculate the 3 ohm accordingly for limiting at around 15 amp.
my battery capacity is 20 amps if i connect to
that battery section that op-amp may damage i need a circuit with an IC specifically used for charging
IC will not get damaged due to current, it will get damaged if the voltage is increased above 18V.
no special IC is required, it just needs to have a CC, CV and auto cut off.
But sorry a mosfet cannot be used here because the voltage is too low to trigger a mosfet, you can use an IGBT or use a 2N2907/TIP36 in Darlington mode.
Sir please I'm having serious challenge after making those changes and connect my power supply at the point were we have the battery connected still the led did not come up when varying, and when i measure, the voltage is not in line with the zener diode at pin#3 i have 13.16v, pin#7 i have 16.2v while pin#2 is 12.6v but when i apply the voltage sample in the opposite side i have at pin#3 4.7v, pin#7 15.18v then when i vary the 10k preset at pin#2 such that i have a voltage higher than that at pin#3 there will be no output at pin#6 but when i vary it such that voltage at pin#3 is greater there will be output at pin#6 which i have to 13.2v
But in all these varying i noticed that the led is on irrespective of fact that the voltage at pin#2 is changing its remain on
Then when i measure the voltage at the point were the battery will be it's 19.23v
Please sir what could possibly be the error and the voltage at the point were the battery will be connected i thought it should be my supply voltage and not less
If this is going to give me little problem please can you recommend another working 24v automatic battery charger please ur advice is seriously needed
Thanks and best regards
Faith, in the previous link of 48V charger which you are trying, you must feed the voltage from the points where it is mentioned "48V"….you cannot apply from the other side for this design because the mosfet would be blocking the voltage….right??
therefore if you are applying the voltage from the left hand side then it is correct and your adjustment results also look perfectly correct.
when pin#2 voltage goes above pin#3 voltage then pin#6 must become zero (cut-off)…that's correct.
Now as for the LED being illuminated all the time, this could be due to the leakage offset voltage from pin#6 of the IC741. Did you connect the shown zener diode at pin#6 of the IC?? make sure you connect that to solve the LED switching problem.
And what did you use for the power transistor, is it a mosfet or a BJT, remember if it is a BJT then you will require a resistor at its base, and the LED shifted towards the zener side, and not at the base of the BJT.
this circuit is the easiest one, and you are almost near….if you are having difficulty with such an easy circuit then just imagine what you might have to face with the other relatively complex ones…actually all opamp designs are extremely straightforward it's just about understanding them patiently.
Please sir the first circuit in this article can i use it for 24v charger?
http://www.homemade-circuits.com/2012/08/make-this-48v-automatic-battery-charger.html
yes you can use the same circuit for 24V also
I really appreciate your help and fast response please i build and tested the first circuit thishttp://www.homemade-circuits.com/2012/08/make-this-48v-automatic-battery-charger.html during setting when vary the preset the led never turn up, could it the 22k or any component i will remove from the circuit to make it work properly
the pin#2 resistor must vary and become higher or lower than pin#3 reference voltage in order to change the output state, while adjusting the preset.
yes, you can try replacing the 22K with 1K, and remove the 4k7 attached with the pin#2/ground since your supply is not 48V rather 24V only
And what could be current rating of the relay that i Wil use at that transformer current rating
I won't recommend the above circuit for a 68amp charging because the relay will need to be rated at 100A…which may be difficult to procure.
better to use the first circuit from the following article….but make sure to remove all the 22K resistors, and zener diode from pin#7 of the IC because we are using a 14V supply for your case
http://www.homemade-circuits.com/2012/08/make-this-48v-automatic-battery-charger.html
Wen i put my digital meter across the transformer and at the same time clap it with my clap meter and power it burn of my digital meter but the clap meter read 68A. My question is can this transformer be use to charge a three 12v @200A connected in parallel?
68A is too high for any standard digital meter but will be OK for a 600AH battery (200AH x 3nos)
Sir please sorry to disturb please can 650va center tap transformer charge a 12v 200A battery?
what is the current rating of the trafo…if it's 10 times less than the AH value of the batt, then it would be fine….
Please sir how do test the current of my power supply because when i use a clap meter to test the current at the positive line its reading 8. 5A could that be the current of my power supply
Faith, you can connect you DMM prods directly with the trafo wires for a few seconds and check the reading which will inform you regarding the current rating of the trafo.
make sure the DMM is set at AC 10 amp or 20 amp range.
Please sir how do test the current of my power supply because when i use a clap meter to test the current at the positive line its reading 8. 5A could that be the current of my power supply
Again i noticed that if connect it to battery for charging the battery voltage rises to the transformer voltage as if its fully charged so please i want to ask it the charging voltage or the its fully charged once connected
your power supply current(amp) rating must be 10 times lower than the battery AH rating….did you follow this rule?…if not then please make sure you do it.
Hi
i have built this circuit but when i try to set it the relay dose not flikers and it only works if the switch is connected pls what could be problem
I have explained the setting up procedure using a few simple steps, just follow those and it will be fixed.
Hi dear Swagatam thanks a lot with this good battery charger circuit. This circuit is for 10 to 20 ok. There five diodes 4 diodes are rectifier and 5 diode is used between bridge positive and battery positive and all diodes have the same value. Now if I charge a 50 ah or 70 ah batteries. should I change all diodes amp or only the bridge rectifier. Thank you very much with best regards. Rohullah.
Dear Nazari, you will have to change all the diodes except the relay diode.
please how can i determine the amp of a transformer?
connect AC ammeter directly across the secondary wires and measure
Dear sir, again my transformer with three terminal produce 14V between the last 2terminal and 7V between any of the last terminal and the center terminal. Is this the type of transformers you recommend?
yes it will do, you can use the 14V for your 12V battery, and make sure the current of the transformer is 8 to 10 times less than the AH value of the battery
Dear sir,
Thanks for this circuit. I couldn't get 6V zener but 6.8V and 3V zener but 2.8V. will still give me a good result. my hope is the 10K pot. please put me through
Dear Elvis, yes those zeners will also do, and 10k preset will also work….do not use pot.
hello swagatam,
Is this a 3-state battery charger? if no, do you have any circuit that is 3-state and charges 300AH battery. Tnx
Hi Jade,
No, the above is a single step charger, for a 3 step charger you can refer to the following article;:
http://www.homemade-circuits.com/2012/10/make-this-3-step-automatic-battery.html
Hi…I am confused that how are u producing dc output just after the bridge because u said in a comment that u can remove 100u capacitor.although if we continue with this capacitor I think it will discharge very quickly and produce huge ripples at output
Hi, 100% pure DC is not essential for charging a battery, however in the other comment my recommendation about removing the filter capacitor in order to eliminate the relay chattering might not be correct.
the correct remedy to prevent relay chattering at the cut-off threshold is to add 100K hysteresis resistor across pin#6 and pin#3. This will latch the opamp at the cut off levels and enable a quick and complete switch OFF of the relay and the entire system.
Filter capacitor need not be removed.
Hello Swagatam,
What are the modifications if I'm going to charge 300AH lead acid battery?
Regards,
Jade
hello jade, only the transformer, the relay and the diode rating will need to be upgraded as per the battery charging current and voltage specs.
the charging current rate of a 300AH batt can be around 30 to 40 amps
hello sir.. still, the relay did not tripped after the battery is fully charged.. i also put and LED in series with the transistor base. there is no changes in the led too after the battery is fully charged. thank you for your response sir…
Erwin, please tell me how did you set the pin3 preset?
did you do it exactly as explained at the end of the article?
when you connect the discharged battery pin3 voltage is supposed to be lower than the pin2 voltage and when battery is fully charged pin3 should become higher than pin2….please confirm whether this is happening or not
sir.. is there any other way to test the circuit (if it is working) without using a battery?
erwin, you can use a 5amp 12V power supply for testing it
sir after i finished making the circuit on the breadboard and tested it… the output voltage of my charger becomes 16~17 vdc even though my battery was discharged…when i pressed the pushbutton, the relay latched but when the battery is fully charged it did not tripped or turn off the charger… i followed your circuit in every detail…by the way sir thank you for your reply on my first question..
erwin, connect an LED in series with the base of the transistor…anode to base and cathode 10K…this will give the exact idea how the opamp is behaving.
I am assuming you have done preset adjustment correctly as per the given instructions
sir…will the circuit still function even if my charger's output voltage is 16~17 volts dc? thank you for your quick reply sir..
It will work, but the current should be significantly less than the battery AH, preferably 1/10th of it.
thank you sir…
Pls sir, I need an auto-cut off 96volts/600amps car battery charger circuit diagram, tnx alot
you can try this
http://www.homemade-circuits.com/2016/01/high-voltage-360v-battery-charger.html
Can I connect a fixed resistor without using variable resistor
yes you can, after correctly calculating it..
Pls reply
What if I have to charge 7.5 v battery from wall?
use a 10V DC input
Hi Swagatam,
I need to change 50-64 amp car battery. Can I use this circuit? How much amp transformer I would be required. And also is there any other changes with capacitors and diode are need to be done here?
Hi Nabeel, yes definitely you can use this circuit for charging a 50AH 0r 60AH battery, the transformer current rating should not be more than 8 amps.
the bridge rectifier diodes must be rated at 10amps each…or a single 10amp bridge module will also work at the indicated position
Sir, can I use this circuit for charging lead acid battery 24v?
yes you can do it….
Oke. Thankyou sir, by the way I need to change that ic or not? Example that relay, comparator, or something else?
yes, just forgot to tell you, you can use a LM321 IC as it's rated to work with upto 32V…the IC 741 IC will burn at over 22V so won't work with 28V inputs
oke, thankyou so much sir..
Plz swagatam videos URL send me
sorry sharanab, there's no video for this circuit.
Hi, this system would serve me to charge a solar battery and 300Ah 24v?
thank you very much
you are welcome popipo
Plz swagatam 100 AH 12 V battery charg. And inverter system circuit send me
My mail : sharanbs.basava39@gmail.com
you can use the above circuit for the charging the battery or the second circuit from the following link:
http://www.homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html
for the inverter I'll need more info regarding its specs
I have a modified pc smps that gives 14v and 20A
so I want a circuit that charges a 12v 100ah battery automatically ie it should turn off the smps when battery is full and turn on the smps when the battery is low
you can try the second circuit from the following article:
http://www.homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html
if i just avoid the rectifier portion and use a varying dc source, will the circuit work .please let me know
i did not understad what you are trying to implement…pls make it clearer
thank you for the replayed sir,no i did not make any modifications but one thing is that i use 1n5399 for the 4 diode showing there and also i used In540(16A4) the one that connect to the battery positive is it 6A or 6.4A? sir i build one of your circuit How to Make a Simplest 200 VA Uninterrupted Power Supply UPS Circuit i build only the charger it work very well but i don't think it can charge 24vDC battery two 12v battery? if it can chard what can i do sir help me with the circuit thank you jah guide you and hop to hear from you soon..
Daniel, Referring to the charger circuit shown in this article:
https://www.homemade-circuits.com/2012/02/how-to-make-simplest-200-va.html
You can use it for charging 24V batt also…you just have to upgrade the circuit with a 0-24V transformer and 24V relays. R1 should be replaced with 10k resistor.
Remember the transformer current should 1/10th of battery AH.
Mr,Swagatam i like your good work you been doing so far but one thing i don't understand is you answer to some people questions but you don't reply to me why sir or they are your family? ok please and again as soon as you received this message please i am burgin you to reply me allow me to be one of the your friend cos i am a electronic Hobie i do like your project.my firs quotation is this 12v battery charger circuit i build it but when i power the the circuit relay switch correctly but the problem is out put is 11v and if i calibrate 10k preset to left side it switch on the relay and it give 11v out put if i calibrate to right side it switch off the relay and give me 13v out put why sir any help? i will be glad for your assistance, looking foreword to hear from you thank you.
Mr Anonymous, I reply to each and every comment and rarely miss any, may one in a million, or as long as it does not have an outbound link.
Anyway, did you make the circuit as it is shown in the diagram, with the start button or did you do any other modifications?
The DC input to the circuit should be 14V DC and the connections to the relay should also be exactly done, and the input current should be rated at 1/10th of the battery
Also did you follow all the instructions mentioned in the article??
It's just about setting up the opamp correctly that's all….the functioning is very starightforward
Hi Swagatam,
Thanks for your prompt and positive response.
I just read, – Hire me for Designing Circuits – Circuit Ideas, Inventions for Sale – in your blog.
I have a special requirement for my set up, the details I will send to your email ids you have mentioned, would you be kind enough to reply whether there is any scope for making them and your charges as well?
Regards
NG
Thanks Naga, I have replied to your email, please check it.
Hi Swagatam,
I wish I had seen your blog earlier. In my set up, I need my charger, connected to the 220 Volts AC mains to start automatically to charge the battery when the voltage drops to 11 and stop the charger when the battery is charged to 14 volts.
Your advise and guidance would be of immense value.
Regards
NG
Thanks NG,
you can try the last circuit from the following link:
https://www.homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html
You will see two relays in the diagram, the lower relay is not required so you can just eliminate it from the design.
Hi Swagatam am just so proud of you i also made this circuit at the bottom.i did not have BC 557 I used 2N2907, 6.8 Zener and for preset i used a 50k. when i connect it to my supply, the relay trips. the problem is in setting the cut off voltage.i tried adjusting but still it was on pliz help me thanx
Thanks very much, you can do the following things:
Connect an LED in series with the transistor base 10k (anode to base, cathode to 10k) for indication.
Keep the transformer disconnected, and apply an external power supply of 14.4v across IC supply pins.
Now flick the preset to and fro until you find a point where the LED toggles ON/OFF, adjust this point to just switch ON the LED.
Your circuit is all set now.
Now carry on with its normal operations through the trafo.
While adjusting the preset do not connect the battery.
…during normal charging operation switch ON the circuit only after connecting the battery to the shown points.
Sir, I need this circuit to be automatic turn on, not manually with the push button. Can you help me with that subcircuit please? Thanks in advance.
Hi sir can you add an automatic starting instead the push Butrón, please? Thanks in advance.
remove push-button connections, connect the trafo directly to mains, and connect the battery positive to bridge positive via relay N/O and pole contacts.
Sir,
Thank you very much for your quick reply. 10 amps would be enough for me , would you be able guide us for using ICs like 338, 196 etc on this circuit ? it would be very useful for you.
Thank you once again sir
With best regards
Maung Pru
Hi Maung,
You can try the last circuit given in this article:
https://www.homemade-circuits.com/2012/07/making-simple-smart-automatic-battery.html
Replace the IC LM338 with LM196 for 10 amp specs.
I haven't built this circuit, but may do so. Can I make a couple of comments.
It can be confusing for some of you readers to mix "ampere hours" with amps, as in you title and elsewhere.
With a very slow change of battery voltage the 741 circuit makes a poor comparator. Especially as constructors will have a variety of relays. Relays are notoriously slow at releasing and the 741 will behave unpredictably when the inputs are close to equal. Best practice surely would be to add a touch of hysteresis by adding a resistance between the output (pin 6) and the + input (pin 3). this would cause the 741 to snap quickly and give the relay a chance to close properly. I am no circuit designer might try 470K to start with.
Also please explain the purpose of the 100uf capacitor on the output. Wouldn't that add to the problem.
Finally, I think the circuit would work much more reliably if the relay (perhaps a stand automotive relay) were connected between the battery + and the comparator circuit, rather than on the mains input side.
Thanks, I appreciate your attempt, here are more precise answers:
AH signifies the charge or the discharge rate of the battery. ideally it indicates the full charge or full discharge rate of the battery in an hours period.
Opamps are excellent comparators and they work very well in battery charge cut off applications.
hysteresis is surely needed so that the relay doesn't keep switching ON/OFF at the thresholds due to the extreme accuracy and sensitivity of the opamp.
Hysteresis delays the relay actions and makes the response slower so that it doesn't chatter…… without hysteresis the relay would snap rapidly producing rapid switching at the thresholds.
A hysteresis can be added in the above diagram to avoid the same.
In the above diagram the position of the relay switches OFF power completely, right from the transformer, so it becomes much safer and reiable.
…the 100uF is not required, because its inclusion actually makes no difference, so it can be removed
Sir,
Thank you once again.
would it be possible to add a charging current controller?
would you please kindly explain us what type of component need to be use ?
Thank you and with best regards
Maung Pru
Hi Maung,
can you specify your current requirement, if it's upto 10 amps then it can be simply done using ICs like 338, 196 etc, otherwise it would become sightly complicated.
hi Swagatam,
a very promising circuits youve always share, actually Im always visit your blog coz im also electronics hobbyist from the philippines… i have read many your posted electronics designs especially on battery charging circuits 🙂 its very simple and yet reliable and efficient circuits, building those circuits using your designs works great and thank you so much swagatam! but until, i was thinking an solidstate automatic dual battery charging isolator for deep cycle agm 100ah batteries, i am using some of your design charging circuits and delay and relay techniques, but unfortunately, always got me an error… what should I do sir?. can you guide me with my issues? thanks so much.
here is the step of how the circuit may do…
1. before starting, the two agm batteries 1&2 will combine in parallel connections to use for starting the engine to provide more smooth and more power to start.
2.then, once the engine is started, the battery 1 will automatically disconnect and relay for automatic fast charging and to float mode ( dpdt relays to be used?)
3.while the battery 2 is connected,a voltage low level cut-off monitoring is standby for 11.5v,
4.so when the low volt reach as 11.5v the circuit will automatically trigger the relay of the fully charged battery 1 in parallel connection.
5. after the battery 1 connected in parallel, a delay relay cut-off circuits of battery 2 will engage for automatic fast charging and to float mode.
6.a continuation cycle of relays, monitor, charging. thats it.
I hope you understand of what i mean.
hoping to hear from your sir. i hope you can help me with this circuits to make.
Thank you so much and more power to you sir!
Thank you Daz,
From the explanation what I understood is, you want to charge two batteries together having separate low and high voltage detection circuits…so when any of the batteries get fully charged it will get removed from the charging system and in case any one gets discharged below the set threshold it would get connected again…right?
….and it will also be used for starting the engine together and once the engine initiates they will return to the detection mode.
yes you're right sir! thanks for the response! can you design that for me sir? thank you so much and more power!
it would be possible to you design that circuit? thank you so much swagatam
Hi Daz,
Thanks!
I have noted it, will try to update the article soon.
thank you so much my friend… youre so very kind and very quick when it comes in response.. once youre circuit done and it worked for me, i will then donate something to you. i am very interested with this design to build. thank you so much and more power swagatam! please keep update me soonest possible. thanks again.
Thank you Daz,
It might take some days to complete it, I'll inform you as soon as it's done.
thanks my friend.. looking forward in your design.
Hi Daz, please check it out here:
https://www.homemade-circuits.com/2013/08/automatic-dual-battery-charger-with.html
Sir,
what do i need to change in this circuit if i use for charging of a 150 Ah lead acid deep cycle battery? would you pls guide me.
Thank you
Maung
Hi Maung,
just use a 20amp rated transformer, rest everything will remain as it is.
also be sure to select the diodes rated at 25 amps and the relay contacts also at 25amps
Hello,
I want to make a car lead acid battery charger for a 72Ah and a 100Ah lead acid battery, could it be possible to use this charger circuit with to different settings for the current that loads the battery. And wich kind of diodes should I use to regulate these currents
best regards
yes the above circuit can be used for your need.
72ah and 100 ah would almost require identical current levels for getting charged, so an added current regulator circuit wouldn't be required.
you may incorporate a 12V 10 ampere transformer for charging both the batteries with the above circuit.
be sure to use a 6800uF/50V capacitor across the bridge positive/negative terminals
but doenst a 72Ah need to be loaded with 7,2A and a 100Ah with 10A? And about the potentiometer which resistance and which power should this component need?
thanks
ideally it should be done in that way, you may add a LM196 circuit stage for that, it's not critical though.
The main thing is to switch OFF the charger when battery voltage reaches 15% more than its rated value….charging at slightly increased current rate won't harm the battery if it's switched OFF when fully charged.
potentiometer is actually an ordinary preset, power rating is not critical, any type would work.
Hello,
Thanks for this circuit I want to understand if I eliminate the switch as u said above how the relay shall be connected.
best regards
Please check out the last circuit in the following article, it should be in this way:
https://www.homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html
Hello,
Thanka very much for your response.
Regards
pk
hello Sir,
Are the 10k's all a variable resistor?
I want to use it to charge two 12v 200AH batteries connected in parallel.
what if I want to use it for 24v 200AH or 2V 400AH.
Regards
PK
Hello Sammy,
only the one which is at pin#3 is the preset, others are fixed resistors.
for 24V replace 741 IC with IC 324…..
hello sir,
Thanks for the reply.
would the circuit be suitable to charge 12v 400AH battery.
I want to charge four 6v 200AH batteries in series parallel, thus two of the 6v 200AH IN series making 12v 200AH.
Two of the 12v 200AH in parallel, thus making total of 12v 400AH. I am using it to connect to an inverter, keeping it connected permanently. Thus charging the batteries when battery discharges and using the batteries when power outages occurs.
Would leaving it connected to the inverter damage the inventer?
Your responses are highly welcome.
Regards
pk
Hello PK,
Yes you can charge them, just make sure the relay contacts are rated accordingly.
This circuit will not initiate automatically, you will have to press the switch for initiating the charging process.
If the battery is connected to the inverter via a cut off relay then it's fine.
Hai swagatami want to make automatic battery charger (without switch) with cut off. I have battery 24v with 200AH. Would u like to show me how the circuit diagram? And the components? Thanks
Regards
Septian
this circute use 24 volt battrey .if any chang please help me.
use 24V relay and 24v transformer….
hello sir,
i have build this circuit but my problem is the switch can i connect the circuit directly to the battery without using the switch or how do i do it.
secondly i connect circuit to 10v dc battery the relay is not energies but immediately wen i connect it to anything 12v dc or above it energies the relay
and am told to charge 12V 200AH battery with 13.5V supply so the relay energies even b4 the battery attain full charge so how do i overcome this problem
becouse normally 12V 200AH reaches i think about 14-14.5V b4 its fully charge
You will have to read the whole article for understanding the operations.
Without switch the system will not cut of after the battery is fully charged.
The preset needs to be adjusted for setting the desired cut off voltage level.
hii Swagatam,
good ckt.
actually am looking for a solar charge controller to charge 150 AH 12V battery. solar panel is 12v/225-250W/ and around 15amps current.
so can i use this circuit by replacing the power supply ckt (transformer,brdige ckt and filter capacitor) with the out put of solar panel?
if yes, what are the necessary changes which i have to do? is there any regulator ckt needs to regulate the voltage to the battery from solar panel?. because the out put voltage of the solar panel will vary up to 20V.
one more doubt,what is the value of potentiometer which is connected to 3rd pin of IC 741.
thanking you ,
mahroof
Hi Mahroof,
The circuit will work with all types of solar panels provided the max voltage does not exceed 20V (if the IC is 741) and 30V if the IC is 1/4 LM324).
Yes you may connect the panel supply at the input of the bridge.
It's a 10K preset.
thank you.
the solar panel open ckt voltage(Voc) is more than 20v as per specification.so any voltage regulator ckt i need to use?
if the voltage is below 20V,we don't want to use any voltage regulator for 12v battery? i mean for 12V battery if we charge by 19V, the battery will not damage?
as the voltage comes from solar panel it self 'dc' i need to use bridge ckt again?
thank fully,
mahroof
A voltage regulator will be required for controlling the output voltage to around 14V, so anything above 14V will require a voltage regulator for 12V batteries.
what is kind of diode i"ll use for this and how many ampere.
what is the AH of your battery???
What type of amplifier is it??…i mean is it inverting,non inverting, Differential??
It's a comparater, not an amplifier….
Thank you very much BRO!!!!!!!!!!!!!!!!!!
can i use 14-0-14 transformer??
for 12V battery you may use the 0-14 tap and for 24V you may use the 14-14 tap, but for 24V, the opamp must be replaced with 1/4th LM324 opamp
hey…i connected a discharged battery which had a volrtage of 10Volt….n i used a 14-0-14 transformer….but the relay switches on and off as soon as i connect the battery….
Did you follow the setting up procedure as given in the article?
yup…..i did…..
i understood…….there was a mistake in ma setup…..i didnt read the word simultaneously…..so….how can i make it trip off when battery voltage reaches 13.5..Coz i have used a 14Volts transformer…and it gives a output of 15.7Approx…..
You will have to use an external 13.5 volt source. Do not connect the battery initially. Connect the 13.5V source across pi#7(+) and pin#4(-) of the IC.
Adjust the 10K preset such that the relay just activates at this voltage.
Seal the preset with some glue.
The setting is complete, now you can remove the external supply and power the circuit through the attached transformer.
Press the switch only after connecting a discharged battery having 5 to 10 times AH rating than that of the transformer current.
Thanks……i will do that….
but the relay fluctuates when i do this….
Add a 470uF/25V capacitor across the relay coil….
K….
hey…..How can i make it fully automatic????…..like i wanna replace that switch so that i dont need to press it for charging….n it should detect BAttery Voltage n automatically start……
The circuit will need to be changed significantly for that, I'll try to produce the modified circuit in the form of a new article soon…
K…..thanks…..but can u do anything….like modify this…… is there any chances of changing this????
Connect power directly to transformer, eliminate the switch.
Wire up the N/O contact with the battery to be charged.
Connect a variable resistor of around 470K across pin#6 and the preset center pin. This must be adjusted for setting the low voltage threshold.
That's all…. Now when the circuit is powered with a battery connected, the relay will activate, the battery will start charging charging via N/O of the relay, once it's full, the relay will disconnect and stay in that position until the battery voltage reaches the lower threshold….the cycle will repeat as long as the battery remains connected, charged and used up…
hello, this is great, can i use it to my 50amps lead acid battery? If not so where get i 50amps charger cutter diagram. plz help.
Thanks, yes you may use this circuit for charging 50AH battery, just make sure that the diode connected at the positive of the battery should be rated at 1/10th of the battery AH, means 50/10 = 5amp to 6 amp diode.
I was wondering about a couple things on this schematic. Is the N/O under the start a switch or relay? Also, the 12v Relay, is it a N/C or N/O and how do you make the connections. I am using ExpressPCB to make the schematic and then transfer it to a pcb for printing. I am unsure about those two items in particular. Any help, preferably detailed and maybe pictures, would be greatly appreciated as I'm still a little bit new to all this. Thanks.
The N/O is for the relay contacts. An SPDT Relay will always come with both the contacts in one package, here we have used an spdt relay, however only N/O has been indicated, the other contact is obviously is the N/C.
I would rather advise you to first test the circuit over a general purpose PCB and then go for making the final PCB layout.
The circuit shown at the bottom of this article would be perhaps a better option
I was talking about the one at the bottom of the article. It shows the N/0 but then it shows a relay to the left of that with a ground coming out the left side and a diode looping from the left side(ground side) to the input from the transistor (BC 557). So I'm assuming that is the rest of the pin out hookup for the 12v relay after hooking up the N/O pins to the switch circuit? Sorry to ask so many questions but I'm rather new to this.
OK got it….the box which shows "Relay 12V" is the relay coil, the wires coming from the transistor and the positive goes to the relay coil….where as the symbol at the left of the box are the contacts of the relay with the N/O and the N/C contacts.
Yes the supply needs to go through the relay contact such that the system shuts OFF completely once the battery charges fully and the relay trips.
Actually I was referring to the circuit at the bottom of the following article, I just forgot to paste the link in yesterdays comment:
https://www.homemade-circuits.com/2012/07/making-simple-smart-automatic-battery.html
The circuit for 10 to 20 amps battery charger is not clear and it is too small. Can you please send me an enlarged circuit diagram. It would be most useful.
Thanks,
Babu
Please click the diagram to enlarge it.
Thanks.
Yes, adding a filter would speed up the charging rate a bit.
Does removal of filter capacitor affects the charging time?
Hi! Great site for amateurs like me. It will be great help if the printed circuit board is also added with ur projects. Many thanks.
Asif Usman
Hi,
Thanks, though designing PCB layouts is a bit time consuming, will surely try to provide them if feasible.
Regards.
There are some simple software that can design PCB like Circuit Wizard or PCB Wizard. Easy to use. Just input Sir Swagatam's diagrams and it will design the pcb. Just make little rearrangement afterwards to make the design neat. Practicing it will enhance your knowledge.
Cheers!
Hi!Great to learn for amateurs like me. One thing which u should add to it is the Printed circuit board for your projects. This will be added benefit for people like me.
Asif Usman
asif.met16@gmail.com
the relay turn off and on. turn off when reaching the cut off but turns on again immediately. what should I do?
That shouldn't happen, because the moment the relay trips, it cuts the power supply to entire circuit and also to itself and therefore cannot switch back.
Did you connect a filter capacitor? Remove it if you have used one.
Also, have you done the connection of the start button as shown in the figure, just check them….
the primary coil trips but the battery is still connected to the circuit, a fraction of the voltage of the battery drops the moment the relay trips, the circuit senses the voltage of the battery again not yet at the cut off, powering the relay again…
OK got it,
connect a diode in between the bridge positive and the battery positive.
Disconnect the transistor emitter from its shown position and connect it to the anode of the above new diode.
I think this should rectify the problem.
Keep the recommended capacitor connected across the relay coil.
Pls sir, can u guide me to upgrade this battery charger to be able to charge my 96vols/400amps car battery, tnx!
King, you can try the first circuit from this article:
http://www.homemade-circuits.com/2012/08/make-this-48v-automatic-battery-charger.html
the relay turn off and on. turn off when reaching the cut off but turns on again immediately. what is the solution?
the relay keep turning off and on. turn off when reaching the cut off but turns on again after about 2 secs. what shall I do?
Connect a discharged battery and then check, and the transformer current must be rated at around 1/10th of the battery AH.
Without a discharged battery the circuit will keep fluctuating.
The relay flickers when reaching the cut off limit, what shall I do?
Hi Ronald,
Connect a 100uF…470uF capacitor across the relay coil.
Ok thanks, I'll try…
pls how can i add led to dis circuit
You can connect it across the 100uF capacitor, remember to connect a 1K resistor in series with the LED
wow! this is the simpliest autocharger circuit.