Battery Desulfator Circuit Explained

Sulphation in lead acid batteries is quite common and a big problem because the process completely hampers the efficiency of the battery. Charging a lead acid battery through PWM method is said to initiate desulfation, helping recover battery efficiency to some levels.

What is Sulphation in Lead Acid Batteries

Sulphation is a process where the sulfuric acid present inside lead acid batteries react with the plates overtime to form layers of white powder like substance over the plates.

This layer deposit seriously deteriorates the chemical actions inside the battery while charging or discharging making the battery inefficient with its power delivering capabilities.

Normally this happens when the battery is not being used for long periods and the charging, discharging processes are not done very frequently.

Unfortunately there's no effective way of tackling this problem, however it has been researched that the jammed sulphur deposits over an effected battery may be broken down to some extent by subjecting the battery to high current bursts while charging it.

These high current charging pulses should be well optimized through some control circuit and should be diagnosed carefully while implementing the process.

Implementing the method through PWM controlled circuit is probably the best way of doing it.

Here's an excerpt from wikipedia, which says,

 " Desulfation is achieved by high current pulses produced between the terminals of the battery. This technique, also called pulse conditioning, breaks down the sulfate crystals that are formed on the battery plates.[16] Short high current pulses tend to work best. Electronic circuits are used to regulate the pulses of different widths and frequency of high current pulses. These can also be used to automate the process since it takes a long period of time to desulfate a battery fully."

The circuit of a PWM battery charger discussed here can be considered as the best design for carrying out the above desulfation process.

The IC 555 is configured and used in its standard PWM control mode.

The output from the IC is appropriately amplified through a couple transistors so that it is able to deliver the said high current pulses to the battery which needs to be desulfated.

The PWM control may be set at low "mark" ratio for implementing a desulfation process.

Conversely if the circuit is intended to be used for charging normal batteries, the PWM control may be adjusted for generating pulses with equal mark/space ratios or as per the desired specs.

The controlling of the PWM will solely depend on an individuals personal preference, so should be done correctly as per the battery manufacturers instructions.

Failing to follow the correct procedures may lead to fatal accidents with the battery, due to a possible explosion of the battery.

An input current level equal to the battery AH level may be chosen initially, and reduced gradually if a positive response is detected from the battery.





If you liked the post, Please Share it

Related Posts

Previous
Next Post »

187 comments

comments
Anonymous
June 15, 2012 at 10:04 AM delete

Great!!!! You are genius

Reply
avatar
June 21, 2012 at 1:53 PM delete

Sorry to disturb you again and again,How can I understand that my battery need desulphator,
and how to adjust the 100k preset

Reply
avatar
June 22, 2012 at 8:11 AM delete

How much amp is required for 7 Ah Battery

Reply
avatar
June 22, 2012 at 9:28 AM delete

If it does not charge within 10 hours or gets flat within minutes of use.

Reply
avatar
June 29, 2012 at 2:21 PM delete

I made this circuit but led does not glow and ne 555 get extremely heated ,please guide

Reply
avatar
June 30, 2012 at 5:14 PM delete

The IC will get hot only under three conditions:

If the operating voltage is higher than 16V

Pin 3 is not connected with a resistor,

Other pins are connected wrongly.

Please check the above issues first.

Reply
avatar
July 16, 2012 at 6:41 PM delete

Hi swagatam,
i bought the parts today and will start making this by next holiday. but i don't want to explode my battery. So please explain how much i turn the 100k pot?

Reply
avatar
July 17, 2012 at 3:23 PM delete

Hi Savyasachi,

Before connecting the battery set the output voltage across the battery points of the circuit at 14 volts, by carefully adjusting the pot.

Reply
avatar
Anonymous
October 29, 2012 at 12:26 PM delete

in PWM, you need to send High voltage or Current, if we set it to 14 out put will it help in removing the sulfur form the plate. kindly let us know how it works, can we design a better circuit to indicate its working. i also suggest to include a fuse for safety for polarity and other effects

Reply
avatar
October 29, 2012 at 1:59 PM delete

A pulsating high current is good for the required actions, just as given in the above article.

15V @ 1/2 battery AH rate would be better with a mark space ratio of 1:3 high:low pulses.

Fuse would be good for avoiding short circuit hazards.

Unfortunately there's no circuit which can directly indicate the proceedings.

Reply
avatar
Anonymous
October 29, 2012 at 2:09 PM delete

Thank you very much Sir, can you help in designing one with an indicator and with safety fuse.

Reply
avatar
October 29, 2012 at 6:21 PM delete

You are welcome!

A fuse can be added in series with the battery positive line.

An ammeter can be used in series with the positive of the battery, in between the fuse and the battery positive.

A dead battery would indicate no response over the meter. In case the sulfator circuit induces any effect, the meter would start showing the current and the charging rate as a result.

Reply
avatar
Anonymous
November 1, 2012 at 11:48 AM delete

Can you help in designing digital amp and volt meter for DC and For AC

Reply
avatar
November 1, 2012 at 8:47 PM delete

I'll try to find s suitable circuit and let you know soon...

Reply
avatar
Anonymous
November 2, 2012 at 11:18 AM delete

Thank you, awaiting your input

Reply
avatar
November 2, 2012 at 12:26 PM delete

There's one circuit link provided in this article:

http://expertscolumn.com/content/making-digital-voltmeter-ammeter-circuit-modules

Reply
avatar
Anonymous
November 2, 2012 at 4:26 PM delete

Dear Swagath, I cold not fined the digital volt and amp meter. the link further takes to the another link http://easy-electronic-circuits.blogspot.in/2012/03/electronic-voltmeter-ammeter-circuit.html.

Reply
avatar
Anonymous
November 2, 2012 at 4:34 PM delete

Dear Swagath, I found the link, however the circuit is not explained clearly and the connection A to F in the circuit is not explained. can you help
http://easy-electronic-circuits.blogspot.in/2012/03/digital-voltmeter-and-ammeter-circuit.html

Reply
avatar
November 2, 2012 at 5:26 PM delete

You can check the following link:

http://users.otenet.gr/~athsam/digital_volt_and_ambere_meter_eng.htm

Reply
avatar
Anonymous
November 7, 2012 at 11:59 AM delete

Dear Swagath, is there a circuit design for AC Amp meter

Reply
avatar
November 7, 2012 at 1:03 PM delete

Can you elaborate a little more regarding the exact specifications.

Reply
avatar
Anonymous
November 15, 2012 at 2:30 PM delete

i intend to use a digital amp meter to display current consumed in a AC line at home

Reply
avatar
Anonymous
December 9, 2012 at 11:48 AM delete

Hi am new her: With PWM can attaché charger on 15v high current terminal

Reply
avatar
December 15, 2012 at 9:39 AM delete

you are giving an external psu of 15 v, on many desulphactor there is no psu needed,is this really working

Reply
avatar
December 15, 2012 at 10:53 AM delete

How can a battery get charged or desulfated if there's no power suypply??

Reply
avatar
December 15, 2012 at 11:45 AM delete

yes,you are right.Even i was wondering where will power supply come from,,,Could you tell me how to construct a trickle charger.Im designing the other pulser,,like Ron Ingrahan circuit,it appears i need a separate charger together with pulser in parrallel.Your circuit seems to be quite precise.

Reply
avatar
December 15, 2012 at 5:56 PM delete

Trickle charging is a process in which the battery is not allowed to discharge if its not being used for a longer period of time, it's an almost zero current charging at full charged voltage level.

Though It will depend on the AH of the battery, typically you can connect a 10K resistor in series with a suitable charger for keeping any battery trickle charged.

Reply
avatar
December 16, 2012 at 5:56 PM delete

If the battery is 70AH ,how will your psu be made,what type of transformer, any current ,wattage requirements?

Reply
avatar
December 16, 2012 at 9:10 PM delete

You can use a 10 to 15 Amp transformer for a 70 ah battery, voltage should be a little higher than the battery voltage..

Reply
avatar
Anonymous
February 6, 2013 at 12:48 AM delete

HI
Sir ..... i am interested in making desulfator,,,, can u plz help me in making it,,,, i am very curious in making a new innovation in it.... plz give me the basic concept of its designing,,, i shall be very thankful to you,,,,

Reply
avatar
February 6, 2013 at 12:10 PM delete

Hi,

I have explained the concept and the circuit in the above article elaborately......

Reply
avatar
Anonymous
February 7, 2013 at 4:42 PM delete

sir .. in above circuit .....is resistor 100k variable? how we set its value....
what is given input voltage?
sir i have simulated this circuit on proteus bt there is no output.... plz help me. how we will give voltage and type of Resistor 100k and about its value selection... and input voltage/...
i shall be very thankful to u

Reply
avatar
February 7, 2013 at 9:39 PM delete

yes the resistor 100K is variable, I'll check the circuit and see if I can correct it....

Reply
avatar
max
February 7, 2013 at 11:42 PM delete

hello
please can you give the value of the inductor in H

Reply
avatar
February 8, 2013 at 11:50 AM delete

hello, you will have to experiment with it until you get around 18V across it...the thickness of the wire should be adequately large for supporting the battery charging current, same would be true for the transistor.....alternatively, it may be replaced with a mosfet.

Reply
avatar
max
February 8, 2013 at 12:16 PM delete

thank you
i want to desulfate a 200ah deep cycle bat. what kind of mosfet can i use ?
i experiment with a lot of desulfetors but noone can do the job efectively
please can you desigh a lifepo4 pcm circuit with balance i think thatis the future of the energy storage problem.
keep on the good work
thank you

Reply
avatar
max
February 8, 2013 at 6:31 PM delete

and can i put the tip136 ?

Reply
avatar
February 8, 2013 at 8:42 PM delete

You may try IRF540N mosfet.

The above circuit is also not a confirmed one, it might work or may be not, would depend on various parameters.

Reply
avatar
February 9, 2013 at 7:07 AM delete

Greetings everyone,
i saw this circuit and i think it is extremely practical, i'll try to do it, because i had a dead battery on my bike. but looking at the scheme and searching i don't see what is the value and type of the L1 inductor. Could you specify, please.
also i'll try to use a microcontroller to do the pwm. I think it just have to be at the same ground, right?

Reply
avatar
February 9, 2013 at 1:12 PM delete

L1 will need to be experimented with, any coil which produces 18V, and is able to handle the specified charging current, would do the job....

Reply
avatar
Anonymous
February 10, 2013 at 3:51 PM delete

hello
i make this but when i connect the battery it causes .sortcircuit

Reply
avatar
February 10, 2013 at 9:44 PM delete

please use a diode with the positive of the battery....

Reply
avatar
February 16, 2013 at 7:00 AM delete

Hey Swagatam,

In general what type of pulse is most effective for de-sulfation?

e.g. short/sharp.....hi volts....hi amps.....hi or lo freq?

Wat do you think

Yours
Carl

Reply
avatar
February 16, 2013 at 2:23 PM delete

Hi Carl,

As far as I know, the voltage should be slightly high than normal, but the current should be sufficiently high, and in the form of pulses.

Regards.

Reply
avatar
February 16, 2013 at 9:09 PM delete

Do you have any ideas on how to observe or test/measure the effects on the battery when searching for an optimum setting?

This circuit of yours is suitable for experimentation as the 555 is so adjustable.

It might be that having the battery in a clear case and observing the effects visually might be helpful.
One would have to keep an eye on temp and gas production.(don't want to boil it away)

Your thoughts.....

Thanks for this
Carl

Reply
avatar
February 17, 2013 at 11:30 AM delete

perhaps the only way to test this is to connect a virtually unresponsive battery to the circuit and set the pot to reasonably high levels, if the battery starts to accept the charge after a period of time, would prove the working the circuit.....however it's just my assumption...

Reply
avatar
February 17, 2013 at 7:22 PM delete

Swagatam,I am absolutely sure your circuit works.

I am trying to think of a way to observe and fine tune it for optimum.

I'm thinking if I took a badly sulfated cell out of a battery and put it into a glass or clear plastic case along with the electrolyte, I might be able to see the action.

What do you or your readers think?
It's great to have a place to ask the question.

Thanks

Carl

Reply
avatar
February 17, 2013 at 9:27 PM delete

Thanks Carl, that looks a wonderful idea.

I am sure all the readers will appreciate this approach from you.

Reply
avatar
March 12, 2013 at 3:05 PM delete

Sir, is the pot value 5k is correct ??

Reply
avatar
March 14, 2013 at 3:35 PM delete

One more question Sir,

What should be the size of coil L1, i mean on how many mm it should be wind ?

Thanks.
Regards.

Rashid

Reply
avatar
March 15, 2013 at 12:30 PM delete

you will have to experiment it by using different types of inductors, start with a 22swg wire wound over 6 inches ferrite rod having diameter of 1 cm, put around 50 turns initially and then vary it by increasing or decreasing the turns. check the output voltages across the coil without load with different number of turns..

Reply
avatar
March 16, 2013 at 12:32 AM delete

Hello Sir,

Thank you for your prompt reply.
Can i use a rounded coil which is used in computers switching power supplies ?

Reply
avatar
March 16, 2013 at 11:09 AM delete

Hi Rashid,

you mean torroidal coil, yes it can be used.

Reply
avatar
March 16, 2013 at 11:37 AM delete

...a coil won't be required actually, please check out the updated diagram....

Reply
avatar
March 16, 2013 at 2:53 PM delete

O.K Sir, Thank you, I will try.

Reply
avatar
March 18, 2013 at 4:18 PM delete

Hello Sir,

I make this circuit and checked all the connections twice. It looks everything
is fine, but I don't notice any change in battery after connected for about 10 hours.
My battery is of 12v, 50 Amp.

How long it will take to d-sulfate it ?

Thanks.
Rashid

Reply
avatar
March 19, 2013 at 10:38 AM delete

Hello Rashid,

What's your AH and how much current are you using in the circuit power supply???

Though there's no confirmed value, the current from the mosfet should be almost equal to the AH of the battery, and the pot should be adjusted to produce short bursts of output.

Reply
avatar
March 19, 2013 at 3:14 PM delete

Sir,

Battery is of 12v and 50 AH and power supply is giving 12v and around 2 amp. to the circuit.

Regards.
Rashid

Reply
avatar
March 19, 2013 at 8:50 PM delete

As mentioned in the article, the current should be considerably high, you should use a 40 amp transformer may be initially for testing.

Otherwise the sulfation will not initiate.

Reply
avatar
Anonymous
May 31, 2013 at 5:37 PM delete

hello sir... i have 12v 7Ah sla battery. what must be the input current for the above circuit to desulfation?

Reply
avatar
June 25, 2013 at 9:05 PM delete

aoa Rashid. I am waqas from Pakistan. How about your experiment . Does the above recomendation solves the issue of desulfation arshad.waqas@gmail.com

Reply
avatar
Anonymous
June 28, 2013 at 3:30 AM delete

hi, swagatam, i would like to confirm if the disulfator circuit uses an inductor coil since i don't see any in the above circuit. i'm just confused. thanks

Reply
avatar
June 28, 2013 at 1:40 PM delete

The inductor has been removed in the present design because according to me it's not required. A desulfation process can be possibly initiated by applying high current short pulses to the battery, which can be achieved by using a high current transformer, probably equal to the battery AH level.

Reply
avatar
Anonymous
June 30, 2013 at 11:07 AM delete

Thank u sir,
Could u please let me know the way to design a battery charger using your charger concept to charge the Generator Battery.
I mean i need to hook the charger permanently of the battery.
Could u please reply me below email. chandanapsd@yaho.com
Thanks advance...
Good Luck and Highly appreciate your knowledge sharing.

Reply
avatar
July 1, 2013 at 1:10 PM delete

Thank you very much!

The following link shows a more elaborate version of the above circuit, you can try it:

http://homemadecircuitsandschematics.blogspot.in/2013/04/simple-solar-mppt-circuit-using-ic555.html

Reply
avatar
Anonymous
July 6, 2013 at 3:14 PM delete

hi swagat, i thin there is some thing missing in the circuit, the inductor and couple of the commentors where mentioning about 100k resistor which i do not find in the ciruit, is this diagram correct?

Pranav BM

Reply
avatar
July 7, 2013 at 9:01 AM delete

hi pranav,

the shown circuit is a new one, the comments refer to the old circuit which has been removed by me because it had some mistakes.

Reply
avatar
Anonymous
July 8, 2013 at 2:21 PM delete

thank you, you don't need the inductor?, wont it be better to add a fuse before batter and the positive power supply.

Pranav BM

Reply
avatar
Anonymous
July 8, 2013 at 3:05 PM delete

Dear Swagat

"An input current level equal to the battery AH level may be chosen initially, and reduced gradually if a positive response is detected from the battery."

You mean if we are desulfating a 100 AH battery you need 15V 100AH?.

Pranav BM

Reply
avatar
July 9, 2013 at 9:29 AM delete

A fuse is always a welcome device for all electrical systems, so you may employ it.

Reply
avatar
July 9, 2013 at 9:32 AM delete

Dear Pranav,

It's my guess only, it will depend on the condition of the battery, if you can arrange for 100amps then surely you can try it with very short pulses for a 100ah battery....again I am just assuming the current magnitude to be suitable.

Reply
avatar
Satyam
July 12, 2013 at 11:46 PM delete

Good day, Swagatam,

I didn't get nF capacitors (not available at the shop I went to), I bought a 1 microF and a 100 microF. If I substitute these into the circuit, how will it affect the output?

Thanks,
Satyam.

Reply
avatar
July 13, 2013 at 12:55 PM delete

Good day Satyam,

The circuit needs to be operated with high frequency so a 1uF or 100uF will not work.

1nf = 0.1uF, so can try other closer values like 0.22uF etc. or any value between 0.01uF to 0.1uF will also do.

Reply
avatar
July 13, 2013 at 1:05 PM delete

better use a 680pF for pin6/2 and 103 or 0.01uF for pin5

Reply
avatar
Satyam
July 14, 2013 at 9:47 PM delete

Good day,

Thanks for your quick response. I've built the circuit with the components that I described, however I'll keep looking for the correct capacitors. (I got some surface-mounted caps yesterday, but destroyed them trying to install them.)

I suspected that my frequency would be affected. Using f= 1/(0.693 x C x (R1 + 2R2)), the frequency of my circuit would be somewhere around 300 Hz, whereas your design is for 300 kHz. Does that sound about right?

At any rate, I'm using it on a number of car batteries where I suspect sulphation. Will come back & update when I replace the caps, or with results.

Best regards.

Reply
avatar
July 15, 2013 at 11:07 AM delete

Higher frequency would produce better effects according to me, however the pwm pulses would finally decide the optimization rate.

Reply
avatar
August 16, 2013 at 11:29 PM delete

Swagatam:
Excellent circuit, I'm about to try arm. I'd appreciate if you tell me regularly cnveniente a zener and 100 ohm resistor voltage to the 555 and ensure it does not overheat.

Thank you for your attention

Reply
avatar
August 17, 2013 at 1:40 PM delete

thanks electronica,

the IC can work safely with upto 15V, yet for extra stabilization you may use a 7805 IC for it.

Reply
avatar
August 17, 2013 at 8:36 PM delete

Swagatam:

Swagatam:

Thanks for your reply and recommendation. If working at 555 with 5 volts regulated from 7805, the oscillation frequency is not affected?

Are pleased to greet and congratulate again the excellent circuits published.

Reply
avatar
August 18, 2013 at 6:48 PM delete

Thanks Electronica,

yes it will not be affected.

Reply
avatar
August 18, 2013 at 9:00 PM delete

Swagatam:
Very nice, I appreciate your attention to my queries. Best wishes from Guatemala.

Hugo

Reply
avatar
August 30, 2013 at 12:53 PM delete

Hi Swagatam, I have installed automatic voltage stabliser for home supply,
the only problem is, when it starts, initialy it supply high volts(300 ) for less den 1 sec. den it functions well..
Pls let me know what is the problem n how can i fix it..

Reply
avatar
August 30, 2013 at 8:57 PM delete

Hi Nawnit,

You will need to add a delay ON timer at the output of your stabilizer as shown in the following link, a similar situation has been addressed at the bottom of the article.

http://homemadecircuitsandschematics.blogspot.in/2013/02/make-this-simple-delay-on-circuit.html

Reply
avatar
August 31, 2013 at 1:35 PM delete

Thanks buddy,
will it work fine upto 4 kw load?

Reply
avatar
August 31, 2013 at 7:08 PM delete

You will have to select the relay appropriately, I think a 30 amp relay would do the job.

Reply
avatar
August 31, 2013 at 9:34 PM delete

Thanks Swagat,
sorry for one more problem,
I inspected the stablizer, it has 24 volts relays, so i need to operate the "delay on" circuit on 24 volts instead 12 volts.
What modification i need?
Thanks

Reply
avatar
September 1, 2013 at 9:05 AM delete

You will have to use a 24V relay in the circuit, that's all, no other change would be required.

Reply
avatar
September 1, 2013 at 9:06 AM delete

The 24v supply for the circuit can be derived from the stabilizer board itself.

Reply
avatar
September 2, 2013 at 8:34 AM delete

Thanks Swagat,
Tryed smthing diffrnt with the stablizer that i must share wid u.
There are 5 taps in auto transformer, 1st n 3rd tap has been used as input with a relay control and rest for output wid 2 more relays.
I inspected the 1st relay status at power on, it was making 1st tap as as input for 1 sec then change it to 3rd tap as input, so there was high volt at power on.
I interchanged 1st and 3rd tap input with relay.
Now its working good .

Reply
avatar
September 2, 2013 at 8:50 AM delete

But m not sure if it will be failed for high voltage input. Vl try to make a diagram of switching.
Please comment.

Reply
avatar
September 2, 2013 at 8:31 PM delete

It's difficult to guess how it will do with high or low voltage condition, we can't say without practical testing, let's see...

Reply
avatar
September 6, 2013 at 3:26 PM delete

Hi Swagat,
I need a signal strength meter for direct to home disc alignment at roof.
Can it be made simply at home with transistor and led.
Thanks

Reply
avatar
September 7, 2013 at 2:16 PM delete

Hi Nawnit,

UHF Signal meters are complex devices, not within my reach.

Reply
avatar
Anonymous
September 14, 2013 at 8:46 AM delete

@Swagatam
Nice circuit I look forward to trying it out.
Just one question, Where should the negative from the power supply go?
Thank You

Reply
avatar
September 14, 2013 at 2:05 PM delete

Thanks!

The negative will go to the rail which is connected to pin#1 of the IC

Reply
avatar
October 10, 2013 at 3:16 PM delete

Hi Swagatam, your circuits are incredibly practical. Thanks for sharing and explaining.
I am a bit confused as I read the thread as I saw reference to a 100K pot and L1 inductor but the circuit above for PWM 555 pulser does not show these. What am I missing ?
http://2.bp.blogspot.com/-L9UBEjJp8XU/UUQLd8oW6YI/AAAAAAAADkk/FlaSh6PwIos/s1600/battery+desulfator+circuit.png

Sean

Reply
avatar
October 10, 2013 at 9:30 PM delete

Thank you Sean,

Actually the circuit has gone through many changes since it was first posted, so please ignore the previous comments as those are with reference to the previous diagram which had quite a few flaws.
The present design looks to be easier and viable.

Reply
avatar
October 11, 2013 at 11:35 AM delete

Thanks for your clarification. I was curious about the use of the inductor (i.e. collapsing magnetic field/pulse, etc).
Anyhow, I will try this circuit out as its simple enough to make. I would like to try to revive some large capacity (100AH) NiMh batteries I have pulsing with high current. I am hoping the technique will lower the internal resistance of the batteries even though the chemistry is different (i.e. they don't sulphate).

Reply
avatar
October 11, 2013 at 8:16 PM delete

I wanted to keep it simple, so I eliminated the inductor part, I hope it works for you....:)

Reply
avatar
October 21, 2013 at 11:46 PM delete

Hi Swagatam
Finally have parts to make the pwm but looking for a hi current supply.
It occurred to me that lead acid batteries will not sink as much current as it starts to get full. Does the circuit take this into consideration ?
When the transistor is on, is it essentially grounding the battery ?
When it is off, is there any ringing without an inductor ?

Sean

Reply
avatar
October 22, 2013 at 10:49 AM delete

Hi Sean,

If the voltage is set at some higher level then that will force the battery to sink the current which in turn will hopefully initiate the desulfation process.

Here you can try with a 15V DC, current may be equal to the AH level of the battery and the pot set to provide short pulses.

When the transistor is ON, it connects the negative of the battery to the negative of the power supply completing the circuit for the battery so that it receives the required charging pulse.

No, there won't be any ringing effect due to the absence of an inductor.

Reply
avatar
October 22, 2013 at 12:17 PM delete

hi Swagatam,
Thanks again for your reply. How do I limit the current ?
I planned on using an old server power supply or rewinding the secondary of a microwave transformer. Won't the circuit try to pull all the current it can unless its limited ?
Sean

Reply
avatar
October 23, 2013 at 1:35 PM delete

Hi Sean,

The circuit will not draw anything above 5mA, as long as the voltage does not exceed 15/16V mark, above this anyway the IC555 would get damaged, so I don't think any current control for the circuit would be required.

Reply
avatar
October 23, 2013 at 3:56 PM delete

Hi Swagatam, I think you mis-understood my question.
With your circuit you recommend limiting the current to the battery initially to 1C. so if I have a 40AH battery, I should limit the pulse current to 40AH. I was asking how I could do this since I don't have a power supply with a current limit. I am thinking of making a power supply by stepping down 240VAC to 15VAC and rectifying it. But this will not be limited. Is there a clever way to control the max current the battery draws ?

Reply
avatar
October 24, 2013 at 9:55 AM delete

Hi Sean,

You can select a transformer rated at around 20 to 30 amps, that will itself take care of the current...actually the current is not a critical value, anything higher than the normal charging method can be employed, and expected to work here.

Reply
avatar
October 24, 2013 at 11:16 AM delete

Thanks again Swagatam, will update the thread with my results.
btw, I read somewhere (maybe here..) that the high current pulse may burn out shorted cells restoring even batteries that are considered unrepairable.

Reply
avatar
October 24, 2013 at 7:34 PM delete

Hi Sean,

Then that would be an added feature of this design.

Looking forward to your updates...best wishes!

Reply
avatar
November 27, 2013 at 6:59 PM delete

i am very proude of you . how can i indicate this circuit is working after design

Reply
avatar
November 28, 2013 at 10:04 AM delete

keep a voltmeter attached with the battry, if the voltage increases gradually within 4 hrs means it's working.

Reply
avatar
Anonymous
December 5, 2013 at 12:01 PM delete

Hi, I don't see any 100k trimmer in your circuit? I have a 100Ah battery. Do I have to inject 50 amps to it? Best regards.

Reply
avatar
December 5, 2013 at 6:46 PM delete

please ignore these initial comments, the diagram has been modified and updated differently, so these comments have no relevance with the present diagram.

Reply
avatar
January 12, 2014 at 7:10 PM delete

Hi Swagatam

I have read some of above posts talking about an inductor L1. Where is that inductor, I can't see it in the circuit or any reference in your article?

By the way, I am working on a trickle charge desulfator. I am considering to integrate a circuit to measure battery's internal resistance (BIR). There are a few BIR measuring circuits on the net but, they need to take occasional measurement manually. Here are two of them:

https://dl.dropboxusercontent.com/u/20969135/internal-resistance-tester-for-batteries-2.jpg
https://dl.dropboxusercontent.com/u/20969135/accutest.jpg

My idea is to have three-LED indication........the red LED to indicate high resistance, yellow to indicate medium and green for very low resistance. The BIR circuit will operate in parallel with the desulfator circuit. The illumination of the green LED would indicate that the battery has been desulfated, now it is ready to use.

A relay could be used to connect the BIR circuit to the battery periodically to check the status. A latch can be deployed to keep the indicator LED on but, I just cannot sort out how to get the output on LED as the output is just 5-50mV.

Can you please help me in this regard? If required, I can send you the links of the sites to have the description of those circuits.

Reply
avatar
January 13, 2014 at 10:16 AM delete

Hi Abu-Hafss,

In the original design I had used an inductor but later found that it could be avoided and came up with the present design , the inductor related comments that you see were posted with reference to the earlier design

A BIR could be a very useful ad-on.

50mV can be amplified by using a opamp may be. What do you think?

Reply
avatar
January 23, 2014 at 12:15 AM delete

Hi Swagatam

I came across a desulfator circuit which, apart from the regular desulfation process, also shorts momentarily battery terminals as shown here:

https://dl.dropboxusercontent.com/u/20969135/Desulfation.gif

I want to know, couldn't the signal from the 555 pin#3 be directly fed to the gate of the mosfet (point A) or at point B?

Reply
avatar
January 23, 2014 at 10:56 AM delete

Hi Abu-Hafss,

How does this circuit desulfate...is it by charging and shorting the battery alternately? I could not understand the concept.

Reply
avatar
January 23, 2014 at 12:12 PM delete

Hi Swagatam :)

One complete cycle includes 3 steps:

1) 15 sec pulse charging
2) 1 sec delay for settling
3) 100ms shorting battery terminals

I am just curious about the driving of the mosfet as I asked in my previous post.

Reply
avatar
January 23, 2014 at 8:09 PM delete

Hi Abu-Hafss :) how are these three steps implemented because i can see only one active input from the IC 555.

I wanted to know the relevance of the transistor stages for answering your question correctly.

Normally we know that a mosfet gate can be integrated with any IC output may it be a 555, a cmos or a opamp, as long as the voltage is below 15V

Reply
avatar
January 24, 2014 at 12:07 AM delete

Hi Swagatam

Since I was focusing only on the mosfet so I didn't gave you the details of the other sections.

As mentioned earlier, one cycle consists of mainly 3 steps + 1 step to monitor battery voltage. Each step is controlled by a 555 and another 555 is controlling all these 4 ICs (the entire cycle). If you want to have a look at the circuit, here it is.

https://dl.dropboxusercontent.com/u/20969135/Desulfator%204-stage.gif

I am sorry, that is maximum available resolution of the picture.

Now, I repeat my question in other way. If the mosfet can be driven directly by the 555, why the author deployed 0.8A transistors to drive the mosfet. You can find them at the top-right corner. I haven't linked the website as per your general instruction however, if you want to see the circuit description I can send you the link.

Reply
avatar
January 24, 2014 at 12:05 PM delete

Hi Abu-afss,

It could be for allowing the mosfet to conduct and restrict correctly, especially the use of the push-pull (PNP/NPN) stage which ensures safe charge/discharge of the internal cap of the mosfet, because as we all know how sensitive these mosfets can be at times.

Reply
avatar
January 27, 2014 at 2:17 AM delete

Hello Swagatam,


I would like to build a hi/lo adjustable relay/contactor.
Say ....12v on 13.5 off
I could then put it in series with any charger.
It would be great for maintenance and prevent over charging.

A variant of this could also kick in a discharge cycle.
This would be good for desulfating.

Do you have a design lik this?

Yours
Carl

Reply
avatar
January 27, 2014 at 4:19 PM delete

Hello Carl,

Please see the last diagram in the following link, it'll fit your need well:

http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-make-simple-low-battery-voltage.html

The second relay shown is not relevant, you may remove it.

Reply
avatar
February 4, 2014 at 3:06 PM delete

Hi Swagatam

Here is my basic design for LED indication of BIR status. The reference voltage is 12mV.

https://dl.dropboxusercontent.com/u/20969135/BIR%20indicator.gif

But, later I realized that the output is is mVAC. Any suggestions, how to deal this issue?

Reply
avatar
February 5, 2014 at 1:01 PM delete

Hi Abu-Hafss,

I am not able to recollect the previous discussions and the simulation made by me with reference to this diagram, so not able to figure out much about the circuit, if you can point out specific concerns in your diagram then probably I can try suggesting my opinions.

Reply
avatar
February 5, 2014 at 1:24 PM delete

Hi Swagatam

Kindly refer to my post of January 12, 2014. Here is the link for your ready reference.

https://dl.dropboxusercontent.com/u/20969135/accutest.jpg

The battery internal resistance is measured in mVAC. A good battery would show less than 12mVAC. And with higher internal resistance would show more than 12mVAC.

I am just wondering how to compare the fluctuating mVAC with a reference voltage.

Reply
avatar
February 5, 2014 at 6:42 PM delete

Hi Abu-Hafss,
I think it would be a better idea to use a LM3915 IC for detecting the relevant voltage levels because the opamp circuit could become too complex.
Refer to the last diagram in the following article, the mic can be removed and the transistor may be directly fed from the 100k pot output

http://homemadecircuitsandschematics.blogspot.in/2012/03/how-to-make-vibration-detectormeter.html

Reply
avatar
February 7, 2014 at 10:37 AM delete

how can i indigate this is working correctly irf 540 get heat?

Reply
avatar
February 15, 2014 at 5:33 AM delete

Lead Lead Sulfate PbSO4 is part of battery charge discharge cycle. The structural form of PbSo4 makes the difference. While amorphous PbSo4 is reversible while hard crystalline PbSO4 is irreversible and inactive. Shallow cycle batteries never have to be discharged under 12.5 volts. If this happens an immediate charge will consume and transform PbSO4 in to Pb, H2O, PbO2 and H2So4. If let staying there for sometime the PbSO4 crystallize and turns inactive. To make a long story short if battery isn’t in use immediately use Float charging with a battery trickle. Harbor freight tools sell a battery trickle (Floater) for $9.99, which I bought on sale for $6.0. The manufacturer 13.2Volts was only a promise, but replacing VR1 with a 100-Ohm trim pot, I can adjust the voltage from 12.6V to 14.25V. I set it at 13.25V but this is only the first aid. What you need is EQUALIZE the BATTERY; this can be done at 14.5V for some hours. During this process the strong cells start boiling but the weakest cells continue charging. This can be done with a battery tender. I bought one from Wal-Mart connected to my VW Touareg and the next day the relay was chattering ON / OF non-stop. Measured Voltage a found 14.85 Volts. The electronic system of the car was fighting hard against this stupid tender. I solved the problem building up my Battery Tender with precision voltage Window 14.5V stop charging and 12.6V restart charging giving the battery a chance to rest, RELAX. Charging a discharged battery you have to deal with Bulk Charge Current Density that depends from electrode surface and is expressed on mA / Cm2. If a have to deal with an accidentally fully discharged battery I use my Automatic Smart Battery Charger, with Equalizing and reconditioning features.

Reply
avatar
February 16, 2014 at 5:14 AM delete

hi
I just realise in the circuit there is no ground to the circuit?
if we use power supply to connect to this circuit the plus 15V pole goes to the battery and the circuit where then the negative pole goes?
I know if I use coil and transistor I have to connect the negative pole to emitter but on mos fet not sure looks like this one joint missing from the circuit
could you please correct me if I am wrong?

Reply
avatar
February 16, 2014 at 12:44 PM delete

The line connected with pin#1 of the IC is the negative line and must be connected with the power supply negative.

Reply
avatar
February 16, 2014 at 6:45 PM delete

So Avenger is saying that there is no coming back from hard crystalline PbSO4 .
OUCH!
One should have all batteries under full time trickle charge.

Avenger ,.... which one of Swagatam's designs did you use for your charger?

Carl

Reply
avatar
February 17, 2014 at 6:08 AM delete

thank you I already done it just downloaded the ic pin out then I know the number 1 leg is the ground.
thank you again for your fast response and attention.

Reply
avatar
May 11, 2014 at 4:05 PM delete

Is it possible to desulphate my 6v,5ah sealed lead acid battery by this ckt.

Reply
avatar
May 12, 2014 at 10:24 PM delete

How it to be possible?what changes in the ckt for 6v,5ah sla battery desulphating.and how much time taken to desulphate.

Reply
avatar
May 13, 2014 at 11:45 AM delete

use 10V supply with 3 amp current,
use TIP122 instead of the mosfet
time is not known....... also the result may not be positive, will depend on how much your battery may be recoverable.

Reply
avatar
May 18, 2014 at 8:37 AM delete

Thanks for your information.tell me the Pin connections of TIP122 while using instead of mosfet in this ckt.

Reply
avatar
June 7, 2014 at 9:51 AM delete

Hi Mr. Swagatam, newbee here.
So I've finished assembling the circuit, how to tell that it's working before I start attaching it to the battery? I mean is there some type of indication there or do i've to measure anything first?
thank you.

Reply
avatar
June 8, 2014 at 10:37 AM delete

Hi Imanul,

There's no circuit which can guarantee a perfect desulfation in dead batteries, so you can only hope that this circuit produces the intended results as it's designed as per the standard recommended specifications.

Use the circuit for about 4 hours and then check the battery with an appropriate load, if the charge sustains for an appreciable amount of time you can assume it to be revived, otherwise you may repeat the procedure with some change in the PWM frequency and/or the input current to the circuit and check the response in a similar manner.

Reply
avatar
June 8, 2014 at 10:42 AM delete

...please change the 1n caapcitor with a 10uF capacitor.

connect an LEd across pin3 and ground via a 1K resistor.

When switched ON this LED must flash rapidly indicating a proper functioning of the circuit, changing the pot would change the flash rate on this LEd

you can keep the new capacitor connected and use the circuit for the required purpose, it won't make any difference in the performance.

Reply
avatar
August 7, 2014 at 12:08 PM delete

Hi,

I started building your old circuit and only realized you have changed them ,but I have bought parts for the old diagram,so can I build the circuit without the inductor with the TIP122 ,or should I Change it IRF540.

Reply
avatar
August 7, 2014 at 4:44 PM delete

I've built the first circuit and when i connect the battery the coil heats up and smokes

Reply
avatar
August 7, 2014 at 5:16 PM delete

Hi, I changed the circuit a long time ago may be a half year ago, it's strange you are building it now.

I would recommend you to make the above shown design instead of the earlier one since adding a coil will not make much of a difference.

Reply
avatar
August 7, 2014 at 5:19 PM delete

please try the above circuit without the coil, the TIP122 will need to be upgraded if your battery AH is higher than 20AH

Reply
avatar
August 7, 2014 at 6:13 PM delete

Can I use IRF540N instead of IRF540

Reply
avatar
August 8, 2014 at 10:57 AM delete

IRF540N will do and will work for an 80AH battery

Reply
avatar
September 7, 2014 at 5:42 PM delete

can we ad two LEDs to show it is charging and one for it is charged?

Reply
avatar
September 8, 2014 at 11:26 AM delete

you can connect one of the circuits from this article with the battery for the required indications:

http://homemadecircuitsandschematics.blogspot.in/2014/06/flashing-led-battery-status-indicator.html?showComment=1410150791188#c5340362629349017259

Reply
avatar
March 5, 2015 at 4:20 AM delete

Hi swagatam! Is there a need to change some parts of the circuit if my battery is ranging 7 to 14 amp?

Reply
avatar
March 5, 2015 at 4:24 AM delete

Hi swagatam! What is the ideal mosfet for a below 20amp battery?

Reply
avatar
March 5, 2015 at 1:33 PM delete

Hi Josue,

no changes would be required for your mentioned application.

Reply
avatar
March 5, 2015 at 1:35 PM delete

IRF540 is the ideal mosfet as shown in the diagram

Reply
avatar
Anonymous
April 8, 2015 at 8:08 PM delete

Hi Swagatam... how will i connect the PWM LED indicator to this circuit? what changes will it be?

MikeL

Reply
avatar
April 8, 2015 at 8:52 PM delete

Hi Mikel,

you can connect an LED across pin3 and ground with a series 1K resistor but it will appear continuously glowing due to high frequency pulses from the IC

Reply
avatar
Anonymous
April 9, 2015 at 4:50 PM delete

Hi Swagatam,

i already tested the circuit in 7Ah battery.. i think it is working but i dont know the sulfation effect if it is working. the battery is charging good. by the way i change the 1nF (102) with 1uF (105), 100k pot. the supply is 15v. is it okey to use IRFZ44n for 100Ah battery?

thanks for this circuit you shared... more power to your good work.

God Bless!

MikeL

Reply
avatar
April 10, 2015 at 8:17 AM delete

Thanks Mikel,

changing 1nF to 1uF will reduce the frequency or the pulse rate, but that will not affect the results, so it's OK.

the mosfet and the supply voltage are also OK, but the current input must be well over 20 amps for desulfating a 100AH battery, so make sure the supply current is at this level.

Reply
avatar
July 12, 2015 at 4:08 PM delete

Sir, I'm planning to add this circuit on my existing 72v ebike charger. It has 6 pcs.12v 20ah battery connected in series. Would it be possible? What ic regulator should I use for LM555's supply voltage? And what mosfet would you recommend?

Reply
avatar
July 12, 2015 at 8:20 PM delete

Hi Jusi, yes you can try it, just make sure to disconnect the battery positive from the shown point and connect it with the +72V supply........and connect the positive of the circuit with the positive of last 12V battery in the series which has its negative connected with the bike's ground or the bike's negative....

the negative of the circuit can be joined with this ground that is the common ground line.

Reply
avatar
July 12, 2015 at 8:22 PM delete

...the mosfet can be a IRF3710


http://www.irf.com/product-info/datasheets/data/irf3710.pdf

Reply
avatar
July 29, 2015 at 2:53 PM delete

Swagatam,

I found an interesting video where electrons are made to flow from -ve side of battery to breakdown the hardened sulphate crystals.

https://www.youtube.com/watch?v=AemT-IgLvS4

Now, I have an idea and you could tell me if it works.

Why not short the positive and negative terminals of the battery directly for a brief time, say 10ms or even 5ms? This would generate high amperes of current through the -ve terminal. This can be performed every 30sec until the grey matter(sulphated crystals) breaks down.

This i think can be implemented using arduino board with simple programming to turn an output pin on for 10ms which turns the relay on for that amount of time.

Would this work?

Thanks
Sachin

Reply
avatar
July 30, 2015 at 9:58 AM delete

Thanks Sachin,

shorting would be advisable only if the battery has sufficient charge on it, unless it's charged fully, shorting won't induce any effect on the plates.

The pulse charger explained in the above article is the ultimate way of dealing with this mess, if the battery responds and wakes up to the pulsed charging only then the shorting of the terminals can be tried, however as shown in the video a high amp resistive load would be more appropriate than shorting since here we don't have to worry about the delay period in ms

Reply
avatar
August 14, 2015 at 11:27 PM delete

Good day to you sir.
Thank you for sharing all the great work.
A few questions about this circuit :
1. What is the 5k POT for ? & how to adjust it ?
2. Does the IRF 540 need a heat sink ?
3. The negative of charger is directly connected to IC Pin #1 ?
4. How to connect a LED to this circuit, that illuminate when connect to battery ?
5. Any harm if connect to the battery permanently ?
Thanks a lot in advance .

Reply
avatar
August 15, 2015 at 8:59 PM delete

Good day Alaa,

1) 5K is for playing with the output pulse width, which might in turn help to implement a optimal desulfating effect....it could be a matter of some trial and error and dependant on the connected battery condition. however it's not so crucial, you can keep it at the center to begin with

2) Normally it shouldn't require a heatsink, however you can test it practically by touching it, to be on a safer side..

3) yes the negative of the charger needs toeb connected to the pin#1 line of the IC

4) charging indication might not be possible, however an ammeter may be connected in series with the battery positive to get a direct reading regarding the batt response to the charging procedure.

5) yes if the battery begins responding and desulfating...an ammeter can be used for monitoring the same as explained in the above point

Reply
avatar
August 27, 2015 at 7:45 PM delete

which simulator i can use to make this circuit and can have a dead battery in it for charging?
if you plz don't mind...can you plz send me the whole process from the begining till the battery desulphation.. what all the pins are doing ... plz .. i will be gratefull to you.

Reply
avatar
August 28, 2015 at 8:03 PM delete

simulation is not required, just procure the parts and the build the circuit, the circuit is explained in the articles itself...

Reply
avatar
hui
September 6, 2015 at 10:25 AM delete

is there any inductor on the above schematic ????

Reply
avatar
January 17, 2016 at 11:08 AM delete

Interesting circuit. I had a thought, perhaps this could be combined with adding a very small (<3ml) of acid to each cell technique for unmucking dead SLAs typically run to death in UPSs.
If they are at 0.0V I doubt any technique will work but its the ones which have good voltage but next to no capacity that could be salvageable.

Reply
avatar
January 18, 2016 at 7:45 AM delete

thanks for updating this info, appreciate it!

Reply
avatar
January 27, 2016 at 2:20 PM delete

hi mr swagatam,i hope you are good
i suggest to add a simple mosfet driver using a transistor cause 555 output voltage is weak and thus will overheat the mosfet,i tried before to connect 555 output to mosfet gate with a resistor and mosfet gets hot.

Reply
avatar
January 27, 2016 at 2:21 PM delete

cause mosfet need at least 5v to operate normally.
best regrads

Reply
avatar
January 27, 2016 at 4:23 PM delete

Hi Hisham, I am good thanks,

555 IC has an output that's more powerful than most ICs, however mosfets never require a powerful signal to operate, they just need a voltage above 9V for operating optimally.

You can try reducing the gate resistor to 10 ohms and check the response....or may be the load you have connected could be above the mosfet range

Reply
avatar
January 27, 2016 at 4:32 PM delete

IC 555 will produce a voltage that's exactly equal to the supply voltage, so in the above case the output will be 15V at pin3...not an issue for the mosfet.

Reply
avatar
March 30, 2016 at 10:01 PM delete

Can we use this circuit for sealed lead acid battery 6 volts please reply

Reply
avatar

Readers are requested not to include external links while commenting. For consulting a diagram, upload it on Google Drive and provide the link here.