In this article we investigate 4 simple yet powerful battery desulfator circuits, which can be used to effectively remove and prevent desulfation in lead acid batteries. The first method uses PWM pulses from a 555 PWM circuit, the second method implements an ordinary bridge rectifier for implementing a 100 Hz frequency based desulfation, the 3rd concept involves high voltage spikes, while the fourth design discusses desulfation using a 555 IC based high amplitude current pulsed circuit.
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.
1) Using PWM
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. 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."
https://en.wikipedia.org/wiki/Talk%3ABattery_regenerator
The circuit of a PWM battery charger discussed here can be considered as the best design for carrying out the above desulfation process.
How the Circuit Functions
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.
2) Desulfating with a Transformer and Bridge Rectifier Circuit
To make this simplest yet effective battery desulfator with charger circuit you would just require a suitably rated transformer, and a bridge rectifier. The design not only desulfates a battery, it keeps the new batteries from developing this issue and simultaneously charges them to the desired levels.
At the beginning of this post I have explained how to desulfate using PWM concept, however a deeper research shows that the process of desulfating a battery may not necessarily require a precision PWM circuit, the supply just needs to be oscillating at some given rate, and that's enough to initiate the desulfating process (in most cases)... provided the battery is still within the curing range and is not beyond the reviving state.
So what would you need to make this super simple battery desulfator circuit which will also charge the given battery, and additionally possess the ability to keep the new batteries from developing the sulfation issue?
A suitably rated transformer, a bridge rectifier and an ammeter are all that's needed for the purpose.
The transformer voltage must be rated approximately 25% more than the battery voltage rating, that is for a 12V battery a 15 to 16V supply may be used across the battery terminals.
The current can be approximately equal to the Ah rating of the battery for those which need to be revived and are badly sulfated, for the good batteries the charging current could be around 1/10th or 2/10th of their Ah rating. The bridge rectifier must be rated according to the specified or calculated charging levels.
Desulfator Schematic using Bridge Rectifier
How Bridge Rectifier Operates as a Desulfator
The diagram above shows the bare minimum requirement for the proposed battery desulfator with charger circuit.
We can see the most standard or rather crude AC to DC power supply set up, where the transformer steps down the mains voltage to 15V AC for the specified 12V battery.
Before it can reach the battery terminals, the 15V AC goes through the rectification process through the attached bridge rectifier module and gets converted into a full-wave 15V DC.
With a 220V mains input, the frequency before the bridge would be 50Hz (standard grid spec), and after rectification this is supposed to become double that is at 100Hz. For a 110V AC input this would be around 120Hz.
This happens because the bridge network inverts the lower half cycles of the stepped down AC and combines it with the upper half cycles, to finally produce a 100Hz or 120 Hz pulsating DC.
It is this pulsating DC which becomes responsible for shaking-up or knocking down the sulfate deposits on the internal plates of the particular battery.
For a good battery this 100 Hz pulsed charging supply ensures that the sulfation ceases to occur on the first place and thus helps to keep the plates relatively free from this issue.
You can also see an ammeter connected in series with the supply input, it provides a direct indication of he current consumption by the battery and provides a "LIVE update" of the charging procedure, and whether or not anything positive might be happening.
For good batteries this will provide the start to finish info regarding the charging process, that is initially the needle of the meter will indicate the specified charging rate by the battery and may be gradually expected to drop down to the zero mark, and that's when the charging supply needs to be disconnected.
A more sophisticated approach can be employed for enabling an automatic cut-off once the battery is fully charge by employing an opamp based automatic battery full charge cut off circuit (the second diagram).
3) Using High Voltage Pulse
The configuration detailed below provides the most up-to-date methods of desulfating lead-acid batteries. It is a circuit which routinely supplies quick yet intense pulses to the battery, while discharging the battery marginally between the pulses.
This technique, as much as recognized right now, is the best way to knock of undesirable build up of sulphate crystals and to bring back the battery plates into a good condition.
Because the voltage necessary for the high voltage pulses comes from the battery itself (this might appear a little bizarre initially, however the discharge of the battery is likewise a part of this technique), it is advised to hook up a charger in parallel with the battery and desulfator once the battery has not much capacity remaining.
Pulse generator
It could be noticed in the circuit diagram that the parts needed for the desulphator tend to be extremely humble. The circuit consists of a couple of stages: a high voltage generator constructed using IC1, IC2d and T1, that generates the charging pulses, and an indicator circuit which involves not more than 3 op amps (IC2a, b, c) and three LEDs, that indicate exactly what condition the battery is in.
Let’s go through the pulse generator initially. Just like the other parts of the circuit, its supply voltage is obtained from the battery itself through K1. Although we’re discussing the supply voltage, this must have a pretty consistent voltage and should be devoid of any spikes (except those produced by the circuit itself).
Inductor L1 works like a suppressor, and is included in order to eliminate undesirable voltage spikes, along with C2 and C3 which work like smoothing capacitors.
LED D1 illuminates as soon as the supply voltage is switched ON. To proceed with the pulse generator, IC1 (a 4047) produces a square wave having a frequency of 1 kHz and a duty cycle which typically is 50 PERCENT. When the Q output of IC1 turns high, FET T1 switches ON. This results in a (discharge) current to move through the battery by means of L2, that boosts linearly until the voltage across R4 is approximately 0.35 V; the current can now be around 1 A.
At this instant comparator IC2d changes state, triggering IC1 to be reset and T1 to become switched off. The stashed magnetic energy inside L2 now gets converted to a voltage spike, which is inflicted to the battery through D3. How big the spike is can be determined by the condition of the battery.
If the battery is in a decent condition and its internal resistance is rather small, in that case the spike voltage level may also be reduced (under 15 V). In case the battery has a high internal resistance then the peak level of the spike could be as huge as 50 V. Its highest magnitude will be restricted and equal to the value of the two series connected zener diodes, D4 and D5.
LED Indicators
Considering that the health of the battery could be dependent on how big the charging pulses are, we have included a straightforward LED circuit which indicates the optimum value of the pulses. The 3 comparators IC2a-c evaluate the peak value inside C4 and changeover at voltages of 15, 20 and 30 V correspondingly.
Therefore in case the battery is in a reasonably good shape, the green LED (D8) illuminates, with a under-performing battery, the yellow LED (D9) lights up, and with an incredibly bad battery the red LED (D10) glows.
We have an information that needs to be pointed out regarding the indicator circuit: in order to prevent all three LEDs from illuminating simultaneously in response to a high peak voltage, they are attached in parallel to a single common series resistor (R9).
Since the red LED carries a smaller voltage drop compared to yellow LED, they may in no way illuminate together. But the yellow and green LEDs have got a identical voltage drop, so a similar technique will not do the job here, which explains why the green LED comes with an normal diode (D7), hooked up in series with it.
You will find three alternative methods through which the desulfator may be used. The first is to apply it within an existing system (inside a car as an example) to avoid sulphation from taking place inside a battery having minimum sulphation.
The advanced desulfator circuit is built-in with the system by hooking it up straight to the battery using shortest possible cabling. Because the circuit could be kept connected forever, absolutely nothing more needs to be done.
The current consumption is approximately 20 mA, therefore the battery might discharge in case it is not charged up from time to time. Recovery of batteries which have previously sulphated can be carried out in a couple of techniques. The first method would be to charge the battery, eliminate the charger and after that hook up the desulfator circuit.
Since the power for the charging pulses is derived directly from the battery itself, it is going to gradually discharge. This technique needs to be observed carefully because a completely discharged battery must be recharged quickly.
Most likely in real life many charge/discharge cycles will probably be necessary before a terribly sulphated battery could be restored to life. Since the approach described above needs a great deal of attention and has a danger that the battery could be left in a discharged condition unnecessarily (which can be extremely harmful to a lead acid battery!), another method can be perhaps much better.
The battery is coupled to the desulfator circuit, using a trickle charger hooked up in parallel. This implies, no chargers must be integrated that supply a current of 7 A or higher, yet one that provides a optimum of 1 or 2 A. This could be left coupled to the battery endlessly with no issues.
4) Using High Amplitude Pulsed Current from 555 Boost Circuit
We are not going to offer you a solution that will magically solve all the problems with lead batteries. However, the battery desulfator that we will describe in the following lines has proven its effectiveness, mainly in the United States for now, and the measurements we have been able to make on our model have been very promising. As it costs less than twenty euros, which is negligible compared to the price of a new high-quality battery, why not try it out and see for yourself?
Understanding Battery Chemistry
As you may know, a lead-acid battery involves a chemical reaction that can be written as follows during the discharge process:
Pb + 2H2SO4 + PbO2 -> PbSO4 + 2H2O + PbSO4
In other words, the porous lead of one electrode and the porous lead dioxide of the other are transformed, in contact with sulfuric acid, into lead sulfate and water.
Conversely, during charging, the chemical reaction that occurs is as follows:
PbSO4 + 2H2O + PbSO4 -> Pb + 2H2SO4 + PbO2
In other words, lead sulfate and water are transformed, under the effect of electric current, into lead, lead dioxide, and sulfuric acid.
The reaction is theoretically perfectly reversible, and that is why a battery of this type can be charged and discharged many times.
Unfortunately, over time and especially due to incomplete or poorly done recharges, the "reverse" reaction, i.e., the one that transforms lead sulfate into lead, is incomplete and leaves lead sulfate present on the surface of the battery electrodes or plates.
The phenomenon is unfortunately cumulative because, as this lead sulfate is a poor conductor, it tends to thicken where it has started to deposit, which only worsens the problem.
When the sulfation of a battery has reached a sufficient level, no traditional recharge process can overcome it.
Indeed, due to the poor conductivity of lead sulfate, the internal resistance of the battery increases, reducing its charging current and therefore the effectiveness of the charging chemical reaction, leaving even more lead sulfate present on the electrodes.
The resistance of the battery eventually becomes so high that it cannot hold a charge, meaning it can no longer supply significant current due to its excessively high internal resistance.
The Working Concept
This phenomenon has been known for a long time, and there is a chemical process that can be used to eliminate lead sulfate from a battery before it's too late.
However, it's delicate to implement and relatively dangerous due to the chemicals involved. In fact, the battery must be emptied of its electrolyte (corrosive!) to fill it with the cleaning product (also corrosive), and once this operation is complete, the battery must be refilled with fresh electrolyte.
The approach we propose is different and comes from various studies conducted in the United States on the influence of high-amplitude pulsed currents applied to a lead-acid battery.
According to these studies, and provided that very brief but high-amplitude impulses are applied to the battery, the lead sulfate crystals would gradually be broken down by the resulting ionic agitation occurring at the level of the plates and electrolyte of the battery.
This phenomenon is very slow, but since it can be achieved by simple electrical means, this process doesn't pose any particular problems as no manipulation is necessary on the battery being treated.
Circuit Description
The diagram that we propose is widespread on the internet on the other side of the Atlantic and, as far as we could verify, is attributed to Alastair Ocup. As you can see from in the following figure, it is relatively simple and has many similarities with a boost-type switching power supply.
IC, which is nothing other than a classic 555, is configured as an astable oscillator operating at a frequency of around kHz. It produces very short duration pulses on its output available at pin 3.
When the level of these pulses blocks T1, capacitor C1 charges to the value of the battery voltage via inductor L2.
When T1 is made conductive, which only lasts for a brief moment due to the duty cycle of the pulses produced by IC1, capacitor C1 discharges abruptly across T1 and L1 since it is almost short-circuited by these components.
As soon as T1 is blocked again, the current generated by this discharge cannot abruptly cancel due to the presence of inductor L1. It is therefore sent to the battery via diode D2.
If capacitor C1 is of good quality and if the connection between the circuit and the battery is short and made of a suitable diameter wire, a current peak of the order of 5 to 10A can be obtained with a moderately sulfated battery.
Given the operating frequency of the 555 and the duty cycle of the signals it produces, the circuit's consumption remains relatively low and does not exceed an average value of 40mA
Hi Swagatam;
My battery is 6V 12A and power is about 1 V at the moment since it is nearly dead or recovery is impossible I do not know. On the other hand, I have the sources 1) DC 12V 2A transformer 2) DC 12V 1A transformer 3) DC 25V 4A transformer 4) 14mF 250 V 50/60Hz 470kOhm/0.5W big capacitor and rectifier bridge diode (1000V 35A)
As a result for the above first 3 choices I can use 7809 and additional diodes in serial to decrease the voltage to about 7 V to charge battery with a 555 PWM circuit and I think also possible to charge by 220 AC for the above parts of item 4. I need your support and opinion. Best regards
Hi Suat,
Since your battery is completely dead it will probably require a pulsed DC for desulfating. You can perhaps try the 12V 1 A transformer and apply the voltage to the battery through a bridge rectifier without a filter capacitor. To limit the current you can use a 12V car headlamp bulb in series with the positive line. Using 7V DC might not help to revive the battery according to me. The bridge rectifier by itself will generate a good 100 Hz for helping the desulfating process.
Thanks for te support Swagatam;
I will try your advise however I have some 12 V car bulbs at home. One consumes about 2 A ann the other one does 0,5 A. Please advice one of them is good for me or I should find headlamp bulb. (I think its ampere is important and please mention how much ampere I should use) Regards
No problem Suat,
I think you should try the 0.5 A bulb first, if it does not help much then replace it with 2 A bulb and check the response.
I am sorry since I am confused and have missed some points on the following matters :
I should use the above first circuit with the IC555 or second choices as the circuit with the bridge rectifier?
And if it is better for me to use IC 555 circuit it is possible to use IRFZ44N instead of 540? And how I can use bridge rectifier to output of DC 12V adapter or I should add just 2 diodes to the DC output of the adapter?
Kind Regards
I recommended the bridge rectifier option since it is very easy configure and the results would be also favorable. For the rectifier option you will have to connect the bridge rectifier directly with the 12 V AC from the transformer as shown in the figure.
If you intend to use the 555 option then that is also fine, but for the 555 circuit you will need a pure 12 V DC supply, probably from an AC to DC adapter. You can use IRFZ44, no issues.
When comparing the above first circuit using pwm; I am able to understand that there is a pulse event since there are IC555 and ir540. in the circuit
However regarding the second one how it is possible to mention about pulse effect since AC is being altered to DC after bridge rectifier and as if it is not desulphating but normal charging process. Please can you explain the point that I missed. Best Regards.
The DC after the bridge is not a pure DC, it will have a 100 Hz ripple frequency. This 100 Hz ripple frequency helps to knock off the sulfation on the battery plates. The AC to DC after bridge rectifier becomes possible only once a high value filter capacitor is connected.
Thanks, I am gratefull and appreciate that valuable information. I have found a new transformer and its legs as output voltage have respectively AC 8 volts, 9,5 volts and 13 volts. And I think its current is lower than 1A. The my other transformers (2 A and 1A)above mentioned are in closed case and I can not gain AC voltage. So please advice which voltage is proper after the rectifier and stlill we need headlamp bulb in the circuit. Best Regards.
You are welcome Suat!
I think you can start with the 8V transformer, it will not require a bulb in series since the voltage and current are quite low. If it doesn’t work then you can try the other higher rated transformers step wise until hopefully you find some improvements. For voltages higher than 8V, a bulb should be included for appropriate safety.
Thank you Swagatham.
So for 12V tall tubular batteries, the spike pulse must be <20V (understood, will tune my circuit).
What about the frequency? which one is best suitable / resonant freq for desulphation? 1kHz / 10kHz / 120kHz ? Is higher the better? if so which is optimal to select?
Regards,
Muthu.
Hi Vairamuthu, sorry presently I do not seem to have the details with me regarding which resonance frequency will be most suitable for a battery desulfation. I will look for it, if found will update it here for you.
Thank you Swagatam. Yes, my ask was based on the latest circuit that I shared. What is the impact of 220uH -> 330uH inductor value change? I see pulse little widens for latter – is that all?
If I make PWM duty cycle to <8% (8% ON and 92% OFF) then no heat and doesn't need a fan, but the peak pulse measured on battery is around 20V or less but above 14V.
So question is what is the ideal peak value of pulses that must be applied to the battery for desulfation? what is the impact of frequency here. Basically I want to know what is best suitable frequency & pulse duty cycle & peak value of the pulse for best result on desulfation.
Also, is there a way to remove shorts within the tubular battery (one if the cell is partially seems shorted) – any suggestions?
Then, I was googling thru' some desulfator liquid (esp from this website: .ecoglobe21 dot com Japan engineers claims it is 100% efficient and doesn't need any extra electronic circuits for desulfation) – still searching where can I get this Ionic Functional water. While searching I came across this "Thermoil Battery Desulfator" – is this same as Japan folks claim – not sure – but still exploring.
Any good suggestions is highly appreciated.
Hi Vaiaramuthu, I received only the oscilloscope waveform through your email, the other image was not visible, was it from the above article?
Anyway there is no ideal value for the spike pulse level, because the desulfating level of different batteries can be different….but according to me for a 12V battery the spike pulse should not be beyond 20 V.
Sorry I do not have any idea regarding how the short circuit between the internal cells can be removed….will need to be researched only.
Hi Swagatham,
I modified the circuit a little bit as shared, Applied pulse width of 10% Duty of 8kHz and I am see this waveform on the simulator. Is this correct? please clarify.
What should be the peak of the pulse that gets applied on Battery? When I increase duty cycle the peak pulse voltage to battery increases (close to 46V) and MOSFET / schottky diode / Toroidal inductor gets heated up. Is this expected?
Thanks Muthu.
Hi Muthu, I guess you are referring to the last circuit. I have not tested it so can’t say much about the peak spike voltage from the inductor. I will suggest you to keep the PWM to a level where the inductor, mosfet and the diodes remain cooler. The peak is not critical actually, any value that comes out without heating the inductor and the associated parts should be a good value.
Dear Swagatam,
I want to use the circuit “Using High Voltage Pulse” for tubular batteries of 160Ah / 12V C10 type. If you have the proto type circuit board which you shown here or may be a bare pcb and components which I can assemble, then let me know how to purchase from you? Also suggest what changes need to be done on MOSFET / schottky diodes for higher AH batteries?
Dear Vairamuthu,
I am sorry, I do not have a PCB design for the mentioned project so it will be difficult for me to provide it to you. For a 160 Ah tubular lead acid battery, you will need to charge it at 0.1C rate, which is at around 16 amp current.
I saw your simulation results, as given below. It appears to be a basic boost converter circuit and should have worked. You can try removing the D3. D4, and the coil L2, and then check the results.
Dear sir,
Good evening, my name is Johnson oluugbenga, many thanks for your effort in putting so much of your time in solving our problem. I have an Idea of how to desulfator a deep cycle lead acid battery, it goes like this.
1. First open the cover on the cell
2. Put some distilled water into it to cover the cell
3. Apply one of your desulfator say the one with 4047.
Pls I hope I make some sense because I have been running away from deep cycle battery for long as it’s not easy to desulfator them. Thanks hope to hear from you sir.
Thank you Johnson, I appreciate your feedback, and I think what you are saying may be correct and must be tried to get better desulfating results.
Thanks sir for your quick response, am going to desufate one of my 200ah and I will post the results thanks God bless.
You are welcome Johnson, wish you all the best!
You might want to use a modified microwave transformer in the first circuit . Remove the secondary and put 14 turns of high current electrical wire in its place. Cheap and effective?
Thank you for the update, hope the readers find the suggestion useful!
Dear Sir
in the circuit “Using High Voltage Pulse” would you be kind enough to share details such as core
size, wire gauge in swg, number of turns etc. for the L1(10mH) and L2(100uH)3A inductors?
Thanks in advance.
Hello Imsa, L1 can be any small 10mH readymade inductor. L2 can be built using a 1 mm copper wire over an air core former. Keep experimenting until you get the indicated inductance value of 100uH.
Thank you very much… will try out and see if I can make it work….
You are welcome!
I am having 12v 120ah battey to inverter,but it is 9 years old so for I hadn’t done desulfation.I want connect first circuit along with 3 amp bridge rectifier.How to set the pot,what may be current
The adjustment of the pot is a trial and error process. You can use around 15 V as the supply input and use the minimum pot adjustment to get the minimum pwm output. Then charge the battery with this pwm for many hours and keep checking the response. If it doesn’t work, try increasing the PWM and so on….
Thank you for good information l will try this
Hi there,
Just build and made it work your circuit with IRF540. Desulphated my 12V 7 Ah battery. As I can not measure the frequency, I set the pot in the middle.
Prior to the desulphation checked the output close to 15 volts. Desulphation lasted about 2 hrs.
After desulphation twice, my battery is now working condition, lights the 25 watt car lamp for at least 30 minutes.
Thank you very much.
During the desulphation process, I measured that my battery draws around 7 amps. Is this OK or likely to be that way or not.
If you can answer this I will appreciate..
All the best.
Hi, glad you could use the concept successfully for your battery, however the main indication of a sulfated battery is that it won’t accept current properly, but you are saying that your battery is accepting 7 amp current which indicates that your battery may be already in a good condition??
And providing 7 amp current to a good 7 Ah battery can be extremely harmful for the battery.
So the results are contradicting.
So please first confirm whether your battery is really sulfated or not?
Hi, thank you for the answer
The battery was well sulfated for sure. It was 11.6 v and 0,03 amps before the desulphation..
The contradicting part is, during the process, amp drawing is quite high from the circuit. (I measured with multimeter, serial to battery on amps position). Since I am not an electronics engineer, I make these circuits and make some basic measurements. What I do not understand is if your circuit capable of giving high amperage with 15 volts dc to the battery ? If it is, then the circuit is fine and running. (as far as I see..it is.)
But for sure, my battery is well working fine after two rounds of desulphation. Thank you again for your answers.
Best regards
OK, it is good that your battery is working normally, but now make sure not to use more than 1 amp for charging the battery. For this you can either add a current limiter circuit to your power supply, or use a power supply which has a maximum output of 1 amps.
Ok, will do.
Thank you for the answers.
Have a great day.
Regards
Zafer abiden ögrendin yutubda?
I have a variable voltage transformer and thinking to use a single diode circuit to built a desulfater . Since only half of the ac waveform will be useful, should I use 32V ac voltage to drive the single diode desulfator? Will it be more or less effective than the bridge rectifier circuit? Thanks.
Single diode rectification will also work for desulfating a battery, however 32 V may not be recommended for a 12V battery….if you want to use a 32 V supply for a 12V battery you can connect a 24V series bulb to protect against accidental high current
please clarify what you mean by “The current can be approximately equal to the Ah rating of the battery” to help me size my circuit. For example with a battery rated at 10 Ah, what would be the required current through the battery? E.g. 1 amp for 10 hours? or 10 amps for 1 hour? My understanding of an Ah value is both an amperage X a time. Thus a 10 Ah battery could deliver 100 amps for 1 hour (theoretically). Ah does not specify a current. Thanks for your help. Your circuits are exciting and I would like to try desufonating some lead acid batteries using this method.
A 10 Ah lead acid battery can deliver 10 amp for 1 hour and that’s it maximum capacity, which will ultimately destroy the battery sooner or later, so this rate is not recommended for lead acid batteries, for Li-ion batteries it may be fine though.
I meant that for 10Ah, use 10 amp current, however this may be OK only for a deeply sulfated battery, so the exact rating is not predictable….you can start with a 1/10th of the Ah current rating and then increase to its full Ah level gradually, and this voltage must be pulsed using a PWM circuit as shown in the above diagrams.
Good day Sir, please does some batteries form sulfation more and faster than the other. Thanks
Seun, sulfation depends on the battery manufacturing quality and how it is charged and discharged
Meaning less quality battery sulfates faster and more than better quality, right.
that is correct….but using it badly can do greater damage….
Thanks for quick response. For lead acid battery, how often should one desulfate, and for how long in a day.
You must desulfate a battery only when its performance drops, otherwise no need to desulfate….however, using a pulsed charging can avoid a good battery from getting desulfated, and increase its life….and also make sure the battery is never over charged, which is a big reason for battery performance dropping and battery slowly desulfating.
Hi, my name is Dan. I’m a mechanic (retired) and I live in Elko BC Canada. I was wondering if you have tried a pulsed current with a small AC component to de-sulphate a battery? I know there would be some AC using a rectifier bridge (0.7V), but maybe a little more say 2 or 3 V at timed intervals. thx looking forward to your reply – Dan
Hi, no I haven’t tried adding an AC element with the pulsed DC, but it looks a good idea and can help enhance the effect.
Hi Swag;
Considering the desulfator circuit with 555/IRF540, I have got two questions;
1- If I would use IRFZ544 instead of IRF540?
2- My source is about 5 Amperes capacity however I am able to limit the curent. My battery is 60 or 72 Amperes. So, please advise which ampere I should let the desulfator to absorb it.
Thanks too much.
Hi Suat,
1) IRFZ544 will work
2) 5 amp is OK for 60 Ah battery.
you can increase the voltage to 16 V for greater effectiveness…
Swag por favor publique um carregador automático para bateria estacionaria com fonte de corrente constante .
Hi Lobrito, you can try the following design, it is current controlled:
https://www.homemade-circuits.com/regulated-car-battery-charger-circuit-for-garage-mechanics/
Hi Swagatam;
Considering above first circuit with 555 IC. I see some familiar circuits with 200 uH inductor. Please advise if that is better to use inductor in such desulfator circuits or not. My other question is how we can test the desulfator circuit if there is no osilloscope device. Thanks.
Hi Suat, inductors can produce sharp spikes of boosted voltage which might to some extent help speed up the desulfation, but there are no strong evidences confirming the facts. The results can be tested with meters, like ammeter or voltmeter. Initially, an ammeter may show no proper response but slowly it may start showing some current reading indicating that the battery is absorbing current and getting charged.
Please what is the effects of using two desulfators on one battery.
I don’t think that is required, and won’t have any different effect
Thanks Sir for your reply, pwm desulfator working well. More grace to your elbow.
What modifications are needed to make 48v desulfator.
Thanks Swag.
That’s great Seun, glad it is working! For 48 V, you will have to provide the 48 V separately to the battery and the MOSFET, and power the IC 555 circuit by stepping down the 48V DC through a 10k resistor, 12V zener, and a 100uF capacitor
Thanks so much Sir, please where can I put LED to light during pulsations
Between pin#3 and ground via a 1k resistor. but you cannot see it flashing since the frequency is too high…
If possible,I want to see it flashing
for flashing you can reduce the 555 frequency to 1 Hz.
Good day Swagatam, for 48v desulfator, which is more efficient 1 single or 2*24v desulfator
2 circuits cannot be used, only a single 48V circuit will be enough
Hi Swagatam;
I realized that my previous message is not logical. Please do not consider since the UPS would be damaged. Thanks again.
Hi Swagatam;
I’ve seen a desulfator circuit which consisting of 220 AC input with serial connected 18 mF 400 V AC capacitor and output DC high voltage (about 300V DC) and low amphere after rectifier bridge diode. My car battery will support my UPS device circuit and at the same time my UPS will desulfate the same battery.(in order that to keep ECU data on) Please advise if this no good idea. If so then please advise I may use the above circuit with 555 IC but IRFZ44N instead of IRF 540. Thanks
For the transformer based desulfator, at what battery level do I cut off the battery full using 15v DC charging voltage
At 14.4V
Please Sir, can I measure the pwm effect by a voltmeter
Yes you can, the voltage will be proportional to the duty cycle of the PWM
Thanks for your reply.
Please is it OK to also add pwm desulfator when trafo inverter
charging is already present to a new battery.
If you use a simple pulsating DC for the battery charging then the desulfation can be automatically implemented
Thanks Swag for this piece. Please is it possible to design the pwm prototype to be connected to battery only without using external power supply? If yes, how
Hi Seun, PWM circuit without a supply connected to battery?? sorry I did not understand your question…
Good day sir, please how many days can I use to desulphate a battery left for 3weeks. What discharge level can the battery reach. Is it charging and discharging or continuous charging will be effective. Thanks Swag
Sorry Adyemi, It can be difficult to predict or assess the results for batteries which are not in a proper condition.
helo sir can we use a 100hz IC555 astable circuit to make this battery desulfator. please guide on it
Any reasonable frequency can be tried, it is a matter of experimentation, there’s no mandatory rule for the frequency
Greetings, think I will be making one of these pending some information as in the following circuit, can you inform me of the missing connection. In the case of the trimmer resistor, can it be replaced with a single resistor, given that no test equipment/o-scope is available to tune. Pin 5 of the 555 timer doesn`t seem to go anywhere. I am leaning in the direction of pin 5 going to the 220k trimmer?
Thanks
The IC 555 circuit shown above is correct, pin5 must be terminated with a 10nF capacitor as indicated to avoid stray signal pick up. Single resistor is not recommended because you must have the facility to optimize the frequency to get the best results.
Hi
Can I de-couple two unequal batteries e.g. 1 – 12volt 90 a/hr battery and 1 – 85 a/hr battery with diodes but charge them from two separate chargers?
I have a caravan with a 90 a/hr battery wired into the internal circuits and I also have another 85 a/hr battery with it’s own charger. I would like to connect an inverter to both batteries in parallel thus having
175 a/hr at my disposal but only for the inverter. I would like to continue powering the rest of the 12 volt circuits from the original 12 volt 90 a/hr battery but would like to have the added possibility of not draining the original (90 a/hr) battery completely, thus leaving power to run the internal fridge, water pump, lights etc. if the drain from the inverter becomes exessive. I have access to dual 40 amp schottky diodes which I thought that I could implement for this purpose but I am not sure HOW.
As the available power from these two batteries is much, I don’t want to experiment with it but would prefer to find a tried and tested circuit. You can guess why!
Can you help, please?
Thanks and regards
Ivor Barnett
The assumed idea by you is possible. You can connect the anodes of the schottky diodes with the positive of the batteries, and join their cathodes with the inverter positive.
You can get a rough idea from this article:
https://www.homemade-circuits.com/parallel-battery-chargerchangeover/
How are you? I used diode 6A10, and it still gets very hot. with the 110v x 12v transformer. Thanks for your attention.
Hi, What is your battery Ah?
lead acid 60 AP
OK no problem, in that case the best way to avoid diode heating is to use a 5 amp transformer. This will never allow the maximum current exceed 5 amps, so your 6A10 will never heat up.
Please. which data can I use to make a diode bridge? Because all the bridges I made, it’s getting very hot, I even changed the 110v x 17v transformer, I replaced it with a 110v x 12v one anyway, it keeps getting very hot. So which diode can I use to make a diode rectifier bridge? thanks.
It means your battery is consuming too much current. By the way which diode did you use? you can try 6A4 and see the response
How are you doing? Please, the indicated full load cut-off circuit, you can receive these 15v, as it says 12V input, on the relays? Thanks.
You can use 14.5 V or 15 V with a 12 V relay, no problem with that.
Hi Swagatam,
Is it possible to design low cost battery-desulphator.
How much it cost if we go for bulk production.
will you help me.
Rohit
8288883678
Hi Rohit, the second circuit is the cheapest one…you can replace the bridge with a single diode to make it even cheaper
sir can i do this? add a 7812 regulator before pin 8 and 4 of 555, sorry i dont know how to attach a image here
Hi Jindro, yes you can add it, if your battery is rated at over 15V
Hi Swagatam. Your contribution to knowledge is highly appreciated. Kindly provide formula for calculating the pulse frequency for the circuit above.
Thank You Abdul. you can get all the required information , in the following post:
https://www.homemade-circuits.com/timer-ic-555-explained/
Thanks a million! Quite explicit.
Thanks! Happy to help!
Many thanks for this selfless service.
I will go through the circuitry and do the needful, while hoping that I will not come across any difficulty as I set off to prepare it.
Thanks.
No Problems!
Thanks a million times for finding time, out of your obviously tight schedule, to go through my mail and respond so urgently.
I wouldn’t mind a charging current that could be varied between the neighborhood of 0 to 20A .
Thank you, it’s my pleasure!! I have a power supply design which has this feature, you can find it here!
https://www.homemade-circuits.com/universal-variable-power-supply-circuit/
FRANKLY SPEAKING, YOU’RE REALLY DOING A GREAT JOB!!! SOMETIMES I WONDER HOW YOU GET REMUNERATED DOING ALL THESE…… MY WORRIES IS HOW TO GET A CHARGING CIRCUIT WITH ADJUSTABLE CHARGING CURRENT. PLS e-mail me.
Thank you! please specify the maximum charging current limit for the battery?
hello sir Swag .. is the circuit above whether it can be connected with car alternator with 60 Ah battery and if required fuse. thanks (sorry I use google translation ?)
Hello Edy, it may be possible if the alternator output is suitably rectified, filtered and regulated at around 15V
Thanks Mr. Swag
Hi Mr. Swag,
Thanks for the reply. I used the 1n5408 diodes in series. Would I measure the current at the output of the Mosfet or the output from the diodes?
Hi Peter, you can connect the meter in series with the positive supply line …anywhere…. the current must pass through the meter, that’s the requirement.
Hi Mr Swag,
I have now built the circuit with the diodes in series, but find that the diodes get very hot after about 10 minutes. The Ic and mosfet however do not. Is this normal?
I have checked for solder bridges and found none. Input to the diodes is 20vdc and to battery pos 15.2 VDC. Output from the mosfet drain is 12.4VDC. Any help will be appreciated.
Hi Peter, which diodes did you use? check the current consumption during the charging with a series ammeter and make sure to use diodes that is rated 2 times more than this measured current consumption
Hi Mr. Swag,
Hopefully the last question. Can I use a 7815 voltage regulator instead of the diodes? What would be advantages /disadvantages.
Many thanks
Hi Peter, you can use 7815, but it will allow only upto 1 amp current for the battery….
Thanks a lot. I will use that until I can get the diodes.
sure, you can.
Hi Mr. Swagatam, thanks for the very good information all over the site. I have an AC to 24v DC transformer and would like to know how to get the voltage down to 15v and can I then use that? Your help is much appreciated.
Hi Peter, you can add 12 to 14nos of 1N5408 diodes in series with the positive line, this will drop the 24V to 15V
Thanks Swag,
If I understand it is 12 1N 5408 in series?
Peter
yes that will do!
Thanks
it is not shown by mistake, but it's understood, otherwise how the circuit will work?
Faith,
I think you are not able see my replies because you are not pressing the "load more" button….unless you do this you won't be able to see the hidden replies.
your second question is very strange, and It can be difficult for me to figure out the solution until I check the circuit practically…
Sir please answer me let know way forward
I have already answered, please press the "load more" button to the hidden comments
Sir this what i observe i noticed that even when there is no gate voltage to the mosfet the battery is still charging i went as far removing the 555timer to confirm this and notice the battery was charging please what could be the cause and how to correct it thanks
Faith, I think your mosfet is already burnt, or was originally faulty….instead you can try a TIP35 BJT, because BJTs are normally more rugged than mosfets and do not get burnt mysteriously…
Hi you are the best
I made this charger and its really working thank you very much please how do i include cutoff to this circuit
thanks Faith, you can use the following circuit for the cut off
ttp://162.240.8.81/~homembc5/2011/12/self-regulating-lead-acid-battery.html
Again should my duty cycle be 95% or 100% advice is needed in this case
duty cycle can be a matter of experimentation , start with 50% initially
Thank u for the reply
Ok can connect mosfet in parallel so that the current can be shared among them.
secondly the circuit seem not to have charge control which means one needs to monitor the battery so that it dont get over charge if that be the case how can i add a cut of can i use this circuit
https://www.homemade-circuits.com/2013/03/automatic-lead-acid-battery-charger.html?m=1 from this your post
Again is the mosfet N-channel or p-channel
If N-channel is it the drain that gose to the negative of the battery? While source to ground
yes connecting the mosfets in parallel will also work to increase the amps.
I won't recommend the linked 555 based design, instead you ca use the following one
https://www.homemade-circuits.com/2011/12/self-regulating-lead-acid-battery.html
the mosfet shown in the above desulfator article is an N channel, and its source is connected with the negative line.
Sir I'm really proud of you for ur good works and quik response you are one in a million. Sir about the above circuit can it be use to charge a 12v@600AH and if yes what modifications should i do. secondly the circuit seem not to have charge control which means one needs to monitor the so that it dont get over charge if that be the case how can i add a cut of can i use this circuit https://www.homemade-circuits.com/2013/03/automatic-lead-acid-battery-charger.html?m=1 from this your post if yes how i attached ithttps://www.homemade-circuits.com/2013/03/automatic-lead-acid-battery-charger.html?m=1
Thank you Faith,
you can use the above circuit for charging any desired battery, through appropriate modifications in the mosfet value.
for your application you will need to replace the existing mosfet with a 100amp rated moefet…
it means your 555 is not working or a is faulty, replace the 5K pot with 100K and replace the pin6/2 capacitor with a 100uF, and check the output if it generates the pulses or not…if still not, then you may think about changing the IC