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 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.
2) 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.
3) Using Simple PWM Circuit
This circuit diagram shows a simple 12V battery desulfator circuit made using a IC 555 timer and an inductor coil. Over time lead acid batteries get sulfated, meaning hard lead sulfate crystals deposit on the plates and reduce battery capacity.
This circuit generates sharp high voltage pulses to break down those chemical crystals and restore the battery.
In this circuit, IC 555 is wired in astable multivibrator mode. The 1k resistor, 5k preset pot, two 1N4148 diodes and 1nF capacitor connected to pins 2, 6, and 7 decide the switching frequency and duty cycle.
By adjusting the 5k pot you can change the pulse width and frequency.
The output from pin 3 of the 555 IC goes to the gate of the IRF640N MOSFET through a 10 ohm gate resistor. The 10k resistor from gate to ground ensures the MOSFET turns off cleanly without floating.
When the 555 output goes high, then IRF640N MOSFET switches ON. Current flows from the +15V DC supply, passes through the ferrite inductor coil (220uH to 1mH, 3 Amp rating), and goes through the MOSFET to ground. During this ON time, electrical energy is stored inside the magnetic field of the inductor.
When the 555 output goes low, then MOSFET suddenly turns OFF. The magnetic field in the inductor collapses rapidly, creating a very strong high voltage back EMF pulse at the junction between the coil and MOSFET drain.
Because this voltage spike is much higher than 12V, it forward biases the UF5408 ultra fast recovery diode. The diode directs this sharp high voltage pulse directly into the positive terminal of the 12V battery.
To protect the MOSFET from getting damaged by unabsorbed high voltage spikes if the battery gets disconnected or has high internal resistance, a 1.5KE47A TVS diode is connected across the MOSFET drain to ground. If the voltage spike exceeds around 47V, the TVS diode clamps the peak voltage safely, protecting the IRF640N from breakdown.
This repeated high voltage pulsing breaks the hard sulfate layer on the battery plates back into the electrolyte, improving battery charging and extending its working life.
Calculations
INDUCTOR ENERGY STORAGE FORMULA
E = 0.5 * L * (I^2)
Where:
- E = Stored energy in Joules (J)
- L = Inductance in Henries (H)
- I = Peak current through the inductor in Amperes (A)
This formula shows how much energy the ferrite coil stores during the MOSFET ON time. Higher inductance and higher peak current result in more energy stored to deliver stronger pulses to the battery.
INDUCTOR BACK-EMF VOLTAGE FORMULA
V = L * (dI / dt)
Where:
- V = Peak back-EMF voltage spike generated across the coil
- L = Inductance in Henries (H)
- dI = Change in current (Peak Current - 0)
- dt = MOSFET turn-OFF time in seconds
This equation tells why fast switching is critical. When the MOSFET turns off very quickly (dt is extremely small), then rate of current change (dI / dt) becomes huge, generating a high-voltage spike (V) to break sulfation.
555 ASTABLE FREQUENCY FORMULA
f = 1.44 / ((R1 + 2*R2) * C)
Where:
- f = Output switching frequency in Hertz (Hz)
- R1 = Resistance between Vcc and Pin 7 (1k ohm)
- R2 = Resistance of the 5k pot branch between Pin 7 and Pins 2/6
- C = Timing capacitor value on Pins 2/6 (1nF or 0.000000001 Farad)
This formula gives the frequency of the pulse generator. Adjusting the 5k pot changes R2 which alters the pulse repetition rate.
MOSFET ON-TIME FORMULA (DUTY CYCLE CONTROL)
t_ON = 0.693 * R_A * C
Where:
- t_ON = Time duration the MOSFET stays switched ON (charging the coil)
- R_A = Resistance in the charge path (1k + active portion of 5k pot via diode)
- C = Timing capacitor (1nF)
Questions & Answers
Hello sir..
i have 13 plate tubular battery 180ah 4 years old only + cell side of the battery is sulfated can i use 555 circuit to de-sulfate it?
sorry for my english..
can you guide me how much amp and voltage and frequency to achieve good results ?
Hi Happie,
Yes you can try the last 555 based circuit. Make sure to increase the C1 value to 470uF/100V or 1000uF/100V and use 2mm thick wire for the inductor…
hai pak
saya sedang melakukan experimen desulfator baterai SLA, menggunakan 555 apakah saya perlu menambahkan pengaturan frekuensi pada rangkaian berbasis 555, agar dapat menyesuaikan keadaan sulfasi baterai yang berbeda-beda
Hi Mahmud, yes you can add a frequency adjust pot to experiment with different battery conditions…
one more question which one is power inductor ?
L1 L2 ? or both need to wind with thick copper wire ?
L1 is the power inductor according to me, but I would recommend using 1mm wire for both the inductors…
This takes too much time, but progress is noted. Is there any other desulfator that powerfully knocks out sulfate crystals and reduce sulphation
Thanks for the feedback…desulfation process will be always slow, ….and it is always, slower the better…
PLS CONTACT MIERAJ 9920233666 WE WANT TO BUILD BLESS CIRCUT DIAGRAM WHICH IS AROUNF 555 IC , WE WANT TO USE IT IN STAND ALONE BATTERY LEAD ACID FLOODED BATTERY,HOW CAN YOU HELP US TO DEGSINE
Yes, I did use a 100uF capacitor instead of the 100nF one and is connected between P1 and P2 and now it measures 165.5kHz
You must change the 1nF at pin6/2 to higher value for testing the frequency.
And please reply to the same thread, otherwise it becomes difficult to track the question…
After sometime, the battery voltage climbed to 4V, but it can’t run a 3V toy motor. After I left it for 3 months, it became 0.03V. Another battery on which the same desulfation was conducted and left for 3 months is now at 0.356V. Is there any way to knock out the worst sulphate crystals without inductors
Please try the new updated circuit with an inductor, please add the inductor and test again…I am sure now will knock out even the toughest sulfation..
But it is a 4V lead-acid battery. So should I reduce the voltage to around 6V? and also, I don’t have IRF640N and 1.5KE47A. Can I replace it with IRF540N and what for 1.5KE47A?
Yes, for a 4V battery and with 6V supply, I think the IRF540 can work well and survive even without the TVS diode 1.5KE47A, because the max voltage spike may never reach beyond 100V even without the battery connected…so you can go ahead with those specifications…
Also, I don’t have UF5408. Can I use 1N4148. Sorry for disturbing you too many times. Thanks in advance
No, 1N4148 cannot handle that much current, you will have to use at least a 1 amp fast diode such as BA159 or FR107 etc…
So I directly connect to MOSFET drain
yes, connect the battery (+) to the MOSFET drain through a diode..
I had suggested this circuit, there’s no P1, P2 in this diagram. Replace the 1nF with 100uF and check the pin#3 with LED/1k to verify if your circuit is oscillating or not.
Please connect an LED + 1k at the 555 output and check its response, by changing the capacitor value to 100uF…that will tell you whether the 555 oscillating or not…
But I get 10V as my output that goes into the battery. Isn’t that harmful for the battery itself, provided the battery (4V 0.5Ah lead-acid) charger only provides 4.8V 150mA
If your supply voltage is 12V, then with PWM ON the DC output should be much less than 10V, maybe around 5V.
How are you measuring the output voltage?
The 12V will be in short bursts of pulses, not continuous 12V DC.
• How long do I need to leave the battery for to reduce sulphation in it?
• Should I get ~ 5kHz as the output?
• Should I also have ~2V at the output (Input 12V)?
• Which voltage is the best to use in the range of 6-12V?
All these will need to be monitored and experimented by trial and error until the most optimal value is found…
Hello Swagatam
As I understand, desulfation is based on applying pulses of higher than 2.45 volts to each cell.
Can “SLA (sealed lead acid) batteries” be desulfated in this way without reducing their electrolyte?
Hi SA,
Yes, but still it will require some trial and error experimentation, until the right specifications are attained.
According to me SLA batteries can be also desulfated.
It is not a matter of right specifications. The matter is that applying higher than 2.3 volts to a fully charged lead-acid cell will cause it to gas. Because SLA (sealed lead acid) batteries are sealed, their electrolyte cannot be added after gassing.
What do exactly mean by “SLA batteries can be also desulfated”? Do you mean that you experimented one of the above desulfation methods on “SLA batteries” and you observed that their electrolyte did not reduced?
When any battery gets sulfated that means it is almost dead and inactive, so to revive it we have to test through some trial and error method until the right PWM, voltage and current specifications are know….we can do this through a series meter connected.
Narrower PWM is better, but you will have to test and verify the results practically.
What is the 5k pot for? And can I replace it with a 4.7k pot if it is necessary
The 5k pot is for pulse width control, you can use 4.7k, or 10k, or 22k…
Try the 1st 555 circuit, use 6V to 12v as the input.
Can you make a desulfator circuit for a 4V lead-acid battery??
You can use the last circuit design…
Good evening Sir
I am an undergraduate student and I am having a bit of difficulty as to selecting a project topic for my mini project. I came across your website in the process of searching and wondered if you could be of help to me. My project has to involve a transformer and a rectifier and I dont want it to involve anything that has to do with smart detection or IoT. I await a positive response. Thank you for your cooperation
Hi Chizulum,
If your project needs to involve a transformer and a rectifier, that means it can be simply a standard transformer based power supply…you can try any one of these circuits, as explained in the following article:
https://www.homemade-circuits.com/how-to-design-power-supply-simplest-to/
hi Swag
how is the desulphation circut by AListair ocup powered if battery to be desulphated is flat
Hi Wayne,
It is difficult to judge if a flat battery would respond to a desulphation pulses, it will depend on the age and internal condition of the battery. Only a practical test could tell us if that’s possible or not.
In that case the bridge rectifier based design looks more effective to me…since it can deliver higher amounts of current.
I need a lead acid battery Desulfator complate cirkit. need things price .
Please can I use 150hz battery charger to charge lithium battery?
Do you mean charging the battery with a 150Hz frequency? Yes, that’s possible, but Li-ion batts don’t have sulfation problem I guess?
Yes to charge, won’t it affect the battery or cause fire
150 Hz won’t cause any harm to your battery, you can use it according to me, although it is not required. You should use a constant DC instead.
Thanks for the information it’s definitely useful.
Please don’t misunderstand but I would like to share some of the methods that I have used which works satisfactorily.
I used a charger that gives 17Volts @5Amp for 150AH Battery. Only important thing is that the caps/indicators have to be kept open because the water inside the battery starts boiling. This boiling water clears the sulphanation and it dissolves internally.
Another method I had used was I removed little acid from the battery. Then I prepared a solution by adding dissolving Epsom salt (Magnesium sulphate) in warm distilled water so that it dissolves quickly. I then top-up this solution to cover up the plates and then kept the battery for charging. This also refreshes the battery.
One more way is to drain out the battery. Pour into it hot boiling water, close the caps, shake well the battery for several times and drain the water. Doing this 3-4 times clears up the sulphanation. Then remove some acid from a healthy battery and add it to this battery and charge it normally. This method is also useful. I have refreshed many SMF batteries also by this method.
Finally one important point to remember is that the internal plates physical condition should also be better. Better meaning not damaged, else no method will work
The information you have provided is extremely valuable, and I hope the other readers will also find it very useful and effective.
Thank you so much for this contribution! It is much appreciated!
Hello, on the third circuit, I’m looking to build it but I don’t have all the exact components. 2 things, Can I replace the mosfet BUZ41 with FQPF4N90C? what are the main requirements for the mosfet? The other thing is the two P6KE 27 TVS diodes in series, can I replace them with SMAJ54? Likewise, in series?
Thank you.
Hi, FQPF4N90C is an ok replacement for BUZ41 if your current spikes does not go over 4 amps and if you use a good heatsink.
SMAJ54 in series will work but it will allow more voltage spike than 2x P6KE27, so it is less safe. Better to use 2x SMAJ27 instead for closer match.
Alright. Thank you.
Please what is the effect of using 500khz 500mA at 15v desulfator for 100ah 12v battery?
You can check it practically and verify the results, it won’t harm your battery for sure..
I appreciate your response. Thank you.
please won’t this also harm 18ah battery, at that frequency and 500mA.
High current and voltage can harm a battery, high frequency won’t harm a battery if the current is very low…
Hello sir, please is there any titration model to combine current, voltage and frequency in getting the best effect on desulfation.
Hi Bayo, the mentioned parameters will strictly depend on the existing battery conditions, which can be difficult to judge externally. So these parameters can be tweaked and tested only with practical experimentation experimentation.
Alimentions 15v
Le PLUS de 15v branché au PLUS de batterie
Mais le NEGATIF de 15v , ou branché ????
You need to get use a buffer between the 555 and mosfet for cleaner switching.
use a 7400 (CD series ic with all buffer paralled.
The first circuit on pwm desulfator, 555 calculator shows from analysis time High and low is about 0.00277ms frequency is 206 khz, the value I got from My design is 0.159ms for Time high/low each, frequency is 3.2khz. please help to compare these results. Thanks,
My goal is to make it as a charger to charge battery fast, so please what is your baseline guide in choice of appropriate parameters.
The charging conditions for aa sulfated battery cannot be predicted.
If you want a universal type of design, then you can build the design using IC 4047
Please any circuit as to this.
In the first 555 circuit, please connect a coil across the battery terminals, built using 200 turns of any thin magnet wire, over a ferrite rod.
Make sure to connect a 1N4007 diode across the drain source of the MOSFET.
The MOSFET can be replaced with a TIP35 transistor also.
Adjust PWM towards minimum and test the results.
I appreciate your response, should I use copper coil or aluminium coil as the thin magnet wire and what wire guage as the thin wire. What is the effect of this.
hello,can I replace BUZ41 with. IRFz44 power MOSFET and also SB560 sticky diode with SR 5400 diode in diagram 3
IRFZ44 and SR5400 will both work here but IRFZ44 has only 55V drain rating, so because this desulfator creates high inductive spikes, a higher-voltage MOSFET like IRF840 is safer for long-term use.
Always use copper coil, super enameled copper wire, 1 mm thick. The ferrite core rod can be 1 cm in diameter.
This will generate high voltage spikes across the battery, and hopefully break the sufation.
Different batteries may have different levels of sulfation, so estimating the PWM and the spike voltage can be difficult because the specs will be different for different batteries, that is why experimentation is necessary.
Hello sir, I made the pwm desulfator, which worked well with the 40ah LA battery. But I tried using same for 18ah la and lithium batteries, I had a fatal experience with explosions and damage to several 18ah la batteries.
Please how can I determine the appropriate pulse Value for the design to use for 18ah la and the lithium. Thanks Swagatam
Maybe the circuit is faulty and it may have caused dangerous conditions for the lithium batteries and they might have exploded
Hello Daniel,
The rule is to use a low current and high voltage (PWM spikes).
If you use low current, there’s no way your battery can get damaged.
For a 12V 18 Ah you can try 200 mA or 500 mA 24V PWM spikes
Hello sir, with 300mA, 35v, the charging is too slow at frequency of 16khz. Please how can I use the pulse charger for fast charging. Thanks.
Hello Daniel,
You will have to keep experimenting with the pulse PWM, frequency, and the voltage spike to find the optimal value, which can be different for different batteries. Alternatively, you can also try the following simple design:
However if your battery does not respond at all, that would indicate the battery is almost dead.
I aim at pulse charger for fast charging not as desulfator, please guide
Pulse charging will not help in fast charging, a step-charging with initial high current charging will do the fast charging.
Ok sir, how will I know the effect of the pulse in relation to the battery. I even used 20mA 19v for the battery.
Daniel, The exact magnitude cannot be estimated, it has to experimented through some trial and error. To can try low current voltage spikes of higher voltages upto 36V.
But 20mA is very less, it should be at least 200mA
Thanks,I will keep experimenting, is 60v 80mA bad for 12v battery
Can desulfator used for lithium batteries
No, not on li-ion batteries, only on lead acid batteries.
Please what should be the recommended frequency range
Again that will need to be verified with some experimentation.
Please sir, how will I know the experimentation is giving positive results?
Hi Daniel, you will have to check the results by verifying how much the battery has charged.
Hello sir, I made the first circuit and I found that for 60v design, it is better to use 5 separate 12v charger for each battery than a single 60v charger, please is there any modification in the circuit that will allow Me to use single charger for 60v. Thanks.
Hello Seun,
For a 60V battery, you can use a 60V supply for the MOSFET separately, and use a 12V supply separately to power the IC 555 stage.
Hi, Thanks for this. A couple of comments: The 2nd circuit should be attributed to Alastair Couper. not Ocup, and I think there should be series resistor in the positive supply rail to the 555, otherwise D1 and C2 will limit the output voltage pulse.
I agree with your comment about a series resistor to decouple the supply rail to the 555. As you say, without this D1 & C2 are effectively connected right across the output of the circuit. My homemade circuit board uses a 100Ω resistor for this.
Hi,
thanks for doing such a gr8 job designing, explaining the electronics with schematics and answering queries of so many visitors.
I was hoping you would be interested in designing a pulse charger for EV batteries. Obviously it’s not for desulphation but it’s widely accepted that PWM pulse charging is the best mechanism for fast and safe charging of EV batteries. It prevents dendritic formation and maximises efficiency. Rather than a continuous DC charge current, pulsed DC is best and it will enhance battery life and charge acceptance which is what EV users need. A CHARGE, DISCHARGE(for 100ms), SETTLE and MEASURE algorithm is needed. I hope this stirs your excellent creative genius.
Thanks for your valuable suggestion, appreciate it. Yes, pulse charging is actually good for all types of large chargeable batteries.
However, is there any critical algorithm for the ON/OFF duty cycle of the PWM, if yes then it could be difficult to design it using an analogue circuit. If not, then the first IC 555 based circuit can be configured to do the job very efficiently and very cheaply.
I have a question about the L1 in the 4047/339 version of these desulfators, it indicates a 10 mh value and I’ve been looking for a part # but not finding one. I see in the other version indicates a 1mh which is much easier to find. Does anyone have input on this?
L1 is easily available from most online electronic stores.
In this project, the current impulses from the L2 coil will discharge through the C2 and C3 capacitor to (-) of the battery, and through the circuit with the L1 coil. There is no other circuit with a battery. This can cause power voltage instability. Current impulses will also be heavily burdened with the C2 capacitor. Was that the purpose of this project?.
Yes, the purpose of the specified circuit is to create voltage spkes across the battery, to knock off the sulphated layers on the battery plates.
The question I have is in my case, I have 4x95a/hr deep cycles in parallel and they are all a little sulphated. I have them for an off grid power supply. I had a cheap PWM charge controller and it failed, so I replaced it with another of the same type which was at the time all I could get and afford until just the other day, So now I have a high quality MPPT which has made a major increase in the applied power from my 400w solar array. I have another 200w coming to add in in a few days. Anyhow, this has been the cloudiest year I’ve ever seen around my location, we can’t seem to get more than 2 to 3 days of sunshine then a week of clouds and rain. Would I need to build a circuit for each battery and connect it to each to give me a higher current output or would 1 circuit be able to recover all the batteries installed in the bank?
Yes you will need one circuit for each battery, or use a single circuit separately for each battery. The entire battery bank cannot be used with a single circuit.
Hi Swagatam;
I have scrap navigator equipment and it has 3,7 V battery inside. I think it is li-ion type battery. İt is possible to use desulfator charge method to charge that kind of batteries?
Regards
Hi Suat,
Li-ion batteries operate differently from lead-acid batteries and do not suffer from sulfation in the same way. Rather than sulfation, the principal degradation mechanisms of Li-ion batteries are capacity loss, electrode deterioration, and electrolyte breakdown over time.
As a result, the desulfation procedures utilized for lead-acid batteries are ineffective for Li-ion batteries. If a Li-ion battery is not working optimally or has lost capacity, it is usually better to replace it rather than try to desulfate it.