Author Topic: Guess What Will Happen: Battery Desulfation Experiment  (Read 41306 times)

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Offline TheRuler8510

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Guess What Will Happen: Battery Desulfation Experiment
« on: February 15, 2015, 05:17:30 pm »
Guess What Will Happen: Battery Desulfation Experiment

I bought a 12V, 12 AH size, lead-acid battery from Radio Shack during their liquidation sale (75% discount) , and it turns out to be completely dead, showing 0.002V and will not take a charge at all. Dummy me for not checking it first.

Since I can't return it, I plan to run an experiment that I always wanted to try. I will put a desulphator on it for day, weeks even months, to see what happens. It is running now. I hooked in parallel another 12V battery of similar size, that it needs to run. It is pulsing 110V pulses at 1 KHz.

So, your challenge is to guess what will happen, will this battery ever regain any life at all? Or is it a total loss and waste of time?

Enter your guess or opinion, and I will report back periodically as to progress.
  :-/O

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Offline NiHaoMike

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #1 on: February 15, 2015, 05:22:37 pm »
Use a standard light dimmer and 1uF or so mains rated cap in series to a bridge rectifier. Set the dimmer about halfway and it will nicely generate the fast spikes that are needed to desulfate a battery.
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Offline Seekonk

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #2 on: February 15, 2015, 06:39:03 pm »
I give it some hope because it was never used (are you sure of that?) but not much.  I have a solar camp and get a lot of batteries from the town recycling.  When those are test below 5 or 6V, they will never recover and I would be happy with 2-3AH.
 

Offline tautech

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #3 on: February 15, 2015, 06:57:24 pm »
I'd be surprised if you get that battery to recover to a state of usefulness.
It may bounce back for light use, but anything like 12 AH  :--

Played with LA desulfating for ~20 years and yes it is useful.
Units I  :-/O would produce 70V 6A pulses @ 1 KHz.

Neat to see the battery OC voltage rise after a session on the desulfator.  :-+

Good luck but I don't like your chances.
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Offline SeanB

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #4 on: February 15, 2015, 07:06:46 pm »
Sealed batteries need water added, and i had some moderate success with popping the top plate off and adding water ( around 15ml per cell) then gluing the top back down. Charge overnight with a current limited 24V supply and see the next morning if it recovered somewhat. About 1 in 10 got good capacity back, but the cheap ones never did.
 

Offline mikerj

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #5 on: February 15, 2015, 07:40:45 pm »
If this is a gel battery then you have almost no hope at all.  If it's a proper lead acid or AGM battery them you might coax some life into it, but it will never meet it's new specs.
 

Offline Fraser

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #6 on: February 15, 2015, 08:11:37 pm »
To the OP

Have you ever seen inside a sulphated AGM battery ?

If you have, you would know the damage that can occur in the gel mat and plates. This is not an absolute however so you may be lucky. I have tried, on many occasions to preserve and recover the capacity of AGM batteries. If AGM batteries have sat at less than around 11V for more than 6 months they may as well be a capacitor. I have been known to prove this by applying over 120V D.C to such a battery in a demonstration of 100% sulfation....... the battery did not take a charge even with such abuse and indicated only a few mA's of current draw. If it will not draw enough current, its hard to convert its chemistry back into a useful battery/cell.  If it draws a reasonable current at 14.8V it should recover OK after some TLC.

Sadly it is my personal experience that a deeply discharged AGM battery that has remained discharged over a long period, is beyond recovery to any meaningful capacity and even if you strike lucky, would you truly trust such a battery ?

You have nothing to lose by trying recovery techniques but the laugh would be if you expend money on a 'special' charger (plus your time), that actually exceeds the value of the battery. Good money after bad ?  Just my 2 Cents  :)

Update: This web page details sulfation, what it is and possible recovery methods. Remember what I said though..... investment Vs return has to be considered if you do not already have teh correct equipment.

http://bestbatteries.co.nz/battery-care/battery-faults.html

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« Last Edit: February 15, 2015, 08:29:30 pm by Aurora »
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Offline cosmicray

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #7 on: February 15, 2015, 08:25:13 pm »
You might want to keep some baking soda handy, just in case you have an unfortunate core breach.  :scared:
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Offline Fraser

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #8 on: February 15, 2015, 08:48:21 pm »
This thread brought back happy memories of maintaining my collection of various AGM batteries. I was in Australia at the time and wanted a means of exercising the batteries as Pb based technology likes to be used in order to provide a long life. Sounds odd doesn't it...yep Pb batteries do not like sitting on charge doing nothing unless they are specifically designed to cope with such stand-by conditions.

I had the correct 2 stage chargers but no way to discharge the batteries automatically so that they went through an automatic charge-discharge-charge-discharge-charge cycle once a month. This was back in 1990 and I know a PIC controller could do this in its sleep but I went the analogue route.

The charger had a 'Chargeng' LED that I tapped for the 'full' state detection (it switched off with no battery or a charged battery) and I used a simple comparator to set a battery discharged (empty) threshold. A relay was controlled by these two state indicators via a transistor (or two?) and this relay applied either the charger or a resistive load to the battery. It only took a heavy duty relay and a few common components to build the little switching unit.

Once connected to the battery, the circuit continuously cycled through the charged & discharged states until disconnected. This simple attachment not only kept my good batteries healthy, but also recovered the capacity of some of my lazy batteries that may have been partially sulfated. I still have that little veroboard circuit knocking around in the loft somewhere. I can certainly recommend a battery exerciser.

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« Last Edit: February 15, 2015, 09:14:45 pm by Aurora »
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Offline Muttley Snickers

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #9 on: February 15, 2015, 09:39:15 pm »
The battery that the OP is conducting a test on will have a date code and this information is relevant in regards to the batteries ability to recover. If the battery is a few years old and in addition to the initial measurement of 0.002 which is rather low and I suspect possibly had its day, my money is on its buggered.

However, if the battery date is recent and no other faults are present then these can come back from the dead but are never the same.
« Last Edit: December 13, 2016, 02:35:10 am by Muttley Snickers »
 

Offline Circlotron

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #10 on: February 15, 2015, 09:51:50 pm »
Back in 1990 I worked at a place that sold UPSs. Some had been in storage for several years and the batteries would be replaced before sale. The old batteries would be typically at 1 or 2 volts. I experimented a whole heap with the old batteries and eventually had great success with the following formula: Apply a REVERSE charge with current limit set to 2% of Ah rating for 48-72 hours. The battery may not draw any current initially but just leave it alone. After this time, set the charge to normal polarity and charge for 3-4 days, still with the 2% current limit. During this time, do NOT be tempted to wind up the current limit - one cell will start to get hot and then it is junk. Fixed many new but neglected batteries this way. One 12v 24Ah SLA Yuasa started off at 2 volts and had been sitting for about 3 years, got it going and used it in my Diahatsu Charade for 2 years until I sold it.
« Last Edit: February 16, 2015, 12:13:58 am by Circlotron »
 

Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #11 on: February 16, 2015, 07:51:18 pm »
It is pulsing 110V pulses at 1 KHz.
What about duty cycle?
I have desulfator mode in my custom car battery charger, but maximum voltage after transformer is 24Vmax and duty cycle <10% .

BTW: Desulaftor mode is switched on by.... shorting inductor in buck converter with 2 x IRFZ44N in parallel on lead-acid battery minus (-) terminal.
However, without capacitors after diodes bridge mosfets worked like 55V Zeners in avalanche while voltage maximum across this switch was about 65Vmax etc  :-DD
Anyway at low duty cycle those caps create nice 24Vmax, so while there is bypassed inductor I have quite nice desulfator when needed  >:D

There is about 5% @ 1kHz in one of those 555 based desulfators which were inspiration to my ATTiny85 based:


Do you have some recomendations about this duty cycle and preferable frequency and Vmax in those desulfators for 12V lead-acid car batteries?
« Last Edit: February 16, 2015, 07:55:49 pm by eneuro »
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Offline tautech

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #12 on: February 16, 2015, 08:16:33 pm »
It is pulsing 110V pulses at 1 KHz.
What about duty cycle?
Duty cycle for a 555 based unit is dependant on the inductor chosen/built in order not to saturate it.
1 KHz is just a convenient switching frequency, however the pulse edges are many times this.
The desulphation is performed by the voltage developed from the colapsing field back emf when current to the inductor is switched off.
Each battery will absorb this back emf pulse in a different way, results scoped at the battery terminals will be different to those at the desulfator output.
For efficiencies sake short heavy leads are a must.
« Last Edit: February 16, 2015, 08:21:58 pm by tautech »
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Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #13 on: February 16, 2015, 11:15:04 pm »
For efficiencies sake short heavy leads are a must.
Probably this is most classic desulfator circuit I've found when was looking for such sort of things a few years ago:
http://www.frontiersprings.com/desulfator.html
Anyway IRF9Z34 P-channel mosfet http://www.vishay.com/docs/91092/91092.pdf is wrong drawn in this frontier schematics, so it might be a trap  :palm:
However, I do not liked messing with inductors and 555 while it is was only a few lines of code on AVR to add support for desulfator mode to battery charger.
It doesn't mater how 1kHz frequency is created, but knowledge of proper duty cycle  might be critical, so it will be difficult to compare different available desulfators without its waveform specyfication  :-\
« Last Edit: February 16, 2015, 11:16:55 pm by eneuro »
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Offline TheRuler8510

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #14 on: February 17, 2015, 11:53:51 am »
Update & more info:

I don't know if it is a gel-cell or AGM, but the exact battery I am using is this:
http://www.radioshack.com/enercell-12v-12ah-sla-battery-w-f2-terminal-250-tabs/2301219.html#.VOMhrHvRXdE

The Desulfator I am using has a very narrow duty cycle, <0.01%. It works by using the battery voltage as a power source, hence why I put another 12V in parallel, and may be a fault in the plan.

The only number that looks like a date code says 12/10, if I am interpreting right. Seeing how dead it is, 5 years old is believable.

So far, after two days the results are disappointing. The OC voltage is now 0.05V--hardly any effect at all.  Part of the problem may be the 12V battery I have in parallel to power the desulphator, may be sapping any effect.

If I get no further improvement in another day, I will try Circlotron's method of applying reverse voltage for a bit. Out-of-the-box thinking may be needed here.


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Offline Muttley Snickers

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #15 on: February 17, 2015, 01:12:04 pm »
The date code of 12/10 will most probably be YY/MM so October 2012, I'm on the fence with this particular one, but out in the field we don't give these any longer than 3 years unless it's a Yuasa or Sonnenschein which can still be ok after 5 years, dependent on installed system.

Cheap nasty brands like Neuton Power would be lucky to last 2 years and your's I suspect will be similar. Also some UPS's tend to cook these batteries and shorten their life. But just a note, I have never bothered to give one resuscitation, we just let them die in peace, the poor old souls, zombie batteries scare the hell out of me and my systems.
« Last Edit: December 13, 2016, 02:29:34 am by Muttley Snickers »
 

Offline Seekonk

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #16 on: February 17, 2015, 02:53:38 pm »
If you place two batteries in parallel, I would place a good size inductor (like a 12V secondary of a transformer) between the two.  That would keep the pulses on the defective battery.
 

Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #17 on: February 17, 2015, 04:04:00 pm »
The Desulfator I am using has a very narrow duty cycle, <0.01%.
Did you checked scope waveforms etc to see how this desulfator waveform on battery terminals looks like and which is Vmax on battery during desulfation when this pulse hit its terminals?
Even without scope it can be done using fast 1N4148 diode and small cap in parallel to battery with hihg resistance multimeter and on bad battery those voltage spikes will be higher and during desulfation this voltage should go down....while internal resistance of repaired battery should improove and be lower than before desulfation...

Really you have 0.01% duty cycle?  ???
Which is operating frequency of this "desulfator"?

I will  :-/O my desulfator tomorow while from time to time trying to improve software in my prototype battery charger, so will try two different batteries-old VARTA L2 12V 640A and new one VARTA Silver to see how those desulfator voltage spikes differ on brand new battery and probably much more sulfated 7 years old VARTA L2  :-BROKE
« Last Edit: February 17, 2015, 04:17:46 pm by eneuro »
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Offline Fraser

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #18 on: February 17, 2015, 04:20:53 pm »
I know this is really just an experiment on recovery of a possibly 'dormant' battery, been there done that, but if the OP had been in the UK I would have saved him any possible disappointment and sent him a replacement at cost of postage only. I have several brand new Yuasa 12V 17Ah and 12v 38Ah batteries in my garage that are in A1 condition. I always like to have some in stock in case of need but give them a top-up charge every 3 months as recommended by the manufacturer.

I have absolutely no issue with people trying to resurrect sulphated batteries but from a commercial point of view, time is money and they are just not worth the time or effort and can never truly be trusted even if they appear to 'recover'. 

As a side note, I also look after my cars batteries and it shows in the life that I get out of them. We do a lot of short trips, often with headlights on and rear screen heater running in the winter. The poor batteries have a hard life as a result as the starting charge is not recovered on each journey. I tend to 'top-up' the charge every couple of months. My Audi and my Wife's Nissan are still on their original batteries and both cars are from 2005. 9/10 years out of a car battery is easy to achieve if the battery is a quality product and looked after. Some owners just hammer the battery in this age of little or no maintenance and then wonder why they need a new car battery every 3 or 4 years, sometimes less. At the end of the day, it is personal choice. I am a electronics and communications engineer (in UK terms) and still believe in preventative maintenance, where appropriate. Some preventative maintenance can do more harm than good but that is another story.

I have just bought two new batteries for our cars, not because the old ones are shot, but purely due to preventative maintenance....why risk a complete failure and resultant stranding when the battery has obviously had a long service life (approx 10 years) and is due for replacement on those grounds alone. The old batteries will be looked after and likely gifted to someone in need of a spare or temporary replacement. The new batteries are from a local car parts supplier (Halfords UK) and are made by Yuasa, a quality brand, and they are decent batteries for around GBP60 each. Risking a complete battery failure for GBP60 would be considered foolish, hence the application of common sense. The old batteries owe me nothing  :)

As a student way back in 1985-7 things were very different. I had a 1971 Mk1 Ford Escort (wish I had kept it) battery charging systems were not as refined as these days and the Escort had a D.C. Dynamo as the charge generator. The battery was so knackered that if the engine did not fire in less than about 10 turns the battery was flat ! I nursed that old battery for two years before finally giving in to the obvious. It was time to replace it. I had resorted to keeping the battery on charge overnight during Winter and warming the spark plugs to get it to fire up on a very cold morning with thick oil in the sump. Extreme measures, but when you do not have the money for a new car battery, you have to improvise. These days I can't believe I went so far to keep the old decrepit battery going......I doubt any modern student would do such and may even consider me crazy. Times change !

So when people talk about looking after Pb based batteries and recovering them from the dead, I know what you are thinking.... been there, done that, got the T shirt  ;D

I wish the OP well in his valiant endeavours to breath life back into the sulphated battery.....but please do not be too disappointed if/when you fail in that objective. As has already been said....maybe it will just be a case of letting it rest in peace  ;)

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« Last Edit: February 17, 2015, 04:27:36 pm by Aurora »
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Offline tautech

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #19 on: February 17, 2015, 06:52:36 pm »
Back in 1990 I worked at a place that sold UPSs. Some had been in storage for several years and the batteries would be replaced before sale. The old batteries would be typically at 1 or 2 volts. I experimented a whole heap with the old batteries and eventually had great success with the following formula: Apply a REVERSE charge with current limit set to 2% of Ah rating for 48-72 hours. The battery may not draw any current initially but just leave it alone. After this time, set the charge to normal polarity and charge for 3-4 days, still with the 2% current limit. During this time, do NOT be tempted to wind up the current limit - one cell will start to get hot and then it is junk. Fixed many new but neglected batteries this way. One 12v 24Ah SLA Yuasa started off at 2 volts and had been sitting for about 3 years, got it going and used it in my Diahatsu Charade for 2 years until I sold it.

interesting ... what does the reverse 2% trickle do?
I wonder too.
This is interesting info and obviously based on trial and error.
The results speak for themselves.  :-+
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Offline tautech

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #20 on: February 17, 2015, 07:43:40 pm »
For efficiencies sake short heavy leads are a must.
Probably this is most classic desulfator circuit I've found when was looking for such sort of things a few years ago:
http://www.frontiersprings.com/desulfator.html

However, I do not liked messing with inductors and 555 while it is was only a few lines of code on AVR to add support for desulfator mode to battery charger.
It doesn't mater how 1kHz frequency is created, but knowledge of proper duty cycle  might be critical, so it will be difficult to compare different available desulfators without its waveform specyfication  :-\
Yes the schematic is a long copied one.
See how the Fet when on supplies a current into what appears to be a short circuit but the inductors absorb the current until they saturate.
This is where the duty time is critical, they must not be allowed to saturate. Fet on time controls this and at turn off the released back EMF from the inductors collapsing field does the desulphating.

The greatest gains of this circuit are made with custom inductors and  :-/O to duty cycles.

A scope Current probe becomes very handy to monitor for saturation and measure the ouput pulse improvements.
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Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #21 on: February 17, 2015, 09:41:17 pm »
This is where the duty time is critical, they must not be allowed to saturate. Fet on time controls this and at turn off the released back EMF from the inductors collapsing field does the desulphating.
Maybe this analog circuit with 555 needs some tricky  :-/O to get it working, so of course never wasted my time to mess with its internals, however made of course simulation of this circuit in software to see how it works ;)

In my car battery charger I can easy update in software desulfator mode simply by limiting maximum PWM duty cycle to lets say between 1% -5%  @ 10kHz PWM with bypassed inductor.
Just looking into its AVR code and probably will have to ensure that battery voltage measurements are made when there is no desulfator spikes, so this charger itself will keep batery at safe  floating voltage 13.5V-13.8V in desulfator mode, while sometimes desulfator spikes can have too small total energy to keep desulfated battery voltage at floating voltage, so if battery voltage in desulfator mode will drop below 13.2V it will automatically increase maximum PWM   to 50% to reach floating voltage 13.5V (switch to standby mode) and then return back to desulfator mode with decreased maximum allowed PWM duty <<10% .
This way power consumption to perform  desulfator mode should be very low while duty cycle will be limited to 1%-5% so @ 24Vmax and it costs not so much kWh even during a few months  of desulfation mixed with keeping battery at full charge at floating voltage 8)

Update: Probably will add AC mosfets switch to make automatic bypassing of inductor and slightly limit spike currents to levels safe for battery.

This is another interesting question-what optimum maximum desulfation spike current might be for 60Ah-70Ah 12V lead-acid  battery?  ::)
« Last Edit: February 17, 2015, 09:59:00 pm by eneuro »
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Offline tautech

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #22 on: February 18, 2015, 01:20:11 am »
Maybe this analog circuit with 555 needs some tricky  :-/O to get it working, so of course never wasted my time to mess with its internals, however made of course simulation of this circuit in software to see how it works ;)

This way power consumption to perform  desulfator mode should be very low while duty cycle will be limited to 1%-5% so @ 24Vmax and it costs not so much kWh even during a few months  of desulfation mixed with keeping battery at full charge at floating voltage 8)

Update: Probably will add AC mosfets switch to make automatic bypassing of inductor and slightly limit spike currents to levels safe for battery.

This is another interesting question-what optimum maximum desulfation spike current might be for 60Ah-70Ah 12V lead-acid  battery?  ::)
The 555 circuit IIRC only produced 2-3 Amp pulses @ 30 V and any reasonable variant will work to some degree.
With some tweaking and a custom 220uH inductor that can be doubled or more.
Power cosumption was never an issue the std desulphater as battery capacity and OC voltage increased while in use.  :wtf: This is the desired result, but how can that be observed when you charge at the same time.  :o

As for good sized starting batteries, the more I could give them the better/faster the result.
I remember spotting a mains powered unit that IMO was a "kill or cure" method as the output was so large.

If I had any LA battery that measured under 10V results were poor.
Sometimes a top up charge followed with rest to stabilize voltage, then desulphate might bring them back, the key indicator was the OC voltage rise after desulphation.
While only tenths of a volt, it indicates battery improvement as the internal chemistry changes even though the desulphator consumes current.
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Offline NiHaoMike

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #23 on: February 18, 2015, 06:29:47 am »
The beauty of the dimmer based desulfator is that you could change the strength of the pulses by changing the size of the capacitor. For a typical car type battery, use a 10uF or so motor run cap. (On 120V mains at least - halve capacitor values for 240V mains.)

A variant on this is to get rid of the dimmer (so now it's just a bridge rectifier with a series cap connected to the mains) and replace it with a SCR and some sort of voltage based trigger circuit in series with the output. That can help if you're dealing with big batteries that require too much current for a common light dimmer to handle. A further variant is to change the bridge rectifier to a single diode so that the cap gets charged to the peak of the mains voltage on the negative half cycle, followed by the SCR triggering near the peak of the positive half cycle.
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Offline eneuro

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Re: Guess What Will Happen: Battery Desulfation Experiment
« Reply #24 on: February 18, 2015, 08:12:45 am »
Power cosumption was never an issue the std desulphater as battery capacity and OC voltage increased while in use.  :wtf: This is the desired result, but how can that be observed when you charge at the same time.  :o
Trick is this charger is powered from charged battery itself, so I can  monitor its voltage all the time  ;)
Additionally its controll circuit without LCD display etc has such low power consumption that its power supply current is limited by 100 Ohm resistor and 24Vz Zener trying to protect LDO LM2940T  5V on its inputs.

Bigger concern is if those spikes are not consumed in charger PSU while it sits on battery, but while even sulfated battery has much lower internal resistance and lower voltage accross battery those spikes should hit battery most of the time.

A further variant is to change the bridge rectifier to a single diode so that the cap gets charged to the peak of the mains voltage on the negative half cycle, followed by the SCR triggering near the peak of the positive half cycle.
With MPU on PCB its better keep full bridge reactifier and measure input voltage on capacitors after full bridge and when it falls below given level (eg. 24V) than switch off PWM and wait in software for proper voltage, so with 250kHz ADC clock and 13 clock per ADC measurement one can monitor this voltage close to 20000 times per second.

Probably will make another MPU based desulfator with support for many batteries at the same time with simply optoisolated voltage feedback when battery voltage reaches 13.5V to have some kind of overvoltage protection and be able to keep all those desulfated batteries at safe floating 13.5V-13.8V voltage  ;)
« Last Edit: February 18, 2015, 08:16:43 am by eneuro »
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“Let the future tell the truth, and evaluate each one according to his work and accomplishments. The present is theirs; the future, for which I have really worked, is mine”  - Nikola Tesla
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