Lead Acid Battery Desulfation? Does it really work?

Yes, it works.

The machines you can buy in the stores or the internet are nearly all useless.

To desulphate effectively within a reasonable length of time you must have strong pulses with straight-up leaking edges to the spikes.

Say for example you've got a 60A/h battery from a car that's been sitting for five years.

The voltage is a few volts with the connections pulled. You try to charge it using a normal charger overnight and the next day it is still useless.

You do another charge and leave it charging for a full day, and it's still not going to crank even a motorcycle. - That's what a sulphated battery gets like.

Lead/acid batteries must be kept charged or they will sulphate. (alleged) maintenance free batteries that are valve regulated and are not flooded are able to be left for longer periods between charges than regular (with caps) batteries, but they don't last long for a few other reasons, and in the end still get sulphated.

Here's what to do:-

1. Open the caps and check the electrolyte's specific gravity. If it's sulphated then the SG will be so low the balls won't float, or the float sticks at the bottom. With this battery, the sulphur in the acid has left to form lead-sulphate on the plates. Over time this has hardened and what you have now is an insulating layer of lead sulphate (crystals) which won't give its sulphur back to the acid, and forms an impenetrable layer so it won't charge or discharge much if at all.

* Sometimes these lead sulphates form a colony so big that parts of it push the plates next to it and can short some or all of the plates. If this has occured then your voltage from a nominally 12V battery will settle at around 10.5V. If this is the case then it's a doorstop. Even if you've got a use for a 10V battery then the chances are if one cell has shorted then the rest aren't far behind.

2. First of all put enough distilled water in each cell to cover the plates. DON'T fill the cells to the max-mark. The reason for this is that the level will rise as a charge is taken in, and if you fill it to the max then it will become over-filled, which means the electrolyte is too diluted and/or you get (highly destructive) sulphuric acid everywhere.

3. Now here's where most won't be able to go. - Have a 20V DC supply pulsed into the battery. Have the duty cycle as 1% to 10% and pulse it with a square wave, or any wave providing the leading edge is pretty much vertical. The trailing edge isn't so important, but that should be a vertical line as well if possible (I'm poor and scavenge parts so the devices I make aren't so great so the trailing edges aren't straight).

* You have to keep your eye on the battery and keep the battery between fifteen volts and sixteen for about two or three days - with the pulses, not a straight charge.

* You'll need to add distilled water to one or more of the cells as you go, so look at them occasionally.

If you smell hydrogen sulphine (bad eggs) then that's a good indication of a shorted cell - if so then the battery's stuffed.

After a few hours of this "punching" by (relatively) high voltage, high current (1 - 200A variable) you should see the SG rising in all cells. After three days they should all be in the green if the battery isn't physically broken. If the battery's plates or internal connections are shot then there is no practical way to fix it.

After three days the battery is ready for a test - it might even do for your car at this stage. When the pulsing is done, then add distilled water to the high mark and test.

If, when discharged slowly, the battery seems to be OK but when under heavy load such as cranking, it goes dead then an internal connection is loose. The battery is junk. - & risky because an internal spark from a poor connection could ignite the hydrogen and oxygen gas given off during charging. (Very big bang).

If the (60A/h) battery's capacity is tested to be more like 10, then it m-i-g-h-t start a small car, but what's happened is the positive plates have rotted over time and are now so effectively small that the battery is acting like a very-much smaller one. The battery is as good as junk, or to mess with low-power stuff on your bench or something.

If one or two cells are bubbling a lot then that's a short. The battery is toast.

If one or two cells' SG is far different from the rest then it indicates the plates of those cells are either disconnected and are just hanging there by the insulating layers or that the plates are extremely corroded. The battery is not much use, but might get you out of a fix.

What desulphating by electronics does is to get the battery to the best condition it can be in depending on its physical condition. It won't fix a battery with plates that are corroded or broken.

I make my desulphators with the transformer of (for example) a mini-arc welder and the pulses exit the transistor blocks I find in the control circuits of inverter air conditioners. I make a simple asymetrical multivibrator with two transistors and vary each side's 'clock' duration with resistors and capacitors. I deliver the signal to the output transistors with a relay, and my pulsers tend to operate at about 10 - 100pp/s. I think low speed high current works better than lower current pulses. I use a relay because they give me a perfect sharp leading edge to the spikes... The residual capacitance in the semiconductors is what causes the trailing edges of my machines to linger - I'm poor so I can't buy a proper driver circuit and make mine from bits here and there.

So yeah, desulphators work - but they work on the sulphates only and won't fix a battery that is basically broken.

I get ten years at least from starting batteries. Deep cycle batteries last me twenty years, and marine batteries somewhere between the two. I fix batteries for friends, and pick them up from junkpiles - nearly all the ones I find I get to cranking again.

* The bought ones are crap. You have to make your own and the spikes should deliver a real whack or it won't work.

The true death of a battery is when the positive plates decompose to the point where it won't hold a useful charge. There's no getting around a rotted positive plate, and today's car batteries are crap and are getting worse. - Well made batteries have thicker plates and can last decades. - still! with care, you can get three or four times the usual use from a cheapo car battery if you know what to do.

I'd advise against the (alleged) maintenance-free batteries, but it's true that they are reliable for at least a year and likely two. MF batteries are fine for women or lazy men. Get the old type with caps you can remove. There is no such thing as a maintenance free lead acid battery - they need maintenance or they will die.

Also - find which company makes good batteries and pay the extra because they'll last much longer than the cheap shit creeping in on the shelves of automotive stores - and finally, put in the biggest battery you practically can for your car. The bigger battery will last longer.

* Sorry about typos.

Last Edited by mael on 01/15/2012 08:06 AM

Car battery MASTER. ^^^^

Some people use various chemicals to desulphate a battery. I have experimented a lot with chemicals. I don't want to go into what I've done or used but I want to say I do not advise using chemicals to desulphate a battery.

Don't add new acid or adjust the SG so it's far-from the 36% ideal. When the electrolyte is low the SG will be a bit high, and if you overfill it then it'll be a bit low. Only add distilled water and nothing else.

*But if the battery is otherwise stuffed then what have you got to lose - such as if it was a freeby or something.

Using chemicals tends to accelerate the rotting of the positive plate. - The negative plates last forever, but the positive ones are formed from lead oxide on a lattice of some lead alloy and will soften, distort and rot. Cheapo SLR batteries are made to fall to bits and although there are some promising chemicals which might harden those positive plates, I don't know any I'm happy with handling - but they do exist, and phosphoric acid is one of the two acids which can be added to strengthen the positive plates.

A battery which has been left sitting in a discharged condition will have its acid concentrated at the bottom. It is the concentrated acid which rots the plates the fastest. When the battery is in the car it gets the acid swished around and properly mixes but if it is sitting then slowly the acid will become concentrated at the lowest part of the battery. You can rock the battery for a bit to mix the electrolyte in a flooded battery that isn't in a car which is driven.

Last Edited by mael on 01/15/2012 08:36 AM

Pulser power supply:-

A mini welding transformer will have an open voltage of perhaps 40 and will deliver at least. These can give good pulses at at several tens of amps and even hundreds if the rectified output of the transformer is stored in caps, so they are good to use.

I said 20V, but that'd be about the minimum I'd like to work with. The priority is the current in a sharp leading edged-spike.

With the immediately above in mind it is also possible to use a rectified DC supply over 20V.

* What I failed to mention is that I store the voltage from the transformer in a bank of electrolytic capacitors. The output transistors connect a bank of large capacitors charged to up to 40V. A common capacitor (condensor) bank of my machines would be about 15,000mFd at (say) 40V. (That's a big whack)! I couldn't get big enough pulses from the rectified transformer output even from a welding transformer.

The store-bought desulphators boast about high frequency X-million amp pulses - but it's bull. Those machines might work if you left them pulsing for a month. They are 'smart' chargers. They are OK for new batteries but they are really just ordinary chargers in essence and effect. They are too small to deliver a desulphating pulse.

The other thing I want to tell you is that if you leave a physically sound lead acid battery on a float charge of 13.1-2V for a few months - shaking once a month or so and topping up with distilled water if needed - then this will also in all likelihood desulphate the battery.

You can start with three sulphated batteries and one 12V charger and if you hook up a pulser to drive two batteries' power into the third and keep alternating which one gets pulsed you can get all three desulphated with only a simple 12V charger (and the pulser).

Last Edited by mael on 01/15/2012 05:31 PM

Well, I suppose car batteries aren't very glamorous but I hope if anyone learnt anything from my experience and experiments then they'll remember it, augment it if possible and share it with someone who can use it.

If anyone's really interested then send me a message and I'll point you to where I have stashed all that I know and have done with lead/acid batteries.

Last Edited by mael on 01/15/2012 12:17 PM

good to see someone on here who knows his stuff

could i ask a question ive been thinking of trying to build
a better battery for my solar setup basically my idea was just to start with thicker lead plates and a greater seperation not looking for great crank amps but just good
storage and very long life.

does this idea have any merit?

For my solar power battery bank I have two Black and Decker battery chargers that have a reconditioning function...every 6 months I pull one battery at a time out of the bank and check it, top it off with water if needed, and then run a recondition cycle on it...it takes 24 hours for one complete cycle, but my batteries are going on 12 years and only a couple have died in that time...

Last Edited by BRIEF on 01/15/2012 12:32 PM

Wow a useful thread. Thanks

I do believe that is how interstate got their start some years back.

Used to sell them old batteries back then.

I don't know, but Interstate sells a high quality battery...I use their deep cycle marine batteries for my solar power and they hold up great.

Build one? Hm! I don't think it's easy to make one that will be much use, but basically you are right in thinking it's the thick plates that will enable the thing to keep going.

Deep cycle batteries are the same as starting batteries only they have fewer and thicker plates. To use a deep cycle battery as a starting battery as a general rule of thumb you fit one with double the rated capacity. SLR batteries have many thin plates so there is a lot of cranking power. Deep cycle batteries are made to last long and deliver steady power down to up to virtually 100% discharge (in some batteries). Starting batteries will soon fall to bits if they are routinely discharged more than a few percent. - Different batteries for different purposes, but the deep cycle ones are made better and though double the weight and size they will last many times longer.

Submarine batteries are the best and longest lasting batteries commercially available. I think they are assured for thirty years. They are basically huge and have solid lead plates (so I gather). I hear it is (or used to be) possible to actually discharge the batteries and run them backwards and this helps to prolong their usefulness.

The most expensive batteries sold for off-grid power supplies have small pumps operating throughout the life of the battery that continually stir the electrolyte which avoids a lot or all of the stratification ofthe acid and as a result, the erosion of the positive plates.

Build one? Well build it huge and use solid lead plates It'll take quite a while to settle into usefulness but once it's settled down it'll last decades.

Theoretically just grab a few tons of old car batteries and recycle them yourself. Melt the plates and cast your own new ones. Filter and use the acid again. That's really hard work and pretty dangerous and toxic but it's one way.

I use this... and it works well just takes some time www.batterylifesaver.com

I made mine from a microwave transformer. Just cut the small gauge wire off and wrap about 12 warps of a heavy wire to replce it, leave the wire to long so you can add more wraps if needed. Put AC to the primary and chech the voltage on the heavy wire secondary. Add or remove wraps to get your required voltage, 20 volts in this case. One one of the secondary leads put in series a heavy inductor, this will give you a square wave. Attach this lead to a heavy diode, this gives the chop effect of 60 hits a second. Attach heavy leads for the battery, one to the other end of the diode and to the other seconary lead. Figure out which one is positive and marked it red or with a + sign. The one I made puts out 20 volt 25 amp square wave at 60 cycles a second. You should add a fuse, on-off switch, grounded case, meter etc. You could also use a 30-50 amp fullwave rectifier instead of the diode.You can put a bunch of smaller diodes in parallel to get the amp load needed. You can also use the diode plate from a automotive alternator. Use at your own risk, read or ask for help.

Mael I have a couple questions.

I have done some reading on the pulse desulphation process and some say that it is not a good idea to raise the voltage over 16v or so because it will break off the sulphation off and will collect in the bottom of the battery. True or no?

Another question- what is the correct frequency for all of this to work? 1Khz? 3KHz?

Also will any of these devises, commercial or not, remove hard sulfation crystals?

eh planting for spring eh gosh dunno salt seems to help.

kills tough salt i threw it once on a snail.

1 time.

Check out
Renaissance Chargers at r-charge dot com

Ok checked site out. they look cheap but with high price. If I pay $200 for something that is just a few inches in size, it better contain gold.


Now....any tips on making a battery last for ev er?

Always wear goggles even if you are positive you won't need them. One splash could ruin your eyes for life.

great info mael

>>* Sometimes these lead sulphates form a colony so big that parts of it push the plates next to it and can short some or all of the plates. If this has occured then your voltage from a nominally 12V battery will settle at around 10.5V. If this is the case then it's a doorstop.<<

not allways the case though... I salvaged a 12v marine battery that was showing 2.36v by throwing it on semi soft ground several times and having it land on a different side each time thinking I could knock loose the sulfation from the plates and this worked!

it has been in service as an overflow reserve from my off-grid system for over a year now. I use it for my 12v coffee maker.

pussy

Thank you battery-san.
Best explanation I have seen.....and about those nukes :(

Ya I have looked at the science behind all those for the past few days and it appears that the high frequency desulfaters, pulse chargers etc and....drumroll pls....the same as leaving a slow 1 amp slow charger on the battery. They work but very slowly removing the sulfation either way as in it takes a few weeks. They are marketing mumbo jumbo- Billy Mays would have a field day with this stuff.

Now there are chemical desulfaters on the market that appear to work extremely well- 1 is Inox mx2, and other is "battery equiliser" <--- is spelled that way on the package.

There appears to be a lot of good from adding a product that contains cadmium sulphate, and doing this very early in the batteries life.

Just out of curiosity, what brand of battery does the army use in their hummers/trucks? I would assume that is about the best there is?

Doesn't matter, you won't spend $40,000 for a battery anyway...

Abrams and M113's used DEKA when I was in(2000-2004.

short version: your battery is junk. sell it for scrap and buy a new one

Has anyone built NiFe batteries for renewable storage. They are bulky, but almost bomb proof.

Just use a CTEK battery charger, from what I understand their patented desulfator, uses a series of 16 volt pulses to desulfate Lead Acid batteries.

Maybe I fall into the lazy man category, but why would I or anyone want to do this. A normal store bot maintenance free battery is about $60 and lasts at least 3 years. While this is cool information, it's not worth my time to spend 3 days to resulfate the battery.