Battery desulphation

[DAPPH]

11.1V this evening. Might be all volts and no amps because as soon as I disconnect the charger, the blinky widget drops out.

I am expecting 2-3 days before the process gets on with whatever it can do.

Switch the charger off . disconnect the charger , rock the battery vigorously to get the gas bubbles off the plates , leave it at least 12 hrs for the gas to dissipate , recheck voltage and if it's risen by about 1.5 volts repeat the exercise for several days . Your fully charge battery should be 2.2 volts per cell , in your case 13.8 volts when fully charged . the charger will need an EMF ( electro motive force ) of about 17.5 volts to start pushing juice into the battery and start reversing the chemical state of the plates

Usually when a battery drops to below 6.5 volts you cannot charge it by normal off the shelf battery chargers, it needs buzz bar charging .
I seem to think the electronic ones need an even higher lowest voltage of around 10 volts to get going & start charging .

 

[DAPPH]

Yeah I figure I had so many dead batteries I'd try everything at least once.

I haven't yet emptied out a battery, cleaned it and put in fresh juice. It's only a matter of time tho. This little bike battery will probably be flushed and refilled, if I can find some battery juice. My local Halfords closed down...

Lots of motor factors used to sell the sulphuric electrolyte recharge as a complete battery enhancer kit , a just add water jobby & refill the cells . I'd need a decent battery hydrometer if I were to try that trick, as the charge state of plates can affect the final SG ( specific gravity ) of the battery electrolyte in each cell differently .

 

[Barking Mat]

We've got a cytek charger at work, with a recovery function, tried it on a few lead acid and AGM batteries, frankly, I've never had any luck with it.

As you know I rent out a dozen odd boats, I've probably got 60 or 80 batteries in all, on these dozen boats.

The boats drive, they charge, if possible, in the evenings the clients plug in, they charge.

We have never, ever, lost so many batteries, as we did last year.

Heat ? Or 2020 and 2021 all those batteries, which just never got sold ?

Still lost for an explanation.

 

[Screwdriver]

I had 12.6V in my head for some reason. I guess the precise voltage can vary around the expected value.

I have been intermittently taking off the charger to see if the HF device can power off the bettery but no luck yet. I then give it a little tap with a hammer to dislodge any stuck crystal (yeah, bad idea) and relive gas bubbles. But there's no real activity yet, I still gobsmacked it's doing anything tbh.

I do have a hydrometer to check it with but after desulphation, it's probably a good idea to flush out any crud and refill with fresh acid.

 

[Wedg1e]

After listening to the man on the internet a few years ago I bought an Optimate for the bike, and then another one for the car.
All seemed to be going well, but then despite the Opti, the bike battery just died. And the clock packed in.
Some time later, the alarm system on the car died for no apparent reason. And then I realised the clock had died. And then the battery died - boiled its electrolyte somehow (the alternator was fine, but the car was mostly stood anyway).
Apparently these chargers desulphate by superimposing a high-frequency/voltage waveform on the charge current (which is probably ony 800mA at best). My guess is that despite the low impedance presented by the vehicle battery (or at least one in good order), the electronics of the clocks and alarm system couldn't cope with the desulphate current (the only devices permanently powered with ignition off).
Ever since then I take the batteries off the car and bike and bring them in the house for the winter, give them an occasional charge from an old-fangled Halfords charger - lasted years like this.

 

[Screwdriver]

I hear you. Also had issues with Optimate. That went straight in the bin. I now prefer big old dumb chargers though you do have to keep an eye on them. Cooked a new bike battery once. Once is enough.

My test battery is looking good and was sucking amps. 3A to be precise and the case was getting warm. So I disconnected the charger and lo and behold...

The winky light winks. So it's getting enough juice to gently dissolve sulphates, I'll leave it overnight and see what's up in the morning.

 

[m_c]

After listening to the man on the internet a few years ago I bought an Optimate for the bike, and then another one for the car.
All seemed to be going well, but then despite the Opti, the bike battery just died. And the clock packed in.
Some time later, the alarm system on the car died for no apparent reason. And then I realised the clock had died. And then the battery died - boiled its electrolyte somehow (the alternator was fine, but the car was mostly stood anyway).
Apparently these chargers desulphate by superimposing a high-frequency/voltage waveform on the charge current (which is probably ony 800mA at best). My guess is that despite the low impedance presented by the vehicle battery (or at least one in good order), the electronics of the clocks and alarm system couldn't cope with the desulphate current (the only devices permanently powered with ignition off).
Ever since then I take the batteries off the car and bike and bring them in the house for the winter, give them an occasional charge from an old-fangled Halfords charger - lasted years like this.

Desulphators do work by putting high voltage pulses through the battery, which IIRC can be in the 40-60V range for a typical 12V battery.
They are a pretty simple bit of kit, just a resonator circuit with a suitable inductor to generate the high voltage pulses.

Although vehicle electronics should be designed to handle some even higher voltage transients, they won't handle them for a prolonged period.
I would never run a desulphator with a battery still connected.

 

[Wedg1e]

Desulphators do work by putting high voltage pulses through the battery, which IIRC can be in the 40-60V range for a typical 12V battery.
They are a pretty simple bit of kit, just a resonator circuit with a suitable inductor to generate the high voltage pulses.

Although vehicle electronics should be designed to handle some even higher voltage transients, they won't handle them for a prolonged period.
I would never run a desulphator with a battery still connected.

Absolutely, but much was made by the likes of Optimate that you could leave your vehicle permanently 'topping-up' on their chargers without issue.
Having to replace two batteries, two clocks and an expensive car alarm suggests there is an issue
I have another charger of that type, no mention of it desulphating, it does seem to work fine but I still only use it on disconnected batteries - an Aldi own-brand thing. It's actually more robust than the Optis, has a better display, chunkier croc clips and thicker cable - and was a fraction of the price.

 

[maroon]

Another thing you can use to get a charger going if you don't have another battery to jump off of is a testlight aka a basic light bulb on some crock clips. That will pull current through to get it started.

 

[DAPPH]

Desulphators do work by putting high voltage pulses through the battery, which IIRC can be in the 40-60V range for a typical 12V battery.
They are a pretty simple bit of kit, just a resonator circuit with a suitable inductor to generate the high voltage pulses.

Although vehicle electronics should be designed to handle some even higher voltage transients, they won't handle them for a prolonged period.
I would never run a desulphator with a battery still connected.

I was just going to say most cars these days have several voltage stabilizers , those high frequency spikes will eventually kill them IMO , so don't de-sulphate or charge the battery on a modern car with the battery connected, put a charged slave battery on in parallel before you disconnect the vehicle battery for charging .
Don't some cars sort this parallel battery thing out via a cigarette lighter socket lead so it's easily put in place before you take the old battery off.

 

[Screwdriver]

Well the desulphator switched off during the night as the battery voltage fell to 11v.

I probably shouldn't have left my precious little multimeter attached either though it was switched off.

Reconnected the charger and it jumped to 4A. Not sure if that's a good/bad thing but I am wary of overcooking it so I switched to a low rate.

 

[Gareth J]

Just, don't blow any of these tired batteries up. I'm sure we all know how/why it happens, and that it does (spoke to a friend of my father's who popped a battery at arms length a few weeks ago). Take care.

 

[Justme]

You'll need a big net for that many.

We have about 200+ that live in our built in bat house.

 

[Turbo]

@Screwdriver - any update on this. I acquired a few new old stock emergency floodlights & they all have Yuasa sla batteries fitted. The batteries are dead due being stored too long & I'd like to attempt to recover them using a desulphator.

 

[Screwdriver]

@Screwdriver - any update on this. I acquired a few new old stock emergency floodlights & they all have Yuasa sla batteries fitted. The batteries are dead due being stored too long & I'd like to attempt to recover them using a desulphator.

Inconclusive I would say. The process did appear to work but the battery ended up being no good. I suspect it is battery dependant but there was so much faffing about involved, I didn't try any further.

 

[arther dailey]

have nt read all the thread , but I bought some battery aid tablets of net, got a ten year old mitsubishi battery, flat as a pancake and left stood near a year , chucked em in , old school transformer charger left for 36 hours , stuck it on my old 135 and spun over faster than the new battery I normally use . So I would use them again .

 

[Mart63]

If you parallel those leisure batteries with a good battery and stick the charger on them you may find the good battery brings the voltage up enought for the charger to start. I done this a few time with completely dead batteries and it works.

I did this regularly when I managed a car spares shop. Brought loads of batteries back from the dead.

 

[Morrisman]

Dangerous stuff stuff playing with batteries, sulphuric acid, other chemicals and electricity

Not read what the internet says

But play safe and don’t get hurt

Serious risk of fire and explosion

I’ve seen the nasty side of a charging 12 battery, when sparks hit the hydrogen that’s emitted and the explosion launched the top of the case into the air, and back down, followed by battery acid raining down in tiny drops.

This was in the far east, my safety gear was shorts and flip flops…..

 

[Screwdriver]

I’ve seen the nasty side of a charging 12 battery, when sparks hit the hydrogen that’s emitted and the explosion launched the top of the case into the air, and back down, followed by battery acid raining down in tiny drops.

This was in the far east, my safety gear was shorts and flip flops…..

Exactly the same thing happened to me, in Libya. I was asked to stick a charger on some random truck which turned out to be 24v. Can't remember how I got it wrong but there were two bloody big batteries and either it was a 12v charger and 2x 12v batteries, or a 24v charger and two 24v batteries or some combination thereof.

I thought I might be able to check by just tapping a lucky guess with the charger leads. I thought wrong.

I didn't even see it explode but I got covered in a light spray of acid. Must have grabbed a bucket of water or something because I survived unscathed but my tee shirt turned into a tea bag!

 

[Onoff]

Just tried starting SWMBO's old pug that's been sitting there since it was written off. Bosch battery is dead. Searched this thread out to read about de-sulphating.

Got me thinking about it being a sealed type and a pity I can't access the cells, they've like a glued on plate.

Copied some text I wrote on another forum when my lad got an old ride on mower going:

"My lad even managed to bring back the completely dead lead acid wet battery. Cleaned it with a bicarbonate of soda solution about 10% bicarb. That reacts & cleans all the crap off the plates. Rinsed. Then filled with 12% Epsom salt solution and trickle charged for 24 hours. Up to about 13V and has started the mower no problem half a dozen times. That's with the Epsom salt solution still in and no "real" acid".