Desulfator Update

[Lin]

I thought I would give an update on my desulfator experiment.  They did not bring my 8d with the bad cell back to life (however, shocking it again with a welder did help a little).  I them put the desulfators on the AGM house bank.  After about 4 weeks, there is no improvement I can see.  As a matter of face, when I started, the bank maintained a resting voltage of about 12.6+v.  When I just checked, it was at 12.5+v.

What should the resting voltage of AGM batteries be?  Although it's been a while, I seem to remember that these batteries used to be at around 13v.  Does this mean that these batts have had it?

[pvcces]

Hi, Lin.

Which kind of desulfator did you use? We had a couple that did not work, but most have done very well. The Solargizers were very slow, but they are limited by the small solar cell size.

Thanks.

Tom Caffrey

[Lin]

The brand was Wizbang, and I bought two on Ebay.  I can not say that they really do not work since it is not fair to expect that it would bring back a shorted cell.  Further, they had warned me that desulfating AGM batteries, like in my house bank, was hit or miss since the glass mat may have been damaged.  On the positive side, after the treatment, the hydrometer readings on the good cells in the 8d batteries were as high as they could get.

My other point was that I was able to get life back into the dead cell on one 8d by attaching the ground from my welder to the negative terminal and hitting the positive terminal several times with the torch.  I did this reaching out from behind a shield just in case there would be evil consequences.  That battery now maintains a charge of 12.5v, while before it dropped down to 10.7.  Now, I do not consider the battery truly rejuvenated, but rather good enough until I find a good price on a new one.
   

[pvcces]

Your observations are good ones, Lin. A friend bought some Wizbangs, and one blew up. I don't know about the other.

The desulfators do the the most good on liquid lead acid batteries because they get sulfated. I don't have enough experience with AGMs to speak to them.

Your observation about the 8D is right on. All the cells that were not leaking are restored to near new performance. The leaky one will be hard to desulfate because it never gets charged up enough for it to work. If the welder succeeds in blowing the short loose so the low cell does not lose it's charge, then the desulfator ought to do it some good.

Good luck with the experimenting.

Tom Caffrey

[Jeremy]

As it happens I've just ordered a bench power supply to experiment with desulphating some batteries using the boiling method. I did tentatively try using my 24v 20amp charger, but the charger clearly wasn't happy so I disconnected it after a few minutes.

Jeremy

[boogiethecat]

Jeremy, just make sure you do it where fire, hydrogen explosions and gigantic splats (or puddles) of sulphuric acid-laden molten plastic goo won't hurt anything, in case things go wrong !!

[Jeremy]

Jeremy, just make sure you do it where fire, hydrogen explosions and gigantic splats (or puddles) of sulphuric acid-laden molten plastic goo won't hurt anything, in case things go wrong !!

Thanks for the concern; the battery will be outside, connected by long cables, and I'm thinking that the variable power supply I've bought should make the whole process very controllable as well. And in any case, I've built myself a Faraday cage to protect myself from Chinese EMP attacks, so an exploding battery should be child's play.


Jeremy

PS. I've been trying to find out how much real harm - if any - is is caused to batteries if they are topped-up with regular tap water rather than ionised or distilled water. I know impurities in the water would theoretically contaminate the acid and/or plates, but I don't know how much that is a real concern rather than a marketing tactic. I do live in a very soft-water area.

[boogiethecat]

I use R/O water for my batteries and have never had a problem.  But I'd NEVER consider using straight tap water, no matter how soft... impurities of any sort will poison the plates over time.  That said, I've seen "professionals" pour gallons of tap water into forklift batteries, but had I been that customer I'd have definitely blown my stack...
Bottom line, if you use R/O or distilled water in your $$expensive$$ batteries, they won't get ruined.  If you take a chance with tap water, it's your gamble and your bucks if you loose...

[Jeremy]

Thanks, that's pretty much what I thought. I've got three identical batteries to desulphate which at the moment are not much better than junk (seem to hold a charge well enough, but no capacity). I know de-ionised water isn't exactly expensive but I'll use tap water in my boiling experiments with the first battery, and if I'm able to restore any usefulness to that one I will invest in some store-bought water for the other two. No point throwing good money after bad at this stage.

Now I just need to decide how best to objectively measure any improvements that might actually take place. I've been doing some reading on testing techniques for lead-acid batteries, and it seems that the usual methods and tools are a minefield of bad science and mis-interpreted results.

Jeremy

[pvcces]

Our favorite way of desulfating large or medium batteries is to connect our desulfator to the battery and then connect a 1 amp 12 volt charger to the battery.

Within a few days, the battery will be up to a maximum voltage which is really a plateau. This voltage will reveal the amount of sulfation. If it is around 13.5 volts, it's heavily sulfated. If it's more like 14.5, it's not bad.

When a battery is worn out or damaged, you won't see the gradual rise in voltage over a few weeks.

Then, I monitor the battery voltage, once a day. As the battery becomes desulfated the voltage will creep up. When it quits rising, the battery is desulfated.

An 8D seems to take around three weeks if it is in the condition that I find them in the scrap pile.

We have some L16 black case batteries that must be nearing 30 years old.

Good luck.

Tom Caffrey