Battery de-sulfators and end-stage batteries

[doc47]

Anyone had any experience with these devices?

Any good advice on restoring dying automotive batteries?

[Dennis Andress]

Hi Doc -

 

From a time long ago...

 

As long as it is fully charged at least occasionally, a lead acid battery shouldn't "wear out." Technically that means the battery's specific gravity must be kept within the allowable range. I have no idea what that range is...

 

There is usually a 1/2" gap below the plates where solidified minerals and other junk collect. A battery dies when this gap becomes full enough that junk becomes wedged between two or more plates. This short removes them from use, lowers the resistance of that cell, and allows more current to flow, which increases heat and further wears the battery.

 

I was told that a lead acid battery could be drained and flushed with the goal being to remove as much of the junk from the bottom of the battery, and from between the plates, as possible. Then fresh acid could be added and the battery charged to bring it up to the correct specific gravity.

 

I've never tried any of this. It's just what I recall a class in the Air Force. For all I know it could be a fairy tale...

 

Dennis

[doc47]

Dennis,

Reading up on several websites (granted, they were sites selling de-sulfating units)the lead sheets gradually get covered with lead sulfate (PbSO4)crystals. When these get thick enough it insulates the lead from the acid bath. This, naturally enough, decreases the usable surface area of the battery leading to battery death.

The desulfating units pulse a high-freq impulse into the battery, theoretically knocking the Pb loose from the SO4, which they claim will renew sulfated batteries and prevent sulfation in new batteries, prolonging their life significantly.

I'd like to see some independent confirmation of that.

[JayW]

So I would presume then, that a GEL battery like the 5 year-old one in my RT, will wear out only due to the lead sheets getting contaminated with lead sulfate crystals (since the gel would prevent any particulates from dropping down below)?

 

On a related note, I read that up to a third of batteries turned in for replacement are still chargeable and then test within spec. What's up with that?

 

Jay

[elkroeger]

I've always viewed those battery restoring potions as so much snake oil. Batteries wear out, period. Pretty much all you can do is use it regularly, make sure it gets fully charged once in a while, and plan on buying a new one every few years.

 

Some people love to hate wikipedia, but I think the explanations there are usually pretty good.

 

http://en.wikipedia.org/wiki/Car_battery

 

Edit: after looking at your post again, I see you're talking about a battery de-sulfating charger, not those "restorative salt solutions", or whatever that stuff is. The Wiki link talks about trickle charging being effective for sulfation. Beats me, I guess.

[Dennis Andress]

Well Doc, I don't know. That the plates can become covered with lead sulfate makes sense. However, considering that sealed lead acid batteries last longer because there are fewer contaminates in the battery, hence the space at the bottom doesn't fill as fast, then I would think that sulfation is more of an issue for a sealed battery. To put it the other way, an unsealed battery would probably die from contamination before lead sulfate build up became an issue.

 

Dennis

 

[doc47]

This guy writes like he doesn't wear a tinfoil hat....

 

...and these folks are flogging their product, of course...