Recovering dead batteries

[henjulfox]

At the office (elderly living building) we have a large battery backup system with 12

110 amp-hour AGM batteries. Seems that soon after they were replaced 2 years ago the

charging circuit popped a fuse so they had been periodically tested and used with

no charging. After yelling that testing involves looking at the volt meter mounted

on the front and after writing a check for $2,800 to replace them I offered to take

them home and mess with them. Worst case I'm out a few amps of electricity and a

sore back.

Had to walk past the beer fridge in the unloading process. Made it through the first

10 before the beer won. Each 12 volt battery measured less than 1 volt. Didn't know

you could get a battery that low...

Put a trickle charger and de-sulfinator on 4 in parallel in the garage and threw a

20 watt solar panel in the back of the car to charge the 2 in there. End of the

next day it was hot in the car, and the batteries were in full sun. Heat is bad for

batteries so I figured I had killed dead batteries. Got home and pulled out the volt

meter. Garage batteries charging for 24 hours were still below a volt. 2 Car

batteries charging from panel and well heated were at 5 volts. Hum...

Shortening up a long story - 3 weeks later each battery has spent a day or 3 in the

hot sun with a trickle charger and desulfinator. I unscrewed the tops to relieve

pressure and added a little water, just enough so that the material between the

plates looked damp, but no standing water. 10 of the 12 show resting voltage

(overnight with no charging) of between 12.85 and 12.91 volts. 2 won't get above 12.

I've had the 10 wired into my system for a week now and they are working great!

I wouldn't try this with good batteries but if you've got some due to be hauled to

the recycler it's worth a try. Note: I'm talking leave them out in the sun heat,

not pre-heat oven to 350 heat!

-Henry

[cr8zy1van]

Good to hear of your success. I also have a UPS laying around the office, but mine appear to be in a little better condition. 3 of the 4 measure about 3~5 volts. I tried charging them with a conventional charger but to no avail, after about 8 hrs they were actually down a volt each.

I really want to revive these batteries. Could a little heat and time really do the trick? Since my office has already replaced the UPS unit, these are mine to do with as I choose. Does anyone have suggestions for kick-starting these back to life?

[richhagen]

I know that in general, for most reactions, the rate of reaction increases with temperature.  Usually, the rate about doubles for each 10 degrees Celsius.  I don't recall ever reading anything about keeping batteries hot being good for them, conversly, I've heard that it is bad.  It's interesting, I wonder what the mechanism was.  Rich

[FishbonzWV]

I'm trying to revive an AGM also. It's on the front porch tied to a solar panel and desulfator charger. Havn't seen much success yet. They get warm in the sun and voltage raises during charging but by morning it's back to 4.9v (6v battery). I also added water to rehydrate the mats. My next step is to try an equalizing charge with the tops off.

Glad you had the beer fridge close by...wouldn't want to hear you had keeled over from exhaustion. ;-)

Bonz

[Devo]

I was at a scrap yard 2 months ago & picked up some cheap batteries , to my surpise  all the ones I took where near 13 volts sitting there & have worked fine , they also

had been in the hot sun  when I got them

Maybe something to that or maybe they were ok when they got left there?

Devo

[Norm]

I've heard that engine heat is the enemy of car

batteries...but maybe a slow gentle charge on a

deep-cycle battery combined with infrared and

ultraviolet rays of the sun is something else

maybe they even help the desulfation process..?

             ( :>) Norm.

[hobot]

Henry,

I'm fascinated and needful of the battery desulfator

spiker charger upper recover'r.

Visited your site, very informative but I'd sure

like to get more info on the basic principle  and

of course the circuit but also on a scale to handle

1700 ah 24V bank. Would rather find offtheshelf RF signal generator to fire a power pak but don't know if thats

fesible.

hobot

[GeeWiz]

Here is a site for Desulfators.  Easy to build, and they sell kits for those who do not have a lot of electronics stores around.

http://www.shaka.com/~kalepa/desulf.htm

Have fun,

Gw