Reconditioning old/dead lead acid batteries.

[G7PSK]

The best treatment for old batteries is to wash the cells out to clear the debris that collects at the bottom of the cells and shorts them out, then refill with fresh acid. I found that doing this with a bank of large lead acid cells on a wind turbine system (the cells were 900 Amp hour each, every five years the battery bank lasted twenty five years and were still good when the property and system were sold. I have washed out large truck/tractor batteries as well and found that they recovered 80 to 90% of original capacity. But you need to do this before the cells are damaged from being internal shorted. 

[SilverSolder]

The best treatment for old batteries is to wash the cells out to clear the debris that collects at the bottom of the cells and shorts them out, then refill with fresh acid. I found that doing this with a bank of large lead acid cells on a wind turbine system (the cells were 900 Amp hour each, every five years the battery bank lasted twenty five years and were still good when the property and system were sold. I have washed out large truck/tractor batteries as well and found that they recovered 80 to 90% of original capacity. But you need to do this before the cells are damaged from being internal shorted.

How did you wash them,  just rinse with water?

[G7PSK]

Rinse several times with distilled or deionised water. Never use tap water, slosh the batteries cells about the best you can repeat until the water runs clear or clear-ish.

[f4eru]

in which state do you do this, charged or discharged ?
One thing to take care is disposal of the lead contaminated water. Were do you dispose it of ?

[G7PSK]

As is when it becomes necessary to do so whatever the charge state, In days gone by I would just throw some lime in the old acid and water then pour it into a hole in the ground but now I have to take it to a recycling center as what was considered acceptable in the 70's is no longer.