I've got a couple of battery packs in the storeroom that need some
attention. Both have been stored for periods of time, need to see if
they are usable or get them out to the scrap dealer.

Pack #1 is a set of 6 deep discharge 6 volt batteries in a mobile cart.
Charger for it was trash, had fried circuit board. Unit has been sitting
for multiple (4+??)years. I'm betting that they are completely
discharged and that there are a bunch of shorted out cells in the set.
Cells were low on water, topped them off with distilled water. I think I
will take a regulated DC power supply, see what voltage it starts to
take current. From my reading, a functioning but fully discharged cell
should start taking current at 1.98 volt and fully charged at 2.10 volt.
So a 6 volt battery with one shorted cell should start at around 4 volts
then go up to 4.2 volts at full charge. Any other suggestions on how to
test, deal, whatever?

Pack #2 is actually 3 packs of 19 each 12 volt gel pack batteries (228
volts per pack, there may be a couple batteries missing). It came from a
huge battery backup for a computer center. I suspect it was set up to
provide 3 phase 208 power. This bunch has been sitting for about a year
with no attention. These are gel pack (??), about the same size as a
standard auto battery, fully sealed, and sit on their sides. How do I
test? What should I do to keep them alive and well for future projects??