In article ,
Chris F. wrote:
I got a couple of rather large gel-cell batteries the other day (the
largest is a 12V 24ah)

That's not large;-) We use 100 Ah types for powering location broadcasting
units. And that limit is purely through the weight for carrying.

but it turns out they weren't such a great find. Neither will take a
charge; with the charger connected, neither battery will draw so much as
a single milliamp. Both batteries have a number of little round covers;
underneath the covers are small rubber caps covering a hole. I noted
that when I removed one of the rubber caps, there was a small inrush of
air as if there was a vacuum inside. My guess is that both batteries
have "dried up", possibly from lack of use. Is it as simple as adding
water, and if so, exactly how much and what kind (distilled, tap, etc)
should be used?

IMHO, when any type of lead acid is dead, it's dead. If they've been left
discharged for any length of time for whatever reason they can't be sorted.

--
*I'm planning to be spontaneous tomorrow *

Dave Plowman London SW
To e-mail, change noise into sound.