On Fri, 09 Mar 2007 16:48:55 GMT, Ron Hardin
wrote:

I have 4 replaced 12v UPS batteries, that might be handy for other
things if I keep them charged. What sort of current should go into
them? I think they're 9AH wnen new, so not automotive class.

One of them says ``constant voltage charge 13.6-13.8v'' but I'm
not sure what that means, operationally.

Lead acid, sealed.
IT means that the best way to keep them fully charged is from a source
that supplies 13.6 to 13.8 volts (depends on the temperature). As long
as no cells are dead, you charge the battery as fast as you want, as
long as you keep the voltage fixed.
Plan B is to trickle charge them at a rate no higher than AH/40, or
about 200ma. SLA tolerate overcharging on that basis a whole lot
better than the tolerate being run into the ground.

BTW, don't ever allow the cells to become fully discharged. That's the
kiss of death in SLA's