On Tuesday, October 9, 2012 12:30:36 PM UTC-7, JK wrote:

I had to do an emergency replacement last weekend. The bad
battery was: 12vdc, 4 amp hour gell cell All I could find
locally was: 12vdc, 5 amp hour gell cell The batteries are
identical except for the amp hour ratings. I don't *think*
moving up an amp hour should be a problem with this type of
battery. Am I right?

An increase like that won't hurt, except to need 25% more time to fully charge the battery, and notice that older backup supplies fully charge in 8-12 hours, while newer ones need up to twice that time (seems to make batteries last longer). IOW even a much lower charging current won't hurt, and it's only when you switch to a far larger battery that current can become too low (car batteries are rated for 60 amp hours).