whats the largest battery an APC 500 will float?

notsobright Solar Expert Posts: 247 ✭✭
I have a couple of APC 500 UPS units and one needs a new battery. the battery is a 12v 7.5ah AGM Ive found a 12v 9ah that is the same size and I think that will be fine as a replacement but I was wondering what might be the largest battery (ah) that this unit will float charge ignoring the physical size as I could run the connectors outside the case and set the battery next to it.

the APC says it has a .40 amp output and when using a watts up meter between it and the dead battery it shows .36 amps.

can anyone here figure or show me how to figure the largest ah batt from the say .35 amp output that I can keep a constant float or indicate what Im missing if its not possible?



  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: whats the largest battery an APC 500 will float?

    the ac draw will not tell you with any accuracy what the battery is actually charging at. i'm sure the 9ah battery will be fine and would only take a tad longer to charge. if you're thinking of putting a much larger battery, like 34ah for instance, to be externally wired then i would not do it if depending only on the internal charger of the ups to charge the battery as it would surly prove to be insufficient.