Does anyone have any idea what could be the problem if an RCT 1000VA UPS works in AC MODE only and does not work on battery mode even if I replace the two 12V 7.1AH batteries .

I would be very grateful if someone has a service manual for the particular UPS .

Your batteries are not large enough... 2 x 12V x 7.4A = 170Wh, IF you could completely drain the batteries (not advisable...). With losses in the system, and only using 50% of battery capacity, you would need at least 2 x 50Ah batteries to be able to use the UPS for one hour.

On 2025/04/08 at 6:28 PM, josiah sakala said:

RCT 1000VA UPS

This ups is sold brand new with

On 2025/04/08 at 6:28 PM, josiah sakala said:

12V 7.1AH batteries

How the china factory rated this at 1000VA is unknown! I have opened a couple of blown 1000VA Mecer / RCT / K-Star / PSS line interactive units, they all come with this crappy battery setup. Why your ups is behaving the way it does - probably something on the pc bord.