APC RS-800 overload problem

[jamespond]

I have 3 pieces of RS-800 UPS with same problem. When pressing power button the unit blinks the overload led. If on-line then no charging and after few seconds powering off.
In the unit all fet-s and diodes double checked. 24v, 12v, -12v, 5v is ok!
I searhed for some info, but not find anything. I need some tips or sm for this UPS!

Thank you!

 

[poweraces]

if all the FET are ok then you may check the charging circuit of the UPS. there is a chance that it will overload the UPS if the DC voltage is not enough., even you have new batteries.

 

[jamespond]

Ok! I will check the charging circuit. I have a new battery.