APC Back-UPS low output voltage if low load

[ehsanelahimirza]

hi everyone

i have APC Back-UPS CS 650. it is giving low output voltage on battery mode if the load is reduced. nominal voltage is 220V AC, when i have load of one CPU and one Monitor then output voltage on battery mode is 204 VAC, but if i turn off the monitor to reduce load, the voltage drops to 170VAC and the CPU restarts. can anyone tell me what would be the problem with UPS.
plz note that battery voltage are 13 VDC and remain normal, and UPS output voltage when AC main is applied remains at 220 VAC regardless of any load changes.

Thanks in advance

 

[tpetar]

How you think battery is 13V ? It cant be 13V at load, what monitor and PC you have CRT-LCD-LED? Is it desktop PC? Why you mention "CPU" what is "CPU" ?

If you mean on CPU as PC CPU this does not reflect much on whole power of PC. Standard Office Desktop PC have around 200W + monitor.

If you have gamer PC with high power demand graphics card this is other story. This GPUs can pull over 150W + other parts of PC.

Try to connect voltmeter to battery and try load test just turn off mains power for UPS, and watch battery voltage.



See this UPS review with inside photos and modified sine wave :
https://www.halfgaar.net/apc-ups-cs-650-review

 

[pplus]

I assume that at the time of power off UPS does not have time to work out load reduction and produces high output voltage, overloading the power supply chassis. He enters the overload protection and output voltage drops, rebooting the system unit. Then stressful UPS output is reduced and the system unit starts.

i have APC Back-UPS CS 650. it is giving low output voltage on battery mode if the load is reduced. nominal voltage is 220V AC, when i have load of one CPU and one Monitor then output voltage on battery mode is 204 VAC, but if i turn off the monitor to reduce load, the voltage drops to 170VAC and the CPU restarts.

I note that the UPS output voltage is not sinusoidal and your measurements are not accurate. UPS maintains a constant amplitude of the output voltage by changing the pulse width at varying loads.

plz note that battery voltage are 13 VDC and remain normal, and UPS output voltage when AC main is applied remains at 220 VAC regardless of any load changes.

This offline UPS and in this mode, it simply passes the input voltage to the output.