I have an APC SMT3000i which I have wired into a 2nd consumer unit (distribution board). It is around 5 years old now, and is still on the original set of batteries, which seem to work fine. I try to limit the discharge level as much as possible.

 

It is a pure sine wave device.

 

It powers several switch mode PSUs, including a PC, TV, LCD monitors, (inverter) fridge, router, boiler, central heating pump, and various small wall warts.

 

When running on batteries, there is a very loud buzzing noise from it, and also from the PSUs that are plugged into it.

 

From this photo, I appear to be overloading it from a VA perspective. The 1566W seems very high, as on utility it normally pulls a maximum of 500 to 700 watts.

 

For those familiar with these UPSes, is this normal behaviour? Would a battery change help?

 

 

 

 

 

I don't think it's something that can be corrected by changing something about the UPS, it may be one or more of the loads, or a combination of them. I recommend getting a "kill a watt" meter and monitoring each of the loads individually over a period of time and mapping the maximum power in watts and VA that each load consumes. If this is a new problem I suspect that you may have a bad capacitor or something amiss in one of your loads. Frankly I'm surprised that you can run all those loads simultaneously and not overload it.

Any dimmers or heating devices plugged into the ups or anything using half-wave rectifier?  Inverter fridge could be cause as well.