Why is the cpu power consumption ~70% more on battery backup than on mains?

[punchsuckr_apc]

This was originally posted on APC forums on 5/16/2011

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Hi

I bought an APC back ups es 650va 2 days back... installed the powerchute software and noticed something rather strange;

the idle power consumption on my cpu only (had disconnected the monitor to check out the power usage of my cpu) was at 27watts. i switched off the mains supply and it immediately went to 46 watts. tried it a number of times with the same result.
can anyone please tell me whats up with this?

thanks 🙂

[punchsuckr_apc]

This was originally posted on APC forums on 5/17/2011

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Thanks JonPro i guess that could be the only explanation for the behavior... however i am concerned if everything would be consuming 70% more power on backup, my cpu stands at 105 watts at full load, the monitor at a 100 watts. i'm even afraid to test it out at full load now.

[BillP]

This reply was originally posted by Jonathan on APC forums on 5/17/2011

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You are welcome.


On my end, I normally advise my customer not to exceed 80% of the load to give the unit more time to do graceful shutdown.

[BillP · Accepted solution]

This reply was originally posted by Jonathan on APC forums on 5/16/2011

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Good day Prabhat,

One thing that I could think of is the kind of wave form that our Back-UPS produces when it is running on battery power. Our Back-UPS is designed to produce whatever is being fed to the unit when it is online. If it is running on battery, the BackUPS wave worm changes to a step approximate sine wave. Some load/units