SUA1500 more efficient than SUA1000XL?

[hkpolice_apc]

I'm considering purchasing a used SUA1000XL but according to APC's efficiency calculator, the 1000XL model uses 5-6w more than the SUA1500 at all points over the "UPS system losses" curve.

Both units use RBC7 batteries so I assume that both have the same internals especially since both are the same size. Why the discrepancy?

I'm using the calculator here: http://www.apcmedia.com/salestools/WTOL-7GKS4S/WTOL-7GKS4S_R3_EN.swf

Could it be inaccurate or out of date? How are the UPS losses calculated?

Thanks in advance!

[BillP · Accepted solution]

Good morning,

The XL has a more powerful charger and a larger transformer that results in the higher tare losses shown by the TradeOff Tool. The tool is up to date and appears correct for this UPS.