I have a APC Back UPS PRO 1000.<BR><BR>The batteries died in it a few months ago and were recycled. I want to adapt this unit for use with a car battery for some testing. Of course the batter was ...

I'm pretty sure that the XS (model with BX) doesn't do AVR Trim (only Boost) and doesn't have an external battery connector while the regular Pro (model with BR) does have those two features.