Battery backup for subpanel

[signal15]

What's the best way to do battery backup for a subpanel? I have some extra UPS's, but is there a way to just do battery backup for 12V power in the panel?

I need to power motion sensors, pulsors, and water sensors which are all 12V. I *could* run a power wire from the main panel, but I'd rather not do that and have this panel mostly autonomous except for the RS-485 connection over the databus.

This is for an M1G, with a separate input and output expander in the subpanel.

 

[rfdesq]

I like this http://www.elkproducts.com/pdf/P112%28K%29...sales_sheet.pdf.

 

[Digger]

Remember to size your battery backup on the aux supply to last longer than your panel battery backup to minimize the chance of a false alarm. Also remember to tie the negative of the aux supply to the negative of the ELK 4 wire buss to common your grounds.