Found this on the C&D Dynasty UPS 12-490MR UPS Battery..
"C&D Dynasty 12volt, 139AH 488 watt sealed lead acid battery, Flame Retardant. C&D designated replacement for 12-475FR and MR12-490.
* Inserted terminal design works with most flag terminal connectors without modification, flame retardent, 10 year design life at 25 degrees C
* 12V 139AH at 20 hour rate
* 12V 488W at 15 minute rate
* 3 year replacement warranty
* Dim. 13.57"L x 6.80"W x 10.93"H (includes terminal), Wt. 100 lbs.
$329.00"
But that was on the internet. I'm going to email back the place I called and see if they will send me a price.
Would one if those batteries be big enough for a 3000W system?