Warming up the batteries

[Gary Dillard]

I'm definitely not used to this problem, being a 5th generation Floridian. We have retrofitted last year's robot to put a shovel in the ground and dig some dirt for the Ceremonial groundbreaking of a new high school in our team's school district tomorrow morning. We did a test run yesterday and everything worked fine, except that the driver said it seemed to be running very slow. I checked the voltage of the freshly charged battery and it showed under 12V no load. Oh by the way, it was 17 degrees F outside when we made the test run, and although the batteries had been stored inside the school I had them in the back of the pickup for the half hour drive to the site.

It's supposed to be up to about 50F tomorrow morning; If we warm up a fresh battery overnight and keep it warm until just before the big show, is it going to be good sitting for an hour during the speeches or do I need to wait until right before we power up to change it out?