Just checked the van's battery, and I wish I had done so last night. I was very tired, and stressed and forgot. It is 12.68, so I started up the van with no inverter, to charge it up.
Once it is charged, is it ok to run the invert off it tonight to charge my house batteries and computer, or do I have to use jumper cables? The latter would be massively inconvenient, as I let a friend store a mountain of stuff on top of the big house battery's box overnight.
Tomorrow, I will have RV park electricity, and access to that battery for checking up on it. (It is one I got used in 2008, and is ailing, or I would be as gentle with it as I am with the good ones, which I charged fully last night. I have been avidly reading the advice in threads about replacement batteries.)