You may not be familiar with Sprinters: but you knocked this one OUT OF THE PARK!!!
I had completely forgotten about really low batteries not liking to take a charge.
But I pulled the Toad around to the side of the rig, pulled the battery cover (under the driver's floorboards...), and hooked them up.
I gave it about 15 minutes for them to get to know each other, and then I gave it the "remote door lock/unlock" test
Boom-Chaka-Laka!
Put the key in the ignition, and things started waking up. Once I gave it a twist: it came to life with a "What are you looking at me like that?" attitude.
For funsies: I also have started the generator, and put a bit of a load on it. I expect to let it idle out here for a couple of hours, and then I'll start doing a systems check.
So until you're better paid> Thanks a MILLION!