Stopped by Batteries Plus today,
Picked up a nice 800 milliamp waterproof batter tender
(has quick disconnects, spade lugs and alligator clamps included)
A red LED nightlight bulb for the house
And a neat power socket splitter with a USB port on the side.
Bends 90 degrees so you can point it down...
Car Power Outlet Splitter and USB Port 90310 - Batteries Plus