Raymond,
               I have found most useful to carry Schumacher Electric - Portable Jump Starter with the air compressor.   If you buy the Cig-Lighter-Plug-Cable  you can recharge your battery by plugging in the cable.   Useful back up battery.

http://www.batterymart.com/p-Booster-Pac-Cig-Lighter-Plug-Cable.html?gclid=CjwKEAiAi4a2BRCu_eXo3O_k3hUSJABmN9N1vbsd3HVjs1gYtaWlCB4sdEvq7KPPLGGDyqHKj-5LFhoCgFfw_wcB

Hello,

Unfortunately, my Vanagon sometimes sits for months and the battery runs dow=
n. Does anyone know of an easy way to jump start a Vanagon without opening u=
p the battery compartment?  Has anyone added external battery connections fo=
r jump starting or charging?

Thanks,

Raymond