You didn't say what box you have but you definitely need the external
adapter like this:
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3625588140&category=1603
5&rd=1>
Use the adapter whenever possible rather than the battery, and then use the
battery supervising it constantly. It helps if you have dual batteries, so
you can always start your motor.

Incidentally, the above mentioned adapter is a good thing to have for other
appliances too. It is a cheap and lightweight source for about 4 amps. Never
leave home without it.

--Gnarlie

Entity Sam Williams spoke thus:

> I bought a 12 V electric cooler box on Sunday in preparation for our upcoming
> trip & left it on to check it out.
> It is a small kind that draws 3 amps.
> Well, the vanagon started on Monday and was moved in the driveway in the
> morning.
> Last night the battery was dead as a dodo.