RE: Jump Start Portable Batteries
I carry one of those (with a built in air pump) all the time in my Westy.
It's bungeed down behind the passenger seat right next to the starting
battery, easy to get to and use if needed.  It's one that has a 17 AH sealed
battery in it, built in charger (comes with a 110 VAC cord for charging) and
beefy cables and clamps.  Carried it for several years and only used it to
help others until a couple of months ago, now I
ve needed it for myself twice in the last four months (That's why they call
it a Light SWITCH dummy!)