It would be a good idea to invest in a "battery maintainer" if the truck doesn't get driven regularly. It's similar to a trickle charger and it prevents the battery from self-discharging over several days or weeks of inactivity. To charge a low battery properly with a generator (or even an alternator) takes several miles of driving. 30 minutes to an hour, minimum.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!