When you say sitting for 2 months, do you mean there is no electrical drain?
If so, as far as I know, there's nothing needs doing ... the battery's will
hold their charge ... or enough to get you going again. As for a deep
cycle/starting battery setup, I charge my deep cycle trolling battery while
underway by simply attaching what we call up here jumper cables (they're
usually in the back of the jeep through the winter, so why not put them to
use over the summer I thought) and I disconnect when trolling.

OT: Although I suppose a $120 diode isolator would make that complex and
difficult task a lot easier. And would provide me with an excuse to use my
cell phone when I go to start up, and find I've got 2 dead batteries. Hmm
.... but if I bought a coupla voltmeters to watch ... or designed and built
an automatic cutoff at say 11.5 volts ... nah ... life's too short, I'll
stick with the jumper cables..

wrote in message
m...
Hello Boaters.

Anybody got this set up? An aux battery is charged by the boat's
engine, but is isolated so that it will only be used in emergency or
by another circuit like for an 800 watt invertor? And while the boat
is sitting for two months, solar energy is maintaining both batteries?

Sounds nice huh? Possible?

Anybody got a working and proven solution and would be so kind as to
share products/vendors and a high level design ?

Many thanks again - you guys are great!