Hello.

I have a 12 volt a Deep Cycle Boat trolling motor battery I'd like to
keep charged via my chevy s10 v6 blazer. I currently have two 4 guage
wires running about 6 feet to the back of the car connecting the
primary battery to an 800watt inverter. With the engine running I can
I drill, cut wood, make popcorn and and fry fish on an electric
skillet - it's awesome.

I'd also like to charge that trolling battery as I drive around. I
know most will tell me to get a fancy isolator and connect it to all
sorts of places in the truck. WHY? Any way I can safely hook it up to
that 4 gauge wire with diodes and pull from both batteries and the
alternator when using the inverter, but never ever pull from the
trolling battery or the inverter for anything relating to the car. I
figure any small amount of current to the second battery will keep it
topped off, but any risk of loosing normal draw for starting or normal
operation of the viechle. Any chance the guys at best buy will be
able to put this simple solution for me? they originally install the
inverted and did a great job for $50. What are the risks?

Many thanks for *any* help or information.