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Adding a second battery

Will9046

New member
Need some advice,
I recently purchased a 21 foot Trophy Hardtop with mercruiser outdrive and a 8hp Honda kicker. I want to add a second battery, not sure about wiring. I see a lot of online info and the more I read the confuser I get. :)

What i think is have one starting battery for the main motor, and a deep cycle for the kicker.
I want to use the deep cycle for the house wiring, but want to make sure it gets charged while running with the main motor also.
I may also want to add a crab puller or electric downrigger later. which battery would I use for those?
Confusion over battery switchs, and Isolators and Automatic Charging relays.
Should I also consider a third battery for house wiring? Space is limited for batterys
 
If you send an e-mail to me at [email protected], I will return a complete write up and diagram of how I do it.

Two batteries should be fine. That 8 hp kicker doesn't take a lot to crank, so just wire it to the same terminal as the Merc starting battery on the battery switch.

As a matter of practice, when I start or run the boat, the battery switch is set to "both" batteries. That way, I keep them charged. Only when I stop the engine and continue to use the electronics do I switch to the "house" battery.
 
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