View Full Version : Dual battery question

Oklahoma 280STS
03-05-2008, 10:46 PM
Our boat has two batteries and each has a big red switch with four positions (Both, One, Two, Off). How can I tell which is the primary and which is the secondary battery? I want to hook up an inverter to the secondary leaving the primary fully charged for starting the boat. Keep you help simple-I'm electrically challenged!

88 PS190
03-05-2008, 10:59 PM
disconnect one battery, turn the switch to one, see if you have power.

03-06-2008, 09:37 AM
This is how I did it I used a battery isolator got it at west marine for like 40-50 bucks then you never have to worry about the switch. It pulls from the aux battery when the boat is shut off. Then the main battery is for starting and charges the other one when the boat is running.

03-06-2008, 10:07 AM
Check out Diesel's Dual battery thread. Do a search

03-06-2008, 10:08 AM
here's the link to it.....