problem wiring dual battery selector

[fishinginmonterey]

so im new to owning a larger boat i have had 12 and 14 footers with small outboards. i just purchased a 18 starcraft with a 90 hp outboard. when i purchased it it only had one battery but was wired for two with the selector already on the boat.
so i added a second battery and wired negative to negative and both positives in to the two different terminals on the selector. the problem i have is that both batteries are connected at all times except for in the off positions. if im on 1 2 or both both batteries work all electronics and turn the motor over. there must be positive connected somewhere up the line im guessing. i also used a new battery selector with the same results. right now i keep one battery completely disconnected and hook it up if i need it on the water (definitively not ideal). what the heck is going on here?

 

[LippCJ7]

Re: problem wiring dual battery selector

uh if its wired properly yes all of your electronics will work properly, but how do you know they are drawing off both batteries? you would have to measure continuity between your load and the battery that is switched off to know for sure, do you have a Digital Volt Ohm Meter(DVM)? measure between the common post and the individual battery posts, this will tell you for sure that you have a problem, but my gut tells me you are over thinking this. So long as between the battery and the switch the batteries are independent you are fine.

 

[tpenfield]

Re: problem wiring dual battery selector

Each battery should have a 'positive' cable (usually red) that leads to the selctor switch. Then a single cable (red) leads from the switch and provides the power to everything.

It sounds like the 'positive' leads of both batteries are connected together leading up to the selector switch. As such, both batteries would be connected in the '1' or '2' and 'both' positions.

 

[Fireman431]

Re: problem wiring dual battery selector