Another Battery Question

gack

I recently replaced my 2 batteries and trays in my 270FV with a Group 27 battery for starting and Group 31 Deep Cycle battery for house replacing the 2 Group 24 auto batteries that came with the boat when purchased last year.  In order to determine which switch position was Start and which was Deep Cycle, I installed one battery first and left the other out.  Turned off shore power and battery switch to position 1 - engine starts.  Moved switch to position 2 - engine starts again.  WTF?  Am I missing something?  Batteries don't look like they are wired in parallel but would have to pull the switch to verify.

gearshift46

I don't know if this will help you. But I had a problem with my dual battery switch. When I would switch to Bat # 2 (deep cycle, when staying overnight & running refrig, TV etc...) the next morning I would switch to either "both" or # 1 battery. Boat was dead. (both batteries) Rather than troubleshoot, I purchased a $6.99 battery switch that connects to the neg. terminal of #1 battery. When we stay overnight, I simply turn my # 1 battery off ensuring that I will be able to start the boat the next morning. Cheap fix.

Dude_Himself

I could be wired to combine the batteries on start.

Mine stupidly has the blower wired to the house battery and the engine to the start battery, so if the house is drained down I'm SOL.

gack

Thanks @gearshift46.