options for two battery setup

Brylk1830

I agree that you do not need a selector switch, you can leave the engine wired up to its battery as it is and keep the trolling battery seperate.
Link the negative terminals of both batteries directly and you can use either a solenoid switch or a relay between the positive terminals.

They both do the same thing except in a different way. The solenoid switches on when it receives power to its coil from the ignition switch.
The relay is voltage sensitive and will not allow your engine battery to be discharged below a preset voltage.

I think the relay is more fool-proof in that you should always have enough power to get started, with the solenoid you have to make sure that the ignition is not left in the on position and I am not certain what happens when you have a flat trolling battery and you switch on. Is there load shedding from your engine battery before you hit the starter? Then again Fast Fred seems to find it works for him.

There is a switch offered with this relay from West Marine but you don't have to have it, the less complicated the better in my view


http://www.westmarine.com/webapp/wc...rue&storeNum=5002&subdeptNum=9&classNum=12106

 

A mosfet and a threshold cut-out circuit would be my preferred choice. Everything is solid state, so no worries about mechanical failure and corrosion. You can also switch the system on/off using very small currents, which means lighter switching cable.

Tim B.

 

Ecopon

 

Query - I go by "ecoPon" because I have a small pontoon TOTALLY powered by batteries. The set up is two marine trolling motors powered by four batteries. The batteries are Optima 24s. The question is if I hook them up in parallel, is there any potential problem that you could think of regarding amps? [The two up front will also power a fish finder. The two in back will also power a portable live well.] Your comments will be appreciated.