Dual Batteries

[joe8395]

I have a 2000 21i that I would like to have a dual battery setup. I can't imagine it's that hard, can anyone offer some direction on how to do this and the material required?

Beyond the switch and some terminal cable (and the other battery) I can't imagine there is much to it. Thanks for any help, I'm trying to avoid the $250.00 the dealer wants.

[Kelley]

I have a 1998 2100 I that I installed dual batteries. One battery is for the stereo and the other is the boat battery. I installed a isolater in the battery compartment behind the dash. The isolater automatically charges the batteries as required and also protects them from over charging. I think this is better that installing a switch that will require you to manually switch back and forth.

[joe8395]

Thanks for the reply...can you give some more details on the isolater? Brand? Where you got it? Pics? It does sound like a better solution especically given the upgrade I'm about to do to the stereo system.

[neilm]

Problem with a 'normal' battery isolator is that there is a voltage drop of 1.3V to as much as 2V across them -- you end up with two batteries that are never fully charged.

Consider a battery combiner http://www.yandina.com/NewCatalog.htm (look up Combiner 50amp) [also available from West Marine]; or http://www.hellroaring.com/simple1.htm

or a simple solenoid, wired to the 'on' side of the ignition switch, to connect the batteries together when the engine is on..