as above, there is a spot on the inside of the driver's side quarter panel that has captive threads in it where you can install a dual battery solenoid, that's where i have mine, and just ran the cabling along the firewall with the fuel lines.i have a 2010 d22 with the dual battery setup, and am trying to make sense of previous comments in this thread, ill just ask what i need:
does the nav have its own isolator on the second battery, saving me a few bucks
no, it doesn't
if not, can i install my own and use it as an accessory battery,
yes, you can install your own isolator. do really do it properly though you need to strip the wiring back to the alternator and remove the wire that goes to the second battery
or does the rest of the car depend on 2 batteries being connected at all times.
no, it doesn't. they only fitted dual batteries for colder climates they sell them in to give them better cranking power, and it's more expense to remove the second one, so we get a bargain
this is very true...but the idea is that i would be using the second battery to crank from, i can't see anything draining the main battery unless the battery has actually died. (as in, it needs replacing)When you flick that switch, there is going to be a massive current from one battery to the other, but it shouldn't last long(seconds), so I'd put in the biggest wire you can obtain.
It would be safer, but take longer, if you could reverse the direction of operation of the inverter/charger.
Would it be easier, on the rare occasion that happens, just to swap the battery to the main position?this is very true...but the idea is that i would be using the second battery to crank from, i can't see anything draining the main battery unless the battery has actually died. (as in, it needs replacing)