Wire to automatically switch battery isolator on when running
#1
Wire to automatically switch battery isolator on when running
I'm planning on hooking up my second battery tomorrow, but I haven't been able to find anywhere the wire that they might have used to have it connect automatically. I will put a switch for a manual override, but still want it to connect automatically any time the engine is running. I was thinking of tying into the signal wire for the alternator, but don't want to damage anythign by doing so. RonD, help me out here.
#2
RF Veteran
iTrader: (1)
Second battery is connected to charging system via an isolator, it is in essence a high amp diode, power can only flow in one direction thru the isolator, so anything hooked up to the second battery is not connected to vehicle battery or any of it's electrics.
Some have used a starter relay, those older fender mounted relays, they can handle the amps.
You run a similar gauge wire that is on the alternators B+ post now from the B+ post to the new relay, then from the other large post on the relay a similar gauge wire to the second battery.
The smaller "S" post on the relay activates it(assuming relay case is Grounded), you can use a hot in run wire, or a switch on the dash.
You should put a mega fuse on B+ wire and second battery charging wire.
Hot in run wires can be found at the EVAP purge valve, Fuse 41 15amp in engine fuse box is hot in run
Some have used a starter relay, those older fender mounted relays, they can handle the amps.
You run a similar gauge wire that is on the alternators B+ post now from the B+ post to the new relay, then from the other large post on the relay a similar gauge wire to the second battery.
The smaller "S" post on the relay activates it(assuming relay case is Grounded), you can use a hot in run wire, or a switch on the dash.
You should put a mega fuse on B+ wire and second battery charging wire.
Hot in run wires can be found at the EVAP purge valve, Fuse 41 15amp in engine fuse box is hot in run
Last edited by RonD; 05-16-2015 at 10:18 PM.
#4
RF Veteran
iTrader: (1)
You won't need a hot in run wire with most isolators, but they do come in 3 or 4 post designs, 4 post would use hot in run hookup.
Normal hook up would be to run the B+ wire to isolator, then one wire from isolator's labelled posts to their respective batteries.
Good look at wiring here: Dual Battery Setups
One of the EVAP purge valve wires will be hot when key is on, computer grounds other wire to activate valve, so remove connector to test which wire is hot with key on, and make sure it is off with key off, it is fused via the EEC relay power fuse, 30amp I believe.
Fuse 41 15amp, is just another key on source for 12v in engine compartment, not part of EVAP
Normal hook up would be to run the B+ wire to isolator, then one wire from isolator's labelled posts to their respective batteries.
Good look at wiring here: Dual Battery Setups
One of the EVAP purge valve wires will be hot when key is on, computer grounds other wire to activate valve, so remove connector to test which wire is hot with key on, and make sure it is off with key off, it is fused via the EEC relay power fuse, 30amp I believe.
Fuse 41 15amp, is just another key on source for 12v in engine compartment, not part of EVAP
Last edited by RonD; 05-17-2015 at 10:26 AM.
#7
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