The diode based isolators are battery killers. Those large finned heat sinks are your hard working alternator amps going up in heat, instead of into the battery. The diode also reduces voltage, basically making it impossible for the battery to ever reach full charge via the alternator, and greatly reducing the amp hours returned into the battery whenever you drive.
Some of the isolators try and trick the alternator into allowing a higher voltage to negate the diode's voltage loss.
You would be better off with a heavy duty continuous duty solenoid rated at 100 amps continuous or higher.
There are voltage sensing solenoids like the surepower 1314 and 1315 or the Blueseas ACR.
I chose the fully manual option with a 1/2/BOTH/OFF switch
