Determine the appropriate gauges of wire, cables and connectors needed. Gauge them to comfortably accept the maximum amperage generated by the charging system when the engine is running. Extended physical lengths demand heavier gauges.
Purchase the appropriate isolator, either diode- or relay-type. Diodes are most reliable and give the longest service but rob a small percentage of the power supplied to the battery from the charging system. Relay (or solenoid) isolators are more complex, and thus more prone to failure, but cause no voltage reduction.
Fasten the isolator to its permanent location. Considerable heat may be generated as a byproduct of proper function, which must be dissipated safely and effectively.
Install a deep cycle battery in a location where adequate ventilation is provided and where access is sufficient for safe wiring and fitting securing straps.
Follow the manufacturer's detailed installation instructions. Most isolator looms require alternator power be fed directly to the chassis battery's positive terminal, branched to one of the two heavy studs on the isolator. The studs will be labeled. Another cable, of equal gauge, will run from the isolator's second heavy stud to the positive terminal on the coach battery, from which a feed is run to the coach equipment. Both battery negative terminals must be grounded.
