This is the first of a series of posts related to the electric system in our GXV expedition vehicle. My aim in this series of articles/posts is to outline the original mission of the electrical system, analyze how well the originally supplied equipment meet that mission, describe what modifications and upgrades I have made and what lessons I have learned, and what problems (if any) are still outstanding.

In this first post I will discuss the mission and original equipment.


Right from the start our GXV Expedition Vehicle was intended for an "around the world" mission. In terms of the electrical system this meant:

  • Operate for extended periods (measured in months) without shore power.

  • When shore power is available be able to use that power regardless of voltage or frequency. Thus the system was required to be able to use both 110V/60Hz and 230V/50Hz shore power.

  • Selectively limit the load placed on the shore power supply. In South America we were often plugged into shore power where the maximum available current draw was limited to 5-10 amps. We also understood from other travelers that such a shore power limit is common in Europe. Hence the system was required to provide a mechanism for limiting the load placed on the shore power supply.

The initial solution


The electrical system as originally delivered consisted of the following elements.

  • A high capacity battery pack for powering camper electrical requirements. Initially this was spec'd as 2xLifeline 4DL AGM for a total capacity of 420 AH. During construction this was upgraded (at GXV's recommendation) to 3xLifeline 8DL AGMs for a total capacity of 3x255 or 765 AH.

  • An OutbackPower VFX28112M (110V/60Hz) inverter-charger, which provided charger, inverter and automatic AC transfer switch functions. The Outback spec sheet claimed that the inverter would deliver 2800watts of AC (110V/60Hz) power for camper appliances, and 125DC Amps of charging current for the house/camper battery pack.

  • Two 180 watt solar panels,

  • An Outback FLEXMax 60 solar charge controller

  • An Outback Hub device which connects and provides communications between all Outback products.

  • A Mate2 system controller from Outback that provides central control of all Outback products.

  • A ChargeMaster 12/35-3 universal battery charger from Mastervolt. This charger will accept any AC input in the range 90-265 Volts and 45-65Hz and hence can be plugged into a shore power source anywhere in the world.

  • A diode battery isolator that provided a one-way DC charging path from the truck alternator/starting batteries to the camper battery pack when the truck ignition is on. The diode function prevented the truck starting process drawing current from the camper battery pack.

  • Two external plugs for shore power connection; one designated for 110V/60Hz sources and the other for 230V/50Hz.

  • An Onan QD3200 diesel generator that could be selected as the 110V/60Hz AC source.

How it works

The Outback inverter/charger is connected directly to the batteries and all DC loads (lights, refrigerator, exhaust fan, 12 volt accessory plugs) are connected via a DC breaker panel.

All AC loads (microwave oven, coffee maker, 110 volt sockets) except the camper air conditioner are supplied by the output from the Outback inverter/transfer switch.

The camper air conditioner is powered directly by 110V/60Hz from either shore power or the onboard generator.

The expectation was that the camper battery pack would be (re)charged from one of:

  • The Outback inverter charger when 110V/60Hz shore power is available

  • The Outback inverter charger when the generator is running

  • The solar panels via the Outback FLEXMax 60 charge controller during daylight hours

  • The truck alternator via the diode battery isolator when the truck engine is running

  • The ChargeMaster when 230V/50Hz (or more accurately non 110V/60Hz) shore power is available.