Thanks, Don and Jeff, for the great information and links - the HiHY seems the perfect solution for standby power with the traction battery feeding the little 12V one. Just need to get a larger inverter now - 1-1.5 KW to give a little headroom in motor starting. It will be interesting to see how often the ICE cycles at a 75 amp or so 12V load (900W).

If my calculations ar correct, the traction battery capacity is 1872 watt-hrs (288V x 6.5amp-hrs per series-connected cell). I would expect the ICE to cycle at 50% capacity or so, recharging to 80% possibly, above which charging usually becomes less efficient. Maybe every 30-40 minutes?

My 700W inverter was not able to start the refrigerator motor or heating system blower earlier this month. I ran it from the Volvo's battery with an added external deep cycle 100 amp-hr battery, and ended up only running a few interior compact fluoro lights for possibly a 100W total. Still had to run the Volvo every hour or so to keep above 12V.

Pete