The AC element on my hot water heater is 1250 watts.

Can you safely draw from an inverter while the engine is running? If
I put in a 1500 watt inverter and used it carefully to only run the
water heater (which would also be getting waste heat from the cooling
water coil) and was sure that my other 12 V loads were minimal at the
time, could I get my hot water tank heated up in the 5 - 10 minutes
that I do with shore power? (It takes motoring half a day to do it
with the waste heat alone from my 20 hp diesel).

Or, will this burn up my little 35 amp alternator? I have a 55 I can
put in but it needs a different voltage regulator.

I would never try to make hot water from the batteries through the
inverter for obvious reasons.

--

Roger Long