Hot water heater through an inverter?

[newhaul]

Originally Posted by goboatingnow

Immersion elements down to 500w are widely available here including 12v versions.

I have a 300 watt 12VDC one and have seen them as low as 150 watt but that would be useless .

[contrail]

I have been heating hot water through an inverter, for years, on three different boats. Sometimes from batteries, sometimes from an engine alternator. I settled on a 2.5 gallon tank, otherwise known as an "under counter" hot water heater, available from several different manufacturers. I go for the 1500 watt element, which heats water from cold in about twelve mnutes, or 300 watt hours, maximum. My current system is the best I have had, which consists of a 2500 watt (continuous) inverter, powered by a 400 AH Lithium battery bank. Since the bank is Lithium, the voltage only drops a tiny bit. 2.5 gallons (mixed with cold) easily handles one shower, and usually two. If I happen to leave it on ( generally, I turn it off before starting my shower), it only turns on very infrequently, as the water in the heater stays hot. So, it never threatens the battery bank. I think the main problem that people may have is a tank that is too large and thus needs to consume too much energy. I have 950 watts of solar, and that is more than enough for dailly needs, includig watermaker and the water heater. Lithium batteries are a great help, but I did not have them in the previous boats. Heating water this way is a proven concept....not sure why people have doubts!