If i somehow found a way of running a emersion element of my battery (i aint no sparky, so not sure if i can be done) and then fitted into the top of my tank. would it mess around with my tds? I thought not as the water is 000 already?
I like the idea of heated water via battery/mains. It the safest option by far.
Unfortunately, as already mentioned our batteries just couldnt take this sort of use.....you'd kill it stone dead in no time!
However, thing are moving along rapidly in the field of battery power/life/weight (see Toyota and Honda for examples).....I dont think it'll be too long before we have 'leisure batteries' able to run this type of set up.
I'm watching and waiting......