[firefly123]

inverter  to power a 500 hundred watt heater off 110 amp battery put it on a timer three or for times a night for ten Min's this will keep van off freezing lag all pipes with radiator foil from b&q do this to your pump to and cover tank aswell d i vessel to not cheap to do but in cold spell you will be able to work if this fails move abroad 

[jeff1]

110 amp battery will give you 1,320 watts of power = around 2.6hrs of use, however a battery stored in a freezing van will have its capacity reduced even more, so in affect giving you around 1.5/2hrs use through out the night with your timer.

Again as the battery drains towards the end of the night this again will reduce the out-put wattage of the battery to around 1/1.5hrs per evening, provided the battery was fully charged in the first place.

A very good idea you have in theroy but in practice its not practical, I would sooner see you spend your money on something better.

(This is without seeing the specs of the inverter that may reduce the batteries out-put even more)

EAOE 

[evil genius]

thats over 40amps a hour if was pure 12v. so with the inverter its going to be a fair bit more.
its also not a good idea to drain the battery a huge amount to much.

good idea tho and might work but for it to work imk thinking it will need to be running for like 45mins at a time maybe 3 time through out the night and that will kill the battery with ease.
i cant see 10minute spells giving out enough warmth to do any good, especially in a van the size of a transit or transporter.
ian