[paulgato]

Thanks 2000mc. And how do you find the 100w pad heater? Do you find it heats up OK? How long do you have to have it on for to do the job?

I have an onboard battery charger operating overnight anyway so my other option is to have a small (100w?) sump heater and leave that on all night together with the battery charger, but it would use over a kwHr overnight, whereas a 250w heater on for an hour in the morning would use only 0.25kwHr. I don't think there is much point having a pad heater on for more than 4 hours as any heat introduced before that will be gone by morning, but the battery charger needs a full ten hours to do its job, so using a mains timer is tricky unless I have two separate mains supplies into the vehicle, which I don't really want.