My wife and my sister-in-law are spending this coming weekend at the Folk East Festival in the Eriba. There's no hook up on site, so she is limited to onboard battery power. The caravan has an 80Ah battery and will be fully charged when parked up. All onboard lighting has been upgraded to LED bulbs.

How long do you think it might last without recharging? I'm guessing the only 12V usage will be lighting and toilet flush (and the onboard tracker, which I could disconnect).

I will put up my 20 watt solar panel to give some limited recharge during the day, but that is only designed for storage trickle charge (for the tracker).

Anyone any thoughts as to how long it may last? I'm giving Claire my power bank to give her phone charging whilst away. I won't be there as I'm away playing cricket for the weekend, so I can't come to the rescue. Also cars have to be parked in the day parking, so no car with the caravan...

That's an 'as long as a length of string' question. It depends on the condition of the battery, not just its stated ampere hours. That depends on how old it is and how it's been treated over its life. Use of a motor mover will take a lot of power, so that should be avoided if possible. Also modern fridges use 12v to run control systems, interior light and gas igniter. Without 12v such fridges and Combi type heater/boilers won't work, even on gas. If you have a compressor fridge it's even worse, as they use 12v to run the refrigeration and that will empty a battery in a day.

On the fridge - many fridges won't run on the on-board battery but only off the tow vehicle 12V. I toyed with the idea of running ours off the battery as it has a max draw of 140W and we have 160W of solar on the roof, but I decided against it.
I would guess a weekend should be comfortably possible if only running pumps and lights - that's about 700Wh if you discharge to 30% and I would guess you don't have much more than 30W of lights. Running those 5h a day over two days would consume 300Wh, leaving 400Wh for the pumps which should be plenty.

Can you use the next couple of days to do a test off grid use ?
Steve

I'm hoping to run the fridge off the Calor bottle (I have a new one to put in) - and I will test out the battery power to see how much it drops overnight tonight with a couple of lights left on all night. Best I can do, I think...

Thanks for the guidance
Simon

We spent 6 nights off grid in our Eriba two summers ago when we had the kitchen fitted in the house. The fridge and cooking on gas and we still motor moved it back into the storage spot after the six nights.

We accidentally ran off battery, forgot to hook the battery up to the EHU. It lasted 4 or 5 days before the lights started to dim and we realised we were on battery. An 80 AH battery so a weekend should be fine.

Thanks for all the help. Very reassuring

I meant to report back on how it went - 13.1V in the battery when I had finished setting it up on the Thursday. When I collected it on the Sunday evening it had 12.8V in the battery. I had had the 20V solar panel connected - and it had been sunny. The fridge ran really well on gas.