new 12v needed

[tellor]

Hi guys,
Can anyone recommend a 12v suitable for a 2 day meeting? Presumably I should be looking at a Leisure/Caravan size one but I’m still not sure on the capacity
I will be charging 5400 lipos about 6 times a day, with no way of charging the 12v overnight.
I used to have a car size 12v but found that Sunday afternoon it was taking ages to charges the lipo, if at all. The lipo charger then says insufficient voltage!

Cheers
Tel