You can always use an Iceytek if you don't have ehu - the electric ones only cool down a few degrees cooler than the outside air temp. It took me 3 years of pondering over whether or not to buy an Iceytek but for anyone wondering how good an Iceytek is:
It was my sons' Sports Day on Monday (9-4pm parents bring picnics, sweltering sunshine).
First outing of my 25L Iceytek, pre chilled it Sat/Sun. At 07:00 i put in two gel packs, 4 bottles of frozen water & 2x 1 litre tubs of homemade ice cream.
For the first round of ice creams i had to leave the tubs out of the coolbox a bit to defrost. The second round at 13:00 the ice cream was more soft scoop. The bottles of water had hardly started to defrost.
Amazing performance on what has been a very hot day. Fair to say that other parents couldnt believe we'd successfully brought ices & my boys were extremely popular with the classmates they shared their cones with.
Certainly have no regrets investing in my Iceytek now and even my husband thinks it was a good buy. ??
I guess for a camping trip I'd be inclined to buy a 40L though. The 25L is a replacement for our electric one which was a pain as you couldn't pack things on top as that's where the fan is (previous one had a side fan).