powering a 12v cool box

[markfenton99]

The auxilliary battery is set up in the custom and is charging nicely so now for the next question.

I'm looking into power options to run a 40L coolbox and some lighting away from the van. I do craft shows and am often in the middle of a field with no power available for 3 days.

I've already got two powerline 80Ah battery which I thought would do but after doing the calcs it looks like I can only expect about 10 hours each without going too low, is this correct? (cooler takes 3.5 amps) (batteries are different spec so I won't be combining them). I was hoping to run the cooler a24hrs per day

I've looked into solar options, looking at 100W with 10A PSM controller and costing upwards of £230 (alot more for kits from 12 v planet £300 up). I've heard the MPPT units are betterthe PWM but that bumps cost up by about £100 again.

I've no experience with solar units so any advice would be appreciated

Firstly I believe 100W is the right approx power I'll need
Secondly does the PWM / MPPT unit make a big difference
Thirdly I don't want to be lugging numerous batteries around by hand, is a small portable set up possible?

Cheers

[Beaker]

Yes you are correct, a 3.5 Amp coolbox will take 35 Amps out of the battery in 10 hours (3.5 Amp hours). That really is absolutely as low as you want to drain your battery before recharging. Remember the less you take out of it, the quicker it will charge, and the longer the lifespan of the battery.

I fitted a 100W solar panel kit from Midsummer Energy like this a few weeks ago for £251:

https://midsummerenergy.co.uk/buy/solar-panel-kits/Flexisun-100W-Kit

As you can see it has an MPPT controller - they are supposed to be more efficient and kinder to your batteries than a PWM controller.
You can find these kits a little cheaper, but their phone advice and support has been superb, so worth the extra cost on that score.

Coolboxes are horribly inefficient, Personally I would either spend more on a decent fridge, or less on passive ice box. A decent ice box will easily keep your food and beer cold for three days or more if well packed with ice or enough ice blocks and properly pre-chilled - all at absolutely no electrical cost to your batteries.

I've gone the passive ice box route myself - a Waeco 42 Litre Cool-Ice.

Any more questions, just ask.

[markfenton99]

Cheers Beaker, I'll check out both the solar kit and the passive ice box.

I do medieval re enactment events which have a strict policy and no modern gadgets etc can be on show so no electric hook ups, generators or solar panels allowed. I was hoping to get a days power from one leisure battery while charging the other and then swap them over but it doesn't sound like that will happen.
I'll still look into the solar kit as it will be good for general camping.

I wasn't aware of passive ice boxes and how much better they are than standard cooler boxes, I could easily hide one of these on my stand so it sounds like this is the way to go

Thanks for your help

[Beaker]

If you get one of the flexible panels like I've got, you won't even know the van has one fitted on the roof as they are only 4mm thick. They are easy to fit too. At this time of the year they will recharge a leisure battery in no time if the sun is out. Even if it is cloudy they still work well, just slower on the recharge.

Passive ice boxes are usually found on the decks of small fishing boats to keep your catch cold, street food stalls and the like.They are also what the emergency bike couriers use to transport organs and blood. They are just better made and far better insulated than the usual picnic ice boxes you get in camping shops. You just fill them full of ice cubes or ice blocks - used supermarket 4 or 6 pint milk jugs 2/3 full of water left in the freezer for 24 hours work a treat.

Yeti, Igloo, Waeco and others make good ones.

A really good way to top up while on the go (at least on the coast) is to call in at a harbour fish market and ask for a few scoops of ice.

My real problem with electric ice boxes is that they struggle to cool down more than about 20 degrees C below air temperature - even the best and most expensive ones. That's fine on a cool day, but on a hot sunny 30 degrees C day in a closed vehicle it is easily 10 degrees hotter than that; your coolbox is madly chewing through electricity just trying it's best to get the contents down to lukewarm.

[blue estate]

If you get one of the flexible panels like I've got, you won't even know the van has one fitted on the roof as they are only 4mm thick. They are easy to fit too. At this time of the year they will recharge a leisure battery in no time if the sun is out. Even if it is cloudy they still work well, just slower on the recharge.

Passive ice boxes are usually found on the decks of small fishing boats to keep your catch cold, street food stalls and the like.They are also what the emergency bike couriers use to transport organs and blood. They are just better made and far better insulated than the usual picnic ice boxes you get in camping shops. You just fill them full of ice cubes or ice blocks - used supermarket 4 or 6 pint milk jugs 2/3 full of water left in the freezer for 24 hours work a treat.

Yeti, Igloo, Waeco and others make good ones.

A really good way to top up while on the go (at least on the coast) is to call in at a harbour fish market and ask for a few scoops of ice.

My real problem with electric ice boxes is that they struggle to cool down more than about 20 degrees C below air temperature - even the best and most expensive ones. That's fine on a cool day, but on a hot sunny 30 degrees C day in a closed vehicle it is easily 10 degrees hotter than that; your coolbox is madly chewing through electricity just trying it's best to get the contents down to lukewarm.

That's where you need a Waeco cf version compressor cool box , I had a cf35 I used in my truck ok last year and have a waeco fridge drawer now and never turn it off

[markfenton99]

How much! I didn't pay that for the fridge in my kitchen. Sounds like a very decent bit of kit but well out of my price range

[mistericeman]

Waeco cfx 40 variable speed compressor type here too....
we have 3 x 100ah leisure batteries charged by 2 X 100w solar panels on the roof and a Durite voltage sensing split charge relay....
Coolbox runs 24/7 all year round and have never run out of cool......

cfx 40 pulls less than an amp when running SO theoretically you could run it off a 100 ah Leisure battery for 50 hours (safe theoretical level of 50%)

though bearing in mind the coolbox isn't running continuously... the battery life is obviously extended.

[vampirequeen]

We have a semi flexible 100W solar panel on the roof. It was so easy to fit. We run our electric cool box from it and charge our phones, tablets etc. Makes life so easy when off grid (which we are most of the time). We also ran a split charger from our engine battery to our leisure battery but it strained our 17 year old alternator so be careful if you do that. When we had a new alternator fitted we went for one with a larger amp and the garage auto electrician said we'd be fine from now on.

[markfenton99]

We have a semi flexible 100W solar panel on the roof. It was so easy to fit. We run our electric cool box from it and charge our phones, tablets etc. Makes life so easy when off grid (which we are most of the time). We also ran a split charger from our engine battery to our leisure battery but it strained our 17 year old alternator so be careful if you do that. When we had a new alternator fitted we went for one with a larger amp and the garage auto electrician said we'd be fine from now on.

What capacity leisure battery/s are you using with the 100w panels? is your cool box running 24/7?
I am going to go with a solar set up but not sure on spec yet. I like the idea of the flexible panels but I may want to be able to use them away from the van. I was thinking about 100w but recommendations vary on websites and I suppose it depends on leisure battery capacity too.
My 2014 custom comes set up to run a starter and auxiliary battery, 150amp alternator as standard I believe which seems to be charging both batteries fine. These are use for interior / exterior lighting, Solar panels will be rigged up to a separate leisure battery purely to run the cool box.

[vampirequeen]

The leisure battery is a 110ah. The cooler runs from it up to 24/7. I say up to because occasionally we have to unplug it because it gets too cold and things freeze lol. Sometimes the leisure battery is charging from the solar panel and, when we're moving, from the alternator through the van battery with the split charger. We plug the cooler into the house mains for a couple of hours before we leave so that it's already cool and we put an ice block in it (the ice block came with the cooler)

[markfenton99]

excellent, I think I'll give that a go then.
Funds are low at the moment so I'll probably try the passive ice box first and look at a solar kit for my cool box next season

Cheers

[Beaker]

That's really good to hear about the Waeco compressor boxes, and that you guys rate them so highly. I looked at them quickly when I started building but discounted them due to the price and the fact that they are described as freezers, which I have no need for.

I've just watched the video for them and now realise that you can run them a as fridge, a freezer or both at the same time (on some models). That's pretty impressive, especially given the tiny current draw making them solar power friendly.

It looks like I completely underestimated them, and I'm going to have to start saving pennies!

[mistericeman]

That's really good to hear about the Waeco compressor boxes, and that you guys rate them so highly. I looked at them quickly when I started building but discounted them due to the price and the fact that they are described as freezers, which I have no need for.

I've just watched the video for them and now realise that you can run them a as fridge, a freezer or both at the same time (on some models). That's pretty impressive, especially given the tiny current draw making them solar power friendly.

It looks like I completely underestimated them, and I'm going to have to start saving pennies!

I thought long and hard before buying one (we had a 3 way coolbox type that served us well ...BUT couldnt use it inside the van on gas as they are not correctly flued )
However after buying a waeco it was truly a revelation AND well worth the cost IF power consumption/reliability/and long periods of usage are important.