New fridge for the Ute

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raytaylor

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#261492 30-Nov-2019 15:43

Went into jaycar the other day and saw they had a new range of 12v fridge/freezers.

My existing one which i had on the back seat of my SUV plugged into the 12v outlet had a slightly warped door/lid so i decided to get a new one.
Paid about $800 for the last one which would have been about 30L and the new ones they have are considerably cheaper, and still have a proper compressor - not those crap thermoelectric ones.

Anyhow here is what I got

https://www.jaycar.co.nz/22l-brass-monkey-portable-fridge-or-freezer/p/GH1624

I work on hilltops and in house attics and hawkes bay gets hot for weeks at a time in summer. So its good to have cold water.

I can go for a few days at a time without starting the car engine (weekends, public holidays) so i needed it to be solar powered rather than running off the main car battery or a dual battery setup. The fridge has a low-voltage protection but that would stop the fridge from running.

Anyhow here is what I did to test it out.
Started with a 50 watt panel with the old fridge but it wasnt enough so i swapped it out for 2x 40 watt panels to make 80 watts and got the new one with a door that properly seals.
I would recommend at least a 120 watt panel and pair of 100Ah batteries if anyone is planning on doing something similar. Although I was surprised in a slightly overcast morning, the panels were still putting out 30-40%.
I made the mistake of thinking the panels and sealed door would be much better and so 80 watts of solar would be more than enough and riveted it to the canopy roof rather than bolted. So i cant swap the panels out for a bigger set now.

The fridge manual says it uses 0.25kwh of power in a 24hr period - 12v 21Ah

However I find it spends most of its time on during the day when set to -2deg. It doesnt help that the ute canopy gets warm so it uses much more power than I was expecting it to. I think it would use more like 0.5kwh or 12v 42Ah over a 24 hour period.

Eco mode uses 2.5-3A and high power mode uses 4A.

Where to from here
- Tint the windows of the canopy to reduce heat on a sunny day
- Vent to replace air in the canopy to help cool it
- Secondary 12v 100ah battery
- Go to jaycar on monday and get some fuses and accessories to tidy up the wiring.

https://www.youtube.com/watch?v=j3Mrvi2gzvI

Ray Taylor

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Geektastic

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#2363727 30-Nov-2019 22:13

Interesting.

I have a standard 12/240v Waeco I take in my Range Rover in Summer but of course it only works when there's power.

You could put one of those spinning vent things in the canopy like they use for dog Van's. Not sure what the proper name is!

Kiwifruta

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#2363769 1-Dec-2019 02:16

So the unit doesn’t need so much power could you put it in an insulated container? e.g. a large chilly bin

RunningMan

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#2363815 1-Dec-2019 07:13

Putting it in an insulated box would make it worse - a fridge generates heat, and this needs to dissipate.

pdh

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#2363819 1-Dec-2019 07:25

I think you're making it work too hard - with the heat trapped under the canopy.

Can you let the hot air vent through the top of the canopy and pull cooler air from beneath the vehicle ?

Shouldn't need a fan - it'll thermo-siphon / chimney - but this will replace the hot exhaust air from the fridge with cooler air.

I believe that'll lower the power consumption.

Fred99

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#2363825 1-Dec-2019 07:41

raytaylor:

However I find it spends most of its time on during the day when set to -2deg.

Why have it set to -2 deg? +4 is about normal for a fridge.

I took a look at these cheap fridges at Jaycar, the specs are "about" the same as for quality name brand small compressor fridges, so they seem to be extremely good value, but who knows what the quality of construction - insulation properties of the container, and durability of the components - is like.

But anyway, I know a lot of people who use them (quality branded compressor fridges) on boats etc, 80w solar seems to be the bare minimum they can get away with but they still need care to keep the panel facing the sun, and monitoring the battery. The answer as to why set the temp low may be that for some people who use them they set the temp low during the day when there's possibly some surplus from the solar panel which keeps the battery charged, then turn them up (or completely off) overnight. A few cloudy but warm days aren't kind, so the more solar panel and more battery capacity the better.

IIRC Waeco (could be another brand) sell optional insulating covers to fit the fridges, which should reduce average power consumption. IIRC the specs quote figures like 0.8A "average" power draw over 24 hours. This is IMO extremely optimistic (not practically achievable).

The greater the temperature differential between ambient and fridge temperature setting, the more power they'll use, so in the back of a ute under a canopy with solar panels on top, do whatever's needed to keep it as cool as possible, maybe some foam insulation or an air gap under the solar panels, if the canopy is a dark colour, then possibly even repaint it white, and keep airflow up.

Some people put a second alternator on 4WD etc, for a separate charging system for the "house" battery rather than having a dual battery setup where the house battery doesn't get switched over to get charge until the main battery is charged. Probably helps extend the life of the standard alternator too - with diesels and alternators with integral vacuum pumps, OEM replacement alternators are very expensive. Good luck trying to do that with some of the utes with v6 diesels shoe-horned into a space made for a smaller engine, there's not a lot of room to do anything in the engine bays.

raytaylor

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#2364083 1-Dec-2019 16:04

I have it set to -2ish which is just enough for slushy / ice. The temp meter isnt totally accurate.

The old jaycar powertech one i would have to set to -10 to freeze things.

Didnt want to put it on the alternator because i regularly go 3 days without turning on the engine - weekends and holidays where friday/monday is a public holiday. I often take a monday or friday off for annual leave too.
(My dream vacation is not on a beach in fiji, its at home in bed watching tv)

Ray Taylor

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