240v fridge off battery

nethergate · Newbie

240v fridge off battery

Aus-Kiwi · Guru

I have 12v 220l fridge freezer with 200 AH batteries. 400watt solar ! If your
Battery is going flat ? Its not getting enough charge through solar ! Ok its 12v ? But the load or energy should be the same !! Inverters take a little out . Double the solar or fit another panel the same size you have . I used 40mm aluminium L section
about 200mm long on each corner to mount on
Roof . Sikoflex and stainless screws then Sikoflex over again to seal big time !! Maybe ugly with the amount but who sees it ? Run same sized wire to controller so each panel is in parallel. Dont worry about over loading regulator . The panels never get to
100 % efficiency!! Your batteries should be fully charged before midday !! Or theyll have issues sustaining power through the night! Not that fridge is operating 100 % of the time ! Make sure wiring is large enough !

yobarr · Guru

nethergate wrote:
Hey everyone, sorry I did a search but didn't get the answers I needed. I'm running a 240v bar fridge in my van and plan on buying a battery and inverter, my mate has a similar setup and his battery keeps dying, he talked to the guy at the camping shop and he says the current draw on a domestic fridge is too great and will kill the battery, even with a second battery, which doesn't make much sense to me. I think what my friends problem is he doesnt have enough solar gain to keep the batteries above 12v and that's killing his battery. So how I'm tossing up weather or not to swap to a 3 way fridge. Any advice would be greatly appreciated Thanks James

First of all, welcome! Much discussion has taken place on the forum about these antiquated 3-way fridges. There are several members here who have in-depth knowledge of electrics, but I am not one! However, I concur with your suggestion that your friend needs more Solar. As I have already said, I know little of electrics, but I have been told that the wattage of the solar panels should be at least 1.5 times the battery capacity. To that end I have 1650 watts Solar on my van, with 540ah Lithium batteries, while the car has 190 watt solar, but only 180ah Lithium because there is no more room on the car for more panels! You might like to investigate 12 v fridges? Good luck with your research. Cheers

Peter_n_Margaret · Guru

Some 240V bar fridges have realy terrible efficiency. What are the power specs of the one you have?

The solar input needs to be related to the power consumption, not the battery capacity (which still needs to be sufficient to get you through the night and the not so sunny day).

Cheers,
Peter

-- Edited by Peter_n_Margaret on Tuesday 17th of May 2022 11:02:28 AM

Whenarewethere · Guru

A lot of the 240 volt fridge are extremely efficient, but there are some which are not so good. You will need to look at the efficiency rating of all the fridges in the size you are after & go from there. Plenty of homework!

Even our old 340L home fridge at a pinch I could run it off our 120 watt solar setup & it's not the most efficient fridge by any means.

nethergate · Newbie

Thanks for the advice everyone, I'm not too sure on the specs if my fridge it's already mounted in the van so I'll have to pull it out and gave a look. I've already got one panel which I'm looking to permanently mount to the van and will add a second one. Along with 2 X 110ah/h batteries is what I'm hoping to run regardless of what I do with the fridge, hopefully I'll just upgrade to a 2 way fridge but will have to run that by the minister of war and finance. Thanks again for all your advice James

Whenarewethere · Guru

There should be a sticker inside the fridge, probably on the hinge side, with model number. Then look up the data.

Jaahn · Guru

Hi smile

The power of the fridge is the first thing to check. The efficiency is not so easy to check as it has to do with the initial insulation. See how often it switches on or get a simple power meter and measure the actual power it uses. Then check the efficiency of the inverter in standby is the next. Having a large inverter that is in stand by for say 50% of the time and drawing quite a lot of current to do nothing, is a very large waste of valuable 12V power. This factor can be improved by having a smaller efficient inverter, better matched to the fridge load and even one which will go into sleep mode to save power, say during the night when there is no solar.

More solar and another battery is always a good idea.

Jaahn

Izabarack · Guru

You can avoid inverter standby draw by getting a 12 Volt thermostat. You do need something like a high current capable relay to turn the power to the inverter, on and off at some set cabinet temp range. 12Volt thermostat? About 10 Bux from our Chinese friends online.

Whenarewethere · Guru

Victron's 250VA (200 watts at 25°C - 175 watts at 40°C) inverter 4.2 watts standby or 0.8 watts in Eco mode which tests every 2.5 seconds (adjustable).

Use a small dedicated inverter just for the fridge.

nethergate · Newbie

Sounds like a good idea, so I'd have another inverter for the rest of the van, and they would both be turned off when there is no demand? Am I better running everything I can at 12v? Eg. Tv and lighting?

Mike Harding · Guru

Izabarack wrote:
You can avoid inverter standby draw by getting a 12 Volt thermostat. You do need something like a high current capable relay to turn the power to the inverter, on and off at some set cabinet temp range. 12Volt thermostat? About 10 Bux from our Chinese friends online.

Are you smoking something illegal?

Whenarewethere · Guru

If you run everything off 12 volts you will avoid having a 240 volt "death box".

We have everything running off 12 volts. Had to buy a Canon 12v battery charger for the camera, cost a fortune. Bought a couple of 2xAA tooth brushes (I did a review on these).

If it is not necessary to run it off 240v, then don't. If you have to use 240v for a computer etc, think carefully how you set things up. Even things like buying a 750 watt Birko kettle rather than using a 2000 watt beast will make a big difference.

If you are going to run heavy load items you need a system that can cope for the type of camping you typically do.

Izabarack · Guru

nethergate wrote:
Sounds like a good idea, so I'd have another inverter for the rest of the van, and they would both be turned off when there is no demand? Am I better running everything I can at 12v? Eg. Tv and lighting?

I dedicate an inverter to run the fridge. Cannot remember what Wattage the fridge is but a Car relay with 100 Amp contacts does the job so far. I use a PowerTech 600 Watt Sine Wave output to run my Home Brew fridge. Fridge is 120 Litre bar fridge. Used a tube of silicone to protect the fridge tubing from vibration. I hang the thermostat in the door and mega insulate the fridge with 100 mm of styrofoam on three sides. Duty cycle on the fridge is down around 15 % on a 27 degree day. This is typically a static setup because the fridge was never intended to go on the road. The fridge does get used as a drinks fridge near the BBQ. Why use a 600 Watt inverter? Because I had the spare. I could get more efficient by doin a bit of metre work and size the inverter. But, I have several ex- car batteries sitting around and lots of Solar so no need to waste time and effort fixing sumping that aint Broke.

in the Campervan, I have a 40 litre Engle for transportable cold and a couple of LED driving lights for shadowless, eye watering lighting, if I want. Driving lights were $6.71 online. Mood lighting, that also goes in the wobble box, is 4 strings of LEDs running on 4.5 Volts. I use a tablet and Bluetooth keyboard for a TV. I use a really really cheap Modified Square Wave inverter off 12 Volts to charge the phone, computer, and AA batteries. 2 x 50 AH LiFePo batteries are charged by 360 Watts of panels.

-- Edited by Izabarack on Thursday 19th of May 2022 11:30:40 AM

Bobdown · Guru

nethergate wrote:
Hey everyone, sorry I did a search but didn't get the answers I needed. I'm running a 240v bar fridge in my van and plan on buying a battery and inverter, my mate has a similar setup and his battery keeps dying, he talked to the guy at the camping shop and he says the current draw on a domestic fridge is too great and will kill the battery, even with a second battery, which doesn't make much sense to me. I think what my friends problem is he doesnt have enough solar gain to keep the batteries above 12v and that's killing his battery. So how I'm tossing up weather or not to swap to a 3 way fridge. Any advice would be greatly appreciated Thanks James

Hi Nethergate,

Sorry, but that fridge belongs in the games room at home. You need a dedicated 12V caravan compressor fridge of what ever size you require, that will run off batteries and solar, no inverter required.

You will need a large battery and solar set-up to run an inverter 24/7, most are only used for short bursts for 240v in the bush......coffee machines, kettle, TV etc

I think your friends experience should tell you it's not suitable.

Cheers Bob

Aus-Kiwi · Guru

Can be done . With enough solar .

Peter_n_Margaret · Guru

The power lost due to using an inverter is tiny compared with that used by a power hungry bar fridge.
I have never conme across a half decent one.
Cheers,
Peter

Izabarack · Guru

Peter_n_Margaret wrote:
.a power hungry bar fridge.

An easy way to lessen the power draw, of any fridge, is to add insulation all round. A piece of Polyiso will usually fit under the condenser on the back and recycled fruit box foam top, sides, and bottom, is a minimum. Disconnecting the heating element in the face that meets the door seal is another trick. Using what was once a freezer cabinet as a fridge, starts with superior insulation and the digital, external thermostat allows the user to adjust cabinet temperatures to where ever you want. A 2 Degree (C) beer beside a creek after a 40 degree day is one memory every traveller should have available to reminisce over.

yobarr · Guru

Izabarack wrote:
Peter_n_Margaret wrote:
.a power hungry bar fridge.

An easy way to lessen the power draw, of any fridge, is to add insulation all round. A piece of Polyiso will usually fit under the condenser on the back and recycled fruit box foam top, sides, and bottom, is a minimum. Disconnecting the heating element in the face that meets the door seal is another trick. Using what was once a freezer cabinet as a fridge, starts with superior insulation and the digital, external thermostat allows the user to adjust cabinet temperatures to where ever you want. A 2 Degree (C) beer beside a creek after a 40 degree day is one memory every traveller should have available to reminisce over.

Love it! Cheers

Whenarewethere · Guru

Extra fridge insulation:

28 litre fridge per hour, ambient 35°C, fridge set at +2°C
0.0140 kW/h The uncovered fridge.
0.0132 kW/h Standard cover.
0.0116 kW/h 30mm XPS foam.
0.0082 kW/h 60mm XPS foam.

https://thegreynomads.activeboard.com/t65059593/extra-fridge-insulation-wattage-test/

Hylife · Guru

Look on the back of that sh!tty little bar fridge (most are terribly bad for efficiency) for its wattage rating then multiply that by 25, for 12 to 240V conversion via an inverter.
Now watts divided by volts will give you the amps draw from the battery, every hour.

Assuming it is a really good bar fridge and the door is rarely opened you might be able to halve that figure.

I think this little exercise will give you your solution.