Running a 12V fridge from MG4 LV Battery

[Grriff]

Can't you buy a portable fridge with 240V input and use a V2L lead? Or am I missing something?

 

[mg4]

Can't you buy a portable fridge with 240v input and use a V2L lead? Or am I missing something?

I thought about that, but i will be driving 2000+ kilometers so i cant use the v2l as i am driving. This might be an edge use case for an MG4 (to tour in), so most likely not what the plug or the entire circuitry is made to do.

Most likely a non-problem if we don't prepare food that needs to be refrigerated. Sometimes it's good to know when to throw in the towel on an idea.

 

[Grriff]

I thought about that, but i will be driving 2000+ kilometers so i cant use the v2l as i am driving. This might be an edge use case for an MG4 (to tour in), so most likely not what the plug or the entire circuitry is made to do.

View attachment 25215

Most likely a non-problem if we don't prepare food that needs to be refrigerated. Sometimes it's good to know when to throw in the towel on an idea.

I'd get a fridge with 12V and 240V input. Use the 12V while on the road and the V2L while the car is not.

 

[dsimpkins]

I'd get a fridge with 12v and 240v input. Use the 12v while on the road and the V2L while the car is not.

That's what my fridge can do. I can precool it at home on 240V, and then put it in the van on 12V.

 

[mg4]

Will it then not still blow the fuse of the MG4's 12V line?
Or, do you say your fridge draws less amps?

 

[dsimpkins]

Will it then not still blow the fuse of the MG4's 12V line?
Or, do you say your fridge draws less amps?

It's designed to be used in a vehicle, and run off a standard 12V socket, never had a problem in our van, and the cable also has its own fuse built in. I would expect it to run in the MG4 without issue too.

Just checked the specs, and my fridge draws a maximum of 2.7 amps. Maximum power is 32 watts.

 

[MozFromOz]

In short, I think the summary is if you try to run the fridge around the clock from the onboard 12V battery you will be sad. The fridge requires way more energy than can be delivered by the 12V battery and you cannot rely on the dc-dc converter in the vehicle to charge the 12V from the traction battery.

 

[Blacksmith]

Did anyone found a fridge that could work? I am planning a roadtrip and would love to get ideas and experiences. We don't need anything big, maybe even find something compact for between the front and the back seats?

This is the fridge I have, It draws about 3-4 amps when running, so not a lot. I was planning on a 90AH lithium battery to run it, so not an issue killing the standard 12V battery.
There are many smaller fridges.

https://www.4wdsupacentre.com.au/fr...e-freezer/kings-escape-40-fridge-freezer.html

There is the Brass Monkey fridge with battery compartment built in. A bit pricey when you add batteries, but you save the hassle of extra wiring, etc.

https://www.jaycar.com.au/15l-brass-monkey-portable-fridge-freezer-with-battery-compartment/p/GH2068

 

[dsimpkins]

Both of those fridges are similar to mine, I noted on the first one that when set to fridge temperature (not freezer) it uses 1-1.3Ah, so a 90Ah battery is going to give you about 90 hours runtime. More than enough for a weekend away. Longer if you boost with solar or recharge while driving.

 

[mg4]

Thanks for the suggestions, at least there is a way. If end up using one in month i will update you here.

 

[johnb80]

There is the Brass Monkey fridge with battery compartment built in. A bit pricey when you add batteries, but you save the hassle of extra wiring, etc.

https://www.jaycar.com.au/15l-brass-monkey-portable-fridge-freezer-with-battery-compartment/p/GH2068

When you look at the specs of this one, the biggest battery would run it for 3 hrs!

Batteries and absorption / peltier fridges never work on a practical level.

 

[Blacksmith]

I am looking to run a 12V car fridge full time in my MG4 77. Is it better to use the onboard 12V battery or add a second 12V lithium battery to do the job?
The fridge draws about 3-4 amps when running.

My concerns are running the onboard 12V battery down too low, that the car won't start, or having the fridge without power for extended periods (if it cuts off on low battery).

I think there is enough space in the front next to the onboard 12V battery to fit a 60AHr Lithium battery as well, and use a voltage sensing relay (for a dual battery ICE setup) from the Onboard 12V battery to keep it topped up.

Any advice or input is welcome.

UPDATE,
After finally getting the car, I have installed a Kings 60Ahr lithium battery to run the fridge, I have a voltage sensing relay between the main battery and the aux battery. It is winter so not a lot of load on the fridge, but so far it has all coped well with the setup.
Next step is to move the LiFePo battery under the bonnet, giving me back some boot space.

The VSR has a low cutoff of 12.6V so the main battery is looked after. So far the lithium battery has dropped to 12.9V after running overnight, so I assume I would get 1-2 days running without turning the car on.

The flexible solar panel on the roof looks like another possibility, that I will look at, to boost on the sunny and hot days with the fridge running a bit harder.

So far so good.

 

[MozFromOz]

Sound like a solid plan. Well done

 

[Blacksmith]

The blue section on top of the battery is a 3D printed housing for the Anderson plugs, VSR, Fuse, circuit breakers, 3.5mm power outlet, and soon to be USB and volt meter.

 

[DerekH]

The blue section on top of the battery is a 3D printed housing for the Anderson plugs, VSR, Fuse, circuit breakers, 3.5mm power outlet, and soon to be USB and volt meter.

You should have asked I have a king's battery box with all the usual plugs (USB, Anderson, meter, isolation switch etc) and a kings Invertor. All new and surplus to my needs. I will call you later.

 

[MozFromOz]

Makers rule the world

 

[Blacksmith]

You should have asked I have a king's battery box with all the usual plugs (usb,Anderson, meter, isolation switch etc) and a kings Invertor. All new and surplus to my needs. I will call you later.

As I am limited on space (as you can see the size of the fridge) I went with what I am hoping is the smallest suitable LiFePO₄ battery. And I don't need an excuse to make stuff with the 3D printer, so I now have what is probably the best compromise for size and flexibility.
I do like the idea of another inverter for the car? Probably shouldn't fill up the boot with nice to have stuff.

 

[mg4]

Reopening this thread, since i think i found a fridge that should tick all the boxes

• It runs off of 12V and 240V
• It has built in protection of the car's battery
• It fits between the two child seats so does not take up boot space

Here are some specs of it and how the protection works. It is set to high (H) protection level, but i can use some advice from the persons on here that know the battery specs of the MG4.

 

[Coulomb]

It is set to high (H) protection level, but i can use some advice from the persons on here that know the battery specs of the MG4.

I would leave it set to high protection for sure. I would prefer an extra-high protection option where the motor cuts out at 12.0V. Lead acid batteries hate regular deep discharges.

If you have the DC-DC on, then the big battery will keep the 12V battery charged, in which case you won't have much of a problem.

 

[Blacksmith]

UPDATE,
After finally getting the car, I have installed a Kings 60Ahr lithium battery to run the fridge, I have a voltage sensing relay between the main battery and the aux battery. It is winter so not a lot of load on the fridge, but so far it has all coped well with the setup.
Next step is to move the LiFePo battery under the bonnet, giving me back some boot space.

The VSR has a low cutoff of 12.6V so the main battery is looked after. So far the lithium battery has dropped to 12.9V after running overnight, so I assume I would get 1-2 days running without turning the car on.

The flexible solar panel on the roof looks like another possibility, that I will look at, to boost on the sunny and hot days with the fridge running a bit harder.

So far so good.View attachment 29166

12 month update:
The fridge has run continuously since I installed the setup. No problems, It hasn't run out of power, and seems to be able to dissipate the heat well enough. I didn't bother with a solar panel, as it has performed well enough as is.