See also: DIY – Portable 12V Power and Fridge Options
So, you have purchased an electric vehicle, and you have a 12V accessory socket in the rear luggage area.
Can you connect your portable fridge to the 12V socket when travelling, and run the fridge from your EV’s battery while you are camping?
Short Answer – The setup is the same as a regular car with an Internal Combustion Engine (ICE). You will need an independent 12V power supply. More detailed info below….
Battery capacity
A regular 12V camping battery is rated at around 100 Ah, 1200 Wh, which will run a portable fridge for around 2-3 days.
By comparison, the batteries powering electric vehicles are massive. The battery that runs the Polestar has a capacity of 78,000 Wh, at 400V.
If a battery of that size was supplying electricity at 12V (for running the fridge) that would be a capacity of 6500 Ah, which would run a portable fridge for about 270 days before it needed a recharge!
Sounds sensational – but don’t get too excited…..
Getting connected
The main engine battery in an EV is 400V, not 12V. Most, if not all, EVs don’t have their accessory sockets connected to the main propulsion battery. It is apparently more efficient (and reliable) to have a separate 12V battery for running 12V accessories – lights, cameras, alarm, central locking, modem, etc.
The 12V auxiliary/accessories battery in an EV is similar to a regular ICE car starter battery. As well as powering the various 12V accessories, it is also used to power the EV’s Engine Control Unit (ECU) and the startup electronics for the main car battery.
If the 12V auxiliary battery is flat your EV won’t be able to start, and the main battery won’t be able run the propulsion motor/s. The accessories battery is kept topped up by the main battery, via an electronic converter, when the car is in Drive.
Like the starter battery in a car with an Internal Combustion Engine (ICE) the EV accessory battery is designed to start the car, not run accessories long term – it is not a deep cycle battery.
In fact the accessory battery in most EVs is an older-style lead acid battery – although Tesla may be moving to use Lithium batteries for the accessory battery.
Some EVs include the electrical infrastructure to provide a Vehicle 2 Load (V2L) facility – where an adaptor can be connected to the vehicle charging port to supply 230V AC to connected appliances.
This is much the same scenario as using an inverter with your 12V camping battery to run the microwave oven, sandwich press, etc. Handy for powering household appliances, but not so helpful running your 12V fridge – unless you run it on 230V, which uses much more battery power than the 12V option.
You are much better off running your 12V fridge from a 12V power supply.
So, when you plug your fridge into the 12V accessory socket in your EV, the same issues and limitations apply as they did for your old ICE vehicle….
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- When you turn off your vehicle, the accessory socket will be disconnected from the battery;
- If you leave the vehicle turned ON, to keep the accessory outlet active with 12V accessories connected, you will eventually flatten the battery and not be able to drive your car.
Powering your fridge
The bottom line is that despite having a huge battery bank to power your EV, you will still need a separate 12V camping battery to run your fridge when you have turned off the vehicle and setup your camp site.
A 12V camping battery can be installed in a wired Battery Box, and strapped into the rear of your EV.
The fridge can be running from the 12V accessory socket while the car is driving, then plugged into the Battery Box when you reach your campsite.
A 120Ah Lithium battery fitted in your Battery Box will run your fridge for around 5 days.
You might also consider a Portable Power Station. These devices are becoming much more affordable, and are equipped with recharging regulators for AC, DC and solar. Power stations are available with batteries from 20 Ah to 180 Ah. An 80 Ah size is probably a good entry level ‘all rounder’ for weekends away.
You can extend the run time of your fridge by recharging your portable battery or power station using a solar panel – either a folding glass panel or a folding solar blanket for added mobility.
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- More info: Portable 12V Power and Fridge Options >>>