How to Power Your Fridge Off Your Electric Car

in #diy2 years ago (edited)

Author’s own photo

What could anybody possibly need a wall outlet in their car for? Aren’t there little inverters sold at Harbor Freight or at truck stops you can plug into the 12 volt cigarette lighter socket? Well dear reader, I live in Portland. I don’t know if you’ve been keeping up with what’s happening here, but Portland is basically real life Death Stranding.

Constantly rainy? Check. Apocalyptic weather? Check. Tent encampments all over the place where porch pirates bring stolen packages back to? Electric trucks and motorcycles? Gorgeous terrain mixed with derelict industrial infrastructure? People living in isolation due to lockdown normalizing remote work, gig delivery guys being celebrated as essential workers, and normalized male pregnancy? Check marks all down the row. 

It would seem prudent then to begin work on a lifeboat. I’m only willing to engage with industrial civilization these days from inside of an escape pod, given how precariously it teeters on the precipice of collapse currently. Texans should be able to relate, though their set of problems is different and enviably less severe. 

Author’s own photo

You may recall the Texas blackouts this past winter, which contrary to certain media voices wasn’t the fault of renewable energy (inherently) but their negligence in declining to winterize their wind turbines. Gas pumps and pipelines also froze, gas stations were also inoperable. Many Texans took notice and thought it wise to invest in backups.

Sales of Jackery and other suitcase batteries (which unlike a generator can be safely operated indoors) skyrocketed. I also saw a few photos of EV and PHEV owners plugging essential appliances into their cars, though. A few, like the Mitubishi Outlander PHEV, actually come from the factory with an inverter preinstalled for this exact purpose.

As my Volt didn’t come with that feature, I bought one. I already had a little 200 watt inverter for running my laptop off the cigarette lighter port, but those allow a max safe draw of 180 watts. I needed at least 1500 to do everything I wanted to, hence the huge honking 2000 watt inverter seen above.

Author’s own photo

Why a 2000 watt inverter? The max load that the Volt’s high voltage to low voltage converter can keep up with (it constantly replenishes the 12v starter battery as you pull from it) is 1500 watts. But any time you’re running an inverter in an enclosed space, you want to over-spec it. It’s designed within certain thermal tolerances.

The max safe temperature it’s designed for is the one it reaches sitting in open air, running at it’s maximum rated wattage. So if you put it inside something where it has a harder time getting rid of heat and draw big amps, it’ll melt itself. Hence a 2000 watt inverter for 1500 watt max loads and a 200 watt inverter for 180 watt max loads. 

The Gen 1 has more watts to spare than the Gen 2. The Gen 2’s voltage converter can keep up with a max draw of around 1200 watts, compared to the Gen 1’s 1500. One of many reasons I went with a Gen 1 besides the price difference back when I bought it in 2017. 

Author’s own photo

It’s vital to know what the limits are for your vehicle’s electrical system before you do this, and to have some experience wiring up outlets, as it would be easy to injure or kill yourself, or start a fire, if you overload it. Anyway here you can see the outlet and remote on/off switch for the inverter mounted to the removable side panel of the trunk, through rectangular holes I dremeled.

The remote on/off switch, which connects to the inverter via a long, thin RJ-11 cable (like the one used for land line telephones). This was an essential feature to have in an inverter as it draws power while turned on even if there’s no load. Since it connects to the 12 volt lead acid starter battery, if you accidentally left it running with the car turned off, it could easily kill your starter battery overnight.

I didn’t want to have to lift the trunk floor every time I needed to turn the inverter on or off, because the trunk is where the stackable, interlocking, wood backed fabric lined foam cushions live when they’re not in the sleeping configuration, shown below:

Author’s own photo

This would make it a pain in the ass to turn the inverter on or off, if not for that remote switch. Anyway the switch connects to the inverter, the outlet connects via crimp forks and a snipped 3ft extension cable to one of the inverter’s two 110v outlets, and then the positive and negative input cables from the inverter connect to the positive and negative terminals of the 12v lead acid starter battery, shown below.

The Volt has one of the larger format starter batteries used in modern cars due to the stressful duty cycle it needs to endure in a PHEV where the engine starts and stops more frequently than it would in a conventional ICE vehicle. Lithium ion drop-in replacements exist, made by Battleborn, but they start at around $800. As yet, I’ve not made that a priority, but it’s coming.

The battery being under the floor of the Volt’s trunk is another design feature which makes it an ideal car for this mod. It’s much more elaborate and difficult for cars with the battery under the hood. The Volt’s catalytic converter is also tucked deep inside the chassis, which has protected me more than most from the recent spate of catalytic converter thefts in this state.

Author’s own photo

I had to drill some holes and do pretty extensive dremeling, but I don’t really plan to ever sell this car, and if I do it’ll be to my dad who won’t mind the modifications. If anything he’ll probably think this is all cool as hell. GM engineers decided it was necessary for the terminal securing nuts to be two different diameters btw, thanks for that.

I’ve been planning this a while. Prepping is an economical hobby because all the same stuff you buy to prep can also be used for camping, or as a safety net in the event you unexpectedly become homeless. All three for the price of one. I’ve also been eyeing van life enviously for some years, but don’t want a van.

What do you get with a van over, say, an RV? Most van life builds don’t have a toilet, shower or kitchen. Maybe a microwave and mini fridge, but besides that, just a bed and a desk. That’s slim benefits for the huge hit to fuel economy you suffer by driving a van around. 

Author’s own photo

The only big benefit is that you get a transportable shelter that keeps you dry, warm and which locks from the inside. I figured I could do that in a sedan (technically a hatchback according to GM) form factor. Lots of people love the Volt for this, and consequently there exists a cottage industry based around selling after market mods that adapt the Volt into a mini camper. 

By using an OBDII bluetooth dongle I can use a smartphone app to command the car not to use the battery even when it’s full, defaulting to the gas engine, so I can drive out to the campsite and still have a fully charged “house battery” for cooking, light, heat, air conditioning and now refridgeration and hot showers.

That’s right, 1500 watts is just barely enough to run compact, portable water heaters. Hot water on demand systems usually start around 3000 watts but the little 2.5 gallon dealies meant to be mounted in the cabinet under an outdoor sink, or the sink in a sailboat can also simply be used as a portable hot water unit.

Author’s own screenshot

That’s one of the next planned upgrades along with a small microwave and a portable shitter. I already have the vertical shower tent to serve as a private space where I can bathe or download a brownload. There’s space for all this in the rooftop cargo carrier, though I’ve been giving consideration recently to building my own micro trailer.

Volt cannot safely tow much weight. Most Volt owner forums indicate 2,000 lbs is the safe maximum, though GM and Chevrolet recommend never towing anything. There aren’t any trailers with a shower and toilet in that weight range. What I really need, since the car is already a sleeping space, is a trailer with JUST a toilet and shower. Maybe a mini fridge/microwave, maybe a small dishwasher at most. 

Just amenities in other words, no living space. Probably not enclosed but something you access from the outside. That way I'm not dragging it around wherever I go like if it was a van, I can leave part of it at home except when camping. As you may have gathered there’s a lot more interesting useful shit you can do with a PHEV or EV and high draw inverter than just powering your home during a blackout. Hopefully I gave you some ideas. 


Just had a scheduled power outage for repairs the other day and it was terrible. My friend mentioned I could rig my Tesla like you just did. I will have to do some research before killing myself as mentioned in your post, thanks for the warning. Very cool detailed post and I really loved the outcome!

No sense in shouldering the burdensome cost of vehicle ownership if you don't squeeze the maximum utility possible out of it imo. A Tesla battery would keep a home going for quite some time I imagine. IIRC Teslas don't like inverters hooked directly to their 12v batteries and register it as a battery fault, but there exist workarounds:

this sounds promising, and with the long range battery I image would be longer use too. It would be nice to be able to use the computer and fridge while the whole neighborhood is shut down! I will start my research with your link ...much appreciated!

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