iMiEV Heater Installation

by Ben N on February 14, 2016


Overall, I love my little electric car, the Mitsubishi iMiEV. It’s a good, affordable, all electric commuter car.

It’s one shortcoming is that it was never designed for COLD Wisconsin winters. The heater is electric (of course!) but it heats a liquid antifreeze (coolant) which then circulates through a heater core, where a fan finally blows the heat into the car. It’s not particularly efficient and has a bit of a warm-up time. On top of that, the system only heats the coolant to around 140 degrees Fahrenheit. Most typical gas cars keep the engine coolant at 190 degrees once they are at temperature!

The car also has the smallest battery pack of any commercially-available battery-electric car in the United States. Combine a small battery pack with an inefficient heater, and a Wisconsin winter, and it becomes a recipe for short range and a cold driver. In this screen grab, red shows energy used by the heater, and blue shows energy used to push the car down the road. When it’s really cold, range can be shortened by a third or more!

So, after reading lots of information about “Winterizing” these cars on the MyiMiEV forum, I decided to install a dedicated fuel-burning heater. The heater I chose was one already used by several of those forum members. It’s a generic version of an Espar 5kW liquid heater. My heater was roughly $500 and was purchased through You can also find the heater through the manufacturer’s web page. It’s the 5kW 12V Gasoline version. There’s also a number of diesel heaters you can look at on Amazon:

So, far, I’m running the heater on E85 from my local gas station. I have a friend who makes his own ethanol from scratch, and I intend to get some pure, sustainably produced ethanol from him. Even with the heater running full blast, fuel use translates into hundreds of miles per gallon.

Mounting the heater in parallel with the original electric heating system allows me to use the electric OR liquid-fueled heater, and I can still use the car’s electric “pre-heat” feature. I intend to use the fuel burner when it’s either very cold, or when I have concerns about range, due to the electric heater otherwise sapping power.

In effect, what I am doing is using a liquid fuel for heating, to maximize battery energy for propulsion – trying to “use the right tool for the right job”!

After the heater arrived in the mail, I first rigged it up on a stand in my garage to learn what I needed to do to hook it up and test it. I also shot some thermal video of the heater running hot water into a bucket as an initial test.

Once I had a basic understanding of the heater, I started the process of the actual installation of the heater into the car.

What follows is a series of 6 videos showing step by step how I installed this heater in the car.

A big Thank You to other Mitsubishi iMiEV owners who have shared information on modifying the heater systems in their cars! I hope these videos help anyone else who is interested in hybridizing their heating system in cold climates!

I’ll add some more information here as I get more experience using this heater!

-Ben Nelson

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iMiEV Dislikes updated
June 1, 2016 at 10:57 am

{ 2 comments… read them below or add one }

1 Kraig Schultz October 11, 2016 at 8:26 pm

Quote from End of part 3 video: “So, other than all the smoke coming out…”

I’m reviewing your installation videos (very high quality, by the way) and thinking about how to get more heat in my little Festiva Conversion. My Festiva still has the heater core in place from the days when it still had a Gas engine, and I have almost the entire engine bay open for adding my heating system. $500 is a lot a for a heater, gosh, that’s more than you paid for your first electric car and Vectrix together, isn’t it? Got any ideas for doing it for less $ after having done the entire project?

Thanks, Kraig

2 admin October 13, 2016 at 9:41 am

Hi Kraig,
The heater I used is really sort of designed for semi-trucks. As such, it’s somewhat niche application, and thus more expensive. Yeah, $500 was expensive for a heater, but it’s also been a very good system and the iMiEV is now my PRIMARY transportation. Also, considering how inexpensively I got the car (compared to new or any USED commercially built EV) I’m really just considering it part of the car purchase.
As for how to add some sort of similar heater INEXPENSIVELY, I’ve heard of people getting similar heaters from salvage yards. If you can find some way to purchase a combustion heater USED or SALVAGED, that would be the way to go.
As for something completely different, I LOVE the “Pre-Heat” feature built into the EV. I can run the heater/defroster (including rear window defrost and heated outside mirrors) from wall power while the car is plugged in. In theory, you could plumb in a 1500 watt engine block heater with pump to a small coolant tank and your heater core. Wire your blower fan so that you can run it without the car being on. When your car is parked and plugged in, run the block heater and blower fan. You can set this on a timer. That way, you can hop into a pre-warmed car on winter mornings.

For another “outside the box” idea, I also used a 12V electric blanket last winter. It worked great! Sort of the same idea as the old-fashioned “Sleigh Blankets”. I always found that with my winter coat, my upper body was plenty warm, but that my legs got cold if I wasn’t blasting the heater (either draining the battery or using the ethanol heater.) The 12V heated blanket warms up almost instantly and is considerably more efficient than using the full car heating system. Also, it puts the heat right where I want it – on me!

The only thing the heated blanket DOESN’T do is defrost/defog the windshield.
I found that on SHORT trips, preheating the car and then using the stock electric heating system works great! On longer trips, I would pre-heat and use the blanket, and then use the ethanol heater as needed to avoid unnecessary drain on the battery.

I also don’t want people to get the wrong idea about the car. It’s a great car, I really like it… BUT… I’m already pushing how far I drive it IN THE SUMMER. I have a friend who lives only a few miles away from me and she doesn’t even ATTEMPT in her Nissan Leaf what I do all winter long in my iMiEV. So, the car isn’t perfect, but it’s very good and very affordable. And, if you don’t like something, change it, fix it, hack it, or otherwise make it better!

The other thing that is promising is that PUBLIC CHARGING availability in my area is improving. Having electricity available to me during the day while working at a location means I have a full battery available to me on the return trip, instead of trying to eek my way home on just barely half a battery.

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