Wanted: Complete Radiant Heat Solution for EVs

OCT 21 2013 BY MARK HOVIS 39

MIT heater prototype uses minimal battery

MIT heater prototype uses minimal battery

So, it is getting close to that time again to turn the heaters on in our EVs.

Some BEVs like the Nissan LEAF are offering heat pumps as an improved method of heating the cabin, as well as proper radiant heated seats and steering wheels.

EREVs like the Chevy Volt have enabled the ability to run their ICE at any time in order to heat the cabin while providing thermal capabilities to the batteries with this inefficient bi-product (heat) of running the ICE.

We are also eagerly watching our esteemed engineers at MIT as they work on scaling their ingenious discovery to fit in an EV.

Meanwhile, I am still in search of a complete radiant heat solution. Pardon me if I find it a bit ironical that in our EV community, we become anxious with why the global market does not comprehend faster the advantages of the EV, and at the same time we hold on to our old forced air approach to keeping ourselves warm.

In colder climates, it is quite acceptable to heat a home through radiant methods and at least until the MIT engineers provide such a product, the best methods are found in keeping our extremities warm.

heat matHeated seats are accepted quite well, and heated steering (or gloves) are generally accepted at least in the EV community. So, why are we so slow to accept warming our head and our feet? I suppose some people’s hair grooming does not allow them to wear the proper head gear but it certainly is an easy solution to the problem.

But for me, it is warming the feet which is the final and simple stage to keeping the body warm and maximizing energy efficiency. Not double socks or electric socks, it is an electric mat that I seek. What is simpler than a heated mat?   Now, certain dead end ads exist,  but I have yet to find a reputable product that works on a timer with maybe two heat settings.   Not a single OEM offers this simple integration  even as an option. This could be a one, two, or four mat option for the OEM. But even more frustrating is that no aftermarket products exist. OK, maybe the mat is over simplifying the issue but I can’t believe engineers have exhausted efficiencies just yet.

We are quite prepared to let the ICE go and for many good reasons, but we just can’t seem to let go of their method of heating. For the ICE, forced air is a given. For the EV, at least for the present, I hope this winter produces some improved options.                                                                 

Categories: General


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39 Comments on "Wanted: Complete Radiant Heat Solution for EVs"

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How about using some of that thermal energy left in the battery (leaf)? solve two problems at once…

Are you saying that thermal energy in the battery is a problem in the cold? I don’t think it is. I know the S manages the temp of the pack as an integral part of the cabin climate control (if one has the energy the other needs, they can share). I don’t think the LEAF has that kind of elegance, but I don’t think that in the cold even the S has any battery heat to spare–at winter temps what heat is generated in the cells once they are pumping doesn’t do anything other than maintain battery performance.

What I would really like to see is an improved method of windshield defrost. Running heat just to get defrost is wasteful, especially when you can heat people easily through seats.

I remember some European cars used to have mesh in the windshield, but that disappeared due to overall costs. Shame, because they could clear the windshield very quickly.

I agree. While the cabin heater may be seen as a wasteful use of energy, there is no other solution currently available to prevent ice from forming on the windshield and side windows while driving. We need targeted solutions for the windshield and side windows.

This problem was solved decades ago. The Lincoln Continental had a fast defrost option which was gold wires in the windshield (gold is so ductile that if you stretch it enough it becomes transparent). I’m uncertain as to the unpopularity due to the expense of the gold itself, or the cost of the 120 volt separate alternator.

How about some thermal storage in the seat and mats. Pre-warm and watch them stay warm for 2 hours, no battery drain at all.

I am presently studying on passive house heating (also studying the effect of thermal mass) at university and really like your idea. In addition, they can also put more insiluation.

I don’t know about you but I wear shoes when I drive. Radiant floor mats have a lot of overcome through the soles of my snow boots.

I was already thinking they should have some kind of radiant heat lining the knee pane.l to leg area.

Make a tiny exhaust vent, install a tiny pellet burner. Haha only extremely serious.

Look, combustion is bad for everything because of wasted heat, right? Heat is always normally seen as wasted energy, right? Whenever you meet up with heat in designing any device, it’s wasted energy. EXCEPT in a heater. What I’m getting at is: put a combustion heater somewhere it can blow heat into the cabin and vent exhaust gases outside. YES, it’s combustion of a fossil or only-semi-renewable fuel. But NO there is no wasted energy. A heater in a small closed, insulated space right next to you is always, by definition, 100% efficient.

I don’t know Mark, I think the heated floor mat might us too much juice but I don’t know for sure. Good to think outside the box though. I ride motorcycles in the winter and I use Gerbings heated Vest. I know you guys have heard that but thought I’d throw it in anyway.


What I wounder about EV’s are the AC’s on them in that you leave a car in a parking lot most likely it will be pre heated by the time you get into it. I really hope these things don’t have weak AC’s.

Is the electric A/C in your house weak?

No, they aren’t weak. They only have a small space to cool as well. Apparently the Volt’s A/C is good for homesick Inuits.

Pre-heating while still plugged in should be used often but that doesn’t help when you are parked where there is no power.

A small propane heater could do the job. It seems like such a waste to use valuable battery energy for heat.

What about an infrared lamp?

Actually the Nissan Leaf heat pump is the right way to go, the only thing that is still left to do is use a better heat pump.
A thermoacoustic heat pump that is. It moves heat trough a stack by a powerfull standing sound wave. No refrigeration gas is required. Best of all it can even double as a range extender by turning heat into electricity. So, you get an airo unit and a rex in a single package.

Pardon my stupidity, not yet owning an EV… But isn’t there a fair bit of heat coming off of the MOSFETs of the ESC? why not use that as the source for the heat to be transferred? Otherwise isn’t it just wasted?

Steven, I own 2 EV’s. I believ the heat is recovered in my volt but it is wasted in my Tesla Roadster.

They have these cool devices called internal combustion engines, which are not very expensive, have a plentiful supply of cheap fuel, and which are very good at making heat. Maybe they could add one of those.

Mark, sorry to join the discussion a tad late. As a fellow Leafer, I thought along the exact same lines as you and researched the same topic, stumbling over the same not-actually-sold floormat… I’m equally frustrated with both cold-ish feet and the apparent lack of products that could elegantly remedy this — because, yes, unless I have passengers or I’m close to solid frozen, I stubbornly refuse to fire up the vehicle’s main heater (mine predates the heat pump). Also, while heated shoes or insoles would surely work wonder, I haven’t found a model which I could wear in public and not instantly die of ridicule (or discomfort). Pointers welcome. So anyhow, for this coming season, I’m about to give a try to at least one of the following less-elegant combinations: 1) Some 120/230V heating element (those are much easier to find than 12V): Either an actual mat, unfortunately not quite the right size, e.g: http://www.samsclub.com/sams/electric-foot-warmer-mat/prod1600036.ip http://www.homedepot.com/p/Cozy-Electric-Foot-Warmer-Mat-FW/202930325 Or heat wire, which I can attach to the existing floormat, e.g: http://www.morelectricheating.com/products/PIPE%20HEATING%20AND%20FREEZE%20PROTECTION.aspx 2) A step-up converter Either some shockingly cheap inverter (but then it’s all-or-nothing), e.g: http://www.aliexpress.com/item/150w-power-inverter-car-laptop-power-supply-converter-12v-110v-charger-belt-usb-mouth/1284164401.html Or a more modest but adjustable DC-DC, e.g: http://www.aliexpress.com/item/DC-DC-Boost-Converter-10-32V-Step-up-to-35-60V-Power-Supply-Module-120W/751733536.html http://www.aliexpress.com/item/LM2577-3-34V-3-7-7-4V-to-4-60V-DC-Step-up-Converter-Adjustable-Charge/754722175.html http://www.aliexpress.com/item/LM2577-rosy-high-voltage-DC-DC-booster-module-IN3-5-35v-OUT5-56v-indicator-light-belt/1143147197.html Note that power in… Read more »

I’d be happy to have some way to heat just the accelerator pedal and a small area to the left of the brake pedal- just enough to keep the toes warm. Surely that wouldn’t draw much juice; Nissan ought to be able to pull that off.