Bosch To Present Heat Pump That Could Extend Electric Car Range By 25% In WInter

SEP 21 2015 BY MARK KANE 56

2016 Nissan LEAF

Nissan LEAF already is available with heat pump option

Bosch announced a new thermal management system for presentation at the IAA this month.

Equipped with heat pump, coolant pumps and valves, the unit can distribute heat and cooling solely on the basis of the vehicle’s coolant fluid, and additionally recover waste heat from the drivetrain.

Bosch claims up to 25 percent increase in electric car range in the winter.

Heat pump enables the system to generate heat equivalent of 2,000-3,000 W using 1,000 W from the battery.

“In the publicly funded GaTE project (integrated thermal management in electric vehicles), Bosch, Mahle, Behr, and other companies developed the basis for optimized thermal management. In battery-driven powertrains, heating and cooling play a significantly greater role than in gasoline or diesel engines, since without a combustion engine, the vehicle does not have a generous supply of heat. For this reason, the passenger compartment is heated using a purely electrical system. The electricity it needs comes from the battery. This in turn impacts range: in winter and summer, roughly half the energy stored in the battery goes into regulating the temperature of the passenger compartment.

Moreover, in order to maintain the best possible supply of power to the electrical consumers drawing on it, the battery needs to be kept at a constant temperature of some 35 degrees Celsius – again with heat or cold generated electrically.

Heat-pump principle: like the domestic fridge
The new thermal management system distributes heat and cold solely on the basis of the vehicle’s coolant fluid. The combination of a heat pump with coolant pumps and valves makes this possible. The heat-pump principle is something everyone is familiar with in their fridges, where the heat created in the process of making the fridge cool is released into the kitchen. With the new vehicle thermal management system, a heat pump with an electrical rating of 1,000 watts will generate heat equivalent to an output of 2,000 to 3,000 watts. Conventional heaters used in hybrids and electric vehicles are only half as effective.

Bosch’s system features precisely controllable pumps and valves which collect heat and cold at source and transport them to where they are needed. The need for heating and cooling is additionally reduced by the innovative use of waste heat from the electric motor and the power electronics, plus controlled air circulation that draws moisture from the air.

System made up of already existing components
The pump makes use of the small amount of heat that is generated in an electric vehicle. For example, heat is released when supplying the electric motor with electricity. And when braking energy is converted into electricity and fed into the battery, usable heat is again created. This is also the case when the battery has to be cooled in order to remain within the optimum operating window. Most of the individual components used in this approach are already to be found in commercially available applications. Technically speaking, this innovation has the potential to bring significant and rapid improvement to electric vehicles. With its smart thermal management, Bosch is premiering a solution that will have a decisive impact on electromobility. After all, efficient temperature regulation will be a requirement for future generations of electrically powered vehicles.”

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56 Comments on "Bosch To Present Heat Pump That Could Extend Electric Car Range By 25% In WInter"

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At what temperature are heat-pumps no longer effective? I usually don’t turn on my heat in my Volt unless it’s 15 degrees or below, and I only do it because the software turns the engine on to create heat anyway.

You don’t use cabin heat unless it’s under 15 degrees? Your name should be PolarBear, not kdawg! 😉

It’s usually just to defrost the windows too. If the El Nino is as strong as they say it’s going to be, I may not use at all in Michigan this winter. I made through all of summer w/out using AC.

Would you sacrifice discomfort if it gained you a range increase of up to 25 percent?

Who said I wasn’t comfortable?

No heat until 15 degrees or below, no a/c in Michigan summer…I assumed you were merely human. Sorry.


That’s the making of a true Canadian right there. I’ve noticed that the range of my Leaf is just fine at -5 or so (I live in Vancouver now, but it wasn’t *always* this way), and the only “sacrifice” I need to make is that I need to wear Kamiks. The bum warmer works just fine.

That’s cold alright almost like a 3 kdawg night.

Nice reference to the Inuit term for a really cold night, 3 Dog Night . . . a phrase also adopted by 60’s-70’s band.

Similar situation here. I only use heat when it affects my safety (wipers not able to keep up with lake effect snow, etc).

A heated steering wheel, heated seats and a jacket reduces the heat requirements significantly, especially if you keep the windshield clean on the inside.

Same in my Leaf. It doesn’t really get too cold in the PNW so I’m fine with heated seats and steering wheel, but the condensation that builds up on the inside of my windshield the whole year other than our brief dry summer is a constant pain

Let’s start an online petition for kdawg to change his handle to kpolarbear!


It depend on what efficiency your looking for.
Heatpump work as air conditionner to produce very cold temperature in sub freezer.
Doing so mean that in fact those system extract heat of very low temperature area, some freezer get down to -50c° or even lower.
Of course the gain in efficiency might be affected, beside the fact that there is no much alternative to produce that kind of cold.
Good thing that a system can use any losses to avoid scavenging precious energy, but ain’t Tesla already doing it in their cooling loop fluid that the motor and inverter are in?
The other point shown here is the possible gain that could be made if you coul pre heat or cool your battery pack, before you unplug your car on a climate adverse drive.


In the Volt, all the heat from the inverters, motors, batteries end up in a coolant fluid… addition to the conventional engine cooling loop and A/C coolant loop.

I think the unique part of this system is that the heat pump is using heat from electronics like motors , battery and inverters as a source to heat the cabin.

So it’s not the heat pump that is unique it is the ability to pull heat from the electronics that is unique.

I should go review WOT’s cooling loop diagrams, but is there no interchange between the loop cooling the drive-train and the one heating the cabin? If note, I wonder if Gen2 has this?

George –

Heat scavenging in a heat pump loop is perhaps new to the automotive conditioning, but not to the general HVAC industry. We in the HVAC industry have been designing water-source heat pump systems for decades that transfer “free heat” from one area/process to another area.

yes agreed…but the Volt is not set up to draw heat from the electronics…..which is somewhat of a shame as there are 4 separate coolant loops and radiators.

@kdawg here is WOT’s article on the Volt system:

I’m not sure about the Leaf though. Where does the Leaf heat pump pull its heat from??……I’m guessing ambient air.

Yeah, this system wouldn’t be of much benefit, if any at all, in a Leaf, which does not circulate coolant to regulate temperature in the motor, inverter, or battery pack.

But then, we already knew that the Volt and Tesla’s cars have superior engineering.

I had to go look it up but it does appear that the inverter and motor in the Leaf are water cooled.

Now I guess the question is if the leaf can use that source of heat for cabin heating.

I’m guessing not.

GeorgeS said:

“I had to go look it up but it does appear that the inverter and motor in the Leaf are water cooled.”

Thanks for the correction, GeorgeS.

I was wondering what the radiator was for when I was mucking about under the hood of my Leaf the other day…

The ASHI home inspectors I use usually say that once the exterior temps drop below 40 degrees most regular heat pumps start to get less efficient and when you go below 30 degrees most heat pumps will switch to some form of supplemental heat. BUT, there are heat pumps that can function in colder temps without supplemental heat, not surprisingly, they are more expensive.

I’ve seen similar comments about heat pumps as car heaters in EVs; that when it gets really cold, there needs to be an alternative form of heating, which is usually a resistive ceramic core heater… which gobbles up electricity like crazy, and creates a real hit on the EV’s range.

This Bosch improved heat pump might lower the cutoff temperature (below which a heat pump isn’t sufficient) slightly, but unfortunately I doubt it would lower it that much. Those of us who live where it regularly gets bitterly cold in winter will still need an alternative heater.

Nah, I doubt that. The fact is that as temperatures get colder, a heat pump’s power consumption goes up way faster than resistive heating does. There just comes a point where it wouldn’t save you any power.

Add to that the fact that you’d start to get some serious ice buildup on the cold end from moisture in the air, and the point of diminishing returns comes even sooner.

I’ve noticed something interesting though. If you only ever use the heater while you’re charging – or even better, quick charging – and send the cabin temperature up to 30C or so, then you can go a considerable distance before the car cools down enough to even need heat.

I think I read somewhere that below 0 degrees F, they become ineffective.

There are a lot of air-source mini-split heat pump systems out there now for home and commercial HVAC use that will make heat down to about -10 degrees F. Their Coefficient of Performance drops to below 2.0 and the compressors are really whining at their highest speed at that temp, though. Below that temp, you’d need some really exotic heat pump refrigeration set ups that wouldn’t work well under more “normal” outside air conditions or during regular air conditioning.

To be a 50-state vehicle operable year-round in any climate, electric resistance, at least as a back up, may always be a requirement. Therein the power of the Voltec concept, with the gas engine as the “backup” for both driven power and heat in extreme cold.

There are heat pumps that still gives a COP of over 2,5 at -25 degrees. Gone are the days where below zero meant straight to COP 1.

Home heat pumps which use long loops buried deep in the ground shouldn’t have any “too cold” cutoff temperature, because below about (if I recall correctly) 6 feet of depth, the ground is temperature stable year-round. (I suppose that isn’t practical in arctic regions, or anywhere with permafrost.)

Sadly, it’s kinda hard to anchor a car to a ground loop and expect it to go anywhere! 😉

Heat pumps have never been known to output very warm heat and that is pretty much what’s needed in cold climate to defrost the windsheild but i may be wrong.
Old VW used glowplugs to get instant heat and while battery energy density gets better, maybe the Volt, for example, should go that way sinse the gas is already there.
I wonder what kind of results we would get with that kind of heat generation cause, on short trips, using a 1.4 liter engine to create cabin heat is kind of weird and overkill?

I look at this as a “nice to have” I have a 2012 MiEV and none of the heater/AC-hoses and the heater itself(under the car) are insulated. EV-manufacturers should do the basics first, getting the HVAC-system and the cabin itself insulated. This would be a one-off cost and would require much less energy/HVAC-system for a comfortable cabin in the long run.

Every solo Winter trip in my Volt is an Apollo 13 mission, at the controls 😉

Bosch, Mahle and Behr are reputable companies. I hope VWG’s transgressions do not taint them, and wish them all the sales of these units, they deserve.

I thought the Kia Soul EV already took excess heat and redirected to the cabin?

This is pretty big! It’s actually Bosh we’re talking about..high quality german producer. I really hope it will be implented everywhere…the winters in Sweden would be perfect to test this heat-pump.

“It’s actually Bosh we’re talking about..high quality german producer.”

Bosch parts are notorious for frequently breaking down in every flavor of German car.

I thought that was Lucas electrics?

Finally, a Lucas joke. Not really, Lucas is a joke.

Nah, I would still say Bosch is pretty good quality stuff.

Automotive parts distributed by Bosch USA (or put into “German” cars built in the USA) can’t be compared to Bosch part in Europe. For the US market, Bosch subcontracts to the lowest bidder for many parts. While in Europe Bosch tends to build their own parts.

I think extreme cold is overrated when talking about heat pump efficiency. Most of us use the recirculation button, so the heat pump will often be using air that’s above zero deg so efficiency is still there.

Mel – it doesn’t work that way. You scavenge heat from another source – typically outside air. The effect is to cool that air so you certainly don’t want to use inside air.

Renault ZOE has Heat Pump as default. Its saves energy in winter AND summer. So no news here. ZOE btw. was developed in 2009.

Still don’t understand why heat pumps aren’t standard.
All EVs have a standalone electric compressor to provide AC/cooling.
The cost between a cooling only system and one that can direct the flow to be a heat pump is not that much and would provide huge efficiency benefit. (Without going into the more specialized/expensive very low temp heat pumps)
Then they have resistant heat to fall back on, or supplement the heat pump output.
So, very efficient at cool temps, falling back to standard efficiency at very cold temps.

But I guess (at least in North America), they really only care about California. So heat isn’t that big a deal.
But ironically, that’s where a heat pump would be most efficient in use due to the milder ambient.

lewl said:

“Still don’t understand why heat pumps aren’t standard.”

I’ll take a guess: Because heat pumps are relatively expensive, ceramic core resistive heaters are cheap, and heat pumps are inadequate below a certain temperature… perhaps about 20° F, from what I’ve seen reported from various people, altho obviously not all cars’ heating systems are created equal.

If the auto maker is looking to save money, and also save a bit of space, the heat pump may start looking optional rather than necessary. Yeah, an EV using only a resistive heater will take a hit to the range in cold conditions, but an auto maker may judge the lower price gained by leaving off the heat pump to be more important.

Heat pumps aren’t efficient at all when it gets close to freezing. It will go from 1.4 to 1.5 at best to about 1.1 or lower in freezzing temperature.

What Bosch has proposed here is slightly different. It uses a “shared” heat/cold reservoir which is great idea (I have always supported it that way).

In fact, if you think about it, human, electric motors, battery, electronics all like about the same operating temperature. Sure, motors and electronics can take a slightly higher temperature and colder temperature, but at the end of the day, we all like about the same operating range (except the cold which motors and electronics has no problem of handling).

So, why NOT combine the heating/cooling loops to the same system and just redirect the heat/cold to where it is needed? It would have been more efficient this way.

Also, regen shouldn’t be used to charge battery in the cold (which is only 60% efficient). It should be used to generate heat which can be 90% to 100% efficient in extreme cold.

You’re right about the use of regenerative kW output to produce heat, instead of not using it at all when the battery is too cold.
It’s pretty easy to dump the excess energy in resistive heater.
I would add that insulation of the cabin and sealing all outside draft would be welcome.
But you’re wrong about freezing point useless heat pump. These day inverter duty heat pump could be efficient at much lower temp because of a very accurate pressure control of refrigerant allowing optimal gain.
The trade off of efficiency could be below -20c° or lower.
Also the air cabin has to be change, so you can push the exhaust air true the heat exchanger of the heat pump before you dump it outside.
The other point to work on is heat accumulation in the battery or any 2 phase’s system that could store some of the really welcome heat or cold has needed before you unplugged your car.
Battery being quite heavy does have a pretty high thermal inertia that could help a lot.
If all those things were applied, the range would not be much impaired.

The problem is NOT that heat pump won’t work or can’t work near freezing. It is the result of the system in design or the refrigerant used.

Typically with the current compressors and refrigerant available, you generally get about 40 degrees of differential at best. When it is on the heat pump cycle, it loses efficiency for the refrigerant to get exceessive colder than freezing due to the fact that the same refrigerant and pump system is used for the A/C in the summer. If a seperate system is used, then it can work below freezing.

Winter is coming.

I’m sure Robb Stark agrees. 😉

The point being missed is converting heat that is in the normal water system which can be colletd from all avable locations via heat pump
If we say 500 watts of water heat cop of 3
This is1500 watts to warm you

Apparently BOSCH is using the “cold climate heat pump technology” currently in vogue by companies such as Misubishi, which have relatively high COPS at low outside temperatures.

Recooping other ‘engine compartment’ heat sources should reduce the icing/defrost requirement of the evaporator since it should then be possible to maintain the temperature at the evaporator above 32 degrees for longer, if the incoming air is preheated by the drive motor and inverter losses. And also the ac charger losses if the heat pump is used to preheat the car in a cold garage.

A heat pump is in itself nothing new if they are using a conventional compressor based system.
What would be new is if they use a thermoacoustic heat pump. That one could also double as a rex in the form of a combined thermoacoustic heat pump and generator.
You heat and cool thecabin and in the same time you can generate electricity from biofuel in case of an extended trip.

Mitsubishi’s Hyper-heat pump delivers 3 X as much heat as resistance heat at 5 degrees fahrenheit.

Now if in this system, the ‘engine compartment’ waste heat can be channeled to the evaporator making it warmer than ambient, it should be able to deliver 3X as much down to a lower temp, possibly even 0 fahrenheit.

The mitsubishi system’s coefficient of performance doesn’t drop to 1.0 until -13 deg F.

Great no how to retrofit this into a 2013 Volt?

GM could start on the heating efficiency – by letting me manually not allow dehumidification. One saves energy when dehumidification is absolutely NOT necessary.

This would improve my range and comfort – If GM are listening ?

“This in turn impacts range: in winter and summer, roughly half the energy stored in the battery goes into regulating the temperature of the passenger compartment.”

I don’t know what they’re basing that on, but my EV does not lose half of it’s range every summer and winter. It’s more like 5-10% most of the time, and maybe 15-20% in very extreme cases.

Assuming their 25% range boost is based on the assumption that climate control is consuming 50% of the energy, I’d assume this means they’re cutting the energy cost of climate in half. If that’s true, that’s still quite beneficial, but it also sounds like they might be using a car with no heat pump for comparison. If that’s the case, the advantage of this specific heat pump over any other might be rather minimal.