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Citroen C4e Shine
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I am asking this question In response to an article where Citroen say they have made changes/improvements to The eC4 heat pump affecting production models from Oct 21. As an owner of a Jan 21 plate I am very interested to know what the difference makes to the newer car given the common experience of drivers seeing a heavy impact in range
due to the cold. A change after such a short period of time seems to confirm in my mind an issue.
 

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MG5
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Hi, a heat pump works like a fridge in reverse. It uses less power than a heating element so won't take so much out of the battery
 

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Don’t know about the ones in cars but domestic heat pumps often have a COP of around 3 meaning that for every kWh of battery power you put in, you get 3kWh of heat inside the car, 2kWh of which you pull from the air outside the car free of charge.

The original resistive heaters just turn what you put in into heat so for 3kWh in the car, you need 3kWh from the battery.
 

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EV manufacturers like to make a heat pump sound like something special, basically it's just the aircon fitted anyway running in reverse.
 

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Ioniq 5
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EV manufacturers like to make a heat pump sound like something special, basically it's just the aircon fitted anyway running in reverse.
Yes, it's exactly this. Although traditionally they haven't needed the 'reverse' cycle due to the presence of an ICE that produces lots of excess heat.
 

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Kia e-Niro 2 LR, Seat Mii
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Ioniq 5
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No. The heat output is energy into the pump + heat input from heat exchanger.
See the clearly iilustrated example here: Heat Pump Efficiency: Equation & Formula | Linquip (scroll down a bit).
These guys should know what they are talking about, and it's also what I remember from university thermodynamics a long time ago.
I think you're getting confused by the terms.

The work done is the energy into the pump itself.

The point being that this then moves heat from one side to the other - Q. Hence if you get 3 kWh of heat into the cabin, this must have come entirely from the other side.
 

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Heat generated by the compressor not absorbed into the gas will be lost to the atmosphere by convection & the motor driving it by a cooling fan on the motor so a small amount of the power driving it will end up as useful heat.
 

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It’s not the heat generated by the compressor that we are talking about. It’s the work done by the compressor. If all that happened to that energy was it warmed up the compressor, the whole thing wouldn’t work at all.

There will be a slight reduction in the figures I used due to the compressor heating losses but I didn’t think it helped in answering the original question.
 

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The PSA group cars around 40-50 kWh do seem to lose a very large amout of range when it gets cold. Hyundai Ioniq by comparison loses a bit less, typically about 10 miles less when teh expected renge is around 160 miles, see in ev-database.uk where yo have to compare their summer & winter ranges, and compare the drops!

H use a heatpump, and I believe they recover heat from anything that's dissipating quite a lot, so for e.g. if your motor is 99% efficient & drawing 50 kW, that's about 500W waste heat usually lost to outside cold air. But if instead you make this an input to your heatpump, and with a nice warm motor the COP could easily be say 5 (or more!), this means the heatpump would need to use 100W to pump 500W of heat from the motor into the cabin. That's a saving of 400W. And there's the inverter which will be dissipating heat as you drive. Those are probably the main heat losses I guess. I think my cabin averages aroun 600-700W to keep it warm on a long winter trip.

In winter I'm seeing my 38 kWh Ioniq GOM predict a range of lets say 170 miles with 100% SOC. Cat has not been preheated, I find it v quick to warm up. As I set off on 160 mile trip, I can turn heating on. This drops my predicted range by 6 or 7 miles, and I'm finding this to be very accurate. Have to say I'm highly impressed by this heatpump system, works a treat helping reduce range loss.
 

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Vauxhall Corsa-E 2022
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The Stellantis platform cars have heat pumps - but I suspect not the best optimised ones. Hence the December 21 onwards models of the various Stellantis EVs all have increased range with press releases stating the most noticeable uplift is in winter range. They’ve done some new fangled thing with the heat pump, software and tires - not sure if its an entirely new heat pump or they’ve just reprogrammed it better.
 

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MG ZS EV
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It could be that they have used a better refrigerant and improved the pump. Domestic heat pumps have moved to R32 and scroll compressors and achieve 10 to 20 % improved performance.
 

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In the context of an EV here in the UK, expect a heatpump to add ~5% - 10% to your winter or colder weather range. The need for a heatpump depends on driving profile. So if your car has a heatpump option for ~£1000 then you need to ask if having an extra 10-20 miles of winter range is absolutely essential. It will never pay for itself in a financial sense, but if your driving profile is loads of longer trips in colder weather. Then it makes the difference between getting there in one go (assuming a destination charger exists), or having to stop for a top up.

Or if money is no object and you want bragging rights an extra 10-20 miles of range will give.

Obvioulsy this is moot if your EV comes with a heatpump as standard.
 

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The Stellantis platform cars have heat pumps - but I suspect not the best optimised ones. Hence the December 21 onwards models of the various Stellantis EVs all have increased range with press releases stating the most noticeable uplift is in winter range. They’ve done some new fangled thing with the heat pump, software and tires - not sure if its an entirely new heat pump or they’ve just reprogrammed it better.
I'm very interested exactly where the line goes. As I ordered a Stellantis car in October 21 and it was done in manufacturing on the 20th of December.
Will I get the modified heatpump or not?
 
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