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Discussion Starter · #1 ·
In his ID.3, but should set directional expectations for ID.4 lack of heat pump.

 

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So, if I followed the test results correctly, with an external temperature around freezing and heating the cabin to ~70 (conservative driving):
  • Driver-only heat increases consumption 13%
  • Full cabin heat increases consumption 20%
 
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So, if I followed the test results correctly, with an external temperature around freezing and heating the cabin to ~70 (conservative driving):
  • Driver-only heat increases consumption 13%
  • Full cabin heat increases consumption 20%
Yes. Moreover I suggested to him that he follow up with a second round of testing of his desire comfort level of 22掳C, rather than the 20掳C he did for the test. Realize when he did the initial consumption, the weather was 20-25掳C outside & he had the HVAC off or turn on the AC if it got too stuffy.

He will likely do the test again when the temperature is -5掳C as it is rare that it is consistently -10掳C where he is.
 

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This consumption seems high to me but VW says its a highly efficient heat pump system:

How does a heat pump work?
Compared to a petrol-driven car, the drive components of an electric vehicle do not produce enough waste heat to adequately heat the vehicle interior.

The solution: a highly efficient heat pump system compresses refrigerant under high pressure. The heat produced is used to heat up flowing cold air.

This uses less energy from the battery for the high-voltage heater, beneficially delivering greater range over electric vehicles without heat pump.

Cold outdoor air becomes warm indoor air in ID.3

Cold outdoor air becomes warm indoor air
Lower current consumption, higher range
The heat pump in the new ID.3 also provides a number of benefits: the refrigerant used to generate the heated air is climate-neutral. This reduces the load on the battery capacity by approximately 3 to 4 kWh/100 km, increasing the range in winter by up to 30% in temperatures as low as -25掳C.

ID.3 with up to 30 % more reach

Up to 30% more range with heat pump
Sustainability takes precedence
Volkswagen is taking responsibility with regard to climate protection in its choice of refrigerant in addition to the CO2-neutral production of the ID.3.

The world鈥檚 first heat pump to use the natural and climate-neutral R744 refrigerant is used in this. Thanks to its excellent efficiency, it is the most energy-efficient way to heat an electric vehicle in cold ambient temperatures.

Family with their Volkswagen ID.3 in nature
 

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This consumption seems high to me but VW says its a highly efficient heat pump system:
remember that the Plus in this video does not have a heat pump. So the energy consumption to heat the cabin is what we will likely see at the freezing mark. A comparison to the range tests done back in Sept & Oct by Battery Life will also provide a linear comparison of scale in consumption as the temperature drops. Especially with an additional data point below freezing. He has done enough videos with this car at 20, 10 & 0掳C that a few of his watchers have spreadsheet his consumptions on top of his own results. Couple in Bjorn Nyland & Nico's numbers. It is a good benchmark on what we will see going on with the ID4.
 

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So, if I followed the test results correctly, with an external temperature around freezing and heating the cabin to ~70 (conservative driving):
  • Driver-only heat increases consumption 13%
  • Full cabin heat increases consumption 20%
13% isn鈥檛 bad for driver only.
I wonder if freeway driving vs city impacts the numbers at all. His test mostly seems freeway
 

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Thanks for posting the heat pump marketing stuff @eVDub . The important factoid in there is that the heat pump adds about 30% of range at -25潞C (-13 F). This finally puts the VW UK claim of 30% range increase into context, in Britain it is actually near impossible to experience -25潞C.

I have run heat loss calculations on buildings over the past two days and have the required math in my head now. The important thing is that heat loss and/or energy use for heating is directly proportional to the temperature difference. Add to this the fact that a heat pump can save up to 60% of energy compared to resistive heating, but in more realistic scenarios around 50%. And you can equate range loss to energy used for heating instead of propulsion.

In other words:
Chris' results of 20% range loss for a temperature differential of 20潞C on resistive heating imply 45% range loss at 45潞C temp differential (-25潞C outside, 20潞C inside).
Add a heat pump at 60% theoretical energy savings, and you might only loose 18% range - or gain 27% of range compared to resistive heating.
Put another way:
For every degree Celsius or 1.8 F temperature difference you loose 1% range on resistive heating.
For every degree Celsius or 1.8 F temperature difference you loose 0.4% range on heat pump heating.

That about sums it up and makes the numbers more or less jive. Keep in mind, this assumes an unusually efficient heat pump.
 

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Thanks for posting the heat pump marketing stuff @eVDub . The important factoid in there is that the heat pump adds about 30% of range at -25潞C (-13 F). This finally puts the VW UK claim of 30% range increase into context, in Britain it is actually near impossible to experience -25潞C.

I have run heat loss calculations on buildings over the past two days and have the required math in my head now. The important thing is that heat loss and/or energy use for heating is directly proportional to the temperature difference. Add to this the fact that a heat pump can save up to 60% of energy compared to resistive heating, but in more realistic scenarios around 50%. And you can equate range loss to energy used for heating instead of propulsion.

In other words:
Chris' results of 20% range loss for a temperature differential of 20潞C on resistive heating imply 45% range loss at 45潞C temp differential (-25潞C outside, 20潞C inside).
Add a heat pump at 60% theoretical energy savings, and you might only loose 18% range - or gain 27% of range compared to resistive heating.
Put another way:
For every degree Celsius or 1.8 F temperature difference you loose 1% range on resistive heating.
For every degree Celsius or 1.8 F temperature difference you loose 0.4% range on heat pump heating.

That about sums it up and makes the numbers more or less jive. Keep in mind, this assumes an unusually efficient heat pump.
Thanks good info. However, one other factor over purely temperature differential is that the batteries have an optimal operating temperature which I believe is 68潞F. Deviation from that impacts efficiency. I'm not sure whether that's a linear or non linear impact and to what extent.
 

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Thanks good info. However, one other factor over purely temperature differential is that the batteries have an optimal operating temperature which I believe is 68潞F. Deviation from that impacts efficiency. I'm not sure whether that's a linear or non linear impact and to what extent.
Good point, and it's factored into Chris' test above. The battery must have been slightly heated.
Technically, keeping the battery warm is another heat loss, which adds to the overall equation of energy drain.
 

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Good point, and it's factored into Chris' test above. The battery must have been slightly heated.
Technically, keeping the battery warm is another heat loss, which adds to the overall equation of energy drain.
BMS on the MEB was to have liquid cooling/heating (winter mode). Unanswered question is: what is the heat source to heat? (if the same for cooling, we know) Not like the motor has a loop back into the pack. No Octavalve in an ID, just Oktoberfest...
 

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Discussion Starter · #11 · (Edited)
Using the assumptions of 1% per 1.8 degrees F, 68F as the optimal operating temperature and 250 miles as the range:

((68-current temp)/1.8) x 2.5 = range loss?

Temperature​
Range loss​
Range​
% Loss​
68​
0.00​
250.00​
0.00%​
60​
11.11​
238.89​
4.44%​
50​
25.00​
225.00​
10.00%​
40​
38.89​
211.11​
15.56%​
32​
50.00​
200.00​
20.00%​
30​
52.78​
197.22​
21.11%​
20​
66.67​
183.33​
26.67%​
10​
80.56​
169.44​
32.22%​
0​
94.44​
155.56​
37.78%​
 

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Your percentage loss
Using the assumptions of 1% per 1.8 degrees F, 68F as the optimal operating temperature and 250 miles as the range:
((68-current temp)/1.8) x 2.5 = range loss?
Thanks for the table, very helpful!
Your equation and values are correct except range loss percentage. 50 miles lost of 250 at 32F is 20%, for example.

For those who watched the video closely, the cabin temperature was set to 21潞C (70 F), and the outside temperature fluctuated between +2.5潞C and -1潞C. Going with a straight up 20潞C temp difference sounds reasonable enough to me.
 

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Good point, and it's factored into Chris' test above. The battery must have been slightly heated.
Technically, keeping the battery warm is another heat loss, which adds to the overall equation of energy drain.
I believe the id.3 first plus is a 65 kWh battery vs 85 on the id.4? So if that's true the impact should be more on the id.4 since cooling the 85khw battery pack should take more energy.
 

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Discussion Starter · #14 ·
Thanks for the table, very helpful!
Your equation and values are correct except range loss percentage. 50 miles lost of 250 at 32F is 20%, for example.
I missed one static variable when I first ran the calcs. I think my edits have it fixed now.

We are having a pretty average "winter" day in the Seattle 'burbs (morning in upper-30's, high in mid-40's). I can deal with the ~20% while keeping passengers comfortably warm. 200 miles would be a really rare, long day trip for me!
 
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Most current EV's, in real world conditions, experience ~40% range loss in winter. Will a heat pump help? Sure. Will it be a magic fix for real world, cold weather range? No. I had an i3 BEV with a heat pump, and real world, cold weather range was only marginally better than an i3 without a heat pump. Also keep in mind, that heat pumps in cars (just like heat pumps in homes) aren't that effective below say freezing, and resistive heating is required to supplement them. Also keep in mind that we're not just talking about heating the cabin air. What about keeping the windshield free from fog/frost/snow? I think the ID.4's heated windshield will help way more than a heat pump.
 

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Most current EV's, in real world conditions, experience ~40% range loss in winter. Will a heat pump help? Sure. Will it be a magic fix for real world, cold weather range? No. I had an i3 BEV with a heat pump, and real world, cold weather range was only marginally better than an i3 without a heat pump. Also keep in mind, that heat pumps in cars (just like heat pumps in homes) aren't that effective below say freezing, and resistive heating is required to supplement them. Also keep in mind that we're not just talking about heating the cabin air. What about keeping the windshield free from fog/frost/snow? I think the ID.4's heated windshield will help way more than a heat pump.
But, VW advertising in Europe says 30% savings In battery. And now refrigerants work to -5 degrees Fahrenheit. They aren鈥檛 quite the same as a house heat pump in that fashion. Plus, heated windshield only available in AWD. So some people have a gripe about this issue. It鈥檚 turned a lot of people off.
 

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But, VW advertising in Europe says 30% savings In battery. And now refrigerants work to -5 degrees Fahrenheit. They aren鈥檛 quite the same as a house heat pump in that fashion. Plus, heated windshield only available in AWD. So some people have a gripe about this issue. It鈥檚 turned a lot of people off.
Europe鈥檚 EV range testing is quite liberal relative to the U.S.鈥檚, so I expect that calculated 30% increase in efficiency with the heat pump would be much less for the U.S.

I think the heated windshield should be standard on all models, but I suspect it鈥檚 quite an expensive feature and it鈥檚 probably much easier to absorb the cost into the AWD model. Also, the AWD models are probably much more likely to be operated in climates that would greatly benefit from a heated windshield. Heck, I鈥檝e had plenty of issues keeping windshield clear of fog/ice/snow with ICE cars that have a seemingly endless supply of heat.
 

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I'm thinking of starting a "basics of heat pumps and heat loss" thread in the Off Topics forum. Any interest?
 

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Discussion Starter · #20 ·
I'm thinking of starting a "basics of heat pumps and heat loss" thread in the Off Topics forum. Any interest?
Maybe VW could drop in and share their test results. 馃槈
 
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