Average energy usage during cold weather

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Trykpaa
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Post by Trykpaa »

keithr wrote: Thu Dec 17, 2020 1:53 pm
Trykpaa wrote: Thu Dec 17, 2020 8:22 am Heat pump may not be the holy grail manufacturers claim.
And don't forget that the Honda e has a battery heater that warms the battery pack up to 25C. That will take a lot more power in cold weather than it does during the summer months. That's why charging the car immediately before a drive helps to improve the range, because it will turn on the battery heater to warm the battery while it is charging, so less power will be used while driving to warm the battery pack (and the battery warming will have been performed with mains power while charging rather than battery pack power).
One of the points of the Video from Nextmove is exactly that. The ID3 has a 9kw heating element running for 10min to heat the battery. Same if cars spec'd with heat pump or not. And in the ID3 that process can only be executed when driving. VW is working on that.

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londiniumperson
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Post by londiniumperson »

keithr wrote: Thu Dec 17, 2020 1:53 pm
Trykpaa wrote: Thu Dec 17, 2020 8:22 am Heat pump may not be the holy grail manufacturers claim.
And don't forget that the Honda e has a battery heater that warms the battery pack up to 25C. That will take a lot more power in cold weather than it does during the summer months. That's why charging the car immediately before a drive helps to improve the range, because it will turn on the battery heater to warm the battery while it is charging, so less power will be used while driving to warm the battery pack (and the battery warming will have been performed with mains power while charging rather than battery pack power).

[Edit] I've now had time to watch some of that video, which shows that the VW ID.3 warms its battery pack up to 13C (whereas I believe the Honda e warms to 25C, although Honda don't give much detailed information!). It was interesting, and surprising, to see that the ID.3 with a heat pump wasn't any better for range than the version without a heat pump. It's still good for the battery life to have a battery heater (and cooler), so I'm still happy with the car! I don't normally go on long journeys during the winter, so it doesn't bother me anyway. I don't mind spending a few pennies on more battery charging so that I can be warm in the car, and the car's expensive battery pack is better cared for.
I'm curious to know where it's documented that the Honda heats the battery pack to 25C.
2022 Advance in Crystal Black Pearl on 17's - 08/2020-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current
Number5
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Post by Number5 »

I would expect the Honda to heat to about the same temp as the VW.
Battery will pick up heat in normal operation so why heat to 25C.
For max capacity 20C is about right.
omara500
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Post by omara500 »

I’ve started relying on the seat heater more now and I avoided setting the pre warming mode on the phone app to “warmer”. Now my energy use seems a bit better.

The “warmer” pre climate really zapped those miles.
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londiniumperson
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Post by londiniumperson »

omara500 wrote: Fri Dec 18, 2020 9:03 am I’ve started relying on the seat heater more now and I avoided setting the pre warming mode on the phone app to “warmer”. Now my energy use seems a bit better.

The “warmer” pre climate really zapped those miles.
Agreed, on my basic calculations it will pull about 3kW on the warmer setting during a cold morning.
2022 Advance in Crystal Black Pearl on 17's - 08/2020-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current
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keithr
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Post by keithr »

londiniumperson wrote: Thu Dec 17, 2020 7:03 pm
keithr wrote: Thu Dec 17, 2020 1:53 pm that video, which shows that the VW ID.3 warms its battery pack up to 13C (whereas I believe the Honda e warms to 25C, although Honda don't give much detailed information!).
I'm curious to know where it's documented that the Honda heats the battery pack to 25C.
I would like to read some detailed technnical documentation from Honda too, but I'm not aware of any freely available (I did say "Honda don't give much detailed information!). I was getting the 25°C value from the animated video that used to be on Honda's website (see here) that shows battery cooling above 25C and battery heating below 25C. That and also data from this Chinese web page - EEWORLD which talks about the Honda e thermal management of the battery pack and states "The target temperature range of the battery is around 25-35°C, and the target temperature of other power electronics is around 55°C". They obtained the information from an SAE technical document which you can preview for free but the full document will cost $33 to purchase (which I'm not going to purchase!).

I've attached a diagram from that document below. (The top right graph is with the EWH - Electric Water Heater - turned off, the bottom right graph is with it turned on.) The Honda e uses the same cooling circuit for the battery pack, onboard charger and the DC-DC converter. It has two three-way valves that allows the cooling circuit to bypass the cooling radiator and/or to bypass the battery pack (second diagram below).

Battery warm and cool.jpg

Battery circuit.jpg

Last edited by keithr on Sat Dec 19, 2020 3:54 pm, edited 1 time in total.
milligoon
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Post by milligoon »

Interestingly the motor is oil cooled and has it's own isolated cooling circuit

cooling.png

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londiniumperson
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Post by londiniumperson »

Well if this is accurate & genuine Honda information then it must be correct, however it seems very odd for many reasons, not least that the document is very inconsistent, for example the left & right diagrams show the same information but are completely different, who in their right mind would do this, it would make more sense to use the same diagrams, also it is attributed to the 'WCX SAE World Congress Experience' event which Honda were not on the exhibitor, partners or sponsor list; It appears to me to be a group student course work project.

Cooling_circuit.jpg

2022 Advance in Crystal Black Pearl on 17's - 08/2020-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current
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londiniumperson
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Post by londiniumperson »

I have just this moment read the following form the Chargemap blog:
https://blog.chargemap.com/5-tips-to-op ... news_en_38

In summary it states:
  • An EV battery works best at temperatures between 20 and 25°C.
  • At an ambient temp of -6°C compared to 23°C, an EV loses 12% of its range on average (not including equipment).
  • When HVAC is taken into account along with an ambient temp of -6°C, the loss of range is about 41%.
  • On average, a heat pump consumes between 500 and 750 watts whereas a conventional heating system eats up between 2,000 and 4,000 watts.
This aligns with what we have been seeing ourselves on the Honda.
2022 Advance in Crystal Black Pearl on 17's - 08/2020-Current
2015 VW Tiguan (Pure White) - 04/2018-Current
1991 Honda Beat PP1 (Festival Red) - 11/2022-Current
milligoon
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Post by milligoon »

As we barely achieve 25C average in the UK that's us buggered then, best we crack open a few coal power plants so we can improve our range with the rise in temperatures 🤣
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