Winter = Summer Driving Performance

[SageBrush]

So far as I know, Tesla is the first EV manufacturer to manage this feat (with an LFP battery, no less !) as shown by Bjorn Nyland in his 1000 km challenge.

https://www.youtube.com/watch?v=LKds_q6A44k&list=RDCMUCG1QcV31eoSaX4rE8avQL4A

Most of the magic comes down to two things:

1. Battery pre-conditioning before DC fast charging
2. Scavenging heat from charging to use for cabin heating.

This really is a big deal, since until now the Achille's heel of EV Vs ICE has been winter driving. And although not mentioned by Bjorn, the feat is only really possible with a well developed and communicating DC network so America is still out in the cold in many areas. Nonetheless, the EV now has a proven path to winter performance about on par with summer.

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As for the LEAF ? Well .... it has issues. Today was our first cold day of winter. I pulled into an EA this morning with a SoC of 25% and pack temp of 27F. I only needed to reach a SoC of ~ 50% to get home. Charging started out at 15 - 20 kW, but by the time SoC was 35% power had dropped to 8 kW. I also noticed that cabin heating power reduced in equal amount the power sent to the battery. I was not expecting that with DC charging.

Yeah.

Signed, Cold feet.

 

[rogersleaf]

Last week had 2 of the coldest days I ever attempted my commute in my ‘19 40KWh LEAF. Temps were as low as -3F. Being that cold overnight it was parked inside, plugged in with timers set so 100% charge and toasty warm when leaving. The car made the commute on 85% of the battery capacity. But it made it ok, where I would not attempt that commute in my ‘14 at temps under 30F.

The one noticeable bad attribute is cold legs and what I think is a cold draft around the ankles. Have been looking all over for a leak/draft source but can’t find any. So got a laugh out of your “cold feet” comment.

 

[LeftieBiker]

I used a 12 volt heated fleece blanket in my 2013. It kept my legs warm, and that helped my feet.

 

[alozzy]

Turning on either partial or full recirculation should cut down on the cold draft at leg level.

 

[rogersleaf]

Turning on either partial or full recirculation should cut down on the cold draft at leg level.

Really only notice the draft at expressway speeds. Thinking a body leak around a door seal, or through a door interior panel, or center console/floor area. Use the partial recirc setting almost all the time, way too cold for full recirc and have glass clear enough to see out.

 

[OldManCan]

... pulled into an EA this morning with a SoC of 25% and pack temp of 27F. I only needed to reach a SoC of ~ 50% to get home. Charging started out at 15 - 20 kW, but by the time SoC was 35% power had dropped to 8 kW.

Thanks for sharing this experience. Did you happen to notice what the pack temp was when the charger started to slow down to 8kW? My logic says (and is clearly wrong.... ) that as you charge a very cold pack it should warm up reaching a better temperature for pack health and this should enable faster charging. That is until the pack starts to overheat which is another cause for charge speed to slow down. Trying to get my head around this so your experience and input will help shed some light on this for me. Thanks

 

[alozzy]

Turning on either partial or full recirculation should cut down on the cold draft at leg level.

Really only notice the draft at expressway speeds. Thinking a body leak around a door seal, or through a door interior panel, or center console/floor area. Use the partial recirc setting almost all the time, way too cold for full recirc and have glass clear enough to see out.

Yeah, sounds like you've got a bit of an air leak somewhere.

 

[SageBrush]

... pulled into an EA this morning with a SoC of 25% and pack temp of 27F. I only needed to reach a SoC of ~ 50% to get home. Charging started out at 15 - 20 kW, but by the time SoC was 35% power had dropped to 8 kW.

Thanks for sharing this experience. Did you happen to notice what the pack temp was when the charger started to slow down to 8kW? My logic says (and is clearly wrong.... ) that as you charge a very cold pack it should warm up reaching a better temperature for pack health and this should enable faster charging. That is until the pack starts to overheat which is another cause for charge speed to slow down. Trying to get my head around this so your experience and input will help shed some light on this for me. Thanks

I expected the same, but IIRC the pack temp barely budged. I figured it was a combination of a small pack (for me, a 15% SoC increase is about 2.5 kWh) and low current, so not much resistance heating. And of course the ambient temp of 10F.

 

[gcrouse]

So far as I know, Tesla is the first EV manufacturer to manage this feat (with an LFP battery, no less !) as shown by Bjorn Nyland in his 1000 km challenge.

https://www.youtube.com/watch?v=LKds_q6A44k&list=RDCMUCG1QcV31eoSaX4rE8avQL4A

Most of the magic comes down to two things:

1. Battery pre-conditioning before DC fast charging
2. Scavenging heat from charging to use for cabin heating.


----
As for the LEAF ? Well .... it has issues. Today was our first cold day of winter. I pulled into an EA this morning with a SoC of 25% and pack temp of 27F. I only needed to reach a SoC of ~ 50% to get home. Charging started out at 15 - 20 kW, but by the time SoC was 35% power had dropped to 8 kW. I also noticed that cabin heating power reduced in equal amount the power sent to the battery. I was not expecting that with DC charging.

Yeah.

Signed, Cold feet.

I'm curious how much of Tesla's advantage is from a really good BMS system with heating and cooling - I'd imagine quite a bit.

With the Leaf it seems like some of the charging rate drop varies based on the charging station. On a trip in December I had a similar experience with my Leaf at a Greenlots charger but later down the road the ChargePoint charger i was using had a minimal drop in the peak charge. From my experience - whatever chargers Greenlots installed in my area perform rather poor in cold weather compared to the ChargePoint station. In theory it shouldn't matter since my understanding was the BMS dictates the kw, but it seems like there's something more going on with how the car and station talk to each other since the Greenlots stations consistently perform worse for me compared to the ChargePoint in the cold.