Best practices of charging in cold temperatures

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minecraft00z

Member
Joined
Dec 3, 2020
Messages
7
Hello, everyone.
I'm looking for advice on the correct way of charging my 2015 Leaf in cold conditions. The weather hit us pretty hard today. It's -26 C or -14.8°F at night and in the morning.

I don't have a garage and my Leaf is parked in my yard under a canopy.
Initially, I thought that it's better to charge at night when the outside temperature is the coldest. The charging process should warm up the battery a bit, not letting it cool down completely.

But then a friend of mine suggested that in temperatures below -10C I should charge my Leaf right after I finished my morning/evening driving commute, while the battery is still somewhat warm.

Because if I leave the car after driving in this cold weather and the battery will cool down significantly until midnight, and then I start charging it when it's almost frozen, this can have a negative impact on the battery health.
In other words, in these really cold conditions, it's better to charge right after driving when the battery is still somewhat warm.

What are your thoughts on this?
Any suggestions appreciated.
Thanks!
 
minecraft00z said:
But then a friend of mine suggested that in temperatures below -10C I should charge my Leaf right after I finished my morning/evening driving commute, while the battery is still somewhat warm.
This

Avoid Li plating
 
LeftieBiker said:
Charging overnight on L-1 worked well for me, under similar conditions, with my 2013.
In this case, due to the very slow charging rate, it will probably be charging most of the night, which would be good. Of course, if the battery starts out with a very low SOC it might not even get totally charged by daybreak, which might not be desirable if the OP needs a full charge.
 
SageBrush said:
minecraft00z said:
But then a friend of mine suggested that in temperatures below -10C I should charge my Leaf right after I finished my morning/evening driving commute, while the battery is still somewhat warm.
This

Avoid Li plating

As I understand Li plating happens when the battery is being charged at low temperatures? Right? I'm still new to EVs, just trying to figure out when is the best time to charge my Leaf to minimize battery degrading during cold winter times.
So, my friend was right? It's better to charge after the ride, when the battery is still warm? (these days I have only 2-3 bars on the battery temp. gauge)
 
minecraft00z said:
SageBrush said:
minecraft00z said:
But then a friend of mine suggested that in temperatures below -10C I should charge my Leaf right after I finished my morning/evening driving commute, while the battery is still somewhat warm.
This

Avoid Li plating

As I understand Li plating happens when the battery is being charged at low temperatures? Right? I'm still new to EVs, just trying to figure out when is the best time to charge my Leaf to minimize battery degrading during cold winter times.
So, my friend was right? It's better to charge after the ride, when the battery is still warm? (these days I have only 2-3 bars on the battery temp. gauge)
Yes.

There is a trade-off to be aware off: the cold battery will have less power and less (or none) regen until it heats up from driving. I'm a lot more interested in avoiding battery degradation than having a few minutes of better power and regen so I also follow the 'charge after drive' routine in the winter. I find the temporary lack of regen the most noticeable because my normal braking behavior has unexpected results and I have to remember to actually use the brake pedal instead of just lifting my foot off the go pedal.
 
One thing to keep in mind is that the ambient temperature only matters insofar as it affects the battery temperature. It is the battery temperature that you need to watch. Sustained cold weather will produce a cold battery, but a frigid night after a relatively mild day won't necessarily do so, as the battery pack has a LOT of mass.
 
I agree with your friend. Here's my reasoning:

* If you start your AC slow-charge with a battery that's already warm from driving, you'll charge more rapidly and efficiently -- because none of the charging power will be diverted to your Leaf's cold-weather battery-warmer.

* If instead you start your charge in sub-freezing weather, your Leaf's battery charge-controller will not start the charge if the battery is too cold to be charged. I believe the cut-off is at 0 degrees C. (Charging a lithium-ion battery cell which is at a sub-zero temperature is likely to prematurely age it -- due to the formation of metallic lithium -- no matter how slowly it is charged. Your Leaf will not fast-charge at full speed until its battery is warm enough to handle it without lithium-plating -- maybe 20 degrees C. See https://insideevs.com/news/338635/study-says-fast-charging-takes-longer-when-its-cold-out/.)

* An added bonus: if you leave your car plugged in overnight, you can program its climate-control system so that the cabin is warm! See https://www.youtube.com/watch?v=j-T9Pmyrcv8 for an amusing video of starting a Leaf at 40 below.

However I see one possible downside to your friend's advice:

* If you live in an area where the %renewable of the electricity supply increases significantly between the time you get home and the time you go to bed, then you might want to lower the %fossil in your Leaf's "tank" by plugging it in just before you go to bed -- assuming that's enough charging-time (including the battery-warmer overhead on very cold winter nights) to give you the range you'll need the next day.

By the way, if you're not going to drive your car for a week or two while it's parked outside in seriously cold weather, you can either

1. unplug its charging cable and close the lid on its charging compartment. Your car's big (high-voltage) traction battery will "vampire drain" as necessary to keep itself from freezing, and it will also top up its 12V lead-acid accessory battery on a timed schedule. Opening the lid on the charging compartment might be a challenge though if there's a freezing rain ... as you'll know I'm sure ;-) https://mynissanleaf.com/viewtopic.php?t=25092

2. keep it plugged in at all times, in which case its big battery will won't freeze and will remain fully charged (because its battery warmer will be powered from your house's AC supply). However (surprisingly) its lead-acid accessory battery will be losing charge and will eventually go flat... so the usual advice is to get in the car every week or three, and put it into Accessory mode (and maybe listen to the radio if you can hear it while your teeth are chattering) for 15 or 30 minutes -- this will allow your car's big battery to run a recharge-cycle on its little battery. https://www.greencarreports.com/news/1075704_going-away-make-sure-your-electric-car-stays-happy-without-you

You should take advice from others if you ever want to store your Leaf for many weeks during a long cold winter. I have lived in Auckland NZ for 26 years now. (Temps in my last year in Mpls MN ranged from -30 F with a stiff wind to +100 F with near-100% humidity. I was born there but I'm now quite wimpish ;-)
 
Regarding lithium plating due to charging at low temps, I came across https://acep.uaf.edu/media/304144/Cold-Weather-Issues-for-EVs-in-Alaska.pdf semi-recently. See page 10 (11 of the PDF) about the subject.
 
A couple of serious mistakes in the advice a couple of posts up:

If instead you start your charge in sub-freezing weather, your Leaf's battery charge-controller will not start the charge if the battery is too cold to be charged. I believe the cut-off is at 0 degrees C. (Charging a lithium-ion battery cell which is at a sub-zero temperature is likely to prematurely age it -- due to the formation of metallic lithium -- no matter how slowly it is charged.

The Leaf will charge its battery right down into the single digits F - and that's battery temperature, not air temp. The battery warmer comes on at about 7F pack temperature for this reason.

However (surprisingly) its lead-acid accessory battery will be losing charge and will eventually go flat... so the usual advice is to get in the car every week or three, and put it into Accessory mode (and maybe listen to the radio if you can hear it while your teeth are chattering) for 15 or 30 minutes -- this will allow your car's big battery to run a recharge-cycle on its little battery. https://www.greencarreports.com/news/10 ... ithout-you

NO! Putting the car in Accessory mode will drain what power the 12 volt battery had left - and the car will NOT recharge it. You need to have it in Ready (to drive) mode, and if the charge voltage stays below 13.0 volts, blip the front wipers once a minute to boost the charge rate for the 12 volt battery.

Last, the EVSE never powers any accessories directly. It only powers the onboard charger, with the car's traction battery always powering everything.
 
Hey, wich option is better 2014 leaf cold weather, battery temp always below 0 degrees and driving/charging doesn't warm it up much. Charge it every day max 80% or over days and then 100%? Or when the battery temperature is so low, then no point use 80% limit to save battery health? I charge it max 3kW power.
 
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