Lowest Charging Temperature

[TimLee]

... Is the Leaf smart enough to run the battery heaters continuously if it is plugged in to keep it warm? ...

If LEAF has the battery heaters and status of charge is above 30% it will do what Tony stated on page 1 whether it is plugged in or not.
Very unlikely they would run continuously even in extreme northern Alaska cold.

... The heaters (six 50w heaters) come on at -20C (-4F), and turn off at -10C (14F).

 

[TimLee]

As you may recall, Nissan sold the the 2011 LEAF in mostly warm weather states; ...

Correct.
I am a bit surprised that no one has directly reported on MNL exactly how a LEAF behaves when the battery temperature goes below -30C, either early one that did not have heaters and was shipped to cold area or one that was left below 30% status of charge in cold conditions.
I think Tony is correct it will not be driveable.
But does it allow low kW power flow say to the cabin heater that will slowly cause some battery warming and the vehicle will become driveable?
Or is it dead in the water and will not even power up at all?

 

[2k1Toaster]

... Is the Leaf smart enough to run the battery heaters continuously if it is plugged in to keep it warm? ...

If LEAF has the battery heaters and status of charge is above 30% it will do what Tony stated on page 1 whether it is plugged in or not.
Very unlikely they would run continuously even in extreme northern Alaska cold.

... The heaters (six 50w heaters) come on at -20C (-4F), and turn off at -10C (14F).

Yes but if it is plugged in and not charging, will it draw the power from the AC connection? Or will it cycle the heaters until the battery SOC got to 30% even though it is plugged in. Sort of like how the 12v is ignored when plugged in but not when on battery only...

And by continuously I should have said indefinitely. It will discontinuously cycle the heaters indefinitely until the battery is too low I guess. But hopefully it is smart enough to power it from a charging source if available.

I'm more curious than anything. I am wondering if some of those exported 2011's in Norway will need to be gone over a few times with hair-dryers before they start up some time in the future.

 

[dgpcolorado]

Even here on the front range part of Colorado we have had it go down that low for many days in a row. I only charge my Leaf every few days and from L1 at work. And on weekends it can sit outside for the entire time not plugged in near that limit. Is the Leaf smart enough to run the battery heaters continuously if it is plugged in to keep it warm? There were at least 10 days last year where the battery temp bar showed 1bar. We are usually about 20C colder than what is reported for the city at the airport. And we recorded a few days at -23C already this year at the airport, over -40C at the house, and I expect a couple more too.

If your car is showing one temp bar the battery shouldn't be cold enough to turn on the battery heater. One temp bar is supposed to cover -15ºC to -2ºC [but there is a lot of overlap because zero bars is listed up to -5ºC and two bars is listed at -12ºC to 2ºC, so when the bars actually go on and off is unclear]. Until you get down to zero temp bars you shouldn't see the battery heater come on. It takes time for the battery to get to ambient temperature and if you drive/charge the car daily or almost daily, it will likely stay warmer than ambient temperature, due to thermal mass.

My understanding of the battery heater is that it will come on while plugged-in and Nissan recommends leaving the car plugged-in if temperatures are expected to go below -20ºC. It will also come on when unplugged but only down to ~30% SOC. The heater cycles on and off as needed, so it does not draw the full 300 watts constantly.

My recollection is that during that big cold snap last winter there were several LEAFers in the upper Midwest who got a chance to see the battery heater in action (it has its own blue light code).

 

[kubel]

What's the lowest temperature you've been able to charge your LEAF at?

-15F, 0 battery temperature bars.

 

[RegGuheert]

In addition to the problem of having extremely low capacity at very cold temperatures, there is a more severe issue: Charging at very low temperatures can result in elemental lithium being permanently plated onto the anode.

According to Battery University, this occurs on some Li-ion batteries at temperatures as high as 0°C (32°F):

Many battery users are unaware that consumer-grade lithium-ion batteries cannot be charged below 0°C (32°F). Although the pack appears to be charging normally, plating of metallic lithium can occur on the anode during a subfreezing charge. The plating is permanent and cannot be removed with cycling. Batteries with lithium plating are known to be more vulnerable to failure if exposed to vibration or other stressful conditions. Advanced chargers, such as those made by Cadex, prevent charging Li-ion below freezing.

I seriously doubt the battery in the LEAF would be damaged at that temperature, but there must be a problem below -20°F or they would not have added the heaters.

I wonder if the BMS also prevents charging at those very low temperatures. If so, your only recourse if the battery gets that cold would be to somehow warm it above -20°F (or perhaps higher if there is hysteresis built in) before trying to charge the car again.

 

[dgpcolorado]

In addition to the problem of having extremely low capacity at very cold temperatures, there is a more severe issue: Charging at very low temperatures can result in elemental lithium being permanently plated onto the anode.

According to Battery University, this occurs on some Li-ion batteries at temperatures as high as 0°C (32°F):

Many battery users are unaware that consumer-grade lithium-ion batteries cannot be charged below 0°C (32°F). Although the pack appears to be charging normally, plating of metallic lithium can occur on the anode during a subfreezing charge. The plating is permanent and cannot be removed with cycling. Batteries with lithium plating are known to be more vulnerable to failure if exposed to vibration or other stressful conditions. Advanced chargers, such as those made by Cadex, prevent charging Li-ion below freezing.

I seriously doubt the battery in the LEAF would be damaged at that temperature, but there must be a problem below -20°F or they would not have added the heaters.

I wonder if the BMS also prevents charging at those very low temperatures. If so, your only recourse if the battery gets that cold would be to somehow warm it above -20°F (or perhaps higher if there is hysteresis built in) before trying to charge the car again.

Perhaps that is a reason Nissan changed the temperature range for the battery heater in the 2015 models to -17ºC (1ºF) to -10ºC (14ºF) from -20ºC (-4ºF) to -10ºC (14ºF) on older LEAFs.

(Edit: fixed typo from the LEAF manual.)

 

[TimLee]

Perhaps that is a reason Nissan changed the temperature range for the battery heater in the 2015 models to -17ºC (-1ºF) to -10ºC (14ºF) from -20ºC (-4ºF) to -10ºC (14ºF) on older LEAFs.

But that is a very small change starting the battery heater at a 3ºC warmer point.
Check the conversion. -17ºC is (+1.4ºF)

 

[dgpcolorado]

Check the conversion. -17ºC is (+1.4ºF)

You're right, I was just taking the info from the 2015 LEAF manual and the "-1ºF" they used is apparently a typo (pages EV-5, EV-6). Didn't notice the mistake. I'll make the correction.