battery heater and days subzero parking

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specialgreen

Well-known member
Joined
Mar 26, 2017
Messages
246
Location
Minnesota
I have a question for cold weather folks: how fast does the battery heater (cold weather package) deplete your traction battery when parked outside at subzero temps, unplugged (e.g. airport parking lot)?

This video:
https://www.youtube.com/watch?v=Brn5FiLFRIg
...mentions battery depleting from 8 bars to 4 bars over 2-3 weeks parked at -18C/0F. But the battery warmer doesn’t even kick-in until below 0F, so maybe that’s not a good test.

I parked in the driveway at 95% dash SOC at Friday noon (probably 23.75 kw-hrs capacity). Saturday noon, the dash read 92%, after 24 hours parked at -10F (hi/low avg). But LeafSpy said 67% SOC and 18.8kw-hrs capacity (very different). If I trust the dash, it only lost 3% charge (maybe 0.75 kw-hrs). If I trust LeafSpy, it lost maybe 4.95 kw-hrs (about 20% of charge). The maximum possible loss should be 300 watts for 24 hours, or 7.2kw-hrs.

I noticed that the warranty excludes damage caused by “Storing a vehicle in temperatures below -13F (-25C)
for over seven days“, which is a bit unclear: is that storing unplugged, or also plugged-in? And if unplugged, does that imply that a 100% charge should keep it from freezing for up-to 7 days at temps above -13F?
 
While those are extreme temps, you now know one of the reasons why Nissan decided not to have a TMS for the Leaf; imagine having that sort of power drain in extreme heat as well. In "normal" temps, I usually see no range loss at all when sitting at the airport for even a week at a time.
 
But the battery warmer doesn’t even kick-in until below 0F, so maybe that’s not a good test.

Not true. Your pack temp was high enough that yours didn't start, but a car sitting around in low single digit temps will start the battery heater when the pack gets cold enough. Mine has been running quite a bit, despite only a few hours a night of only slightly subzero temps. I can't give you exact figures, but the warmer can use something like 15% charge a day, maybe more. IIRC it will shut off at 30% charge, and the car will "hibernate" after that.
 
LeftieBiker said:
But the battery warmer doesn’t even kick-in until below 0F

Not true.

My 2017 manual claims this:
The Li-ion battery warmer automatically turns on when the Li-ion battery temperature is approximately -1°F (-17°C) or colder. The Li-ion battery warmer automatically turns off when the Li-ion battery temperture is approximately 14°F (-10°C) or higher.

The manual could be incomplete or wrong, of course. But also, if battery temp is mostly in single digits, but dips to -1F, then I could imagine that it may take hours to raise it to 14F. That could explain the battery drain you are seeing.
 
I would think our 13 kicks on much higher than -1F. I believe it is about 5F, above that and I don't see any drain sitting, below that I start to noticed a drop. Right now it's -7F (-22F wind chill) and I pretty much see once the heaters turn on they stay on becasue they cant warm it up to 14F if it is sitting outside. I would say when they come on it uses about 3% an hour to keep warm. The part I don't know if is they just stay on until they hit 30% or until they are warm enough. Luckily most of the time I can have the Leaf in the insulated attached garage, which is just about freezing 32F right now, but way better than outside.
 
Nissan's owners manual says not to leave the battery at low or zero charge for more than 14 days. That's on page EV-24 of the 2014 owners manual.

Leaf Pro has shown 377 watts being used parked in the driveway the last few days. The temps have gone to the low single digits (F) and the battery temps have been around 34F degrees. Might be the battery heater or Leaf spy pro or my OBDII have a glitch, or it might be that when the car's external temperature reading is below 7 F the battery heater goes on.

I don't know which it is.

Hyper-miling (sp??) works well in this car.

I can squeeze out 3.0 miles/kw at 6F (outside temp) with the heat set at 60F and the seats and steering-wheel heated. I just did that this morning on a 13-mile drive.

It's not easy to get a 3.0 when it's this cold, but I try to use hyper-miling (sp??) tricks since my Civic Hybrid in 2002.
 
Rxleaf said:
Nissan's owners manual says not to leave the battery at low or zero charge for more than 14 days. That's on page EV-24 of the 2014 owners manual.

The 2017 manual says that, but also not to “store” the car below -13F/-25C for more than 7 days. By “store,” it’s unclear if Nissan means “stored unplugged,” or if they mean “whether plugged or unplugged” (because the 300w heater can’t keep-up).

Also, it’s unclear whether “stored below -13F” means “7 consecutive days with the daily high temp below -13F/-25C” (which will never happen for me; but maybe could happen every 10 years in Winnipeg); or “7 days straight where the low is below -13F/-25C” (any given December in Winnipeg; maybe twice per decade for me); or “7 consecutive days with day/night average below -13F/-25C (Winnipeg December avg. temp -22C in 2000, and -21C in 2013).

I’m sure Nissan wanted to keep the manual simple, but the warranty is tied to following the manual, so having unclear wording doesn’t help. Without hints about “plugged vs unplugged” or “high vs low vs avg temp”, about the only clear way to comply is to drive it once per week (so it’s not “stored”).
 
BrockWI said:
Actually it does say "Watts" because as you mentioned it is displaying the rate.

The problem is that you can't use a rate measured at one moment to determine how much power was used from the pack over several days, unless it was a fixed rate / drain.
 
LeftieBiker said:
BrockWI said:
Actually it does say "Watts" because as you mentioned it is displaying the rate.

The problem is that you can't use a rate measured at one moment to determine how much power was used from the pack over several days, unless it was a fixed rate / drain.

I am sorry I didn't mean to imply you could, I agree that you can't, I was just replying to your question.

LeftieBiker said:
Does it maybe say "watt-hours"?

I was just stating that Leaf Spy can only show the rate in Watts. All you can see is the snapshot at any given moment and take that in to account as to what the car might be doing.

For instance if I have a Leaf sitting outside, unplugged and take a reading of 377 watts with a pack temp of 0F at 10pm and it is -15F with a -30F windchill. Then the next morning I check Leaf Spy again at 6am and see the same 377 watts and the pack is at 0F I can infer that the heaters were on all night. I understand there is a chance that it may have warmed the pack up to 15F and shut off and then got cold and came on again, but I find that highly unlikely. I find it more likely the pack consumed 377 watts for 10 hours or 3.77 kWh

Obviously this isn't a normal temp the Leaf will sit at and in most cases the heater would cycle.
 
Windchill does not apply to battery.
Internal heater doesn't run at 2 or more temperature bars.
Power is taken from the pack at any temperature due to 12V battery trickle charging,
that happens once per 24h on newer Leafs and car not plugged in.
 
arnis said:
Windchill does not apply to battery.
Wind chill makes a difference to the battery or any object for that matter. The wind moves any remaining heat or temperature difference from the item faster. Granted it will only get to ambient temperature (unless it is wet). Think of taking two frying pans right off the stove. One sits in the back of a van and one sits on the roof rack, it's 70F outside, the van is moving at 62 MPH or 100 KPH after 5 minutes the frying pan on the roof rack will be much cooler than the one sitting in the back, that my friend is wind chill. The Leaf as a whole is affected the same way, granted the battery pack is in the belly of the car but I can assure you the battery and car will cool down much quicker to ambient temp with a 15 mph wind than no wind at all.

So in our case the battery pack heaters kick on and with a wind blowing it is pulling more of that heat off with it.
 
I was just stating that Leaf Spy can only show the rate in Watts. All you can see is the snapshot at any given moment and take that in to account as to what the car might be doing.

For instance if I have a Leaf sitting outside, unplugged and take a reading of 377 watts with a pack temp of 0F at 10pm and it is -15F with a -30F windchill. Then the next morning I check Leaf Spy again at 6am and see the same 377 watts and the pack is at 0F I can infer that the heaters were on all night. I understand there is a chance that it may have warmed the pack up to 15F and shut off and then got cold and came on again, but I find that highly unlikely. I find it more likely the pack consumed 377 watts for 10 hours or 3.77 kWh

Obviously this isn't a normal temp the Leaf will sit at and in most cases the heater would cycle.

I agree that a consistent reading of 377 watts over many hours is a good indication of what the car is using. There should also be one blue light lit on the top of dash charging lights when the warmer is on.
 
Windchill is given in degrees and is not about temperature but wind speed and humidity.
It is not a "yes/no" answer. Therefore giving any windchill values says nothing about battery temperature heat extraction rate.
Wind at ground level is way lower. So that lessens the effect even more. Can't be wet - heater doesn't operate at those temps.
 
Is there any way to potentially turn on the battery heater using Leaf Spy or some other tool? Essentially I would love to have my battery heated in the morning to 40 or 50F as with this extreme cold I'm just barely making it to/from work on one charge where during the summer I would have 20 miles remaining. That's being very conservative with the heater and also pre-heating the car before departure while connected to L2 power.
 
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