2018 Leaf battery overheating

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40kWh Leaf has very basic battery overheat protection, similar to previous Leafs.
Throttled charging/regen and power output.
This also happened on 24kWh and 30kWh Leafs, but at much higher temperatures.
Something like 50-55C before charging current is reduced.
New battery supplier demanded more protection and Nissan had to agree.
And this is how RapidGate came to life.
New "logic" tries to avoid battery going over 30C to prolong life. Which is not possible at ambient 25*C or more.
And it gets very aggressive at 50*C. And this avoids going any higher.
AFAIK, even power output will be limited at very hot temps. That is mostly noticed by slower acceleration.
Max speed driving requires just 40-50kW power output so temp hardly changes top speed.

At least 40kWh Leaf will not degrade extremely fast if battery management throttles that much :lol:

Unfortunately Leaf2 doesn't have "keep battery cooler" button or "chill" button like Tesla has. But to do it manually:
Avoid heavy regen.
Avoid accelerations above 30kW.
void speeds above 100km/h 60mph.
Avoid charge state below 30%.
 
arnis said:
Max speed driving requires just 40-50kW power output so temp hardly changes top speed.
Steady state speed on level ground ?
Much less kW, more in the range of 20 kW
 
SageBrush said:
arnis said:
Max speed driving requires just 40-50kW power output so temp hardly changes top speed.
Steady state speed on level ground ?
Much less kW, more in the range of 20 kW

Not kW per distance but kW per time. Battery doesn't care about vehicle speed.
It cares how fast is energy flowing. Looking at power gauge it stays between 40-45kW at full speed 145km/h.
 
arnis said:
SageBrush said:
arnis said:
Max speed driving requires just 40-50kW power output so temp hardly changes top speed.
Steady state speed on level ground ?
Much less kW, more in the range of 20 kW

Not kW per distance but kW per time. Battery doesn't care about vehicle speed.
It cares how fast is energy flowing. Looking at power gauge it stays between 40-45kW at full speed 145km/h.
I have no idea what kW per time or kW per distance means in this context. kW per distance is nonsensical and kW per time is the rate of change of power.

I admit though, I was thinking more in the 70 - 75 mph (110 - 120 kph) speed range.
According to my aero drag and tyre friction table, 140 kph in a LEAF at sea level is 31 kW. Add in drivetrain losses and assorted fixed loads and I would guess ~ 35 kW steady state speed on level ground.
 
kW per distance is kWh/100km or Wh/km (this unit is used for "fuel consumption" in many places).
Unit per time is regular kW. Regular power output.
Check this example (bad weather, slightly better in ideal conditions).
https://youtu.be/HIwQ09CajIY?t=2m10s
At max speed, more than half of bubbles (more than half of motor power, half of 80kW) are in use.
Even though it shows 160km/h 99mph, it's actually less. Speedo error (legal s**t).
 
arnis said:
kW per distance is kWh/100km or Wh/km (this unit is used for "fuel consumption" in many places).
Unit per time is regular kW. Regular power output. ...

Nope, because of the "h". Watt-hour is a measure of energy. Watt is a measure of power or force; it's an instantaneous measurement. It exists outside of time or distance. In order for those Watts to perform work, they must be sustained over a given amount of time.

One thousand Watts sustained for an hour is one kWH.
Five thousand Watts sustained for 12 minutes is also one kWH.
One thousand Watts sustained for ZERO time, is simply one kW. No work has been performed, it's merely a potential.

"kiloWatts per kilometer" makes no sense; kiloWatt-hours per kilometer does.
 
I just got back from a 300+ mile round trip from Centralia to Ellensburg in our 2018 SV. Much of the day the temperature was in the 90s. Did a quick charge in North Bend, but a 30 minute session only netted about 40%. Apparently the heat limited the charging. Due to traffic, we were getting pressed on time (not enough time to get another charge), so we drafted a semi into Ellensburg. Had to use AC (set at 72 with 3 fan bars) and the battery registered in the red for temp. After the car sitting in a sunny parking lot at 95 degrees for a couple hours, we went over to the QC and it took 80 minutes to bring it up from 10% to 80%, again in the red zone. This time the warning come on saying the battery is hot and we should drive conservatively. Set the cruise for 55, but as we began to go up the pass, the warning said power would be reduced and put us in 2018 turtle mode. I was in the slow lane with the semis doing 40 mph. Made it to North Bend with 20% and went to the QC and parked in the shade w/ water poured under the car for evaporation cooling. 30 minutes only netted 20%, so we went another session to get up to 60%. Then we set the cruise at 55, turned off the AC and opened the windows as we went downhill to minimize battery usage. Needless to say, it was a bit of an antsy situation. Bad traffic in Tacoma helped keep battery usage down and the turtle mode warning finally went off. South of Tacoma we drafted a semi home at 65 mph with 5% left in the battery. This was my first long trip with the car and I'm not favorably impressed. I will not take it beyond its normal charge range in hot weather again.
 
bnewkirk said:
I just got back from a 300+ mile round trip from Centralia to Ellensburg in our 2018 SV. Much of the day the temperature was in the 90s. Did a quick charge in North Bend, but a 30 minute session only netted about 40%. Apparently the heat limited the charging.
...
Made it to North Bend with 20% and went to the QC and parked in the shade w/ water poured under the car for evaporation cooling.
...
This was my first long trip with the car and I'm not favorably impressed. I will not take it beyond its normal charge range in hot weather again.
Bummer. The temp in the 90's didn't help.

The bolded part probably had little to no effect. You're going to need Leaf Spy to sensor the pack temperatures. For me, on my 24 kWh Leaf, I find that the pack has a lot of thermal mass and it takes awhile (MANY hours) to cool down to cooler ambient temps. You DC FCing when it's already 90 F out I'm sure pushed the temps up quite a bit. My wild guess is that once you got the temp warning, the pack temp was past 120 F.

https://web.archive.org/web/20170717073322/http://www.mynissanleaf.com/viewtopic.php?t=22134 really heated up his pack.
 
bnewkirk said:
I just got back from a 300+ mile round trip from Centralia to Ellensburg in our 2018 SV. Much of the day the temperature was in the 90s. Did a quick charge in North Bend, but a 30 minute session only netted about 40%. Apparently the heat limited the charging. Due to traffic, we were getting pressed on time (not enough time to get another charge), so we drafted a semi into Ellensburg. Had to use AC (set at 72 with 3 fan bars) and the battery registered in the red for temp. After the car sitting in a sunny parking lot at 95 degrees for a couple hours, we went over to the QC and it took 80 minutes to bring it up from 10% to 80%, again in the red zone. This time the warning come on saying the battery is hot and we should drive conservatively. Set the cruise for 55, but as we began to go up the pass, the warning said power would be reduced and put us in 2018 turtle mode. I was in the slow lane with the semis doing 40 mph. Made it to North Bend with 20% and went to the QC and parked in the shade w/ water poured under the car for evaporation cooling. 30 minutes only netted 20%, so we went another session to get up to 60%. Then we set the cruise at 55, turned off the AC and opened the windows as we went downhill to minimize battery usage. Needless to say, it was a bit of an antsy situation. Bad traffic in Tacoma helped keep battery usage down and the turtle mode warning finally went off. South of Tacoma we drafted a semi home at 65 mph with 5% left in the battery. This was my first long trip with the car and I'm not favorably impressed. I will not take it beyond its normal charge range in hot weather again.
Where was the temperature bar at before you started your trip? And what speed were you traveling before your first quick charge? Based on that very first QC being throttled already I'm guessing you were going 70+. Limiting your speed will really help with the temps and won't hurt you near as much time as what people think.

I've done several 200+ round trips (near 90 degrees) and kept the temp bar at halfway until the very last portion of the trips. I find trickle charging as much as possible before the trip, avoiding my L2 if possible, really keeps the temps down on start up. I don't think L2 raises temps by much, if any, but it definitely doesn't seem to let it cool down to ambient either. Trickle charging will let the battery cool down to at or near ambient temps.
 
bnewkirk said:
I just got back from a 300+ mile round trip from Centralia to Ellensburg in our 2018 SV. Much of the day the temperature was in the 90s. Did a quick charge in North Bend, but a 30 minute session only netted about 40%. Apparently the heat limited the charging. Due to traffic, we were getting pressed on time (not enough time to get another charge), so we drafted a semi into Ellensburg. Had to use AC (set at 72 with 3 fan bars) and the battery registered in the red for temp. After the car sitting in a sunny parking lot at 95 degrees for a couple hours, we went over to the QC and it took 80 minutes to bring it up from 10% to 80%, again in the red zone. This time the warning come on saying the battery is hot and we should drive conservatively. Set the cruise for 55, but as we began to go up the pass, the warning said power would be reduced and put us in 2018 turtle mode. I was in the slow lane with the semis doing 40 mph. Made it to North Bend with 20% and went to the QC and parked in the shade w/ water poured under the car for evaporation cooling. 30 minutes only netted 20%, so we went another session to get up to 60%. Then we set the cruise at 55, turned off the AC and opened the windows as we went downhill to minimize battery usage. Needless to say, it was a bit of an antsy situation. Bad traffic in Tacoma helped keep battery usage down and the turtle mode warning finally went off. South of Tacoma we drafted a semi home at 65 mph with 5% left in the battery. This was my first long trip with the car and I'm not favorably impressed. I will not take it beyond its normal charge range in hot weather again.


Thanks for the info. I will be doing trip to Yakima next week for DCFC opening there so will likely see similar temps. I am guessing you didn't have LEAF Spy? This will be first real challenge for heat issues for me. I did do Ellensburg right after their grand opening but temps only in mid 90's. Yakima is expected to be in the mid 100's so definitely a bit "warmer"

Next time you do trip, I would suggest Suncadia or something. Its a bit of a detour being 5 miles off I-90 but its a great walkabout along with a QC that does not have a timer and its generally cooler as well. Be warned, the wind there is "brisk"...
 
cwerdna said:
bnewkirk said:
I just got back from a 300+ mile round trip from Centralia to Ellensburg in our 2018 SV. Much of the day the temperature was in the 90s. Did a quick charge in North Bend, but a 30 minute session only netted about 40%. Apparently the heat limited the charging.
...
Made it to North Bend with 20% and went to the QC and parked in the shade w/ water poured under the car for evaporation cooling.
...
This was my first long trip with the car and I'm not favorably impressed. I will not take it beyond its normal charge range in hot weather again.
Bummer. The temp in the 90's didn't help.

The bolded part probably had little to no effect. You're going to need Leaf Spy to sensor the pack temperatures. For me, on my 24 kWh Leaf, I find that the pack has a lot of thermal mass and it takes awhile (MANY hours) to cool down to cooler ambient temps. You DC FCing when it's already 90 F out I'm sure pushed the temps up quite a bit. My wild guess is that once you got the temp warning, the pack temp was past 120 F.

https://web.archive.org/web/20170717073322/http://www.mynissanleaf.com/viewtopic.php?t=22134 really heated up his pack.


I am putting together a chart that covers at what temps TBs come and go (since $50 is simply too much for some people to spend on LEAF Spy...) and 10 TBs run the range (turn on/off) between 119-122º

9 TBs run 112 -121º (full range)

Now 10 TBs are the low end as have not yet hit 11 TBs but guessing that will all change in 7 days. ;)
 
bnewkirk said:
This was my first long trip with the car and I'm not favorably impressed. I will not take it beyond its normal charge range in hot weather again.
My wife would be demanding that I get rid of the car after a trip like this, and I don't think she would stop until the car was gone.

It would not be so bad if the car allowed 100 - 150 miles to a destination without charging, 6 - 20 kW charging at the destination, and then back without further charging but driving in reduced power mode on the way back is painful. Not to mention the thought of the battery cooking the entire day and beyond. So this ends up being a car with a ~ 65 mile radius on a hot day, about the same as my 5 year old 24 kWh model.

What a bummer.
 
bnewkirk said:
I just got back from a 300+ mile round trip from Centralia to Ellensburg in our 2018 SV.

I decided to parse this trip in terms of miles per minute added during DCFC.
I used 287 Wh/mile for the consumption rate based on EPA
Presumed 38 kWh capacity so 1% = 380 Wh and 1.32 miles of travel
Google Maps says 170 miles each way and North Bend about half way, so 85 miles

Ambient: in the 90s F (over 32 C)
DCFC #1 at 85 miles: 1.65 miles/minute
DCFC #2 at 170 miles: 1.15 miles/minute
DCFC #3 at 255 miles: 0.88 miles/minute

Miles by charging at 1 mile/min results in a net travel speed of ~ 30 mph
 
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