2019 Leaf battery overheating

[DougWantsALeaf]

Most of us with Plus models never hit the thermal limitations, as it usually required driving more than 2 full charges in a day with minimal breaks, or over 400 miles. I have done over 500 (with a visit with a friend in the middle) without hitting any throttling.

It does appear that the new Leaf battery (+) deals with heat better, but that said, you can throttle if doing extended driving in hot weather).

[lorenfb]

It does appear that the new Leaf battery (+) deals with heat better,

Anecdotal! You can still "cook" the Leaf battery on a hot day (>80F) driving at high speeds. QC charging the Leaf is not its only heat related problem,
whether the Leaf2 has a 40kWh or a 60kWh battery.

[OrientExpress]

Anecdotal! You can still "cook" the Leaf battery on a hot day (>80F) driving at high speeds. QC charging the Leaf is not its only heat related problem,
whether the Leaf2 has a 40kWh or a 60kWh battery.

Anything is possible, but in the case it is unlikely, and the lack of anecdotal reports from owners world-wide seems to support that.

[GerryAZ]

It does appear that the new Leaf battery (+) deals with heat better,

Anecdotal! You can still "cook" the Leaf battery on a hot day (>80F) driving at high speeds. QC charging the Leaf is not its only heat related problem,
whether the Leaf2 has a 40kWh or a 60kWh battery.

I am not sure what you mean--QC will heat the battery, but air flow around the battery compartment during highway driving actually cools the battery (2011, 2015, and 2019 all exhibited this when monitoring the battery temperature with Leaf Spy). It is rare to see the temperature bar display drop from highway driving unless the battery is really hot after QC, but it is possible to have enough cooling to see the temperature display in the dash drop. During the summer, I usually see battery temperature (as indicated by Leaf Spy) increase during city driving after getting off the freeway and cool down slightly if I get back on the freeway.

FWIW, the 2019 battery seems to run cooler than the 2015 did when new and the 2015 ran cooler than the 2011 battery in my climate.

[DougWantsALeaf]

GerryAZ are you still seeing 97% SOH?

[DaveinOlyWA]

It does appear that the new Leaf battery (+) deals with heat better,

Anecdotal! You can still "cook" the Leaf battery on a hot day (>80F) driving at high speeds. QC charging the Leaf is not its only heat related problem,
whether the Leaf2 has a 40kWh or a 60kWh battery.

Work at it hard enough and I am sure you can figure out a way to get it done.

[lorenfb]

I am not sure what you mean--QC will heat the battery, but air flow around the battery compartment during highway driving actually cools the battery

You're joking, right? Describe the air flow around the battery. The battery is basically thermally isolated from ambient which results
in its having a long thermal constant, i.e. to heat-up or cool down from ambient effects. Since high speed driving develops heat quickly
from the I^2*R heating from the motor current, the battery will heat up fairly quickly as in QCing. With regard to QCing, do you fail to
understand the I^2 * R heating effect from a high charging current that affects battery degradation, and why "throttling" occurs?
So given the fairly long thermal time constant for cooling, the Leaf battery "cooks" the result of excessive QCing/high speed driving,
versus a BEV with TMS.

It is rare to see the temperature bar display drop from highway driving unless the battery is really hot after QC, but it is possible to have enough cooling to see the temperature display in the dash drop. During the summer, I usually see battery temperature (as indicated by Leaf Spy) increase during city driving after getting off the freeway and cool down slightly if I get back on the freeway.

And what's the conclusion, if there's any?

[GerryAZ]

I am not sure what you mean--QC will heat the battery, but air flow around the battery compartment during highway driving actually cools the battery

You're joking, right? Describe the air flow around the battery. The battery is basically thermally isolated from ambient which results
in its having a long thermal constant, i.e. to heat-up or cool down from ambient effects. Since high speed driving develops heat quickly
from the I^2*R heating from the motor current, the battery will heat up fairly quickly as in QCing. With regard to QCing, do you fail to
understand the I^2 * R heating effect from a high charging current that affects battery degradation, and why "throttling" occurs?
So given the fairly long thermal time constant for cooling, the Leaf battery "cooks" the result of excessive QCing/high speed driving,
versus a BEV with TMS.

I am serious--air flow over the battery case at highway speeds will dissipate some of the heat and reduce the temperature displayed by Leaf Spy if the battery is significantly hotter than ambient (such as from QC). Since power required to maintain highway speed is much less than QC charging, the discharge current is not high and the internal I^2*R losses (and hence heat generated) are low. The internal resistance of new (not significantly degraded) LEAF batteries is quite low. The internal resistance increases as the batteries deteriorate so 8-capacity-bar batteries will generate more heat during discharge from highway driving (and especially from QC charging) than 12-bar batteries, but the internal resistance of even an 8-bar battery is still relatively low.

If the battery is cool, then highway driving will increase battery temperature until it reaches an equilibrium temperature enough higher than ambient to cause heat transfer through the thermal resistance(s) between the cells and ambient equal to the heat generated internally. The battery cells together make a large thermal mass so that large mass heats and cools slowly, but the heat transfer is dependent upon the temperature differential between the cells and ambient. In normal day-to-day driving, the battery will cool while the car is parked overnight, but battery temperature will ratchet up during a long trip with multiple QC's because more heat is generated during each QC than dissipated by driving between QC's.

[LeftieBiker]

There is plenty of anecdotal evidence that with the Gen I Leaf, at least, highway driving after heating the battery with a QC will cool the battery somewhat. The airflow space present above the battery in the Gen I is essentially nonexistent above the battery in the 40+kwh cars, but that still leaves the underside to dissipate heat to the air stream.

[DaveinOlyWA]

There is plenty of anecdotal evidence that with the Gen I Leaf, at least, highway driving after heating the battery with a QC will cool the battery somewhat. The airflow space present above the battery in the Gen I is essentially nonexistent above the battery in the 40+kwh cars, but that still leaves the underside to dissipate heat to the air stream.

Maybe. I found that to be rather inconsistent. The issue is cooler weather usually means wetter roads, less efficiency, higher power output.

But I have also noticed a difference even between the 40 and 62 kwh packs. The Plus packs simply stay cooler. Whether the extra cell count makes that much of a difference or that some sort of ventilation has been added or simply what was "high" power in smaller packs is simply not in the larger packs.

Guessing its a combination of all those things. FYI; a very reputable dealer in the Seattle area let it slip that the plus packs had cooling. When asked for details he clammed up. He is privy to considerably more information than most LEAF salesmen due to his status in the company ( 3X NA #1 LEAF sales) So a slip of the tongue?

Knowing him personally, I would find it hard to believe he made the comment to generate sales.