High Temp on #64 sensor -

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Well-known member
Feb 10, 2015
Just wanted to put this up in it's own posting as it gets lost in the other thread.
PLus I had a tad higher reading on this #64 once, so I want to keep an eye out on it.

RobertC said:
JoeS said:
... even though both the failed #87 cell and the typically hot-running sensor are on the right side of the CaniOn screen, I don't know what their relative proximity is within the battery pack. Didn't someone identify that particular temperature sensor as being close to a coolant line?
Temperature sensor #64 runs high when charging:

The temperature sensors and voltage sensors are shown in this illustration:

The battery layout is shown in this illustration:

Here is a picture of an open battery pack:

Here is an illustration showing the radiator hose:

The battery pack is composed of ten LEV50-8 battery modules with eight 3.7V LEV50 batteries and six temperature sensors each, and two LEV50-4 battery modules with four 3.7V LEV50 batteries and three temperature sensors each, for a total of 88 LEV50 batteries and 66 temperature sensors.
The two LEV50-4 battery modules sit in the battery pack so as to have their battery management circuitry and temperature sensors mounted on top of the batteries, while the ten LEV50-4 battery modules sit in the battery pack so as to have their battery management circuitry and temperature sensors mounted on the side of the batteries.

According to these images, Joe's bad cell #87 lies between temperature sensors #65 and #66.

And this

RobertC said:
Temperature Sensor #64 high readings during charging.


siai47 said:
I also have the temperature anomaly at sensor #64. I don't know what causes it but it is apparent during charging, not operation. When the car has been sitting (not on charge) all 66 sensors read the exact same temperature.
Malm said:
I have no doubt what makes 64 heating. That´s the tube of the charger refrigeration that gets very close to the battery box, in a point very near the 64.
I believe that Malm is correct.
Temperature Sensor 64 is high during charging due to its proximity to the radiator hose that gets hot with circulating coolant during charging. The cooling system is dissipating heat from the charger. I hear the water pump run often during charging.


Malm said:
Yes. The tubes get very close to the battery box, but specially in that point close to the sensor 64. All along the car, on the top of the box, there are these two tubes, but only in particular points they are very, very close to the upper part of the battery box, and one is near the 64 sensor. So, cells 85, 86 should suffer a little more from the heat then the others, and never will be the ones in better shape.

I have other cells that are more affected then 85 and 86, like the 64. That's the price to pay for being an internal cell in a car that can have more then 40º C in their batteries.

siai47 said:
If the coolant tubes running close to the last battery module is causing a rise in temperature in the sensors, it should be reflected in more then one sensor. The battery module that should have sensor #64 in it should be the last module in the string. This is a four cell module that runs parallel to the coolant tube which means that all the sensors within the module should be running hotter then the rest. In fact #64 runs hot in my car when I am using an external charger and providing cooling air into the pack. Something else must be going on. In regards to moving cells around, that would be a real difficult problem as the modules are a bear to disassemble. I am not even sure the modules themselves can be moved around in the pack let alone the individual cells. I don't know if the CMS (cell monitoring system) address the modules by were they are located in the wiring harness or by coding the module itself with the ID information. I do know this. When you look at the airflow distribution in the pack (when supplying A/C to cool it, the bulk of the air is distributed into the area between the front and rear sets of modules with the lowest airflow reaching the five modules in the rear of the pack. The air enters the front right corner of the pack and goes into a distribution tube that directs it to the center and the left front of the pack. The air exhausts through the top cover over the rear modules. This uneven distribution shows up on the CANION temperature display after cooling.

EDIT: NO! See post below.

Today I looked at the CaniOn battery temperature screen on my used i-MiEV with its new battery pack (which had been installed a couple of months ago), and here's what I saw:


DonDakin said:
Is this screen shot just after charging ? The temps look too even. Tell us more....
My bad, don't know what I was thinking, as i simply took a CaniOn snapshot after the car had been sitting there for a while. Sensor #64 is still doing its thing.

Let's see if this makes more sense: I took a quick 34-mile round trip to the train station yesterday evening. Charged up a little higher than normal just before leaving, and leadfooted all the way keeping up with the 65mph++ traffic for perhaps 25 miles total on the freeway. Ambient temperature was around 65degF (18degC). Turned on CaniOn a little after I started:



At the end of the trip, here were the readings. Note, I made no attempt at driving efficiently as the distance was well-defined and I was in a hurry to get back home:



My two guesses are that the coolant tubes for the motor are actually affecting this sensor, OR, there is some component in the pack (contactor, maybe) that is in close range of this sensor. This component only heats up when the car is on.
PV1 said:
My two guesses are that the coolant tubes for the motor are actually affecting this sensor, OR, there is some component in the pack (contactor, maybe) that is in close range of this sensor. This component only heats up when the car is on.

I think the first one is the right answer. And that is my opinion for a long time, as you know. The cells near this sensor should suffer a little more because of the heat then the others, but not such a difference that should worry us.
Here's a picture of the i-MiEV undercarriage with the battery removed (JoeS's post from Battery only charging halfway, page 3). It looks like the coolant tubes are metal here and could quite easily radiate enough heat to affect the temp sensors (I was under the impression they were rubber hoses all the way), but are they in the right spot to affect #64?

hello everybody,

I finally move up to the Canion world, it's truly eye-opening. So, like everybody else, my cell 64 is high, actually usually the highest whether charging or driving. It was around 85F outside today and cell64_T showed 36C after charging level 2. It got up to 37C/99F by the time i get home after the 2200ft climb. So I am concerned.

Is it consensus that the reported cell64_T is actually cell 64 temperature ? and that cell64 is warmer being near the coolant line. The highest other readings were 30C, that's a 6C delta.

More importantly, how high can we let cell64_T get to ? would it help to direct some cooling air into the battery pack with the flap modification ?

Paul, that is sensor #64 and NOT cell #64. In your scenario and knowing where you live, I wouldn't worry about it at all. Your climb home is relatively short-lived and we are still in a very temperate environment, especially compared to Phoenix.

JoeS, that captured my attention. So 56,5% SOC was 7,475 kWh from the battery. Then, 100% should be 13,23 kWh.

Look to one of my readings:

100% is 11,91 kWh (began at 99,5% SOC).

But in conditions similar to your journey (higher speed), the value will be 10,6 kWh (100% SoC). 20% less energy then yours.

Did you saw the temperature, 18,6 ºC? That was a trip in a summer day, 25º C outside. More at http://www.nissanleafpt.com/viewtopic.php?f=32&t=1556&start=1960
Malm, if I understand you correctly (and after playing with Google Translate on the nissanleafpt link), you are trying to make two points:

1. The pack capacity based on energy-used vs. SoC varies as a function of vehicle speed (consumption rate); however, comparing your performance with mine your battery is showing a 20% lower number.

2. After all that driving your pack temperature was significantly lower than ambient (18.6C pack vs. 25C ambient)

Each of these two subjects should be discussed in the appropriate topic (thread) and not here, as this topic is strictly about temperature sensor #64.

1. In the Battery Capacity Testing thread we have already talked about uncontrolled variables affecting SoC computation, different discharge rates being one of these variables. Would you like to make a cohesive entry in that thread, perhaps pointing out the relationship to Average Moving Speed?

2. I'm confused as to whether you are trying to show that running the air conditioning unit resulted in the lowering of the battery temperature? I don't know if you've modified the ductwork or not, but perhaps that discussion should be better undertaken in the Passive Cooling thread?

Would you like to address each of these two issues in those threads?

Malm, to answer your question (I think), my own battery temperature had started off at 21.4C and ended up at 26.0degC, in an evening ambient of around 25C. This is the almost brand-new pack, replaced just a few months ago. Interesting that you came up with a capacity of 13.23kWh for this relatively high-speed drive, just one data point with an uncontrolled variable. IMO, average speed is almost useless unless it is shown to be steady-state. Five minutes of driving at 80mph followed by five minutes at 0mph is quite a different battery load than ten minutes at 40mph.

Note: I may move these last two posts out of this thread if the discussions continue elsewhere.
Sorry :oops:

Just saw the results of your trip, was interesting to compare.

For me, the question of #64 sensor is resolved. The coolant tube in that particular point, is really close to the battery box, maybe even touch it.

That was not really a question. That 20% lower number in mine is due to a reduction in capacity compared to a new pack. Yes, modified the ductwork, otherwise that temperature would be impossible.
Just nosing around and noticed this #64 thing again. I would also agree that something other then the battery module is causing a rise in the reading---and it is related to the inverter/charger cooling system. I think I mentioned in an earlier thread about this issue that both my I-MiEVs showed the same anomaly when charging normally. However, when my modified I-MiEV was charging with a external charger (which didn't operate the inverter/charger cooling system) #64 temperature was consistent with the other temperatures again pointing to the cooling pipe location above the end of battery module #12 about where sensor #64 would be located.
I have another bit of evidence to the coolant line theory of #64 rising.

Situation: Sitting in the garage in ready mode for a couple of hours drawing power from the 12V system (emergency power 120VAC from main pack testing). In ready mode the coolant pump runs full time rather than cycling like it does when charging. The only source of heat would be the DC to DC and motor controller at standby. #64 went right up just like when charging but not as high 1deg C lower than when charging (cooler coolant?). It looks to me to fit the coolant line theory.

Now the question that comes to mind is how much heating are the cells in that proximity actually getting, since temp sensors are on the BMS boards??

Aside: once I saw #64 high I turned on the cabin blower to the battery duct on medium and in 15 minutes it was much lower, in 25 minutes it had reached the same temp as surrounding sensors.

Aerowhatt said:
how much heating are the cells in that proximity actually getting, since temp sensors are on the BMS boards??
Not much I suppose. Cells covered by temp sensor 64 would cool down much slower if they were affected by hot tube when you stop the car. I noticed that sensor 64 temperature is matching other values pretty soon after I put the car in the garage which makes me think the outstanding sensor 64 values don't represent the cell temperature.