Cabin Air Cooling the Battery

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Danl

Well-known member
Joined
Mar 6, 2016
Messages
69
Location
Vancouver, Wa
I Have a 2013. I am doing some experimenting with battery temperature and I think the cabin air exhausts down into the Battery area.

If this is true, I am amazed that someone has not found it before in order to cool the battery and therefore prolong its life.

What I did was to turn on the AC set at 73degF with the fan running full. It is set to outside air input and then I rolled all the windows up. I did this with an L2 charge happening at the same time.

First I checked Leafspy. 4kw going into the charger. 2.5kw going into the battery. so we have 1.5kw going into the AC. After 15 minutes or so, the AC power drops to about 0.75kw. Also I see T1 is the lowest temp. Without AC T1 is normally the highest.

Then look for warm and cool airflow around the car.
The radiator fans are running. Hot air is blowing out over the front tires.
The cabin blower is running. it is sucking air in at the bottom of the windshield.
The cool air exhausting from the cabin appears to be coming out around the battery shield.

I have data logging going on LeafSpy so later I will chart the temps and see if the battery is being cooled.

This is important Because this gives us a tool to cool the battery during charging and therefore increase the life of the battery.

Has anyone else seen this?
Am I crazy, or has this been available but Nissan has not given us instructions on how to improve the battery life?

Thanks,
Dan
 
I take it this would only work with the "fresh air" setting and not "recirculate" setting? You can get right into the battery from the safety disconnect fuse in the center, I've often though about running a tub down into it to force cool air into the battery compartment. :)
 
knightmb said:
I take it this would only work with the "fresh air" setting and not "recirculate" setting? You can get right into the battery from the safety disconnect fuse in the center, I've often though about running a tub down into it to force cool air into the battery compartment. :)
Hello Knightmb,
Yes, you are correct. Run in Fresh air mode all the time. Then turn on the cabin fan while charging.

No, you do not need to run a tube, the Leaf is already plumbed for the cabin air to exhaust into the battery area.

Thanks,
Dan
 
It might explain why some cars do much better than others in similar situations and locations. I *always* use the A/C if it's Hot, and while it's often on Recirculate, when I switch to Fresh (which do regularly while driving) that would blow extra chilly air down around the battery cases...
 


Here is todays data.
You see that during the last charge T3 stayed level and did not climb as it had done in the first charge of the day when the AC had not been on.

Thanks,
Dan
 
LeftieBiker said:
It might explain why some cars do much better than others in similar situations and locations. I *always* use the A/C if it's Hot, and while it's often on Recirculate, when I switch to Fresh (which do regularly while driving) that would blow extra chilly air down around the battery cases...

Yes, I would advise never run in Recirculate. The cool exhausted cabin air is of more value to cool the battery than the cost to cool down new air coming into the cabin.

In addition I would advise running the cabin fan with the windows up even when the AC is not needed.

Thanks,
Dan
 
Yes, I would advise never run in Recirculate. The cool exhausted cabin air is of more value to cool the battery than the cost to cool down new air coming into the cabin.

In addition I would advise running the cabin fan with the windows up even when the AC is not needed.


I use Recirculate to block exhaust fumes more than as an energy saver. I still have 12 bars and 89% SOH, and my lease is ending in the next 12 months, so I'll keep up what I'm doing. If this info proves true, it will help those who regularly avoid A/C use to extend range, to reconsider.
 
LeftieBiker said:
I use Recirculate to block exhaust fumes more than as an energy saver. I still have 12 bars and 89% SOH, and my lease is ending in the next 12 months, so I'll keep up what I'm doing. If this info proves true, it will help those who regularly avoid A/C use to extend range, to reconsider.

Yes, I use Recirculate when I get on a gravel road and then turn it off when the dust clears.
 
Danl said:


Here is todays data.
You see that during the last charge T3 stayed level and did not climb as it had done in the first charge of the day when the AC had not been on.

Thanks,
Dan
Now that is fascinating for sure! I can actually run some data logging on LeafSpy because my Charger Connection and Office Window are right next to each other. So I can run LeafSpy from my Phone inside the office (bluetooth link can reach just far enough for LeafSpy). I'll see if I can get the same result. :mrgreen:
 
You are full of surprises @Danl! I don't remember this phenomena being discussed much way back, but there's one thing I would like to see (with all of your data actually): hotter ambient temps (like 100 degrees). If this method can drive a 7TB event to a 6TB event (or even lower), that would be a big benefit to the battery pack.
 
I just did some testing and it appears that the waste heat from the AC might actually work against this.
I started a L2 Charge at 15% SOC.
I put the Leaf in standby mode so I could activate the AC, set the Climate Control 72F at full fan power and vent outside air through both top and bottom vents. The outside ambient temperature at this time was 92F. I used LeafSpy to monitor the Leaf from my Office next to it and it was using 1,500 watts the entire time for the AC. I then recorded the T1 through T3 temperatures every 5 minutes with LeafSpy.

11:50AM
93.6 92.4 92.2

11:55AM
94.0 92.8 92.4

12:00PM
94.2 93.2 92.6

12:05PM
94.2 93.6 92.6

12:10PM
94.4 94.0 92.8

12:15PM
94.4 94.4 93.0

12:20PM
94.6 94.8 93.2

12:25PM
94.6 95.2 93.4

12:30PM
94.8 95.8 93.6

12:35PM
95.0 96.2 93.8

12:40PM
95.2 96.4 94.0

12:45PM
95.2 96.8 94.2

12:50PM
95.4 97.0 94.4

As you can see, there was a steady temperature climb for the whole hour. I then shut-down the AC in the Leaf and let it continue charging as it had reached 45% SOC by now. I then recorded the temperatures from this point via LeafSpy.

12:55PM
95.4 97.0 94.4

1:00PM
95.0 96.4 94.4

1:05PM
95.0 96.2 94.4

1:10PM
95.0 96.2 94.2

1:15PM
94.8 96.0 94.0

1:20PM
94.6 95.8 94.0

As you can see, the temperature started to decrease. I finally stopped after 1:20PM because I could already see the pattern. The ambient air temperature was actually up to 94F when I finished.

The AC was actually making the temperature rise and I suspect it is because the Leaf is designed to allow air flow from the front of the vehicle to out the back around the battery pack. With the AC running, the waste heat was being sent around the battery pack. The inside of the Leaf was nice and cold after I ended the AC test and it was using 1,500 watts the entire hour so I know it was doing max cooling allowed the entire time.

So I think any benefit from having the vent AC to cool the battery pack is defeated by the waste Heat produced by the AC since this air also flows around the battery pack. :(
 
^ ^ ^ Nice test. Higher ambient temps (than @Danl) may also have a compounding affect: we all know that pack has a lot of mass.
 
Here in FL we almost always run car ACs in recirculate mode because the humidity is so high the latent heat (if that is the correct term) of outside air coming in makes it nearly impossible to cool the car.

So this may explain why LEAFs in FL do so poorly.
 
Stanton said:
You are full of surprises @Danl! I don't remember this phenomena being discussed much way back, but there's one thing I would like to see (with all of your data actually): hotter ambient temps (like 100 degrees). If this method can drive a 7TB event to a 6TB event (or even lower), that would be a big benefit to the battery pack.
Yes, I would like to see that also.

Where I live we normally get a few days that hot, but not last year and so far not this year. So what is needed is people further south collecting data. If anyone can get the data log file from LeafSpy to me then I can get a chart like this back to them and also post it here.

Thanks,
Dan
 
Danl this is another great post. Thank you.

This should be the same in the Soul EV because cooled air will use the same exit pipe for air from the cabin as it uses for forced air cooling. Hence some cooling will occur before the battery temps get to 31C and the battery fan begins running.

1zfinav.jpg
 
knightmb said:
I put the Leaf in standby mode so I could activate the AC, set the Climate Control 72F at full fan power and vent outside air through both top and bottom vents. The outside ambient temperature at this time was 92F.
Do you think the effect would have been greater if the AC was set to 60 instead of 72? Why set it to only 72?
 
knightmb said:
I just did some testing and ........ :(
Just sent you a PM. Can you send me the log file over regular Email?

Today I did the fan with the AC not turned on. That may be the right answer.

Thanks,
Dan
 
LeafMuranoDriver said:
knightmb said:
I put the Leaf in standby mode so I could activate the AC, set the Climate Control 72F at full fan power and vent outside air through both top and bottom vents. The outside ambient temperature at this time was 92F.
Do you think the effect would have been greater if the AC was set to 60 instead of 72? Why set it to only 72?
No, He had the AC running max already.

thanks,
Dan
 
LeafMuranoDriver said:
knightmb said:
I put the Leaf in standby mode so I could activate the AC, set the Climate Control 72F at full fan power and vent outside air through both top and bottom vents. The outside ambient temperature at this time was 92F.
Do you think the effect would have been greater if the AC was set to 60 instead of 72? Why set it to only 72?
The AC can only use 1,500 watts when the vehicle is traveling less than 15 MPH (In parked included), so it wouldn't matter if I set it for 72 or 32, it will run the max cooling that it can until it reaches the set temperature. I did the test in blazing heat, so I never reaches a low enough temperature to start using less cooling power.
 
Danl said:
knightmb said:
I just did some testing and ........ :(
Just sent you a PM. Can you send me the log file over regular Email?

Today I did the fan with the AC not turned on. That may be the right answer.

Thanks,
Dan
That would be great, it would use a lot less power. :mrgreen:
 
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