Using air conditioning to reduce battery pack tempature

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We proved that forcing cool air down the Service Plug port does cool the battery pack. We also proved that using the air conditioning system to cool the air going down the port is not very efficient, the faster charging rate we get because of the cooler battery is eaten up by the power consumed by the AC compressor motor. So the question begs to be asked, "How can we more efficiently cool the air going down the port".

The answer is obvious, find some way to cool the air besides using the AC system. I can think of several ways to do this. One way might be to use a ice chest as an ice filter and force the air through the ice chest before the air goes down the port.

Another way might be to use one of those large chemical spray bottles to spray ice water down the port. You could use a mist nozzle so the spray pattern is even going into the port. You can even get a battery powered spray bottle that you could rig up to spray while you are in WalMart getting more water and ice or while you are driving down the highway.

I'm not planning to try any of these ideas any time soon but I can easily see how someone planning a trip across the desert Southwest in the middle of summer might seriously consider some alternative method of cooling. Hopefully if anyone does try some form of alternative cooling they will provide a post so we can benefit from their experience.
 
TexasLeaf said:
but I can easily see how someone planning a trip across the desert Southwest in the middle of summer might seriously consider some alternative method of cooling.
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If someone is planning a trip across the desert Southwest in the middle of summer, I'd suggest you pick a different EV. The LEAF is a shorter range car best used as a commuting or around town car, with only occasional trips beyond range usually one QC per day.
 
During one of my tests I identified by comparing the EVgo charge report with the LeafSpy information that the waste heat during the charge sessions was 3.11 kWh. I also identified by comparing the information on charge session that did not use AC for cooling with the charge session that did use AC for cooling that the AC system consumed 2.72 kWh during the charge session. Most AC systems have Coefficients of Performance of 3 or 4 so the AC system should easily have been able to cool the battery pack during charging at least to ambient temperature levels.

I noticed that the AC system really had to struggle to get cabin temperature down. The air coming out of the vents was just a little above 60 degrees F but the cabin temperature hardly dropped below 75 degrees F. Even though I had a solar screen on the windshield I think the solar radiation and the heat transfer coming in to the cabin through the windows and body panels was overwhelming the AC system.

One thing I’m planning on doing next time I take a trip with multiple charges is cover the car with a reflective car cover when charging. I would leave the car cover off the hood so I could open the hood to release heat off the condenser. If we can keep the heat out of the cabin with a car cover or even two car covers then the AC would be cooling the fresh air as much as possible to send it across the battery pack.

The AC system should do a much better job of cooling the battery pack if we can eliminate as much cabin cooling load as possible. The cabin AC controls only go down to 60 degrees F so the controls will still limit how much cooling we can do. The AC system will be useless if it’s already 60 degrees F or less outside so then we would have to depend on ambient temperature or some type of supplemental cooling to reduce cabin temperature.

I have been thinking of a bunch of different ways to provide supplemental cooling to the cabin and to improve the AC system cooling efficiency. Some are pretty elaborate but some are pretty simple and would cost very little to implement. I’m sure most of you would be able to come up with some pretty creative cooling ideas yourselves if you put your mind to it.

Here’s one simple idea; get a big ice chest and fill it with ice. Get a 12V fan with a clamp the attaches to the side ice chest. Plug the fan into the 12V outlet, turn the fan on when you are charging blow the air across the open ice chest, 74 pounds of melted ice would remove all the waste heat of one of my charging sessions.
 
TexasLeaf said:
Here’s one simple idea; get a big ice chest and fill it with ice. Get a 12V fan with a clamp the attaches to the side ice chest. Plug the fan into the 12V outlet, turn the fan on when you are charging blow the air across the open ice chest, 74 pounds of melted ice would remove all the waste heat of one of my charging sessions.
Click to expand...
I more I read about these various schemes, the more I think the 2018 is just not an appropriate vehicle for such a trip.
 
TexasLeaf said:
Here’s one simple idea; get a big ice chest and fill it with ice.
Click to expand...

It looks like a lot of other people have already thought of this idea. There are a bunch of portable vehicle ice coolers on the market that would work very well at helping to cool the Nissan Leaf battery pack through the Service Plug port. Here are a few links;

https://www.thecomfybuddy.com/portable-air-conditioner-for-car-and-truck/

https://www.sportys.com/pilotshop/arctic-air-portable-air-conditioner-38-qt-single-fan-24-volt.html

http://stellaindigoriverside.blogspot.com/2012/04/ordernow-ice-12v-portable-air.html

https://www.amazon.com/Iceandplug-Volt-Portable-Air-Conditioner/dp/B008473X8C

http://www.kooleraire.com/

These coolers could sub cool the already chilled cabin air and that sub cooled air could be ducted directly to the Service Plug port. This would be a great way to get the air going through the port cooler than the 60 degrees F limited by the cabin AC system and could also supplement the AC system to cool the battery pack when it's really hot outside. I'm sure some unit would work much better than others so you better do your homework when you make a selection.

It's such a simple solution to use one of these coolers it doesn't make any sense not to have one of these coolers if you own a Nissan Leaf. It almost looks like Nissan was thinking about these coolers when they designed the Leaf without a thermal management system. And they might have said, "Why make Leaf owners pay for an expensive TMS when for a few hundred bucks they can buy an ice cooler for those rare occasions when they need extra cooling for the battery pack".

I'm sure I'll end up getting one of these coolers but, since Fall is almost here, it probably until next summer when it heats back up again and more of the Electrify America network gets built. If anyone has any experience with these ice coolers I would like to hear about it.
 
TexasLeaf said:
It's such a simple solution to use one of these coolers it doesn't make any sense not to have one of these coolers if you own a Nissan Leaf.
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Well, I disagree. Never had my battery hot enough to worry about it. The main use for the LEAF, Commuting, just doesn't get the battery much above ambient, usually stays cooler than the daily high temperature during the summer. If you live in someplace really hot and want to take long trips then the best answer is probably buying a different EV.
 
I built a portable car A/C unit 20 years ago when my Civic's A/C failed. You DON'T want an ice-based system unless you live in a dry climate, and even then there is the added moisture going where it isn't desired. Instead you want to use sealed freezer blocks - the white kind that stay much cooler much longer than the gel type blue blocks. You blow air over the blocks, which are stacked in a baffle that maximizes surface area, then out of the unit, and water collects in the bottom.This kind of unit will dehumidify the cabin air just like a heatpump type unit. The difference is you have to dump the water out after each use.
 
The outdoor air temperature in the DFW area hovered just below 40 degrees F today with overcast skies. I decided to perform a test to see how ambient temperature affected the charging performance of my 2018 Leaf. I repeated the test I discussed in my Aug. 19, 2018 post but with blowing unconditioned cabin air through the service plug hole instead of conditioned cabin air.

For driving on the highway I set the cabin temperature to 60 degrees F with the fan speed set to auto. Once I got off the highway I turned the heat off, opened all windows and set the ventilation fan speed to full to evacuate all the heat from the cabin. Once I started charging I closed all the windows and left the ventilation fan at full speed with the relief vents taped up to force as much air as possible service plug hole.

I started the trip with a battery temperature of 45 degrees F. The battery temperature had reached 65 degrees F by the time I started the 1st charging session and had reach 90 degrees F at the end of the 1st charging session. The battery temperature was at 83 degrees F at the start of the 2nd charging session and 99 degrees F at the end of the 2nd charging session.

During the 1st charging session the battery reach a peak battery temperature of 92 degrees F at about 20 kW. During the 2nd charging session the battery reach a peak battery temperature of 102 degrees F again at about 22 kW. The peak charge rate for the 1st charge session was 45 kW and the peak charge rate for the 2nd charge session was 36 kW.

36 kW is the fastest I have ever been able to charge at the EVgo charger I was using so I consider this to be full speed for this charger. So I was able to achieve TWO FULL CHARGE CYCLES with no evidence of the Rapidgate phenomenon. With battery still heating up I would have expected the Rapidgate phenomenon to rear its’ ugly head on the third charging session.

I started the trip at 5:36 am and I finished the trip at 10:53 am for a total trip time of 5 hours and 17 minutes. This trip time beats the trip times for the tests I wrote about in my Aug. 19, 2018 posts by over one hour! It is very obvious the cold ambient temperature can be used to improve charging performance of the 2018 Leaf.

I didn’t perform a test to determine how much ambient temperature improves charging performance without blowing cabin air through the service plug hole. I have already proven that cool air blown through the service plug hole cools the battery pack and I saw little reason to repeat that test. My confidence grows that supplemental cooling can used to improve charging performance under most ambient conditions.

I plan to buy an ice chest air cooler very soon so that I can start testing, before warmer temperatures start setting in, how ice chest air blown through the service plug hole helps cool the battery pack. Even when its’ colder outside, like it was today, an ice chest cooler should be able to help cool the battery pack and improve charging performance. On hot days, ice chest battery pack cooling might be a necessity for long trips in the 2018 Leaf with multiple fast charging stops.
 
TexasLeaf said:
The outdoor air temperature in the DFW area hovered just below 40 degrees F today with overcast skies. I decided to perform a test to see how ambient temperature affected the charging performance of my 2018 Leaf. I repeated the test I discussed in my Aug. 19, 2018 post but with blowing unconditioned cabin air through the service plug hole instead of conditioned cabin air.

For driving on the highway I set the cabin temperature to 60 degrees F with the fan speed set to auto. Once I got off the highway I turned the heat off, opened all windows and set the ventilation fan speed to full to evacuate all the heat from the cabin. Once I started charging I closed all the windows and left the ventilation fan at full speed with the relief vents taped up to force as much air as possible service plug hole.

I started the trip with a battery temperature of 45 degrees F. The battery temperature had reached 65 degrees F by the time I started the 1st charging session and had reach 90 degrees F at the end of the 1st charging session. The battery temperature was at 83 degrees F at the start of the 2nd charging session and 99 degrees F at the end of the 2nd charging session.

During the 1st charging session the battery reach a peak battery temperature of 92 degrees F at about 20 kW. During the 2nd charging session the battery reach a peak battery temperature of 102 degrees F again at about 22 kW. The peak charge rate for the 1st charge session was 45 kW and the peak charge rate for the 2nd charge session was 36 kW.

36 kW is the fastest I have ever been able to charge at the EVgo charger I was using so I consider this to be full speed for this charger. So I was able to achieve TWO FULL CHARGE CYCLES with no evidence of the Rapidgate phenomenon. With battery still heating up I would have expected the Rapidgate phenomenon to rear its’ ugly head on the third charging session.

I started the trip at 5:36 am and I finished the trip at 10:53 am for a total trip time of 5 hours and 17 minutes. This trip time beats the trip times for the tests I wrote about in my Aug. 19, 2018 posts by over one hour! It is very obvious the cold ambient temperature can be used to improve charging performance of the 2018 Leaf.

I didn’t perform a test to determine how much ambient temperature improves charging performance without blowing cabin air through the service plug hole. I have already proven that cool air blown through the service plug hole cools the battery pack and I saw little reason to repeat that test. My confidence grows that supplemental cooling can used to improve charging performance under most ambient conditions.

I plan to buy an ice chest air cooler very soon so that I can start testing, before warmer temperatures start setting in, how ice chest air blown through the service plug hole helps cool the battery pack. Even when its’ colder outside, like it was today, an ice chest cooler should be able to help cool the battery pack and improve charging performance. On hot days, ice chest battery pack cooling might be a necessity for long trips in the 2018 Leaf with multiple fast charging stops.
Click to expand...


Your pack didn't get hot enough to see RapidGate. You have to start with hot pack and your 2nd one starting in the 80's was not hot at all. You can tell if RapidGate will happen on temp gauge of car. Any reading past the mid point (7 bars or more) is what you need. You were only at 6 bars.

What would be more interesting is the knee on your first charge. Knee is when charging current starts dropping. If you have LEAF Spy you can check the logs to see what SOC it happened. Also check knee on 2nd charge. You will find the knee happens much later when batteries are not cold.

https://daveinolywa.blogspot.com/2018/12/cold-verses-leaf.html
 
DaveinOlyWA said:
Your pack didn't get hot enough to see RapidGate. You have to start with hot pack and your 2nd one starting in the 80's was not hot at all. You can tell if RapidGate will happen on temp gauge of car.
Click to expand...

Does the charge time estimation screen give accurate information for L3? I noticed that the 2018 has a "time to charge" for L3.
 
WetEV said:
DaveinOlyWA said:
Your pack didn't get hot enough to see RapidGate. You have to start with hot pack and your 2nd one starting in the 80's was not hot at all. You can tell if RapidGate will happen on temp gauge of car.
Click to expand...

Does the charge time estimation screen give accurate information for L3? I noticed that the 2018 has a "time to charge" for L3.
Click to expand...

Up to 75% and no RapidGate, it seems to be pretty accurate. Above that, I can't say as I have too little experience there to comment.

But also realize its all based on 50 KW charging so if on a slower one...
 

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