Using air conditioning to reduce battery pack tempature

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TexasLeaf said:
There was still a lot of fresh air coming out of the vents with the vents taped up and I could not figure out where the air was going.

There is a very large gap at the bottom of the panel with the vents in the trunk. I'm pretty sure that is where the air is getting out to the relief vents behind the bumper when the trunk grilles are taped up. The gap does all the way around the edge at the bottom of the trunk.

When I go on a long trips I will try to tape this gap up to force as much air as possible through the Service Plug port. The only problem is the trunk liner that covers the gap sits under the sub wolfer. It looks possible to work around the sub wolfer but it might be easier just to remove the sub wolfer when you tape up the gap
 
WetEV said:
Batteries degrade. They degrade slower at 60F than at 70F. Even slower at 50F. Probably slowest somewhere near 0C/32F. This is a complex chemical reaction.

There are different reactions that happen below about 0C, and batteries probably degrade faster below about 0C. Battery heater tries to keep battery above -20C, unless you have one of the early LEAFs without a battery heater.

I'm not sure I would modify the car to add battery cooling. The possibility of getting condensation where there shouldn't be any raises the worry of battery fires at worst case. Sure, unlikely, but Li-ion batteries don't mix with moisture very well.

I was trying to avoid this topic. This thread is about cooling the battery using the air-conditioning system to improve charging speed on long trips, not about battery degradation. But I think I need to chime in to get this thread back on track.

At this time I could care less about battery degradation on my 2018 Leaf. You need an EV that can go the distance in Texas. Slow charging on long trips is a much more serious issue for me than any potential battery degradation.

One of the reasons I got the 2018 was that it has so much range I figured I could lose a little battery capacity and still be able to make the trips I needed to. And in Texas, if you don't want your battery to get hot you better leave the car in garage. My mind set on EV batteries is that they are like tires, EV batteries are going to wear out and they are going to have to be replaced eventually.

If the battery goes down to seven bars before the end of the 8 year/100,000 mile warranty then Nissan is going to be buying a new battery for the car. If the battery goes bad after the warranty ends then I will pay for a new battery. But, I figure by the time I have to pay for a new battery I will have gotten my money's worth out of the car and I would have no problem with just parking the car on the side of the road and walking away from it.
 
TexasLeaf said:
There is a very large gap at the bottom of the panel with the vents in the trunk. The gap does all the way around the edge at the bottom of the trunk.

I removed the sub-wolfer and taped up this gap and the grilles and ran the AC in Fresh Air mode again. I couldn't really tell any difference in air flow from without the tape. My tissue test seemed to indicate that air was going under the rear seat.

I thought there might be an air opening through the floor under the rear seat so I pulled the rear seat. It's easy enough to remove the rear seat, all you have to do is pull up on the front. There are not any air openings through the floor under the rear seat.

Even though the unit was in Fresh Air mode, I thought that air might be getting back to the fan through the return air opening in the AC unit. I found the return air opening above the drivers feet. With the AC in Recirculate mode my tissue pulled up into the return opening but with the AC in Fresh Air mode my tissue was limp.

So even with the grilles in the trunk taped up air still gets out of the car somehow. I tried the tissue test on the Service Plug port with the trunk grilles taped up. With the AC in Recirculate mode the tissue would just hang limp in the open port but when I turned the AC to Fresh Air mode the tissue really flapped away in the port.

I think tapping the grilles up in the trunk does some good in forcing more air into the Service Plug port and it's pretty easy to do. Tapping up that gap around the trunk was a chore and I really didn't see any significant gains. I don't think I'll be tapping up the gap again.

I'm not going to worry anymore about how the air is getting out of the car in Fresh Air mode with the grilles tapped up. I'm pretty sure most of the air is being forced down the Service Plug port. I am just going to assume that air gets out the door seal, window seals and the like but most of the air will seek the path of least resistance down the open port.

The next order of business will be to take a long trip with multiple fast charges and see how well I can keep the battery cool with the trunk grilles tapped up and the Service Plug port opened up.
 
I am likely wrong but I thought the service port in to the battery was the only opening in to the battery pack? Where is the air escaping from the pack? Are there relief port on the pack somewhere?

I thought there was another thread about someone fan forcing air in the service port, but using a fan at that location and just forcing in to the pack?
 
BrockWI said:
I am likely wrong but I thought the service port in to the battery was the only opening in to the battery pack? Where is the air escaping from the pack? Are there relief port on the pack somewhere?

I thought there was another thread about someone fan forcing air in the service port, but using a fan at that location and just forcing in to the pack?

The Service Plug port we are talking about is in the floor board of the car in front of the rear seat; not in the battery pack itself. There is a gap about a half inch deep between the battery pack and the floor board over the entire top of the battery pack. Cool air from the cabin can be forced down the port and spreads out through that gap cooling the top of the battery pack.

I don't know what thread you are talking about but I don't see the point in using another fan when the cabin fan seems to do a pretty good job of pushing air down the Service Plug port.
 
So basically the air is going through that port and then down around the pack itself. I agree a positive pressure from the HVAC system will force air out that location.

Here is that other thread

http://www.mynissanleaf.com/viewtopic.php?t=17682
 
BrockWI said:
So basically the air is going through that port and then down around the pack itself. I agree a positive pressure from the HVAC system will force air out that location.

Here is that other thread

http://www.mynissanleaf.com/viewtopic.php?t=17682

I read through all the posts on that thread. There didn't appear to be any posts discussing using cabin temperature and cabin air to cool the battery pack. I think what this thread discusses is different approach that deserves consideration and further investigation.
 
TexasLeaf said:
...
Using the Service Plug port for additional battery cooling was very easy to do. It worked so well that it makes me think that the Service Plug port is actually intended to be used for supplemental battery cooling. ...

It's meant as a means to disconnect power in the event of an emergency. There is a high-voltage warning which I would take very seriously.
 
Nubo said:
It's meant as a means to disconnect power in the event of an emergency. There is a high-voltage warning which I would take very seriously.

Nobody is proposing doing anything with the Service Plug. The Service Plug is already weather proof, a little cool air blowing over it shouldn't hurt anything. If you are worried about something dropping down the opening then you can always put a screen over it.

One way I have thought of screening the opening is to drill holes in the cheep plastic cover. You always go buy a new cover for when you don't want to vent or if you want to sell you car. Sure, take the warning seriously, but until Nissan comes up with a way to cool the battery using the Service Plug port for ventilation is one of the best options we have.
 
Nobody is proposing doing anything with the Service Plug. The Service Plug is already weather proof, a little cool air blowing over it shouldn't hurt anything. If you are worried about something dropping down the opening then you can always put a screen over it.

Are you suggesting removing the plastic cover plate, or also the metal plate secured with 10mm bolts?

If only the former, the HV components would seem well-protected; but without the metal cover, what would prevent a spilled drink (or a water from a firefighter's hose) from infiltrating and shorting the 400V DC fuse assembly?

At the very least, some sort of splash-resistant cover would seem in order.
 
Nobody is proposing doing anything with the Service Plug. The Service Plug is already weather proof, a little cool air blowing over it shouldn't hurt anything. If you are worried about something dropping down the opening then you can always put a screen over it.

Are you suggesting removing the plastic cover plate, or also the metal plate secured with 10mm bolts?

If only the former, the HV components would seem well-protected; but without the metal cover, what would prevent a spilled drink (or a water from a firefighter's hose) from infiltrating and shorting the 400V DC fuse assembly?

At the very least, some sort of splash-resistant cover would seem in order.
 
agt said:
Are you suggesting removing the plastic cover plate, or also the metal plate secured with 10mm bolts?

If only the former, the HV components would seem well-protected; but without the metal cover, what would prevent a spilled drink (or a water from a firefighter's hose) from infiltrating and shorting the 400V DC fuse assembly?

At the very least, some sort of splash-resistant cover would seem in order.

Removing both the plastic cover plate AND the metal cover plate. You appear to be struggling with the concept of "weatherproof". The car could be sitting at the bottom of a lake and the Service Plug still wouldn't short out.
 
Removing both the plastic cover plate AND the metal cover plate. You appear to be struggling with the concept of "weatherproof". The car could be sitting at the bottom of a lake and the Service Plug still wouldn't short out.

I'm curious - what in particular makes the connector weatherproof? I admit I haven't opened my own disconnect, and am only basing my questions off images on the net, e.g.

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Is there gasket material not displayed here? Otherwise it seems like a couple of cups of liquid could short the two HV legs to the chassis...
 
agt said:
Removing both the plastic cover plate AND the metal cover plate. You appear to be struggling with the concept of "weatherproof". The car could be sitting at the bottom of a lake and the Service Plug still wouldn't short out.

I'm curious - what in particular makes the connector weatherproof? I admit I haven't opened my own disconnect, and am only basing my questions off images on the net, e.g.
Is there gasket material not displayed here? Otherwise it seems like a couple of cups of liquid could short the two HV legs to the chassis...

That latch creates a pressure seal. Plus there are channels to keep any moisture that makes it past the seal from getting to the contactors. The only way you are going to get moisture on those contactors is if you pull the latch and pour water directly on the exposed contactors.

I also might point out that the service plug is located on the OUTSIDE of the car and is not otherwise protected from the elements. Whenever you drive the Leaf through heavy rain or through a big mud puddle the entire battery pack will get drenched, including the service plug. Your entire argument that a little moisture that you might spill through the service plug port is going to short out the service plug defies all logic.
 
BrockWI said:
Lemon Tea trying to do this as well

https://www.youtube.com/watch?v=6HcM47nWEoQ

I think there are things James could have done to significantly improve his results. One thing is that James did not use the air conditioning to cool the battery, he just forced fresh air ambient air down the port. Forced air that's cooled 20 degrees F below ambient, especially during charging with the hood open to release waste heat, should do much better at cooling the battery.

Also those fans probably did more to restrict the air flow than to improve it. Just having the AC in Fresh Air mode with a fully open port should throw plenty of air down the port. Also taping up the exhaust grilles in the trunk should guarantee that most of the Fresh Air goes down the port.

I am planning a structured test this weekend to see how much blowing cold air down the Service Plug port, using the techniques I have outlined, helps cool the battery. I will post my results once I have completed the test.
 
Even if the plug did not create a water tight seal (it does) realize a bowl over the top of the plug would prevent water from getting in due to pressure, right? Any water would have to rise inside the bowl against that pressure which will be done if enough water is added but realize its not contained so water will just run out thru the bottom making any random spill HIGHLY unlikely to do much of anything.
 
I haven't found precise specs on the Nissan service disconnect, but did locate a similarly designed AMP connector which is only rated at IP5K2, suitable for "Dripping water when tilted up to 15°". The sealed version of the same plug, with integral gaskets, is IP6K9K and is probably fine to 100M as suggested.

http://www.te.com/content/dam/te-co...lity-solutions/global/8-1773465-86-sd-125.pdf

I look forward to hearing how the experiments go.
 
TexasLeaf said:
I am planning a structured test this weekend to see how much blowing cold air down the Service Plug port, using the techniques I have outlined, helps cool the battery. I will post my results once I have completed the test.

I just finished the test to see if conditioned air blown through the Service Plug port could reduce battery temperature. I travel two identical trips on separate days under identical conditions, the first trip with the Service Plug port bolted closed the second trip with the Service Plug port open. Both days the outdoor air temperature was 82 degrees F for the 1st charge and 87 degrees F for the 2nd charge and with each trip I started out with a fully charged battery.
For the first leg of each trip I traveled 90 miles and CHAdeMO charged until the charged rate tapered to L2 (6.6 kW). For the second leg I returned the 90 miles and CHAdeMO charged again to L2 levels. I limited my speed to 60 mph and I monitored battery temperatures and charge rates using LeafSpy.

For the first trip with the Service Plug port bolted shut, I left the cabin AC temperature set-point at 60 degrees F on the travel legs with the AC in Fresh Air mode. I let the exhaust escape through the grilles in the trunk to simulate pushing air through the Service Plug port in the second trip. I didn’t want the energy consumption of the AC compressor on the travel legs to skew the results but I also did not run the AC during charging sessions.
For the first trip I started out with a battery temperature of 96.2 degrees F. The battery temperature had reached 102.2 degrees F by the time I started the 1st charging session and 117.6 degrees F at the end of the 1st charging session. The battery temperature was at 117.9 degrees F at the start of the 2nd charging session and 126.6 degrees F at the end of the 2nd charging session.
During the 1st charging session the battery reach a peak battery temperature of 118.1 degrees F at 15 kW. During the 2nd charging session the battery reach a peak battery temperature of 127.1 degrees F at 15 kW. Because I was using EVgo chargers that only allow 30 minute charge sessions and required multiple restarts to complete the charge, the battery temperature of 127.1 degrees F and 15 kW were both constant for quite some time.
I started the trip at 5:11 am and I finished the trip at 11:29 am. For the 1st travel leg I consumed 21.1 kWh, for the 1st charge session I added 19.9 kWh, for the 2nd travel leg I consumed 21.1 kWh, for the 2nd charge session I added 21.9 kWh. The peak charge rate for the 1st charge session was 29 kW and the peak charge rate for the 2nd charge session was 20 kW.

For the second trip with the Service Plug port open, I left the cabin AC temperature set-point at 60 degrees F with the AC in Fresh Air mode the whole time. I used the AC fan to push air through the Service Plug port. I covered the wind shield with a sun screen and I opened the hood to release condenser heat during charge sessions.
For the Second trip I started out with a battery temperature of 98.8 degrees F. The battery temperature had reached 102.7 degrees F by the time I started the 1st charging session and 115.1 degrees F at the end of the 1st charging session. The battery temperature was at 114.8 degrees F at the start of the 2nd charging session and 122.0 degrees F at the end of the 2nd charging session.
During the 1st charging session the battery reach a peak battery temperature of 115.6 degrees F at 20 kW. During the 1st charging session the battery reach a peak battery temperature of 122.8 degrees F at 17 kW. Again because I was using EVgo chargers that only allow 30 minute charging and required multiple restarts to complete the charge, battery temperature of 122.8 degrees F and 17 kW were both constant for quite some time.
I started the trip at 5:17 am and I finished the trip at 11:36 am. For the 1st travel leg I consumed 20.0 kW kWh, for the 1st charge session I added 18.7 kWh, for the 2nd travel leg I consumed 22.3 kWh, for the 2nd charge session I added 22.6 kWh. The peak charge rate for the 1st charge session was 29 kW and the peak charge rate for the 2nd charge session was 22 kW.

Even though the charge rates were generally higher for the second trip the total trip time was about the same for both trips. The additional power consumption on the second trip can be accounted for by the AC compressors running during charging sessions. But after two identical trips the battery was almost 5 degrees F hotter on the trip that did not use the Service Plug port with AC in Fresh Air mode to cool the battery.
I think it is pretty conclusive that the AC can be used to help control battery temperature on the 2018 Leaf. This trip only covered two charging sessions but on very long trips with multiple charging sessions, keeping battery temperature down may be far more important than consuming a little extra energy. My test did uncover some other pretty important discoveries but I’m going to start a new thread to discuss those.
 
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