how is cooling air ducted around the leafs battery; ideas for augmented cooling

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There are openings in the splash shield to allow air flow to the underside of the sealed battery case. There is also air flow over the top of the sealed battery case from under the hood through the "tunnel" under the console. This air flow above and below the sealed battery case is somewhat effective because I have noted battery temperatures drop a few degrees while driving on the highway after charging or being parked. I have also noted battery temperatures increase a few degrees when the car is parked after being driven on the highway.

Gerry
 
Here is an interesting thread that can be read. It was a while ago, but still applies.

http://mynissanleaf.com/viewtopic.php?f=9&t=13106&start=10
 
TomT said:
The battery has significant thermal mass so I don't think any practical external cooling would be effective...

Brenthasty said:
Any ideas for augmented cooling?


I live in Las Vegas and this is my first summer with the LEAF. I have read extensively on here about the heat problems with the battery on the leaf and I have come up with something that is pretty effective so far.

I have modified a small A/C unit to do what I needed and can cool the battery down approximately 2 degrees Fahrenheit per hour using about 500 watts of electricity from my house. So basically as it's parked I cool it down and when I'm ready to drive it the battery has cooled from approximately 95 degrees to 75 degrees in 10 hours. So 5 kw of electricity and I only pay about $.05 KWH so about $0.25 a day to cool it.

Worth it to me so far for the three hottest months here to extend the life. It was a new battery when I bought the car and I'd like to help it survive. Something interesting to note that I have found is about the thermal mass time to heat/cool. The cooling air flow around the battery at freeway speeds is actually very effective with enough temperature differential. With a 30 degree cooler air differential and the air flow I can use to maintain this the battery will cool, like I said, about 2 degrees per hour. However the same 30 degree hotter differential when I drive to work will heat the battery 20 degrees an hour. Significantly faster with the increased volume of air. Of course there is some pack heating from discharging the battery but is seems to be minor in comparison to the heating that takes place on my commute.

I am looking to find a way to actually stop the "cooling" air flow that goes across the battery when driving as this is actually heating the battery under my conditions when leaving with a cool battery. Anyways just wanted to comment, I will be posting more info about what I am doing as I develop it. I just wanted to test the concept so far and what I have built is quite ugly but was less that $200. I want to refine it, do some more experimentation with air flow etc. and see if I can improve the efficiency.
 
Vincam said:
TomT said:
The battery has significant thermal mass so I don't think any practical external cooling would be effective...

Brenthasty said:
Any ideas for augmented cooling?


I live in Las Vegas and this is my first summer with the LEAF. I have read extensively on here about the heat problems with the battery on the leaf and I have come up with something that is pretty effective so far. I have modified a small A/C unit to do what I needed and can cool the battery down approximately 2 degrees Fahrenheit per hour using about 500 watts of electricity from my house. So basically as it's parked I cool it down and when I'm ready to drive it the battery has cooled from approximately 95 degrees to 75 degrees in 10 hours. So 5 kw of electricity and I only pay about $.05 KWH so about $0.25 a day to cool it. Worth it to me so far for the three hottest months here to extend the life. It was a new battery when I bought the car and I'd like to help it survive. Something interesting to note that I have found is about the thermal mass time to heat/cool. The cooling air flow around the battery at freeway speeds is actually very effective with enough temperature differential. With a 30 degree cooler air differential and the air flow I can use to maintain this the battery will cool, like I said, about 2 degrees per hour. However the same 30 degree hotter differential when I drive to work will heat the battery 20 degrees an hour. Significantly faster with the increased volume of air. Of course there is some pack heating from discharging the battery but is seems to be minor in comparison to the heating that takes place on my commute. I am looking to find a way to actually stop the "cooling" air flow that goes across the battery when driving as this is actually heating the battery under my conditions when leaving with a cool battery. Anyways just wanted to comment, I will be posting more info about what I am doing as I develop it. I just wanted to test the concept so far and what I have built is quite ugly but was less that $200. I want to refine it, do some more experimentation with air flow etc. and see if I can improve the efficiency.

Please share what you have done! Even the proof-of-concept would be neat to see.

I don't envy you guys in hot climates. But I applaud your ingenuity in solving a problem that Nissan chose to ignore.
 
to reduce the hot airflow warming your battery on hot days, make some simple foam plugs that can partially block the grille. leave yourself about a 1' gap in the middle for the airflow to the cabin AC
 
GerryAZ said:
There are openings in the splash shield to allow air flow to the underside of the sealed battery case. There is also air flow over the top of the sealed battery case from under the hood through the "tunnel" under the console. This air flow above and below the sealed battery case is somewhat effective because I have noted battery temperatures drop a few degrees while driving on the highway after charging or being parked. I have also noted battery temperatures increase a few degrees when the car is parked after being driven on the highway.

Gerry
it does seem the battery is in a wind tunnel formed by the bottom of the car, and the bellypan, that is aspirated through the grille.

I have now done a complete down to the last bolt teardown of a leaf, and have observed this duct in detail, the battery has an inch or two of space around it for the air to flow. Incidentally after this teardown i discovered the very first piece it appears they attach to the car is the firewall sound dampening insulation...

they took the trouble to seal the engine compartment and wheel wells so the grille could scoop up air to flow through the radiators, over the motor, around the battery and out the tail.

what the leaf and other ev's appear to need most is active shutters.

I have a simple foam plug I take in and out of the grille as needed to cool OR conserve heat depending on the season.

Incidentally this foam plug when installed gives me about an extra .5 miles per kwh and aerodynamically helps significantly at 70+ mph freeway speeds. At 80 mph im still about 3.5 m/kwh (with my other aeromods)!
 
Brenthasty said:
to reduce the hot airflow warming your battery on hot days, make some simple foam plugs that can partially block the grille. leave yourself about a 1' gap in the middle for the airflow to the cabin AC
Could you post a photo of this on a Leaf? I'm trying to visualise what it might look like but unless the foam is painted the same color as the car I'd have to think it might stick out like a sore thumb. Are you using white flexible closed cell foam? I can't imagine one would want open cell foam or even the white or pink rigid foam, but I don't know.
Note my state licence plate covers the top half of about the center 1' of the opening I believe your talking about, would it still be sufficient to just leave that foot open or might I need more because of the licence plate?
Lastly, I plan on using this more to keep out the 0F air when it gets cold(like people do with cardboard on a ICE vehicle) but are you saying it's OK to leave this on in the hot? I'd think doing so may block the needed air for the air conditioner......do you simply not use the A/C when it gets hot?

One more question, if this air duct is for both cooling the battery and cooling the A/C condenser, I'd have to believe running the A/C in the summer would greatly heat the air that later cools the battery, I know holding your hand behind a radiator/condenser coil on a ICE car results in very hot air. Now maybe most of this is from the radiator but I'd have to believe some is also from the A/C condenser.....talk about a poor design, cool the cabin and warm the battery even more than it might normally be :?
 
Most of the heat under the hood in an ICE vehicle comes from waste engine and exhaust heat. I can hold my hand on anything under the hood of the LEAF after running the A/C in traffic in Phoenix on a summer afternoon.

Gerry
 
jjeff said:
Lastly, I plan on using this more to keep out the 0F air when it gets cold(like people do with cardboard on a ICE vehicle) but are you saying it's OK to leave this on in the hot? I'd think doing so may block the needed air for the air conditioner......do you simply not use the A/C when it gets hot?

One more question, if this air duct is for both cooling the battery and cooling the A/C condenser, I'd have to believe running the A/C in the summer would greatly heat the air that later cools the battery, I know holding your hand behind a radiator/condenser coil on a ICE car results in very hot air. Now maybe most of this is from the radiator but I'd have to believe some is also from the A/C condenser.....talk about a poor design, cool the cabin and warm the battery even more than it might normally be :?

This is something I'm trying to understand too. So in the summer the heat pump is in AC mode and heats the air before reaching the battery. Then during the winter, the heat pump cools the air before reaching the battery.

So some people recommend blocking off the grill. Either they don't use their AC or Heat, or I just don't get it. It would seem to me to be better to somehow block the airflow between the motor compartment and the battery somehow. Or maybe even after the battery, if that would be easier, since that would also slow down or stop air flow around the battery.

I like the A/C system on the battery. I'm trying to think of ways to both heat the battery during the winter and heat it during the summer. In a dry climate, maybe water mist would work. :?:
 
I've been using a grille block for three Winters, now. I think it's less effective with 2013+ cars because of the lack of liquid cooling/heating, but it also doesn't seem to hurt anything. I whipped it up from a piece of scrap cardboard and a black plastic garbage bag. ;-)
 
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