Cooling the Leaf Battery with Ice, This Actually Works?!?

[knightmb]

Yes, that will work. I did something similar a couple of years. I attached micro-fiber cloth to the upper case of the battery with magnets. I ran soaker hose across the top and pumped distilled water to it with a metering pump. I run it during hot weather and it works. I have been doing this for about 3 years. My biggest concern is rust and corrosion. I should probably drop the battery and check it about now. I pump when the car is running.

I think I've seen a picture of that here, awesome!
Given how quickly my ice test gets "dried" out while driving, my guess is the water doesn't stick around too long for your water cooling setup. My question would be, do Leaf owners in very humid, rainy places have rust issues? I haven't read about any in regards to the Leaf and the battery case itself. I think I read the case is made of high tensile strength stainless steel. It would probably take a lot to make it rust, but I'm not a metal expert in the case design, maybe someone else here knows.

 

[xboxice]

wow interesting i think on a 40kw leaf the effects might even be better.

 

[kmcmahan]

I was surprise at how rusty the top of a battery pack was that I received from a North East US state. I spent a day cleaning it up and repainting it. I think that we will see case tops rusting through in areas that use salt to melt road ice and snow.

 

[MikeinPA]

Nothing to worry about! Well, actually, aluminum, steel and water make a different kind of a battery. Kind of a battery on a battery.

 

[knightmb]

Did another "let it sit and then drive" test today. This time, I was able to get better measurements of the ice. So, I started with a 7 lb (3.2 kg) bag of ice at 0 F (-17.8 C). Took a quick LeafSpy battery temperature screen-shot. Shoved all the ice into the cavity, bolted it down.

Came back about an hour later, get another temperature reading. Can confirm cooling effect again, even with rising outside temperatures. Lots of water leaking out the back.

Then drove around for half an hour doing errands but after only 30 minutes, the ice was gone at that point. Temperatures starting to go back up.

So far, I have not determined the maximum amount of ice that can be shoved into the cavity yet, but I feel I am getting close.

The cooling effects work best when the Leaf is not moving, otherwise the ice only seems to work for about an hour before it is all melted and blown out the back with 7 lb (3.2 kg) of ice at least.

While the results of these experiments are interesting, I'm not sure how practical it is to try and use this.

1. First issue is that the cavity needs to be air tight, which means having to bolt the cover down after you fill it with ice. It's not difficult with the right tool, but then you'll need to carry a ratchet, extension arm, and 10 mm bit all the time.
   
2. Getting all the ice in takes a little hand work to shove it around to the edges to allow more ice to flow in.
3. Bags of ice cost money, but are fairly cheap and easy to get at least.
4. The cooling effect is basically gone in an hour of driving, but last much longer if the Leaf is just sitting still, even in hot weather it works longer this way.
5. The cooling effect takes time, so dumping in a bag of ice and then doing an immediate QC session might not be useful. Still waiting to test this...

Just some napkin math, but if you have a road trip ahead and you need to keep the battery cool, it's basically a 7 lb (3.2 kg) bag of ice per hour. So either you would need a big cooler with a bunch of bags to keep dumping in or some kind of device would have to be created so you can replace the metal bolted piece with something that is air sealed and faster and easier to open or close to dump in more ice like a door or twist cap. If the space above the cavity would be bridged, a lot more ice could be dumped in, probably double the amount to flow in as it melts. So my guess would be even with that extra space you'll be putting in more ice every 2 hours if the weather is really hot outside. The benefits would be though that arriving at a QC station with a battery that is in the low 80s F (26.7 C) or high 70s F (21.1 C) for temperature is a lot faster than arriving with a battery way above +100 F (37.8 C) to +110 F (43.3 C) doing a QC because it would be really slow.

 

[MikeinPA]

You could make a thermoelectric cooler for the top of the case. Use an air duct to carry the heat away. This will move 2500 btu per hour https://www.thermoelectric.com/air-conditioners/500-1000-watts/ahp-4250-series/

• Mass of case 800 - 1000 lbs for plus
• thermal capacity of lithium batteries , 0.5 btu/lb
• = 500 btu per degF change in Leaf battery.
• thermoelectric cooling, 2500 btu/hour
• 5 deg F cooling per hour
• energy use 800 watts

I'd still want to at least sample the humidity inside the case. Any cheap sensor would do.

edit: one could probably fit water cooled TEGs to the top of the battery enclosure by working through the disconnect access. The balance of the system could be CPU water coolers.

Removing 500 btu per hour while the car is parked at night would cool the battery by as much as 10 deg F.

 

[rsbrax]

I did a driving test today to see if the cooling benefits are too slow versus pack heating while driving. I was not expecting much but was surprised yet again.

I get a LeafSpy screenshot to record the starting temperature. I open up the safety disconnect switch cavity again and fill it with ice once again. Same temperature as before 0 F or (-17.7 C). I bolt the cover back down and immediately take off for my driving trip.

Are the LeafSpy Battery Temperature Sensors 1 2 3 4 still available to post?
Would like to see how the rear stack did. Per MUX and Dala, the rear stack would be a challenge to cool down compared to the rest of the cells.

 

[Chad E. Mo]

I looked at peltier (thermoelectric) cooling. It was unclear how much the battery temperature rise from powering the coolers would negate the cooling they provide. Challenging to set up a proxy test.

One thing for certain: there is precious little room above the 60/62 pack for anything other than airflow. The sides have a fair bit of room, but obviously little surface area compared to the top and bottom of the enclosure.

 

[MikeinPA]

I looked at peltier (thermoelectric) cooling. It was unclear how much the battery temperature rise from powering the coolers would negate the cooling they provide. Challenging to set up a proxy test.

One thing for certain: there is precious little room above the 60/62 pack for anything other than airflow. The sides have a fair bit of room, but obviously little surface area compared to the top and bottom of the enclosure.

I see this as externally powered during night time parking. That battery has a lot of thermal mass in the cells. Cool it slowly overnight, by morning the cells are cooler. Repeat as needed.

New idea. Rather than put the TEGs on the battery clamshell, run a coolant loop through a 12 volt TEG cooler and then through a cooling plate on the clamshell. You could spread it out in the underside of the clamshell to create uniform cooling.

edit: Actually, applying a coolant loop to the underside of the clamshell might work well and would be easy to implement. Then just cool the loop somehow at night, disconnect by day.
further edit: Easy to implement and easy to test by using the temp sensor that's plugged into the middle of the rear stack.

 

[BillAinCT]

How would a zig zag of 1/4" copper pipe across the top of the case recirculating through a container with ice in it do? Can the battery be dropped an inch to slide a good amount of coiled pipe on the top of the case? When rebolted up, it would be down 1/4". If this worked out, circulate through a closed system with active cooling on the container, or continue the loop to the AC cold side. If the coil could be preassembled to just slide it over the case top, then it's a viable DIY addition. Can the battery be dropped an inch without removing any wiring?

 

[MikeinPA]

It be lowered somewhat without disconnecting the three cables, but they are clipped up in tunnel. Can't remember how much slack there is.

The real issue is getting the shields off, because now you are under the car, it need to be lifted somewhat to get under. You could use 4 low ramps, get under and undo the shields, the build cribbing under the battery, then put in the guide pins for the battery, then unbolt the battery, then use a jack and jack stands to raise the car in place. This may seem like a slow approach, but I wont go under heavy things unless I am absolutely certain they are not moving.

But the more I think about it, lowering the battery and applying some hydronic cooling plates or just copper tube with some copper sheet bent over it, JBwelded in place, with some insulation, would allow even cooling similar to what the battery experiences when coming from a warm garage into a cold night. Worth doing a go fund me to pay someone to prototype it and run thermal testing in various scenarios.

 

[Bombastinator2]

ROFL. incontinent car.

 

[FrancoVecchi]

Just yesterday I took a trip from Rome to Modena with the LEaf e+, just under 500km, on a really hot day. the first fast charge brought the batteryto the first red mark on the dashboard, I had to drive carefully at no more than 120km/h to avoid heating the battery further. The second charge was really slow as the BMS limited the charging power to around 15-18kW.... Consequently I think that even lowering the temperature by a few degrees every hour is still useful on a long journey. I also noticed that the car in motion causes the battery to heat up less, and if you travel at low speed (< 80km/h) the battery tends to lose heat visibly, certainly more than when the vehicle is stationary.

 

[DougWantsALeaf]

Just yesterday I took a trip from Rome to Modena with the LEaf e+, just under 500km, on a really hot day. the first fast charge brought the batteryto the first red mark on the dashboard, I had to drive carefully at no more than 120km/h to avoid heating the battery further. The second charge was really slow as the BMS limited the charging power to around 15-18kW.... Consequently I think that even lowering the temperature by a few degrees every hour is still useful on a long journey. I also noticed that the car in motion causes the battery to heat up less, and if you travel at low speed (< 80km/h) the battery tends to lose heat visibly, certainly more than when the vehicle is stationary.

You needed more than 1 DC charge for 500km?

 

[FrancoVecchi]

You needed more than 1 DC charge for 500km?

yes, on the motorway I can do around 200km starting at 100% from home until the first recharge, (SOH 88% and speed about 120km/h ) and then the subsequent stages even less, because I cannot recharge to 100% but at most to 75-80% otherwise the recharge becomes very slow in summer with heat. The ambient temperature was over 35 degrees C°. In Italy, few service stations have charging stations, so I can't plan tapes with little residual battery, I always have to keep some battery margin for broken or unavailable charging stations... and traveling on state or regional roads takes a prohibitive amount of time.. .

 

[FrancoVecchi]

Yes, that will work. I did something similar a couple of years. I attached micro-fiber cloth to the upper case of the battery with magnets. I ran soaker hose across the top and pumped distilled water to it with a metering pump. I run it during hot weather and it works. I have been doing this for about 3 years. My biggest concern is rust and corrosion. I should probably drop the battery and check it about now. I pump when the car is running.

Very interesting! Did you have to remove the battery or did you manage to insert the microfibre mats with the battery installed? I would like a quick assembly system to be able to cool my battery pack a little, as this is a particularly hot summer in my country, and I also have to travel more than usual. Your system seems to me to be a good compromise between functionality and construction simplicity. It could be fed by distilled water for irons, which is quite economical and should be less chemically aggressive than tap water....

 

[Bombastinator2]

Very interesting! Did you have to remove the battery or did you manage to insert the microfibre mats with the battery installed? I would like a quick assembly system to be able to cool my battery pack a little, as this is a particularly hot summer in my country, and I also have to travel more than usual. Your system seems to me to be a good compromise between functionality and construction simplicity. It could be fed by distilled water for irons, which is quite economical and should be less chemically aggressive than tap water....

Pic looks not installed to me.

 

[kmcmahan]

Very interesting! Did you have to remove the battery or did you manage to insert the microfibre mats with the battery installed? I would like a quick assembly system to be able to cool my battery pack a little, as this is a particularly hot summer in my country, and I also have to travel more than usual. Your system seems to me to be a good compromise between functionality and construction simplicity. It could be fed by distilled water for irons, which is quite economical and should be less chemically aggressive than tap water....

I did it when I installed the battery. I think that will be the only way because of the small clearance the battery has to the car.

 

[Bombastinator2]

Nothing to worry about! Well, actually, aluminum, steel and water make a different kind of a battery. Kind of a battery on a battery.

That could theoretically be an issue if it’s done often enough. Galvanic corrosion is real. One assumes this will eventually dry though.

 

[Bombastinator2]

I was surprise at how rusty the top of a battery pack was that I received from a North East US state. I spent a day cleaning it up and repainting it. I think that we will see case tops rusting through in areas that use salt to melt road ice and snow.

There should be some sort of preventative on that. You’re saying there was none?! I smell possible future recalls and lawsuits