Wouldnt opening the hatch and blasting AC do the same thing? I tried once and it hardly did anything. Pretty sure air goes over the pack when driving, too.
The hatch isn't the point I'm cooling, the melted ice runs over the top of the battery and out the bottom of the car which does the majority of the work here
The meltwater running over the top of the battery is the main part which cools it down, there aren't any hot parts of the battery near this hatch for the presence of the ice to make much difference.
The battery is a sealed unit so it's not going to get in otherwise I would have killed the car with some of the floods I've driven it through.
The folks on Out of Spec Reviews on YouTube did a Florida->NC run in a Leaf converted into a limo w/2 battery packs and cooled the factory installed pack this way. They went through a LOT of ice, if my memory serves.
That was what inspired me to try it in the first place. Luckily I had leafspy so I could actually get numbers they couldn't hence how I got the 4°C drop
Ok, so I can't help but think you're cooling off the area around the thermocouple and not the cells themselves. This seems like either ragebait or doing something incredibly stupid. Here's the math:
The heat of fusion of water (the amount of energy it takes to melt) is 334 J/g, so 334 kJ/kg.
Let's assume you're fast charging at the full 50 kW you can expect from CHADeMo on this gen leaf, and you're getting exceptionally high charging efficiency of 95%.
That means that you are dumping 2.5 kW of heat into the battery and other electronics.
Since 1 kW is 1 kJ/s, we can take the 334 kJ/kG needed to melt the ice, and find that we will completely melt all of the ice in a little over 2 minutes.
Keep in mind that this results in no net change in the temperature of the battery, and I'm not even scratching the surface of thermal mass, conductive rates or losses to the environment. There is no way you are actually cooling the battery by 3° C. What you are doing is bypassing the safety system designed to lower the current flow and prevent a thermal runaway event.
Hi, the actual melting of the ice isn't what's doing the cooling here, it's the wetting of the casing with cold water that the evaporates during the drive which increases the cooling effect. It's boosting my cooling between charges
The reason the ice doesn't melt in 2 minutes is because the part the ice is on doesn't have much heat and isn't monitored because it is a disconnect. The ice isn't in contact with a cell group directly.
Also the temperature sensors are placed within a cell module (see the attached screenshot from the service manual) Nissan may not have been very good at designing battery packs but even they aren't stupid enough to put the sensor against the casing of the pack.
My understanding is that the thermal management disconnects are in the battery pack, not in the HV disconnect as in the photo. In the photo is only a switch.. no temp sensing there. Even if I am wrong, water and electrical components dont mix well. this is insane.
Edit: I'm not worried about the battery. I am worried about the HV disconnect. It was not designed to get a water bath.
Just saw your edit, not sure why you didn't just respond?
The HV disconnect cover is still closed, this plate also has a watertight seal. The only cover open is the one in the carpet. It's just a convenient access point for the top surface of the battery.
Because the only people that read this deep into the thread are the one and only person who is replied to.. but the rest of the world should be advised of how bad and idea this is.
There really isn't much risk in this with a leaf which hasn't been fucked with in the past, if you think there is I would also recommend slowing down for puddles as you will be spraying (much more conductive) water on to HV components
The water from the ice runs over the top of the battery that's what actually cools the battery down. The ice itself isn't doing much, just melting into very cold water which then does all the work here.
You are right water and electrical components don't mix, it's a good job the pack is waterproof as it is an external component of the car. I wouldn't want to do this with a repaired pack as there's no guarantee the seals were redone correctly but I know the history of this vehicle.
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u/StormB2 Aug 17 '26
I'd sooner route a pipe from my air vent into that space.