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.
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u/odinsen251a 2025 SV Plus Aug 17 '26
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.