external cooling system

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johnrhansen

Well-known member
Joined
Aug 12, 2013
Messages
1,100
Location
Seattle, WA
I understand how a thermal management system adds to costs, and decreases range and it seems that these disadvantages have caused Leafs to not come with this system at the detriment of the very expensive battery. More pronounced in the very hot climates.

I propose that you incorporate liquid cooling lines throughout the battery pack connected to a 2 stage coaxial quick disconnect somewhere on the car where an external stationary cooling chiller pack can connect. All cars sit far more than they move, and having this system available when the car is idle could drop the average temperature of the battery, prolonging it's life. It will also remove the heat produced in quick charging so that more quick charges can be done in a trip. Right now with too many, the battery over temps.

Make that coolant connector so that when pulled out halfway, it opens one side to the atmosphere, while the chiller sucks all of its fluid out of the other line, then allows the connector to be taken off without fluid dripping everywhere, and not leaving any coolant in the cars lines to leak or require any maintenence. This way only those who need battery cooling have to pay for it, and nobody needs to have to carry the extra weight around or draw the power from the battery for the cooling system.
 
That would be more expensive and complex instead of just circulating the pack through the existing cooling system in the car. There is no point as the majority of the cost is the part in the pack. There is no value to this system only potential issues and more external cost. As soon as you do the point to where your connector is the cost to finish it internally is almost moot.
 
I think this is a great idea; especially the part about putting the active elements of the cooling system in the DC fast-charging stations, which are, as far as my PNW-dwelling self can see, the only places it's needed anyway. And who'd notice a measely extra couple thousand bucks in the cost of a DCQC installation?

I'd suggest an open, one-pass refrigeration system, with compressed air as the coolant. As johnrhansen says, add a 1/4" nylon hose to the existing DCQC hawser, port it through into the battery pack, and let it just spray onto the cells inside. Pressure vents spill the expanded air back out to the environment, while sealing against ingress of water at reasonable submersion depths. This would add next to no extra weight to the car (a bit of nylon tubing; I presume the pack already has to be watertight), avoid concerns about fluid leaks (except for a tiny bit of condensation that the hot cells would bake right back out again). So maybe there'd be a bit of hissing while you were charging; I'd be OK with that, especially if the cooling effect didn't come on for packs below 7 bars, say...
 
I'd be worried about introducing anything to the sealed battery compartment. Oil from the compressor or worse, moisture could be introduced. It would work if you mounted the cells to a heat sink and sprayed air on the backside of it.

Not really sure how one could come up with the idea that fluid circulation lines would cost all that much. Its a low pressure system. Surely, the pumps and a large enough heat exchanger to reject the heat would not cost less if it were integrated into the car. Not to mention all the control systems. They run miles of the stuff in hydronic heating systems in homes.
 
A mineral bath could work well. High thermal capacity, and non-conductive. Non-toxic as well, so in a collision, a leak would be environmentally safe compared to typical ICE coolants.

The mineral coolant could be pumped though a coil in the heat pump, or even a dedicated one added.

The only problem I could think of is the viscosity. It tends to be a little thick, but it shouldn't be a significant issue.
 
If you want minimal modification, just add a fan system, with duct adapter boot(s), to blow cold air into the pack air-cooling channels already present. This would be less effective than liquid cooling, but simple and cheap enough for Leaf owners to actually buy or lease. Hot weather is the time us non-QC-users would need it, as the pack doesn't cool enough, fast enough, to charge without heating it more than is wise.
 
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