I was told it was forced air cooled by the VW uk marketing people at Goodwood (high ups at VW uk running the project, not minions)

Although the same guy refered to a battery capacity in terms of kilowatts so his knowledge can be taken with a pinch of salt

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Forced air cooling is inferior to liquid cooling surely

 

Direct ac like in the i3 is the best method but maintenance is a nightmare if the compressor fails and sends metal shards into the ac pipes within the battery. Relatively lightweight system too.

Watercooled is the next best, but cooling power will be reduced if you dont chill the coolant with an AC system. Also the weight of the coolant and pipework for the required cooling capacity can be considerable water is 1kg per litre.

Forced air cooling like in the imiev makes use of existing hardware (cabin AC system) to push dry, chilled air into the pack and only requires a few extra air ducts so can be very lightweight. Decent cooling power for the weight of the system.


Passive cooling is the lightest of all because there's no hardware, but the cells can get larger temperature fluctuations and cells in the middle of the pack can end up warmer than cells on the edge leading to capacity issues in the long term ( from lots of rapid charging)

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What matters is how well the battery performs, not how it is cooled.

LEAF 30 does just fine with passive cooling.
Early Tesla Model S can hit thermal limits even though the pack is liquid cooled.

 

What matters is how well the battery performs, not how it is cooled.

LEAF 30 does just fine with passive cooling.
Early Tesla Model S can hit thermal limits even though the pack is liquid cooled.

The Leaf 30 might be fine with passive cooling, the Leaf 40 has all sorts of problems. Generally the data shows that the better cooled batteries capacity loss is slower and high charging rates can be sustained for longer.

Liquid cooling seems to be the gold standard, A model S Tesla works its batteries far harder than a Leaf with higher power charging and powerful motors. The Model 3 battery pack cooling is more efficient than the S and the car can be pushed harder for longer.

I wouldn't take the risk of purchasing a car without a good battery TMS.

 

I think the concern is around longevity, not performance.

 

Battery chemistry, margin and BMS have a lot to do with longevity too.

When it comes down to what is "best" BMW are the clear winner. They have the best cooling system, large margins and the pack life is very good.

But is the i3 the best overall package? I don't think so. The i3 is too expensive for what it is. On top of that early ones are plagued with issues. On an i3 the pack will out live the car. A good design will have the pack last slightly longer than the car.

 

BMW and LG have patents on direct expansion cooling. That is probably one of the reasons why no one else is using it.

 

Interestingly the MG eZS uses a very similar system to the i3

 

Interestingly the MG eZS uses a very similar system to the i3

The captions imply MG use water/glycol cooling. The layout is similar but the i3 is direct expansion(DX) cooled.

As far as I know only BMW are using DX.

 

MEB packs will have liquid cooling (ID.R's air cooled battery is for racing purposes)

There is great arcticle on Jalopnik (title: The Fascinating Engineering Behind VW's Electric Car Platform of the Future) explaing a lot of the MEB tech. It even includes picture showing the location of coolant inlet/outlet.

Unfortunately the forum software automatically blocks my post if I include the actual link.

 

Unfortunately the forum software automatically blocks my post if I include the actual link.

This -->

The Fascinating Engineering Behind VW's Electric Car Platform of the Future

Volkswagen, the company that brought us Dieselgate, wants us to forget its last eco-disaster by promising to bring affordable electric cars to the masses starting in 2020. Those cars will ride on an all-new electric platform called MEB. The automaker calls it “one of the most important projects...

jalopnik.com