Air passes through motor compartment between the pack and body. To observe that, just open the
safety hatch at rear seat footwell. There is a cover. Observe airflow while driving. Or look at Leafs that are cut in half.
Just running AC fans is enough to have some air flow happening while stationary. Though if AC
is doing a lot of work (more than 1kW) the air cooling the battery might be slightly warmer than ambient when stationary.
There is no point to drive fast as battery metal case is not going to take in internal heat to the surface fast enough.
New 30kWh battery has cell pouches closer to each other - and have worse heat transfer rate into the air inside the pack.
Also, much faster charging rate allows more heat to accumulate in shorter period of time.
Battery pack cooling system makes vehicle considerable more expensive. At least 500 $€. And it doesn't solve degradation problem
that happens due to hot climate. Only one that happens due to heavy usage or DC charging. Which is not a majority of that problem.
It's the chemistry that likes lower temperatures. Leaf battery can handle cold temperatures (below +5C) way WAAAY better than Tesla's
chemistry, that can't handle ANY charge (without damage) at 0*C even when almost empty. Leaf can charge/regen at low temperatures.
Tesla can handle heat without accelerated degradation. +35*C is totally fine. Leaf on the other hand is cooking chemistry at that point.
Active cooling won't cool down pack when vehicle parked. At all. And if it is +30*C in the sun, pack will be at least 35*C after driving.
So no. Forget the idea that active cooling will prolong Leaf battery degradation in hot climate. It will only do that if it is NOT hot but
DC charging makes it hot. This is why e-NV200 has that. It is designed to be rapidly charged all the time (as a company vehicle).
If Tesla didn't have Supercharging capability (so like up to 50kW) and it wasn't powerful (like up to 150kW)
I'm pretty sure it wouldn't even have battery cooling loop, as there wouldn't be any point. It can handle 40*C easily. Actually, Tesla tries to
warm up battery to at least 30*C, sometimes to at least 40*C and even 50*C when ludicrous. It would just have heating elements like Leaf does. Tesla uses battery cooling only when supercharging or after extreme driving, like autobahn or many powerful acceleration events. It usually cools the drivetrain, not the battery.
Devil is in the details... or.. chemistry in our case.
Why 40kWh Leaf doesn't have active cooling? Because it can only charge at 50kW rate (exactly the same as 30kWh Leaf), it can only discharge at averaged 45kW rate (top speed limitation) and it's still not suitable for long distance driving. Aka battery will not heat up enough and passive cooling is absolutely fine. Why 60kWh Leaf will have battery cooling? Because it will charge at faster rate ( up to 100kW expected) and it is suitable for long distance* travelling.
*That means it can be used to drive far and charge fast enough for long distance travelling. 50kW charging, whatever the range, is not suitable for long distance travelling.
Why Volt has active cooling? Because it has an ICE (aka free heat). More battery range out of smallish pack.
Why BMW i3 has active cooling? Because it doesn't have acceptable air cooling (very crammed due to small vehicle).
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW