Long Distance Travel Battery Thermal Concerns

[Aerowhatt]

I guess pressing MAX is the key. That last trip to Butler pegged one of the sensors at 107 F (41.6 C) with the fan on high and airflow one click to dash vents.

No AC on in this scenario right, just ambient air?

I disagree with pressing MAX (starting to feel like a broken record). The battery ducting has a lot of flow resistance to it. Using MAX has a marginal effect on the actual volume of the flow to the pack. What it does more of (when running all the air to the pack) is create a lot of back pressure on the blower. Blower motor runs hotter (cooled by the airflow) and the blower uses more power per volume of air moved.

If you are cooling the pack only . . . then MAX doesn't make much sense while driving. If you are running significant air out the dash vents too (at least two clicks to the dash vents) then OK, MAX could make sense.

As far as cooling the pack with cold air from the AC while driving. Doesn't it make more sense to run less colder air into the pack than more, less cool air? If you run enough cool air into the pack you are also pushing cool air out of the back of the pack which isn't too thrifty. Better to run slower colder air in. The cells are at the bottom of the pack, the exhaust vent is at the top back. Bathe those cells in nice cold air (Cold air falls) and let it languish around them until warmed up (warm air rises) to be gently pushed out of the rear, top, pack vent.

Even with a quite a few 104F days this summer I never found MAX necessary except for the initial blow out of a very hot (parked in the sun) car.

As a rule of thumb properly using the AC for cooling the pack can keep the battery 9 to 12 deg F cooler (average temp) than using the systems as Mitsu intended for the same conditions.

Try it, "you just might find, that you get what you need"

Aerowhatt

 

[DonDakin]

Well i cant speak much about the flow of the ac to the battery but i do remember that when i had the fan on the highest position the battery temp was not really decreasing. In order to get the temp to decrease in those conditions i had to set it to max.

I was blowing one click into the cabin as it was really needed to keep me cool.

I was trying to get the ave temp below 30 deg c before the next qc i did always manage that but that was the goal.

I think it was a pretty extreme case in terms of all highway driving with a big elevation increase and a very hot day.

Don.....

 

[PV1]

I guess pressing MAX is the key. That last trip to Butler pegged one of the sensors at 107 F (41.6 C) with the fan on high and airflow one click to dash vents.

No AC on in this scenario right, just ambient air?

That was with A/C on and 85-90 F outside air for nearly the entire trip. I can get the front half of the pack cooled down, but that back doesn't really want to move. That trip was mostly highway with two quick charges to ~93%.

On Saturday, I was parked in a parking lot killing time, so I had the A/C on MAX with one click to the dash vents (75% battery, 25% cabin), and I was able to get the back half to start dropping a bit. The problem is that they only dropped to about 90-91 F and wouldn't go any lower. The front of the pack (higher half of the temperature modules) dropped to about 75 F. Saturday night, average pack temp was 99 F :shock: .

The car spent all day yesterday parked in the grass, and a heavy rain came through that finally dropped ambient temperature below 70 F (something that hasn't happened for at least two weeks). Right now, the battery's at 81 F average.

What we're likely going to find, similar to gaming computers, is that air-cooling can only do so much. I'd go for a liquid cooled pack IF I had some control over the pack temperature.

 

[ChrisEV]

I did about 250km in the imiev today, driving down from Toronto to Niagara Falls and back.

I did about 5 DCQC sessions today. 3 full charges to 80% and 2 5 minute charges as I needed a bit of a boost.

Forgot to run Canion most of the trip but by the end of the day Canion reported an average temperature of 42C. Cells ranged from 37C to 45C.

Ambient temperature was 28C today.

Probably not the best day for battery health

Interestingly the car was still charging at around 35kW. The 2018 Leaf with no cooling would have been at half that from what I'm reading.

So I guess the main goal of blasting the A/C on the pack during charging is to prevent the need to limit charging speed.