Battery Cooling fan Service/Cleaning

[invader166]

Good day all,

Does anyone have information with regards to how regularly you should service/clean the HV/traction battery cooling fan in the lower trunk area of the car?

I'm nearing the 2 years of ownership mark, and have yet to find any mention of such maintenance. Either online or in the manual. I have instead read about other vehicles with high voltage hybrid battery systems that had battery cooling fans full of dust and debris, and eventually suffered a complete battery failure due to overheated cells. All because the cooling fan had lost its efficiency could not supply enough air.

I did not any see any filter in the fan intake the last time I checked, so I would imagine you would need to take apart the unit to reach the fan and clean it properly.

Any DIY guides on how to do this?

 

[JejuSoul]

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The only other thread I can remember about taking apart the battery cooling fan was for flood damage.

Problem with battery cooling fan

Here's a schematic from the service manual.





Please let us know how it goes.

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[notfred]

With the intakes at the front under the seats then I'm not sure how much dust and debris will have made its way through the battery pack to the fan. If the fan is dirty then that would mean that the battery pack is dirty.

I wonder if other cars are setup the other way around with the fan blowing air in to the battery pack rather than sucking air out? Then it would make sense to clean the fan and any filters on it.

 

[JejuSoul]

With the intakes at the front under the seats then I'm not sure how much dust and debris will have made its way through the battery pack to the fan...

Correct. Here's two pictures of my 2015 getting a new battery pack.

This shows the original battery cells. Look how dusty the higher front group of cells and metal rails is. This is directly under the air vent opening. There is much less dust at the back.




In comparison here are the new cells being unpacked from a wooden crate.



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[invader166]

Well, had a look at the fan...really nothing to report. All practically brand new.
I guess it is true. The battery pack is kept under vacuum by the fan, not pressure as I was expecting to find.

 

[IanL]

So the battery acts as a filter to protect the fan

 

[Locuturus]

@JejuSoul do you think it would be possible to direct cool air from the HVAC into the little air inlets underneath the driver and front passenger seats to provide cool air into the battery?

I managed to get my remanufactured battery with the upgraded harness to pretty toasty max 50C (while charging) min 18C while driving and DCFC about 160km, got it pretty darn hairy - 1%, low battery notification, turtle mode, --- range on GOM, the works. pretty scary the first time ever. Would be nice to DCFC, turn on the HVAC while I do it, open the trunk, take out the insert, and blast cold AC into the vents below, for the fan to vent out the back.

 

[JejuSoul]

There's an old thread about battery fan cooling here :- TMS Behavior
When the battery reaches 50C the BMS will begin to reduce power. From 90kW to 63kW.
The battery fan will be running at level 8.!
No one has posted data beyond this.

Status Feedback [Hz] Temp[C]
Level 0 0 < 31
Level 1 42 31C - 33C
Level 2 50 33C - 36C
Level 3 58 36C - 39C
Level 4 67 39C - 41C
Level 5 75 41C - 43C
Level 6 85 43C - 45C
Level 7 88 45C - 49C
Level 8 95 50C - ???
Level 9 100 ?

I do run the AC if I'm charging on a hot day. But I assume the effect on cooling the battery is marginal.
My testing is in the thread linked above and the results were inconclusive.
Make sure the HVAC is on fresh not recirculate, because all the hot air from the battery is being blown into the back of the car.

 

[Locuturus]

There's an old thread about battery fan cooling here :- TMS Behavior
When the battery reaches 50C the BMS will begin to reduce power. From 90kW to 63kW.
The battery fan will be running at level 8.!
No one has posted data beyond this.

Status Feedback [Hz] Temp[C]
Level 0 0 < 31
Level 1 42 31C - 33C
Level 2 50 33C - 36C
Level 3 58 36C - 39C
Level 4 67 39C - 41C
Level 5 75 41C - 43C
Level 6 85 43C - 45C
Level 7 88 45C - 49C
Level 8 95 50C - ???
Level 9 100 ?

I do run the AC if I'm charging on a hot day. But I assume the effect on cooling the battery is marginal.
My testing is in the thread linked above and the results were inconclusive.
Make sure the HVAC is on fresh not recirculate, because all the hot air from the battery is being blown into the back of the car.

Yup, I noticed that the fan status was 8 at the time. Though for some reason it stopped DC charging at 64% (speed didn’t drop yet), and the check EV system light came on. I forgot to check the code, but I imagine it had something to do with the OBC (it’s been popping up randomly, and already have a warranty replacement on the way)

If anything might be better to find a way to directly vent the hot air outside the car instead of circulating in the cabin trapped beneath the trunk storage….

 

[JejuSoul]

I don't think it is trapped beneath the trunk storage. Aren't there two vents one on each side that allow that hot air into the back.

 

[Locuturus]

I don't think it is trapped beneath the trunk storage. Aren't there two vents one on each side that allow that hot air into the back.

Hmm I will check for the vents, you're probably right anyhow. I guess the idea is to use the HVAC to exchange that hot air for cool air using the cabin... will have to try charging with the HVAC fully on (it'll impact the charging speed, but at this point I think I prefer cooler battery than faster charging speed)

If it works, then theoretically it may be possible to design some air channels to route cool air into the seat intakes to improve cooling;

 

[JejuSoul]

TeslaBjorn has a video showing his attempt to cool the battery by manually setting the AC to max while the car is changing. He fails. Even though the battery inlet cools down to 14C the battery remains at 48C.

The video : -


His AC settings :-



He opens up the back to allow hot air to escape without noticing the vents on the side.
If you leave the cargo area panels in place, the battery fan will dump the heat out through the vents. ( Although this will only work when the outside temperature is less than the heated air flowing out of the battery. The vents won't work on a very hot day.)
By removing the cargo panels, it will dump the heat into the interior.



The two air inlets are under the front seats.
Here's how it looks when the battery is removed.

 

[Locuturus]

@JejuSoul I wonder if this is possible:

would it work if we did heat pipes like in laptops/desktop PCs - a series of cold plates, no liquid (aluminum with a thermal pad in between), soldered to closed heat pipes (which would be running to the blower fan at the back, with a set of cooling fins to disperse the heat faster in the trunk space, and opening a second vent above the trunk space in the cabin so the warm air directly disperses into the cabin rather than slowly dissipating through the car body. That way, we prioritize wicking away the heat as fast as possible from the batteries, to dump it into the cabin so the heat pump can do what it does best. Will need to figure out how to mount it so it doesn't rattle or slide around too.

Theoretically, in the winter the heat pump won't need to work so hard, and actually will be in better condition since the heat dumped into the cabin will be free heat, and in the summer while the cabin will be marginally warmer than normal, the heat pump will do what it needs to normally.

It's quite invasive as a process, but so long as I can find an EV repair shop that will help me with it (i.e. raising/lowering the battery); it should be a relatively good way to have not-quite-liquid-cooling for the car that's better than air cooling...

 

[JejuSoul]

New TeslaBjorn videos : The answer to the first question "Will this work?" was no. But it was certainly an interesting experiment.