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Coolant Pump in cold weather runs for 2 hours after parking??

Coolant Pump in cold weather runs for 2 hours after parking??

Our coolant pumps continue to run for at least 2 hours after parking the car. I imagine that this has something to do with cooling the battery and power unit between drives but during the winter, when we're doing all we can to keep the battery warm, the car is still trying to cool itself.

I did a little testing this morning using the ScanMyTesla app and found that the battery cools over three times faster when the pump is running then it does after it enters the "sleep" mode. Considering that the batteries need to be kept warm to get normal capacity and regenerative braking this seems like it would make sense for the pump to only continue running when it's warm outside.

Tom11-18 | 2020年3月8日

I find this interesting, but it does bring up more questions. Can you find out how much the pump draws, and is the pack temp falling fast or slowly? My thinking is it's important to keep all of the cells at or near the same temp. If the coolant isn't going thru a heat exchanger it isn't trying to cool the battery, just maintain consistent temp.

Concestor0 | 2020年3月8日

The Battery Current showed 0.5-0.7 Amps with the pump running. When I did the test the outside temp was -5°C (23F) and with the car "sleeping" the battery cooled at 0.4°C per hour. With the pump running the battery cooled at 1.5°C per hour - almost 4 times faster. I also tried this with sentry mode on and because the car doesn't sleep the pump continues to run.

"If the coolant isn't going thru a heat exchanger it isn't trying to cool the battery, just maintain consistent temp."

There are a couple of valve positions that the ScanMyTesla app monitors - the Five Way Valve and the Radiator Bypass valve. The Five Way valve goes from the 135° position to the 95° position (I don't know enough about this valve which is probably on the SuperBottle to know if this is significant). The Radiator Bypass valve is fully closed (100% position) when driving in the cold but is remaining fully open (0.00% position) when parked with the coolant pump running.

The flat plate layout of the battery allows the battery to cool very efficiently and quickly compared to a box shape, so I'm not sure how much Tesla needs to be concerned about even cooling.

Concestor0 | 2020年3月8日

I forgot to mention that I have insulation installed on the bottom of my battery and on the heat/cooling hoses so it's probable that the batteries on most cars would cool down more quickly than mine does.

jordanrichard | 2020年3月8日

Just how did you put insulation on the bottom of the car?

In over 6 years of being here on the forums, this is the first I have ever of anyone adding insulation.

jordanrichard | 2020年3月8日

Meant, ever heard of anyone....

Concestor0 | 2020年3月8日

jordanrichard | March 8, 2020 "Just how did you put insulation on the bottom of the car? In over 6 years of being here on the forums, this is the first I have ever of anyone adding insulation."

I have a thread going over at Tesla Owners Online detailing what I am up to. I've had the techs at the Toronto Mississauga Service Center look it over and they were very helpful. The first question I asked was if there was any way that the insulation could cause the battery to over heat and they assured me that the cars thermal management would not allow that to happen. So my battery stays a little warmer than most peoples over the winter. I also designed seasonal insulation for the sunroof which is working very well.

https://teslaownersonline.com/threads/insulated-battery.10854/page-10

Tom11-18 | 2020年3月8日

"The Radiator Bypass valve is fully closed (100% position) when driving in the cold but is remaining fully open (0.00% position) when parked with the coolant pump running."
So this seems to validate what I was saying, when you drive the car it is cooling the battery and motor due to high power output, but once you stop it bypasses the hx and tries to keep all cells cooling at the same rate. Any cells at the edge of the pack would cool much faster than the ones in the middle, which would cause problems with unbalanced wattage due to different cell temp.

Tom11-18 | 2020年3月8日

Before you ask, yes I don't believe that the car is driving around (for any length of time) without some cooling. I would not be surprised that you or your app has the valve position backwards.

Tom11-18 | 2020年3月8日

I just visited your link, didn't realize how much time you have into this.
BTW I would not suggest driving with this setup in the summer, especially anywhere south of Canada. No matter what the techs told.you, they aren't the design engineers and they.are only going by the "seat of their pants". The engineers make assumptions, such as - the heat loss will always be at least x, due to the surface area of the pack, and the temp difference with the ambient air. Your insulation negates all of their assumptions and you risk overheating your ~10000 $ battery. Best of luck.

Concestor0 | 2020年3月8日

" Tom11-18 | March 8, 2020
Before you ask, yes I don't believe that the car is driving around (for any length of time) without some cooling. I would not be surprised that you or your app has the valve position backwards."

It doesn't sound like you know how the heating/cooling system works. Here is a link explaining the system. https://www.gizmodo.com.au/2018/12/the-tesla-model-3-superbottle-easter-...

Tom11-18 | 2020年3月9日

Thanks, yes I don't know how it works, and reading schematics or watching videos about it is way too close to what I do at work to be fun. Interesting that you ignored my comment that the pump running after use was to prevent the cells from cooling at different rates thus protecting the pack from having a string pulling more or less current than others. Not sure what your point here is, if you aren't looking for ideas to persue.

Concestor0 | 2020年3月10日

The Gizmodo Superbottle article really does explain it well doesn't it, another good resource I found was this https://www.youtube.com/watch?v=vgfXyLLaO7I

" Interesting that you ignored my comment that the pump running after use was to prevent the cells from cooling at different rates thus protecting the pack from having a string pulling more or less current than others. Not sure what your point here is, if you aren't looking for ideas to pursue"

You might be correct but as I mentioned earlier, the flat plate design allows for more even shedding of heat (as opposed to a box shape where the heat would be more centralized).

The ScanMyTesla app shows 6 different temperature measurements related to the battery and drive unit, the ones for the battery seem to remain within a degree or two of each other.

Do you live in an area that gets cold yourself?