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request for battery temperature data

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Do any of you Tesla owners have TeslaFi (or equivalent) data acquisition in your car??

The reason I ask is I need battery data to calibrate our heat transfer model.

The particular question I have is the following:

What temperature does Tesla heat the battery to when they pre condition the battery before a fast charging session? Also what is the normal running temperature range for the battery. I would prefer the data came from one of the Model 3 or Model Y packs.

Thanks ,
George
 
The temps are sort of clumped around the 120° range, both when pre-conditioning and driving. I would say the low is 109° and the high that I see is around 122°. During charging I have seen it get to 136° before the fan goes into overtime trying to cool the pack. I have seen it charge successfully at full speed at 100°. Full speed is obviously controlled by more than just the batt temps, so I may be optimistic on that low temp. You can charge at an Urban SupCh speed when it's closer to ambient.
 
The temps are sort of clumped around the 120° range, both when pre-conditioning and driving. I would say the low is 109° and the high that I see is around 122°. During charging I have seen it get to 136° before the fan goes into overtime trying to cool the pack. I have seen it charge successfully at full speed at 100°. Full speed is obviously controlled by more than just the batt temps, so I may be optimistic on that low temp. You can charge at an Urban SupCh speed when it's closer to ambient.
Thx Randy. I passed it on to our heat transfer consultant. I'll get back w/ his response
 
The temps are sort of clumped around the 120° range, both when pre-conditioning and driving. I would say the low is 109° and the high that I see is around 122°. During charging I have seen it get to 136° before the fan goes into overtime trying to cool the pack. I have seen it charge successfully at full speed at 100°. Full speed is obviously controlled by more than just the batt temps, so I may be optimistic on that low temp. You can charge at an Urban SupCh speed when it's closer to ambient.

Keith Ritter is our consultant. He's a PE, BSME. I'm a BSME. We publish our work on insideevs web site. Here's a link to our articles.

Keith is the heat transfer expert and wrote the spreadsheet for the Thermo-electric model we are discussing here. We are not payed by insideevs they are just nice enough to give us a place to publish our work. We also developed a Performance model that I was more active in since I did performance modeling for gas turbine engines @ Honeywell. (Was AiResearch).

Anyway. Keith is becoming a member of TMC so he can post but also has a paid job that takes priority over our EV studies. So while he is getting his membership thing finished I will just quote what he said about your great data you provided.

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That's some great data. I think I've read Randy's posts on TMC before.

It likely is not just the condenser fan, but also the AC compressor and pack cooling system pumps that are working overtime to cool the pack when it is that hot.

"charge successfully at full speed at 100°". That would make sense, as the internal resistance/cell temp charts I've seen suggest that at about 35 C, the R is low enough to allow for high amperage charge/discharge. I'm not sure if "full speed", though, refers to the V3 max 250 kW "full speed" or V2 max 150 kW "full speed". I'd suspect Tesla would want the cells to further warm up to optimal temp before slamming them with 250 kW.


109-122 F translates to 43-50 C. 139 F is 58 C high for charging. I think we saw 114 F (45 C) max cell temp with Scott's Dashdaq data on his old S when he was SC charging a few years ago. I believe those cells were NCA. Aren't the US 3/Y cells NMC? I know that NMC can run hotter than NCA, but this just "feels" pretty darned high for a max cell temp. Most of the literature I've read on NMC chemistry suggests that long-term cell core temperatures above 40 C tends to degrade cell life and excursions to 55 C, though great for internal resistance reduction to allow max amp charging/discharging, takes a heavy toll on the cell's life.

That said, as far as attempting to reverse engineer why the M3/Y (and now the new MS) have their unique V2 and V3 charging curves, the pack thermal model I created isn't so much based on the absolute operating temperature, but the max allowable temperature difference both between cells and within the layers of a cell's jelly roll. And everything I've read suggests 4 deg C is the max cell variance before the thermal-related differential internal resistances between cells create unacceptable current/voltage imbalances in the cells. When I add in the pack's thermal mass heat storage capacity to absorb excess heat and allow high kW sustained charging with the AC maxed out, I've typically assumed an allowable max 12-13 C temp rise in the pack. If the cells start a typical SC charge session at about 45 C and can go up to 58 C before the BMS starts to throttle the charging amps, it looks like we're pretty close.

That data we got from Scott had real-time cell temp plots plus real-time AC compressor and pump status and glycol coolant inlet/outlet temps, as well as kW charge rates. This allowed us to correlate the charge rate, cell temp, and pack cooling system cooling capacity in real-time and really dial in our original Model S thermal model and identify that the older MS (pre-P100D) cooling snake design was a major thermal bottleneck limiting charging speeds and sustained high kW race track driving.


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