Curious 150 kW SuperCharger behavior

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bwilson4web

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Monday and Tuesday, I had occasion to use two, upgraded, 150 kW Superchargers:
sc150_010-jpg.34443

sc150_020-jpg.34444

What surprised me was the double charge curve. Both quickly reach 90 kW but then begin a gradual increase to ~135 to 144 kW peak charge rate. In the past, I've seen a smooth increase to the peak rate and then taper down. But this stepped, double curve has me scratching my head.

In both cases, the SuperChargers were the navigation destination. Yet when I arrived, the batteries were in the cooler, operating range. There was no evidence of pre-heating before arrival. This suggests this behavior is associated with the software in my particular car (2019 Std Rng Plus Model 3, 25,413 mi, 2020.20.12.

Bob Wilson

I'm using 'tesLAX' to capture the data but I'd notice the charging screen showed a similar pattern.
 

JasonF

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I'm not familiar with how Superchargers work internally...if I had to guess, maybe Tesla believed it was safer to ramp up slowly initially, but recent data showed it was better to get up to maximum more quickly. So they upgraded the Supercharger firmware accordingly.
 

Bigriver

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I haven’t supercharged my model 3 much, but I’ve probably got hundreds of SC sessions on my model X. The only thing I am sure of is that it doesn’t always do the same thing. There are times that I stop at the same supercharger on the way there and back, and I even develop my preferred stall on some of my common routes.... can start at the similar state of charge, similar temps, not sharing with a coupled SC, etc. and yet get quite different charging curves.
 

JWardell

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Were you parked next to anyone? Remember the v2 superchargers share charge banks withe stalls A&B, so the other car could have been using some and limiting you to 90kW, and then freed up another charge bank and your car was then allowed to ramp up to 145.
And sometimes those charge modules are just lazy (heated? indecisive?) and take a bit to switch in, or fully renegotiate. Superchargers are just a pile of old hacked Model S AC battery chargers anyway
 

bwilson4web

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Were you parked next to anyone? Remember the v2 superchargers share charge banks withe stalls A&B, so the other car could have been using some and limiting you to 90kW, and then freed up another charge bank and your car was then allowed to ramp up to 145.
And sometimes those charge modules are just lazy (heated? indecisive?) and take a bit to switch in, or fully renegotiate. Superchargers are just a pile of old hacked Model S AC battery chargers anyway
At Memphis, I was alone. At Athens, I was on the end unit, 4B, and a Model S was at the other end, 2A.

Reviewing my earlier benchmarks, I had been using minutes for the X-axis. It appears the initial jump to ~90 kW was evident followed by a smooth, fast rise to the peak at 60 seconds, 1 minute.

Here are my earlier benchmarks:
April 2019 (transcribed from video) :
batt_charge_020-jpg.34490


June 10, 2019
super_100-jpg.34491


December 16, 2019:
batt_chg-jpg.34492


March 8, 2020 at Nashville V3 Supercharger:
250kw_020-jpg.34493

So the initial jump to ~90 kW with an increase to peak rate by the end of the first minute is visible. Whether this comes from the SuperCharger or Model 3 remains a mystery. Perhaps others with 'ScanMyTesla' or 'tesLAX' might gather some high resolution data to look for the 90 kW jump and subsequent ramp up?

Bob Wilson
 

iChris93

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Perhaps others with 'ScanMyTesla' or 'tesLAX' might gather some high resolution data to look for the 90 kW jump and subsequent ramp up?
I have data logging setup now, so I can do this the next time I use a supercharger, that may be a while though. How often is the data logged?
 

bwilson4web

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I have data logging setup now, so I can do this the next time I use a supercharger, that may be a while though. How often is the data logged?
Both 'ScanMyTesla' and 'tesLAX' record the CANbus data at speed, ~1 msec per metric. ScanMyTesla logs just the requested data metric while tesLAX saves the group that comes in the CANbus packet.

When tesLAX requests a single 12 V metric, it records the 7-8 associated metrics in the .ASC file, typically ~1 MB per minute. After the capture, the built-in, CSV converter can aggregate the data at different time values up to one record per second, ~0.1 MB per minute. This makes a much easier file to load into a spreadsheet and analyze.

ScanMyTesla makes pretty large files that require more spreadsheet processing time.

Bob Wilson
 

JWardell

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So the initial jump to ~90 kW with an increase to peak rate by the end of the first minute is visible. Whether this comes from the SuperCharger or Model 3 remains a mystery. Perhaps others with 'ScanMyTesla' or 'tesLAX' might gather some high resolution data to look for the 90 kW jump and subsequent ramp up?

Bob Wilson
There are a number of limits that the car and the charging must operate in, determined by the BMS and the charger. You can monitor voltage and power limit values of each for example. If you have teslax you can search for those.
 

jsmay311

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In both cases, the SuperChargers were the navigation destination. Yet when I arrived, the batteries were in the cooler, operating range. There was no evidence of pre-heating before arrival. This suggests this behavior is associated with the software in my particular car (2019 Std Rng Plus Model 3, 25,413 mi, 2020.20.12.
A bit off-topic, but I’ve read elsewhere that RWD Model 3’s can’t effectively preheat their battery while en route to Superchargers when driving at highway speeds. (https://forums.tesla.com/forum/forums/battery-heating-explained)

Does that align (or conflict) with either your latest observations or previous observations of battery heating behavior? (Your comment seems to suggest that you’ve seen it preheat before, but that it failed to do so this time on the 2020.12 software version, and you think the software is to blame.(?) Although I’m not sure what your speeds were in this instance.)
 

bwilson4web

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A bit off-topic, but I’ve read elsewhere that RWD Model 3’s can’t effectively preheat their battery while en route to Superchargers when driving at highway speeds. (https://forums.tesla.com/forum/forums/battery-heating-explained)
Thanks, I don't remember reading that one.

Does that align (or conflict) with either your latest observations or previous observations of battery heating behavior? (Your comment seems to suggest that you’ve seen it preheat before, but that it failed to do so this time on the 2020.12 software version, and you think the software is to blame.(?) Although I’m not sure what your speeds were in this instance.)
I've been working with ScanMyTesla and now tesLAX. So I went back to review earlier data. I have seen 50 C for the Stator Temp while at a SuperCharger. Furthermore, I've seen the 3.5 kW rear heating BUT it went away while the battery temperature continued to warm up. But my ambient temperatures were in the ~70 F (~21 C) range whereas his study was closer to 0 C.

We've had improvements in tesLAX and the 10 bit to 11 bit shift. So I remain convinced I need to replicate my earlier tests and have a plan for that. I just need about 5-6 hours which I should find a window someday this week.

BTW, I had been using a video camera to record charging profiles in the past. One of my earliest videos show the jump to ~90 kW plateau followed by a rapid rise to the peak SuperCharger capacity. These were earlier firmware suggesting this a constant behavior of my Std Rng Plus Model 3 not tied to a specific firmware version.

Bob Wilson
 
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JWardell

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A bit off-topic, but I’ve read elsewhere that RWD Model 3’s can’t effectively preheat their battery while en route to Superchargers when driving at highway speeds. (https://forums.tesla.com/forum/forums/battery-heating-explained)

Does that align (or conflict) with either your latest observations or previous observations of battery heating behavior? (Your comment seems to suggest that you’ve seen it preheat before, but that it failed to do so this time on the 2020.12 software version, and you think the software is to blame.(?) Although I’m not sure what your speeds were in this instance.)
Well that depends on what your opinion is of "effectively." The Model 3 can definiently heat up the battery. If you're one minute away from the supercharger when you activate it, it's not going to heat much. Then again it doesn't need to heat nearly as much to achieve higher charging rates than the S.
You can watch the waste heat values of the motors in TesLax as you drive. Watch them jump up when you navigate to a supercharger.
 

jsmay311

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Well that depends on what your opinion is of "effectively." The Model 3 can definiently heat up the battery. If you're one minute away from the supercharger when you activate it, it's not going to heat much. Then again it doesn't need to heat nearly as much to achieve higher charging rates than the S.
You can watch the waste heat values of the motors in TesLax as you drive. Watch them jump up when you navigate to a supercharger.
I don’t have any tools to look at real-time stator or battery temps when driving en route to Superchargers, so that’s what I was wondering. But the guy who posted the thread that I referenced above *does* have those tools, and he observed that stator temps *dropped* when driving at speeds at highway speeds en route to a supercharger, suggesting that the motor may not be capable of self heating while driving at highway speeds like it can when stationary. That’s the main thing I’m trying to understand.

So I guess by saying “effectively” heating, I was just intending it to mean that the RWD motor was actively heating the battery while driving at highway speeds and not just passively heating it through normal waste heat.

(The few times I’ve driven long-distance in cool (not even sub-freezing) temps in my LR RWD M3 since Tesla enabled battery preconditioning when en route to Superchargers, I’ve been surprised that the charging speeds were still relatively slow despite plenty of time/distance to warm the battery before arriving at the SC. So I was wondering if this theory about the motor might explain that.)
 

JWardell

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I don’t have any tools to look at real-time stator or battery temps when driving en route to Superchargers, so that’s what I was wondering. But the guy who posted the thread that I referenced above *does* have those tools, and he observed that stator temps *dropped* when driving at speeds at highway speeds en route to a supercharger, suggesting that the motor may not be capable of self heating while driving at highway speeds like it can when stationary. That’s the main thing I’m trying to understand.

So I guess by saying “effectively” heating, I was just intending it to mean that the RWD motor was actively heating the battery while driving at highway speeds and not just passively heating it through normal waste heat.

(The few times I’ve driven long-distance in cool (not even sub-freezing) temps in my LR RWD M3 since Tesla enabled battery preconditioning when en route to Superchargers, I’ve been surprised that the charging speeds were still relatively slow despite plenty of time/distance to warm the battery before arriving at the SC. So I was wondering if this theory about the motor might explain that.)
It does, it can, I've seen it.
So one case proves all cases?
There are so many variables invovled. But there are target temperatures that immediately tell you wants to do, and those jump as soon as you activate it.
Yes, waste heat depends on a lot of things, and I'm sure there are situations where there are none, but it very much depends on driving and thermal demands. All I know is the motor suddely gets a lot less efficient when they want it to. Tesla does some brilliant things.