Cold battery Supercharging

jsmay311

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#1
The "Tesla Model 3 Road Trip" guys documenting their cross-country drive on Facebook posted tonight about their experience trying to Supercharge after leaving their Model 3 unplugged in (relatively mild) 20F temps.

(Link to post is "facebook dot com/tsla3/videos/857552894416181/". I can't figure out how to include a plain link without it getting converted to an embedded media.)

They got zero charging for (at least) the first 11 mins after plugging in. After 45 mins it was only up to 34kW.

+14 min: 4kW
+15 min: 5kW
+20 min: 9kW
+25 min: 14kW
+45 min: 34kW


I'd read some horror stories about Model S's failing to charge *at all* for over an hour after plugging into a Supercharger with a cold battery. I had hoped the Model 3 would have improved performance in this respect with some kind of elegant solution, but it appears maybe not.

Some questions I have include:
  • Any idea if the Model 3's lack of a dedicated battery heater hurts it's ability to quickly warm the battery? (Is there any way to measure the max kW draw for battery heating?)
  • When charging a cold battery on L2, is the charging rate similarly limited as when plugged into a SC station? (What I've read re: the S/X suggests it's not, but that makes zero sense to me.)
  • Is there any good reason why Tesla doesn't update their Supercharging display screen (for all models) to better communicate to the driver just what the hell is going on when the charging rate stays stuck at "0kW" for an extended period of time after plugging into a Supercharger?
    • A little explanation to the driver could go a long way in helping understand the root of the charging rate limitations and soothe any associated frustrations.
    • Maybe showing how many kW are being drawn from the SC specifically for heat would be helpful so the driver can see that something is happening.
Any other thoughts on this?
 
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#2
  • Any idea if the Model 3's lack of a dedicated battery heater hurts it's ability to quickly warm the battery? (Is there any way to measure the max kW draw for battery heating?)
Model 3 has paid supercharging with a readout in the bottom right of the video. Plug in, start a stop watch, when the charge kW goes above 0, unplug and stop the timer. Some math will then give you the average draw from the supercharger (unless energy not going into the battery is free).

  • When charging a cold battery on L2, is the charging rate similarly limited as when plugged into a SC station? (What I've read re: the S/X suggests it's not, but that makes zero sense to me.)
If cell chemistry (charge acceptance) is the reason, I'd expect it to be the same.

  • Is there any good reason why Tesla doesn't update their Supercharging display screen (for all models) to better communicate to the driver just what the hell is going on when the charging rate stays stuck at "0kW" for an extended period of time after plugging into a Supercharger?
    • A little explanation to the driver could go a long way in helping understand the root of the charging rate limitations and soothe any associated frustrations.
    • Maybe showing how many kW are being drawn from the SC specifically for heat would be helpful so the driver can see that something is happening.
Room for improvement here I'm sure. I'll try it myself and send feedback.
 

mbrucem

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#3
The "Tesla Model 3 Road Trip" guys documenting their cross-country drive on Facebook posted tonight about their experience trying to Supercharge after leaving their Model 3 unplugged in (relatively mild) 20F temps.

(Link to post is "facebook dot com/tsla3/videos/857552894416181/". I can't figure out how to include a plain link without it getting converted to an embedded media.)

They got zero charging for (at least) the first 11 mins after plugging in. After 45 mins it was only up to 34kW.

+14 min: 4kW
+15 min: 5kW
+20 min: 9kW
+25 min: 14kW
+45 min: 34kW


I'd read some horror stories about Model S's failing to charge *at all* for over an hour after plugging into a Supercharger with a cold battery. I had hoped the Model 3 would have improved performance in this respect with some kind of elegant solution, but it appears maybe not.

Some questions I have include:
  • Any idea if the Model 3's lack of a dedicated battery heater hurts it's ability to quickly warm the battery? (Is there any way to measure the max kW draw for battery heating?)
  • When charging a cold battery on L2, is the charging rate similarly limited as when plugged into a SC station? (What I've read re: the S/X suggests it's not, but that makes zero sense to me.)
  • Is there any good reason why Tesla doesn't update their Supercharging display screen (for all models) to better communicate to the driver just what the hell is going on when the charging rate stays stuck at "0kW" for an extended period of time after plugging into a Supercharger?
    • A little explanation to the driver could go a long way in helping understand the root of the charging rate limitations and soothe any associated frustrations.
    • Maybe showing how many kW are being drawn from the SC specifically for heat would be helpful so the driver can see that something is happening.
Any other thoughts on this?
I had ZERO problems starting a charge at any Supercharger (I hit 9 of them on my trip, see my other post on this. Now, I did have a problem that Tesla is looking into after 1 night of -15 degree weather... but not with the range batteries, but with the 12V battery.
 

Bokonon

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#4
The "Tesla Model 3 Road Trip" guys documenting their cross-country drive on Facebook posted tonight about their experience trying to Supercharge after leaving their Model 3 unplugged in (relatively mild) 20F temps.

I'd read some horror stories about Model S's failing to charge *at all* for over an hour after plugging into a Supercharger with a cold battery. I had hoped the Model 3 would have improved performance in this respect with some kind of elegant solution, but it appears maybe not.
Apparently, the Model 3 can run current through the motor (even when idle) to warm the pack. Not that this appears to have helped You You, of course... :eek:

I suppose there's an outside chance that this capability hasn't yet been enabled in the firmware. (Such an omission might even help explain the higher-than-expected vampire losses that he has reported as his journey has ventured into colder climes.) But inasmuch as this capability directly impacts the health and longevity of the battery (i.e. the most critical and expensive component in the car) this doesn't strike me as the type of feature that Tesla would defer until after deliveries began, like it has done with the rear heated seats. My guess is that Tesla designed this "virtual" heating system to perform at or about the same level as the Model S/X battery heater, and You You's experience last night seems to reflect that level of performance.

The practical tip that I see mentioned often by Model S/X owners is to drive the car for a little bit (preferably on the highway) prior to supercharging. Doing so seems to warm the battery faster than letting the internal heater do the job. I'm guessing that Model 3 owners like us will learn to do the same...
 

jsmay311

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#5
I'm assuming that's already active. How else would the battery be warming up at all if it's too cold to charge at the beginning? (Rhetorical)

The practical tip that I see mentioned often by Model S/X owners is to drive the car for a little bit (preferably on the highway) prior to supercharging. Doing so seems to warm the battery faster than letting the internal heater do the job. I'm guessing that Model 3 owners like us will learn to do the same...
Sure, that's a workaround. But it's a waste of time and energy. And it won't work if your battery is already very low. And it won't work well if you're in a congested urban area where it would be difficult to drive the car very hard due to traffic (like this case in NYC).
 

Bokonon

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#6
I'm assuming that's already active. How else would the battery be warming up at all if it's too cold to charge at the beginning? (Rhetorical)
Agreed. Unless there's some other as-yet-undocumented means of heating the pack (which I haven't seen any evidence of), I'd assume it's using the motor.

Sure, that's a workaround. But it's a waste of time and energy. And it won't work if your battery is already very low. And it won't work well if you're in a congested urban area where it would be difficult to drive the car very hard due to traffic (like this case in NYC).
Right, I saw his reply to that effect. And I agree that there aren't too many cases where this makes sense from an efficiency or time-value standpoint. I think it's more that if you have the option to drive around and warm up the battery first (e.g. to take care of an errand prior to Supercharging versus afterward), then you should.

One other special case would be if you don't have free Supercharging and happen to be in a state where Supercharging is billed by the minute (rather than per kWh)... you might be able to save a buck or two by warming the battery up prior to plugging in. I can see that case applying to urban apartment-dwellers who don't have access to home/work charging or a heated parking facility.
 

Brokedoc

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#7
Rule #1 - Try to stay at a hotel with destination chargers (Hilton just announced a partnership with Tesla to expand destination chargers at their hotels)
Rule #2 - on a road trip in cold areas, Supercharge before stopping at a hotel overnight or plan on driving to heat the battery before stopping to SC.
Rule #3 - charging warms the battery so if you're parked in the cold, you may want to calculate your charging to start and finish right before you plan on leaving so the pack is warm and regen isn't limited. If you're at a hotel with destination charging where they need to rotate out your car for someone else then this may not be a possibility.
Rule #4 - Preconditioning your car while still plugged in will not use battery and expand your range.
 

jsmay311

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#8
Another bone to pick with Tesla on this: the estimated time to complete the charge doesn't appear to account for any of these temperature-related charge rate limitations.

That should be a simple thing for Tesla to model into their time estimate if they know the current battery temp, the outside air temp, and the power of the battery heater.

There are threads from MS owners going back to 2014 about this issue, so there's no excuse for Tesla to not be managing this experience better IMO.
 
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4701

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#9
There are threads from MS owners going back to 2014 about this issue, so there's no excuse for Tesla to not be managing this experience better IMO.
Well said. Some things just don't happen and that is not acceptae.

Also it's weird that charging current is actually zero. I've never heard about chemistry that actually can't charge at all below 0*C.

After 45 mins it was only up to 34kW.
This is not acceptable. At all. I'm extremely dissatisfied with thermal system. I think it is a programming mistake. Again. Tired of those.
Math doesn't support that. Starting from no less than -5C. Adding kWh's of heat. WTF.:weary:
 

jsmay311

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#10
More discouraging examples:


After 45 minutes of Supercharging it still had a "blue bar" and was only up to 21kW.


After 90 minutes, only up to 28 kW. And the "Time Remaining" estimate was comically wrong.

It's not totally clear from the comments what the car was doing immediately prior to plugging in. Idk if they stayed in Champaign overnight and plugged in after it was cold soaked, or drove down from Chicago in the morning. Hopefully it was cold soaked.
 

Mike

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#11
Rule #2 - on a road trip in cold areas, Supercharge before stopping at a hotel overnight or plan on driving to heat the battery before stopping to SC.
I just found this thread and as I am reviewing it, this particular recommendation was proving not to be effective in helping You You at the Kingston, Ontario supercharger the evening of 04 Jan 2018.
Approximate situation: at the tail end of a 90 minute run at 100 kph, with about 5% battery left and ambient temperature of -20C.
No snow flake icon.

1+23 spent charging and battery was only 2/3 full.....we had to get going to carry on with our test drive and then his trip.

My takeaway from that experience: whatever technique the Model 3 is using for battery heating is not very effective at -20C temperatures. The battery should have been warm enough to get more than 60% (from 5% to about 66%) added charge in 1+23 time frame.
 
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#12
It should be effective, but not effective enough.

Rapid charging heats up battery more than driving in cold weather.
Especially Model 3, which uses much less power to move, therefore less losses.

I don't believe battery will be (without SC) any higher than 20-25 degrees (not F) over ambient without
additional heating (which, as it appears, M3 does not have yet).

With Leaf, getting more than 15 degrees over ambient is hard (non-stop driving and 16A charging for whole day).
Even if rapid charged and it is 25 degrees over ambient, it will cool down DURING driving due to wind (passive cooling)
within few hours.
Tesla does use drivetrain residual heat. But on M3, there is very little of that (less than 1kW theoretical maximum, out of
which likely less than half can be used, as drivetrain is outside in the wind).

The more efficient EV is, the less residual heat it makes, that includes pack warming up due to driving.
Model X definitely has more residual heat.
This is why most smaller EV's do not try to scavenge heat from drivetrain. Pointless.
 

viperd

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#13
Since Tesla uses the motor to heat the battery in Model 3, could it be possible (theoretically) for an AWD vehicle to (while driving) use one motor to spin the wheels and the other to heat the battery.
 

Lgkahn

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#17
i just tested this drove 30 miles to supercharger 28 degrees out battery was at 67% would not charge over 19kw.
 

Lgkahn

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#19
hookset toll plaza in nh, no other cars in the plaza and tried 2 different chargers.. they tried to tell me on support that it is normal, but i had driver around 30 minutes so battery should have been hot enough. guess the supercharger could have been cold, but guessing there is some problem with my port as i am on 44.2 and frequently get warnings your cable may not be plugged in correctly, i will have them look at it at next service call. hopefully
 

garsh

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#20
hookset toll plaza in nh, no other cars in the plaza and tried 2 different chargers.. they tried to tell me on support that it is normal, but i had driver around 30 minutes so battery should have been hot enough. guess the supercharger could have been cold, but guessing there is some problem with my port as i am on 44.2 and frequently get warnings your cable may not be plugged in correctly, i will have them look at it at next service call. hopefully
Plugshare notes for that location seem to have mostly satisfied Model 3 owners.
https://www.plugshare.com/location/60157

I agree - contact your service center. But you may also want to try again after running your battery down to a much lower SOC.