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Strange Charging Behaviour to 100%

Paddy3101

Member
Mar 20, 2019
267
402
San Diego, US
Just charging the car to 100% to see if it re-adjusts the BMS.(Doubtfull, but worth a go as my wife ran it down to 6% last night)

Has spent the last approx 45minutes charging AFTER it got to 100% without adding any miles to the reported range. The charging rate didn't start to drop off till 5mins AFTER it hit the full miles. Will see if it now re-adjusts the milage upwards, to get back the 'lost' miles. As a rough number, it must have added 10-12 miles range in those 45mins, but without it registering!

upload_2019-10-1_17-21-39.png
 

ucmndd

Well-Known Member
Mar 10, 2016
6,905
13,045
California
Hard to know what any of that means without column headers.

I will say it’s quite normal for a car to keep trickle charging for up to an hour after it hits 100% before it says “charging complete”, presumably doing some cell balancing activity.
 
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Paddy3101

Member
Mar 20, 2019
267
402
San Diego, US
With the headings this time.

No, wasn't trickle charging, was charging full on 30A, didn't start to taper off until after.
So it's charging at 30A then tapers off, but doesn't add any mileage or charge to the battery.

Supposedly adding 22.5 m/h (tapering off down to 3.5) over 40 minutes but ZERO miles added to the range.
That's an average of 13 m/h over 40 minutes should have added another 9 miles of range (approx)



upload_2019-10-1_18-37-3.png
 
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ucmndd

Well-Known Member
Mar 10, 2016
6,905
13,045
California
Lots of weird numbers in there that don’t make sense. Where is this data from - Teslafi? Something else?

would have been interesting to see what the car was reporting at this time from the app or charger screen.
 

Paddy3101

Member
Mar 20, 2019
267
402
San Diego, US
Lots of weird numbers in there that don’t make sense. Where is this data from - Teslafi? Something else?

would have been interesting to see what the car was reporting at this time from the app or charger screen.

Yes from teslafi. All the numbers match what the app was saying.

App was saying the same range number. Turned on the air at 5:12 and it finished charging about them.

Was continually saying 30mins to complete for about 90 minutes.

Was sat there waiting for it to finish before I went home.

It's on a 208v 30A charger, so that's right.

Also looks like the cabin overheat protect doesn't work anymore, which is a separate issue.
 

srs5694

Active Member
Jan 15, 2019
1,169
1,397
Woonsocket, RI
It looks like it's saying a 100% charge is 287 miles, which is a very strange number for a Model 3. Is this why you're trying the 100% charge, in hopes that it will re-calibrate a mis-calibrated BMS?

In any event, this looks to me like a rounding issue. Even when doing a Level 2 charge, the charge rate drops off as the SoC approaches 100%, and TeslaFi rounds the reported number to the nearest percentage point, so it could well have been going from 99.6% to 99.7% and so on, but be reported as 100% in TeslaFi. It's also conceivable that your mis-calibrated BMS (if that's what you've got) is contributing to some weirdness in the TeslaFi display.
 

user212_nr

Active Member
Aug 26, 2019
1,407
748
US
Its interesting, but does not look concerning. It could be balancing the battery. Also, Tesla has "reserved capacity" in all batteries, so it may decide to actually charge that but not allow you to see the range.
 

Paddy3101

Member
Mar 20, 2019
267
402
San Diego, US
It looks like it's saying a 100% charge is 287 miles, which is a very strange number for a Model 3. Is this why you're trying the 100% charge, in hopes that it will re-calibrate a mis-calibrated BMS?

Yes, the car started off with 307 reported miles on a full charge, and is now down to a reported 287 (Varies 286-288 daily at the moment, but with a downward trend)

Not sure I believe that the <10% to 100% charge does anything, but it's conceivable, and since the car had been discharged to 6% I though I would give it a go.

In any event, this looks to me like a rounding issue. Even when doing a Level 2 charge, the charge rate drops off as the SoC approaches 100%, and TeslaFi rounds the reported number to the nearest percentage point, so it could well have been going from 99.6% to 99.7% and so on, but be reported as 100% in TeslaFi. It's also conceivable that your mis-calibrated BMS (if that's what you've got) is contributing to some weirdness in the TeslaFi display.

In the past, yes the changing rate would drop off as it approaches 100%, but yesterday, it didn't it stayed at a full 30Amp "Charger Actual Current" column until about 30minutes after is said "100%" AND about 5 minutes after it reached the final "Battery Range" number. (which is what is displayed in the car).

If you look at the data, the charge current, is at 30Amp still when it hits the top-line range number. THEN carries on charging for another 45 minutes!

Same for Charge Rate which is miles gain/h BUT the miles DON'T go up at all.

The car is quite steadily loosing 'reported' miles, at a significant rate, on an ever downward trend, which is actually accelerating, and is at about 3-4 miles range per 1000 miles (Steadily over the last 6 months with 16K on the car).

Been brushed off by SC a couple of times, saying its 'normal'. It's adjusting to your driving style, you've had your air-con on more, heater on more, Shouldn't charge to 90% all the time, bs. bs.

No, not been gradually changing my driving style over the last 6 months 15K miles in a nice linear fashion.

Last time, they said, come back if it gets to 30 miles loss.

Now this could be real-loss, or 'imaginary/calibration' loss. However, empirically, the journey where it got down to 6% (16 miles left - which is cutting it too close for comfort) would have previously had 30-40 miles left.
 

user212_nr

Active Member
Aug 26, 2019
1,407
748
US
Yes, the car started off with 307 reported miles on a full charge, and is now down to a reported 287 (Varies 286-288 daily at the moment, but with a downward trend)

Not sure I believe that the <10% to 100% charge does anything, but it's conceivable, and since the car had been discharged to 6% I though I would give it a go.



In the past, yes the changing rate would drop off as it approaches 100%, but yesterday, it didn't it stayed at a full 30Amp "Charger Actual Current" column until about 30minutes after is said "100%" AND about 5 minutes after it reached the final "Battery Range" number. (which is what is displayed in the car).

If you look at the data, the charge current, is at 30Amp still when it hits the top-line range number. THEN carries on charging for another 45 minutes!

Same for Charge Rate which is miles gain/h BUT the miles DON'T go up at all.

The car is quite steadily loosing 'reported' miles, at a significant rate, on an ever downward trend, which is actually accelerating, and is at about 3-4 miles range per 1000 miles (Steadily over the last 6 months with 16K on the car).

Been brushed off by SC a couple of times, saying its 'normal'. It's adjusting to your driving style, you've had your air-con on more, heater on more, Shouldn't charge to 90% all the time, bs. bs.

No, not been gradually changing my driving style over the last 6 months 15K miles in a nice linear fashion.

Last time, they said, come back if it gets to 30 miles loss.

Now this could be real-loss, or 'imaginary/calibration' loss. However, empirically, the journey where it got down to 6% (16 miles left - which is cutting it too close for comfort) would have previously had 30-40 miles left.

You're going too far into Tesla's internal hardware and software engineering trade secrets for anyone to be able to help you on this one. Its not a large loss, and yes, your are not advised to often charge to 100%.
 

Paddy3101

Member
Mar 20, 2019
267
402
San Diego, US
You're going too far into Tesla's internal hardware and software engineering trade secrets for anyone to be able to help you on this one. Its not a large loss, and yes, your are not advised to often charge to 100%.


Not really looking for help, more making an observation, that this behavior is strange. The car is reporting that it is charging for 45minutes, but not adding to the range. It IS obviously drawing a significant amount of power during that time, but it's not being registered as an increase in range.



So the car is reporting a (significant) loss of range, and at the same time not increasing that reported range, while at the same time, it's reporting it's charging at a high rate. Doesn't add up.



No internal engineering, trade secrets here. Just using publicly available tool (teslafi) which anyone could use. Lots of people do.

I have charged to 100% a total of 3 times, and then immediately used that charge because it was needed. 90% is the regular daily charge, charged every day.
 

ewoodrick

Well-Known Member
Apr 13, 2018
5,285
3,735
Buford, GA
Just charging the car to 100% to see if it re-adjusts the BMS.(Doubtfull, but worth a go as my wife ran it down to 6% last night)

Has spent the last approx 45minutes charging AFTER it got to 100% without adding any miles to the reported range. The charging rate didn't start to drop off till 5mins AFTER it hit the full miles. Will see if it now re-adjusts the milage upwards, to get back the 'lost' miles. As a rough number, it must have added 10-12 miles range in those 45mins, but without it registering!

That's exactly how balancing works. Once it gets to a reported 100%, it keeps watching the current until all the cells report 100%. It may take a long time for some cells to come up to the full charge. Once the batteries have balanced, it seems as if the car then resets the 100% number to the new setting.
 

Sophias_dad

Supporting Member
Supporting Member
Jul 29, 2018
1,459
1,489
Massachusetts
You described exactly what I did on Sunday afternoon, for exactly the same reason... my AWD 3 with 24k miles on it is lately charging to ~261 miles at 90% for a reported ~294 miles at100%. I charged it from ~30% to 100% on a supercharger(the first time the car has ever been taken to 100%!). Up to like 95% was very fast, and once it reached 100% it sat there seemingly charging at a good rate(10 mi/hr or better) for another 45 minutes or more, yet added only like a mile to my 100% number. I was mildly disappointed.

At least I got to sit and watch Netflix!
 

Paddy3101

Member
Mar 20, 2019
267
402
San Diego, US
That's exactly how balancing works. Once it gets to a reported 100%, it keeps watching the current until all the cells report 100%. It may take a long time for some cells to come up to the full charge. Once the batteries have balanced, it seems as if the car then resets the 100% number to the new setting.

Ahh, that makes sense, and might explain the charge to 100% periodically advice to reset the BMS, balance the pack or whatever. It doesn't do that when charging to 90%, just charges till it hits the number and completes.

Will probably try that cycle again shortly, as I will be needing it's full range. Hopefully it might give me back some of the lost range (which may indicate that it's not a real range loss)
 

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