My car won't charge to 100%

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3V Pilot

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#1
Well, I've had my car for a week and it's just over 700 miles on the odometer. So far I've been charging nightly to 70% using my hard-wired wall charger and getting a regular 48 amps without any problems. Temps during charging are mid 70 degrees in my garage so that isn't a problem. Today I attempted to charge to 100% for the first time just to see what the range would be and also take it on a little road trip. Well, at 98% and 308 miles it said "charging complete" and wall charger indicated no more juice flowing (solid green light). I thought maybe I didn't have the limit set fully to 100% so I attempted that (several times) but all it would do is charge for a minute or so and then quit again. It finally ended up showing 99% but still only 308 miles. It's not "balancing" the pack because it's not charging any more and I've read ever other forum I could find on this. Just wondering if anyone else has had this happen? My guess is that the BMS just discovered what 100% really means for my battery and next time I'll see 100%@308 miles. I'm going to call service tomorrow and see what they say about it. Any electrical engineers out there with any other ideas as to what might be going on???
2018-05-20-09-50-15-jpg.9024
 

PandaM3

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#2
I plugged mine in via UMC on a 14-50 and set it to full charge since I was planning on driving out to SD.

The morning of I had a range of 314 miles.

Well I got a 24 hour virus and was sick so I couldn’t go to SD. So I just left the car plugged in with charging scheduled to start at 10:00pm.

By noon it said 310 miles.
By afternoon it said 308 miles.
Now it says 304 miles.

Only difference is between Friday and today it has gotten colder. Also maybe vampire drain maybe.

I probably should’ve unplugged it and taken it for a drive to relax how tightly packed the electrons are in the battery. Tried to get the wife to drive it to work today... but she’s afraid that she’ll scratch it so she took our Spark EV to work instead. I probably should’ve driven it to work too, but I’ve been driving it too much. Also I wanted to clear my V8M3’s exhaust pipes which I haven’t driven in a week. Yeah I know too many cars lol.
 

PandaM3

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#3
Thinking about it some more, I am hoping that software is just preventing it from charging again until it is driven. The worst damage occurs when repetitively charging to 100%. Because of vampire drain if the car is plugged in and looses a percent it will repetively charge back to 100%. Me thinks that software is preventing this from occuring.... I hope.
 

3V Pilot

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#4
Thinking about it some more, I am hoping that software is just preventing it from charging again until it is driven. The worst damage occurs when repetitively charging to 100%. Because of vampire drain if the car is plugged in and looses a percent it will repetively charge back to 100%. Me thinks that software is preventing this from occuring.... I hope.
Well, at least yours goes to 100%. I know it's only a couple of miles but I'd still like to see my battery get to 100% charge. From what I understand and read the worst damage is not repeatedly charging to 100% (although that is not good for it) but it's letting stay at a high (or low) state of charge. If it gets used (or charged) right away then it's not that hard on the battery in the long run.
 

PandaM3

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#6
Yep it’s been sitting for the past 48 hours.

I wonder if the software is just giving enough electricy to run the car’s computer and stuff while it sits and just letting the battery slowly discharge. Because if I am loosing energy from vampire drain then I’d get an alert at night that it is charging and then I’d get an alert after that says charging complete like usual. That isn’t happening.

Oh well I’ll just take it for a drive when I get home I guess.
 

John

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#7
It's important to realize that the only "real" thing happening here is plugging it in and the car saying that charging is complete. That is very trustworthy because there is a physical indication (charging current) that the charger can go by. The battery lets you know when it is full.

Everything else is "made up", like it saying "99%" or "308 miles." Those are software calculations, and they have whatever logic they have. It doesn't matter (really) what they say. The battery is fully charged. The car will go as far as the car will go. If you drive 35 mph, it will go about 600 miles. If you drive like I do, it will go 270 miles. Probably if it was me, I'd just program the car to say 100% and 310 miles until the day you sold it, no matter what the actual battery capacity ended up being. Remember, a battery that has degraded by 10% (which would be a lot of degradation for a Tesla) can still go 400 miles (if you drive slow).

Yes, it's disconcerting that it doesn't say "100%" and "310" miles after a full charge. I don't know how their algorithms make up those numbers—do they coulomb count, apply cycle logic, adjust to your daily drive, all of the above?—but the important thing is that you filled it up. The numbers are full of noise and inscrutable guesstimate logic.
 

3V Pilot

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#8
It's important to realize that the only "real" thing happening here is plugging it in and the car saying that charging is complete. That is very trustworthy because there is a physical indication (charging current) that the charger can go by. The battery lets you know when it is full.

Everything else is "made up", like it saying "99%" or "308 miles." Those are software calculations, and they have whatever logic they have. It doesn't matter (really) what they say. The battery is fully charged. The car will go as far as the car will go. If you drive 35 mph, it will go about 600 miles. If you drive like I do, it will go 270 miles. Probably if it was me, I'd just program the car to say 100% and 310 miles until the day you sold it, no matter what the actual battery capacity ended up being. Remember, a battery that has degraded by 10% (which would be a lot of degradation for a Tesla) can still go 400 miles (if you drive slow).

Yes, it's disconcerting that it doesn't say "100%" and "310" miles after a full charge. I don't know how their algorithms make up those numbers—do they coulomb count, apply cycle logic, adjust to your daily drive, all of the above?—but the important thing is that you filled it up. The numbers are full of noise and inscrutable guesstimate logic.
Thanks for the reply, that is pretty much what I was thinking but you put it into words much better than I could of. I'm not all that concerned, just wondering if others have had similar experiences. From what I've read about Model S/X the calculations don't adjust for driving style, they just use a straight calculation all of the time. Not sure if the Model 3 follows that same way but my overall Wh/mi is 248 with just over 800 miles on car at this point. I think I'll try running the battery down to a low SOC and then topping it off at a supercharger to see what kind of results I get.
 

LUXMAN

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#9
Thanks for the reply, that is pretty much what I was thinking but you put it into words much better than I could of. I'm not all that concerned, just wondering if others have had similar experiences. From what I've read about Model S/X the calculations don't adjust for driving style, they just use a straight calculation all of the time. Not sure if the Model 3 follows that same way but my overall Wh/mi is 248 with just over 800 miles on car at this point. I think I'll try running the battery down to a low SOC and then topping it off at a supercharger to see what kind of results I get.
Thru “sources” :p, the Model 3 uses 250 Wh/mi. So with the usable capaciy of 78kw, yields 312 miles. So if you can keep it to 250wh/mi, you should get to the rated range. Should bring the key word. I use that is my driving to see how much energy I am using, not that I will slow down or turn off the heat/AC tho!
 

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#10
This thread is making me worry a little...since I don't plan on driving Quicksilver a couple of days (rain is coming :p), I don't want to set it to 100% yet. I'll test this on Wed. when I plan to do some driving. crossing fingers that I'll get at least 310.
 

3V Pilot

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#11
This thread is making me worry a little...since I don't plan on driving Quicksilver a couple of days (rain is coming :p), I don't want to set it to 100% yet. I'll test this on Wed. when I plan to do some driving. crossing fingers that I'll get at least 310.
I don't really think it's something to worry about, like @John said above, it's really just a made up number. We all have the same number of 2170 batteries that are all made to the same specs. The number shown at a given state of charge does not imply your pack or any cells are "less" than perfect, it's just a matter of how it's being calculated. In my case I'd bet the system is still calibrating itself since it's so new. At least that is my hope, I'll see what happens after running it down then charging it back up again.
 

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#12
Not that I'll ever know, but I wonder what it would say on a full charge if you drove so slowly on a trip that you averaged 500 miles a charge for a couple of full charges. Would it still say 310, or start migrating towards 500?
 

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#14
Not that I'll ever know, but I wonder what it would say on a full charge if you drove so slowly on a trip that you averaged 500 miles a charge for a couple of full charges. Would it still say 310, or start migrating towards 500?
Good question. Have you seen any increase? I personally have not. In my Leaf, I would see drastic changes in range estimates after high speed driving when I got off the freeway. Like from not making it home to 10 extra miles.
But with that 3, I have not seen that at all. What I have seen is the range stays where it was for longer. Meaning it will show the same range over several miles of driving. I think this is from the use of a fixed number for range calculations that I believe they use. It would be interesting to see results of someone hypermiling the 3 and what the range meter did to bear this out
 

3V Pilot

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#15
Not that I'll ever know, but I wonder what it would say on a full charge if you drove so slowly on a trip that you averaged 500 miles a charge for a couple of full charges. Would it still say 310, or start migrating towards 500?
I've read on other forums that Tesla uses a fixed number to calculate range. It does not change based on your driving habits. Somewhere I even saw the number used as someone pulled it out of the software on a Model S. Not sure what it is for the Model 3 though.
 

3V Pilot

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#16
I called service today about this issue and they told me it's a known firmware issue. They said it should be fixed in a future update so I'll just wait it out and try a full charge again after the next update.
 

John

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#17
For what it's worth I'm struggling with this same issue on my company's products—also using lithium-ion rechargeable batteries—and it's painfully clear that battery values that aren't 100% when charged or values that jump up or down really bother users.

The problem is that the actual "reality" jumps up or down, depending on lots of factors. Do you show the current estimate of reality to the user, or do you show arbitrary numbers after after a charge and put a really low-pass filter on it so that it only very slowly reacts to reality? Not a no-brainer...
 

goto10

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#18
Yep it’s been sitting for the past 48 hours.
Eek! Leaving it at 100% for that long is really not advised. I realize there's nothing you can do about it now, but if a similar situation occurs in the future you should do whatever it takes to bleed that off power rather than just letting it sit. If there's just no way you can take it for a 30-40 mile drive, I'd just turn the heater on full blast in your garage until the miles drop down to 280 or so. It'll shut off after 30 minutes so you'll probably need to restart it a few times.

The few times I've charged to 100% I timed it so I could start driving immediately upon a completed charge. 48 hours of sitting at ~100% would represent several years of 100% idle time for me.
 

3V Pilot

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#19
Well, since the service center told me it was a "known firmware issue" and they must know best.... But.....I just had to test it out for myself. I drove the car until I had 5% battery remaining and attempted another charge to 100%.

8 hours later it showed 312 miles and 100% charge! From what I've read this is not really "balancing" the battery but it does reset the algorithm used to calculate range. The computer is always guessing what the batteries can actually store (or have stored) and doing a full charge from a low state of charge helps it to reset. At least that's my understanding in laymen's terms.