Battery management or the BMS

[gangzoom]

Is it just paranoia or should I be concerned?

Just let the BMS do its thing, loads of people get hung up on range at 100% and trying to work out if they have bad degredation.

Don't forget Tesla DON'T warranty against degredation at all, only pack failure. By charging to 100% all the time trying to make the numbers look better your probably damaging the pack.

I've never seen the car report more than 69kWh of usable energy from 100-0% extrapolated from energy reports from the trip meter for our 75D X. Infact day to day fhe extrapolated figure can be as low as 55kWh.

On loaner 85s, 72kWh is the best I've managed, and even on 100s 88kWh, which is far short of what the reported 'usable' kWh figures give.

To give you an idea how nuts the BMS is in the summer on a long run the extrapolated usable kWh in our car was around 65-66kWh.

A few Ks later and its now reporting around 60-61kWh usable for the same trip.

It that 'real' degredation? Unlikely, is it Tesla fiddling with software? Maybe. But in all honesty what are am I going to do about it? Nothing, so why stress?

 

[WannabeOwner]

If I set the car to charge to 100% I'd expect it to do that, not stop short ...

I think the question here is whether that is normal (for some reason ... I've never seen it), or perhaps an indicator that something needs seeing to.

I would look at the minute-logs in TeslaFi (Help : Raw Data Feed) and see what the "Charger Limit SOC" and "Battery Level" are. I am assuming that you will see LIMIT set to 100, and not changing "by itself" during the charge, and then you will see charging stop at some point in time. Maybe those things will lead you to something else (e.g. a scheduled stop at end of Off Peak?) if not my suggestions would be to send a screen print to Tesla to ask them what they think.

 

[vitesse]

If I set the car to charge to 100% I'd expect it to do that, not stop short ...

I think the question here is whether that is normal (for some reason ... I've never seen it), or perhaps an indicator that something needs seeing to.

I would look at the minute-logs in TeslaFi (Help : Raw Data Feed) and see what the "Charger Limit SOC" and "Battery Level" are. I am assuming that you will see LIMIT set to 100, and not changing "by itself" during the charge, and then you will see charging stop at some point in time. Maybe those things will lead you to something else (e.g. a scheduled stop at end of Off Peak?) if not my suggestions would be to send a screen print to Tesla to ask them what they think.

Both times the target was definitely 100.

OK, I'll see if Tesla can offer some advice.

 

[WannabeOwner]

Both times the target was definitely 100

TeslaFi shows that in raw data? I'd want that reassurance before assuming that e.g. screen was showing the right thing.

 

[vitesse]

TeslaFi shows that in raw data? I'd want that reassurance before assuming that e.g. screen was showing the right thing.

Yes, Teslafi shows 100% charge end-target both times.

I have read somewhere that polling from third-party apps via the API can be problematical when charging to 100%. I must admit that I was checking the charge state via Teslafi when charging was in the high 90s, as well as the Tesla app.

Teslafi reported: "API Error - Data Request Timeout." - just at the time charging completed at 99%

and:

03-11-2019 13:15:35 online Charging 99 100

..at the end.

 

[Yev000]

Don't forget Tesla DON'T warranty against degredation at all, only pack failure.

Well that's not entirely true

Model 3 - 8 years or 100,000 miles, whichever comes first, with minimum 70% retention of Battery capacity over the warranty period.

Model 3 with Long-Range Battery - 8 years or 120,000 miles, whichever comes first, with minimum 70% retention of Battery capacity over the warranty period.

Vehicle Warranty

But S and X deredation is not covered, for some reason (probably more likely to happen?)

 

[vitesse]

@gangzoom Thanks for that - just to clarify I'm not obsessing with 100% range but as I stated originally I would like to do anything to help the BMS do its work and there seems to be consensus that very occasional (no more than once in several months) 100% charging helps the BMS level the cell voltages, which is beneficial.

I follow all the advice. I routinely charge to 90% or less at home and haven't 100% charged at a Supercharger since we first had the car. In fact I only Supercharge when on fairly rare longer trips and then only to about 75% max (usually less) as charging slows down considerably by that time. 15 supercharges in total vs 187 AC charges in 6 months we've had the car. I have never let the car sit for more than a few minutes when it's charged over 90%.

As @WannabeOwner appears to agree, I think I should be mildly concerned that the car won't reach 100% on a full charge.

 

[vitesse]

Well that's not entirely true



Vehicle Warranty

But S and X deredation is not covered, for some reason (probably more likely to happen?)

I'm not at all concerned that the pack is faulty I get very good range for my car's age and specification and I know that the previous owner, who I managed to get in touch with, looked after the car as well.

And the car itself is Tesla warrantied for another 4 years or 50K miles as it was a CPO purchase from Tesla. That warranty reset doesn't extend to the battery pack of course, but so far I have a very good relationship with the SC where we collected the car from and they have been very helpful with all other issues we've had.

I feel the BMS may not be fully 'synced' to the pack. Others on this forum have experienced similar situations and these have been eventually fixed via various strategies, including Tesla service.

@gangzoom was correct in that he was responding to my case and it's clear from my profile that I have a MS

 

[Roy W.]

...and it's clear from my profile that I have a MS

It’s only clear if you’re using the forum on a large-screen device. On phones the signature section isn’t displayed.

 

[MrBadger]

It’s only clear if you’re using the forum on a large-screen device. On phones the signature section isn’t displayed.

Looking in landscape mode on phone will show sig if required. But like many others, I prefer portrait mode on phone so as Roy says, no sig.

 

[vitesse]

A Ranger mobile technician is coming on Friday to check out some oddity with passive locking and an obscure knocking sound when on hard right lock - I will mention it then.

 

[Adopado]

A Ranger mobile technician is coming on Friday to check out some oddity with passive locking and an obscure knocking sound when on hard right lock - I will mention it then.

Did you ever resolve your battery calibration concerns?

 

[vitesse]

Did you ever resolve your battery calibration concerns?

To be honest the Ranger was too busy with other things. I haven't tried a 100% charge since. Otherwise everything is fine.

 

[MrBadger]

So I got home last night with 9% battery and attempted to charge to 100% by this morning. However, the charge completed at 97% rather than 100%. Here's the Teslafi chart:

View attachment 468412
I'm pretty sure I didn't make a mistake with the charge setting as in the app there is a small gap between the green and the charge % line. So I am rather bemused now.

First home charge today, seen similar but know why for us, maybe you.

Charge limit set to 90%, but car charged to 91%

However, since TeslaFi now splits the battery usable* (value in blue) as a separate reading, I could see that car charged to 90% usable (blue), which equated to 91% battery (larger black). On some days, I have seen Teslafi report usable as several % different from ideal, so that could be what you are seeing - except your usable is 97% and actual is 100%? However I have not looked inside car to see what it thinks is the %.

*May not be exact term

 

[MrBadger]

However, since TeslaFi now splits the battery usable* (value in blue)
*May not be exact term

Now TeslaFi is back, its called 'cold battery level'.