What should be 80% SOC is only 68%

[lupend88]

Maybe not... More from the same Tweeter:





I don't think they actually tested the range, but service told them that it would be a problem. So it sounds like don't daily charge to 70% until Tesla resolves the issue.

Very interesting. I was under the impression that many people charge to roughly 70-80% so I'm surprised we haven't seen more of this in the community.

 

[lupend88]

Another "70%" victim apparently. I will try to run my pack down to 10% and charge up to 90% and see if that fixes it. I really hope a firmware fixes this, we shouldn't be punished for charging to 70%.

 

[brkaus]

Another "70%" victim apparently. I will try to run my pack down to 10% and charge up to 90% and see if that fixes it. I really hope a firmware fixes this, we shouldn't be punished for charging to 70%.


View attachment 357641

I believe the car needs to see broader voltage swing to deal with the balancing. I don’t expect there is a firmware fix possible.

Charge above 90 once a month.

 

[notAnExpert]

I have a 310 mile LR RWD Model 3. When I charge to 80%, I should roughly see (310 x 0.8 ) 248 miles. But in reality I see 212 which equates closer to 68%, a pretty substantial difference. I live in Portland Oregon and charge indoors in my garage. Is this normal battery health?

We have had al LR RWD for two weeks now. I've set the charge limit to 70%. The est. range at the end of the charges has been 217 miles. So that's 5 miles more for 10% less charge than what you are seeing. Hmm!

Edit: I'm also on firmware 2018.42.4

 

[lupend88]

I believe the car needs to see broader voltage swing to deal with the balancing. I don’t expect there is a firmware fix possible.

Charge above 90 once a month.

I think I will start doing that, and if that is good for the battery balancing, it would be helpful if that was communicated so people like me and that LikeTesla Youtube'r don't freak out when seeing substantially off percentages.

 

[insaneoctane]

I guess the question is if the car is not able to balance the battery properly at lower SOC, are you doing more harm than good? If I have to charge my battery to 90% once a month instead of 70% to "fix" things.....am I better off, from a long-term battery degradation standpoint, just going to 80% and not having this problem??

 

[apacheguy]

What firmware version is on your Model 3? There are some issues in the BMS state of charge estimates if you charge to less than 90% most of the time causing the remaining range to be reported lower than it actually is. Newer firmware version might have improved it, but other people have found charging to 90% daily for a while brings the range estimate back up.

Hmm. I haven’t had a problem with any firmware version (since delivery in May) altering the rated miles displayed at a given percent.

I am on 2018.42.4. I consistently charge to 70% every night. So you're suggesting to try charging to 90% for a few nights in a row?

I’m on the exact same firmware and I follow the exact same charging routine. Still get 217 miles at 70%.

I believe the car needs to see broader voltage swing to deal with the balancing. I don’t expect there is a firmware fix possible.

Charge above 90 once a month.

Well, this is definitely not true on the Model S. Ive measured cell voltages and they are still within 4 mV even after a few months of only charging to 70%. Unless Tesla radically altered the balancing algo in the M3 I don’t expect any difference.

 

[MP3Mike]

Hmm. I haven’t had a problem with any firmware version (since delivery in May) altering the rated miles displayed at a given percent.

I’m on the exact same firmware and I follow the exact same charging routine. Still get 217 miles at 70%.

Well, this is definitely not true on the Model S. Ive measured cell voltages and they are still within 4 mV even after a few months of only charging to 70%. Unless Tesla radically altered the balancing algo in the M3 I don’t expect any difference.

This issue only impacts Model 3s as far as I have seen. (And lots of people have reported it.) Maybe there is a temperature component? Or maybe it has to do with shallow discharges from 70%? (How much do you discharge your Model 3 before you charge it back to 70%?)

The entire BMS system was redesigned on the Model 3, so I would expect a difference.

 

[TexasEV]

It’s not a matter of balancing the battery. The issue is how the car estimates the state of charge. It can’t be measured directly, and the algorithm to estimate it is less accurate when the car isn’t usually charged most of the way. Stop limiting your charge to 70%. It has no practical benefit for the battery and could leave you short of range in an unexpected occurrence. Model S owners such as myself charged to 90% routinely for years (and 100% for trips) with no ill effect.

 

[lupend88]

It’s not a matter of balancing the battery. The issue is how the car estimates the state of charge. It can’t be measured directly, and the algorithm to estimate it is less accurate when the car isn’t usually charged most of the way. Stop limiting your charge to 70%. It has no practical benefit for the battery and could leave you short of range in an unexpected occurrence. Model S owners such as myself charged to 90% routinely for years (and 100% for trips) with no ill effect.

The issue with that is that many professionals (including Elon himself) have mentioned 70% to be a good place to charge to. There seems to be a wide range of opinions/routines depending on who you ask.

That being said, I have scheduled a SC appointment for this Wednesday afternoon and will report back after Tesla takes a look at it.

 

[TexasEV]

As Elon said, the relative benefit is small. Like it’s measurable, but has no practical impact on how you would use your car. If a few miles of range after 10 years is really important to you, you probably bought the wrong car.

 

[lupend88]

As Elon said, the relative benefit is small. Like it’s measurable, but has no practical impact on how you would use your car. If a few miles of range after 10 years is really important to you, you probably bought the wrong car.

Are you claiming everyone who charges to 70% in an attempt to get the most out of their battery pack “bought the wrong car”? No need for an attitude.

 

[SageBrush]

When in doubt, go for a drive.
Or even better, go for a metered charge.

 

[Gavyne]

I would follow Elon’s recommendation and charge to 80% daily and 90% once in awhile. Bjorn Nyland on youtube also had to reset the BMS by running the car low then charging up to near 100% recently, and it worked fine. The miles he lost came back no problem.

 

[Big Earl]

I would follow Elon’s recommendation and charge to 80% daily and 90% once in awhile. Bjorn Nyland on youtube also had to reset the BMS by running the car low then charging up to near 100% recently, and it worked fine. The miles he lost came back no problem.

90% is fine according to Musk. Elon Musk on Twitter

 

[Eno Deb]

Another "70%" victim apparently. I will try to run my pack down to 10% and charge up to 90% and see if that fixes it. I really hope a firmware fixes this, we shouldn't be punished for charging to 70%.

For the record, I charge daily to 70% (and my commute is only around 25 miles roundtrip so most of my charge cycles are pretty shallow). For occasional longer trips I usually charge to 90%. My range estimate is off by no more than a few percent in each case. It used to be more, but firmware 42.x fixed it.

The difference you are seeing seems to be too big for just an estimation error. Probably a good idea to contact service (from what others have reported they can diagnose many battery problems remotely).

 

[lupend88]

For the record, I charge daily to 70% (and my commute is only around 25 miles roundtrip so most of my charge cycles are pretty shallow). For occasional longer trips I usually charge to 90%. My range estimate is off by no more than a few percent in each case. It used to be more, but firmware 42.x fixed it.

The difference you are seeing seems to be too big for just an estimation error. Probably a good idea to contact service (from what others have reported they can diagnose many battery problems remotely).

Thank you for that info, my driving habits (charging habits and commute distance) are basically identical to yours. I have a service center appointment set up for this Wednesday and will report back then.

 

[TexasEV]

Are you claiming everyone who charges to 70% in an attempt to get the most out of their battery pack “bought the wrong car”? No need for an attitude.

I just don't get why so many Model 3 owners obsess over the battery, much more than early Model S owners did, especially since we have lots of experience now from the Model S over the past five or six years that how you charge (within reason) just doesn't have a meaninfgul impact on battery degradation.

 

[apacheguy]

This issue only impacts Model 3s as far as I have seen. (And lots of people have reported it.) Maybe there is a temperature component? Or maybe it has to do with shallow discharges from 70%? (How much do you discharge your Model 3 before you charge it back to 70%?)

The entire BMS system was redesigned on the Model 3, so I would expect a difference.

Right, I discharge at least 30% before charging again. Small depth of discharge will definitely make the algo go a bit haywire.

How do we know that the BMS was entirely redesigned for the M3? I don’t recall hearing that before.

 

[hamtonp]

Looks like there is a trade off. If you constantly stay in the middle range, your cells get out of balance quicker. I used to charge to 70-75% and not let it drop lower than 40%. My range did drop. I did a cycle of 93% to 30% and it appears to recovered a little bit. I'm not going to fret about it and plan to charge to 80% and let it drop to 30% before charging again. I'll do a deep cycle on my next road trip this Xmas.

There is someone on reddit that just posted his max range is 310 miles after 25k miles driven. He said he charges to 90%.

Constantly triggering the rebalance is not answer either. The BMS discharges the battery to balance the cells. This is when users freak out about Vampire drain.