Reading the group voltages should show if a cell has gone bad. If it has, there will be a large difference between the highest and lowest group voltages.
Seems like something that could be done remotely
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"Balance Required" BMS Alert on Plaid
- Thread starter Muzzman1
- Start date
Seems like something that could be done remotely
WilliamG
Hinge Fanatic
You’d think. Tesla doesn’t seem too interested. Just the usual keep charging to 90% and let the cells balance malarkey.
Well, that would help if it was just a drifted group and the balancing software requires a high SOC to provide an accurate voltage to charge relationship. To diagnose a failed group would require giving the BMS time to self correct. That said, a sudden drop in range is indicative of a failure (or software update) and a large imbalance at any SOC seems worrisome.
Group voltages over time would be a great diagnostic aid, as opposed to just a single snapshot.
In general, early types of BMS did balancing by limiting the max group voltage, so the pack would get charged until all the protection circuits kicked in.
WilliamG
Hinge Fanatic
For some reason not all the data is here in Stats (for a short period I had 295 miles reported) but here’s what data I do have since day 1. 5 weeks in now.
Attachments
WilliamG
Hinge Fanatic
Stats for iOS.
Stats: For Model S/X/3/Y
[+] Compare your car's max range against similar cars [+] Shows your car's total battery capacity [+] Connect your storage device to your iPhone/iPad and view recorded dash-cam videos on iPhone/iPad [+] Warm-up battery at specified time [+] Climate scheduling [+] Charge scheduling [+] Learn...
apps.apple.com
Electric700
Active Member
Escalate this to a Tesla manager if needed. Also ask to see a new Plaid with a similar configuration, and check the rating at the same charge level (use the % setting and switch to rated miles to compare - so 90% = n miles of rated range displayed).
WilliamG
Hinge Fanatic
I have done. However, Tesla doesn't seem interested in anyone else's results, - just mine. They said as much. Just have to play their game for the time being, despite knowing something is very wrong with these cars.
WilliamG
Hinge Fanatic
For those that care/follow my saga, here's the results of leaving the 21"/Plaid pretty much an entire week at 90% charge, allowing the car to cell balance. I seem to have "topped out" at about 321-322 miles (per 100% charge - versus 348 miles it should be). I suspect when I drive the car any long distance this cell/voltage imbalance will reoccur and I'll be back into the high 290s again.
There's something really awesome about having a car with at best a 10% range deficit over everyone else's new Plaid, along with crazy charging anomalies, - and Tesla unwilling to do anything except tell me everything looks just fine.
There's something really awesome about having a car with at best a 10% range deficit over everyone else's new Plaid, along with crazy charging anomalies, - and Tesla unwilling to do anything except tell me everything looks just fine.
To further improve the system's estimation of pack capacity, it's important to let the car go through a few sleep cycles at lower states of charge in addition to the high states of charge that you've just performed. That can be whatever you're comfortable with, but I'd say 10% will yield better results than 20%. A "sleep cycle" being parked overnight without Sentry, Climate Keeper or Smart Summon on so that the car can fully shut down for 8 hours. I'd follow that up with another few sleep cycles at 90% for more cell balancing. Hopefully this will add to the improvement that you've already seen.
Electric700
Active Member
Sorry to see that. What about escalating to the next highest manager? Show them proof too, e.g. your car at 90% versus another car with the same main specifications at 90% and also the same two with the rated range miles setting turned on. If that doesn't work, you could wait another one or two weeks and then request a trade in, with them covering all fees. Consider writing a professional letter with all of the facts and pictures there too.
I hope everything works out!
WilliamG
Hinge Fanatic
In your opinion given how soon that initial range drop-off occurred, wouldn't you assume a hardware issue of some sort, or do you think this was just a software glitch, and more driving/cycles will fix it? This was a couple of hours ago (90% SoC).
I've already done the above, sadly - they just want me to keep monitoring/driving/charging.
The brick balance is within one significant digit (10mV) and the SOCs are only 1.4% apart, so it looks good there. Could you post this display with a lower pack SOC?
WilliamG
Hinge Fanatic
Exactly what I’ll be doing tomorrow evening after my long drive! Will report back then.
I’m reluctant to say it’s a hardware issue. I’ve seen pretty big fluctuations in my own Model 3 that I attributed to software changes. Considering how new the Plaid is, I’d go through the software training motions before ascribing it to a hardware problem.
I hope you are right! My car is at the SC for minor issues as well as my pack that shows total energy as 71kWh. Voltage disparity as much as 320mV at low SOC and best case I've seen is 70mV at 100%.
Today I am told they are going to "reset the BMS" and see how that goes.
I hope it's just a fluke. I just want it fixed, new pack or software, a new Plaid should not show 259mi at 100% SOC I just want to see about 348mi with 21" wheels set in the MCU.
It sounds like your situation might be different than @WilliamG’s. I find both of your sagas very interesting and hope you both have positive outcomes.
WilliamG
Hinge Fanatic
We appreciate the support. Hopefully I'll have an update in the next day or so. I don't feel comfortable charging the car overnight, so after tomorrow's longer driving session I may wait till Friday morning to charge if I won't be awake last enough Thursday, to keep an eye on the on/off charging issue I've had in the past with this car.
By the way, what kind of fluctuations have you seen with your Model 3?
SucreTease
Teslarian
From where are you getting 348 miles as a "should be"? The Plaid is listed as having an EPA estimated range of 396 miles.
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