I see that, but what is the mechanism that would normally allow those cells to balance either by having never reached 4.2, or in a subsequent charging phase have charge shuttled to other cells?
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Wiki Sudden Loss Of Range With 2019.16.x Software
- Thread starter Dutchmeeuw
- Start date
Yes I do, if you compile all of the evidence, everything is geared towards not shock charging the battery (regen lowered) not over heating the battery (slower charging speeds) No load packing the battery (not able to fully charge to 100%) and less charge load on the battery (more phantom drain)
glhs272
Unnamed plug faced villian
Not necessarily... We don't know from the data if the pack is being charged or is at rest. If it's in the process of being charged, ~92% SOC might not be unusual. It would mean it's in the constant voltage phase of charging.
Ah, you are right, I guess I'll have to try charging to 100% to see what that looks like.
islandbayy
Active Member
I'm sure. I 100% charge every 1000 miles usually, to benchmark (Of course using it right away). I do about 1000 miles every 2 1/2 weeks on my MX, and 1000 Miles about every 8 days on my MS. I started 100% the MX every 500 miles though since to keep a eye on things and that brick of cells with the imbalance.
I "COULD" squeeze the trip on a single charge, if I absolutely had to starting with a 100% SOC, however, with a 9 month old, and a disabled 11 year old, and no emergency charging locations the last 20 miles, I don't much like the idea of pulling in with 5-20 remaining miles. The last 15 miles of the freeway portion, there are NO exits in either direction. Welcome to Wisconsin
islandbayy
Active Member
Agreed. The most over 4.2 i've seen was 4.21, and even that was only for a short time before charge rate dropped and car bled off the excess power.
cpa
Active Member
Agreed, intent versus poor decision-making is a wide gulf.
However, I think that intent would likely be fairly easy to prove if indeed there were ill intent. There are many percipient individuals who have worked or still work for Tesla over the years that are privy to the innermost agreements and understandings that were promulgated to these select individuals by senior management. JB Straubel comes to mind. I am sure there are others. These folks have emails and other evidence to confirm or refute decisions that made their way into the batteries and/or the BMS system. Non-disclosure agreements are voided during discovery.
It is entirely possible that Tesla did not believe at the time that there would be long-term significant deleterious effects from their engineering. This would not equate to intent. But once Tesla became aware of these matters and started their dissembling, deceit, and other unsavory business practices, to me, that is intent.
Where it gets murky is if Tesla knew about the issues from the outset, and they intended to come up with reasonable solutions to these issues through future software updates. But those software updates were not forthcoming until May this year, and by then it was too late.
Well, I don't know if it's a huge problem or not, but assuming that the BMS is capping the cell voltages to 4.2V, the problem is that the BMS thinks the car is only 92% charged when it should be reporting 100% charged.
I have to wonder if this is what people's cars are doing when they won't charge to 100% and stop at something like 96-98% - cell voltages hit 4.2V before the internal SOC tracker (remember, SOC just like capacity is always an estimate and should periodically adjust).
I would be curious to see if there is any significant imbalance at lower SOCs, 17 mV isn't bad at full charge. Also would be good to confirm that the car wasn't charging at the time the snapshot was taken, either.
Ferrycraigs
Member
At the risk of demonstrating how little I know, but does the 3.9V not just show what the Voltage is at 74% rather than Vmax? I thought Vmax would only show at 100% SoC.
Plus, I like the look of the black screen. I presume this is not from TMSpy.
Now, this is a pack that has some serious imbalance issues. At 74% SOC and under light to no load. I see about 4 kW being draw, was the HVAC on? Would be nice to get a snapshot with as little load as possible.
Still - there is one module 95 mV lower than the peak - the only time you should see that kind of difference is down near empty (< 20% SOC), or possibly on a well-used pack under heavy load. And not just one module is low, but there's 3 other modules pretty low as well - 50-60 mV low.
This is one seriously out of balance pack. Really would be nice to see cell voltages at 100% and near 0% as well.
IMO this pack has modules that have failed and should be refurbished.
Does anyone have a cell or pack -voltage / SOC chart for Tesla cells? You could then estimate just how much capacity is being lost due to these weaker modules when you see a snapshot like this. Based on some charts I've looked at, the difference between 3.85 and 3.95V is around 10%.
The vMax as displayed is the highest voltage of your battery. Not your maximum allowable charge - that should be 4.2v, except it isn't if your battery is artificially capped. You have to charge all the way to 100% and see if vMax comes close to 4.2v in order to confirm you have been capped or not.
2170s are used in Powerwalls I think as well at gigafactory 1.
Tesla told is in plain English they were going to implement capping before they did it, phrasing it as "revising charge and thermal management settings" out of "an abundance of caution" after several fires. No deception that early, they were as forthright as Tesla can be considering their communication problems. I don't think they realized the impact would be so debilitating, or impact so many cars. By the time they knew the size of the problem it was too late, they had already gone from a well meaning update to the ill intent of defrauding the NHTSA and every one of us that asked them for an explanation and by then the official lie was already disproven with volt readings. I think this turn was right about the time that German "talking points" memo showed up here. The moment someone at Tesla decided to go forward with deception and lies the intent became criminally motivated.
I agree, it probably started with someone suggesting they could avoid a recall with a software update. Still technically illegal to go unreported, but not a problem if they could fix the issue without any negative impacts. When the negative impacts surfaced, they must have decided they were too far to go back and apologize and that's when ill intent became the purpose of the coverup. IMHO ill intent was someone covering their own butts when they found out they were caught in the act, not the purpose all along.
Keep in mind that 2013 S's often made it to 200K miles or more on the original battery on v8 or earlier. Some of those with frequent supercharging. Whatever went into their decision making to limit charge range on 85s that include 2015s is either because of a possible safety concern or more likely an attempt to lower their warranty costs from having to replace 5% of the battery down to say 1% (or whatever those numbers really are).
I'm still on 8.1 and therefor not effected. My Ludicrous upgraded P85D has seen 107K miles of spirited driving with 303 wh / mile lifetime efficiency, 13 miles of lost range, and supercharging speeds close to what they were when new.
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At 80% or higher its around 4-5 mV. At 50% its at 6-7 mV. At 10% it's around 9 or 10 mV. For 265 k miles and 6 years that's as good as it gets.
BTW I noticed after driving it takes about 10 min for the cell voltage to settle. To get a good reading I would recommend parking the car and waiting 10 min before measuring balance.
Not at all. When charging a Lithium battery you will reach the maximum and then reduce the charge current while continuing to charge. The cell isn't full when the 4.2 limit is reached during charging. It is full when the charge current is practically zero and the cells are at 4.2. During normal charging at 10 kW. The cells reach the max at just under 90% and then stay flat until 100 % is reached. When charging at higher power you reach the max even earlier. It's Lithium battery charging 101.
You have 265K miles on your original battery???? Mines about 3 mv at 90% and 10mv at 10% so nearly the same as yours with 107K miles on my battery. In fact, if it wasn't for module 58, I'd only have a 2mv difference at 90% and 4 mv difference at 10%.
That is my understanding too. So do individual cells get balanced by some technical means right throughout the charge cycle at all states of charge or does cell balancing by implication have to be take place during the constant current phase?
