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Hansjörg von Gemmingen Roadster pack out of juice?
- Thread starter Model S Man
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I actually looked around and learned something about fundamental tech used by Tesla. Switch from LiCoO2 should substantially prolong battery usable life in Model S in comparison to Roadster. In fact, it do looks like LiNiCoAlO2 is the most advanced cathode tech around. It have benefit of slightly increased specific energy (energy density, not to be confused with power density). But substantially decreases both calendar and charge discharge degradations. On both metrics LiNiCoAlO2 competes very favorably with other advanced chemistries, such as LiNiMnCoO2. With LiFeP04 being very different beast, because of it relatively low energy density.
But there is not cathode alone out there. In fact, right there in Fremont, CA, next door to Tesla Factory Leyden Energy having it research center and developed tech that allows Li-ion batteries to last much longer while having expended temperature envelope. They did it by creating new electrolyte material. And there is anode...
Ok, you might find this pdf interesting, it talks specifically about LiNiCoAlO2.
I agree. The picture in Elon's tweet shows 66 km range with ~30% SOC, i.e. ~200 km range after 200 Mm. For the range to drop to only 100 km after another 44 Mm sounds more like a defect or an exaggeration than normal degradation.
Unfortunately many of our German friends don't hang out here any more, but the car in question is here:
Tesla-Fahrer und -Freunde Forum Thema anzeigen - 1.Roadster hat 200.000 km Laufleistung erreicht
Tesla-Fahrer und -Freunde Forum Thema anzeigen - 1.Roadster hat 200.000 km Laufleistung erreicht
Word is that Hansjörg's pack suffers not only from normal degradation but is seriously out of balance. I don't know why the pack cannot be rebalanced by charging. Tesla would like to see the Roadster in its Munich shop to look at the battery whereas Hansjörg would like a new pack.
Thank you for this bit of information. You probably have a better idea of what's happening with Hansjorg's battery pack since you are in Germany vs. us here in the US on an internet message board.
"Out of balance"...as I'm not an EV owner (yet):
1) What does "out of balance" mean?
2) Can this occur with the Model S? TSLA's website says Roadster and Model S share same battery technology - "Lithium ion".
3) Are there steps to prevent this from happening?
4) Is this covered under Tesla's battery warranty?
Forgive me if this is basic stuff, but for a person new to the EV world, I'm still trying to learn about it, want to make sure my car will last, and of course am very skeptical of the Model S and TSLA's long-term viability. That is just my nature. I have to see and own the car myself to learn about its quirks and disadvantages as a vehicle - and its eventual acceptance with the mainstream public - or not. I could wait to make this purchase to find out more, yes, but I just want to have a full tank of "gas" every morning and not have to stop at the gas station and have a long range and be a luxury (premium) car and have the car last 200k miles with minimal battery degradation.
I do not want to be disappointed with this vehicle.
All EVs have a battery / pack which is comprised of many cells chained together in some fashion.
A balanced pack would have all cells of the same capacity and health so that a full charge would bring all the cells up to the same voltage, and a full discharge would drop them to the same even level. For example, using a fictional but relevant example, lets say a pack had 100 cells each with a normal range of 3V to 4V.
So, a pack might have a per cell "full" of 4V per cell, and "empty" of 3V per cell, where the total pack is 400V when full and 300V when "empty".
Now lets say one of the cells is aged prematurely and refuses to charge above 3.8V. The BMS ("Battery Management System") could see when charging that a cell was not accepting any more charge when it got to 3.8V so it could stop charging the rest of the pack and leave you at 380V max full. There could be 99 other healthy cells that had the potential to get to their 4V, but the system would not charge them to full because a laggard dragged everything else down. You basically have some lowest common denominator that affects overall pack capacity.
Now, in some cases, the problematic cell(s) could be brought back into line if was conditioned properly with a different charging method. Perhaps if you charged it more slowly, or (some other battery charging magic I don't understand) you could get it to come back up to 4V and get the pack back in balance and everything happy again.
I think that packs can get out of balance if you have erratic charging and driving. Lets say you were at a dragstrip and doing heavy discharge, then did partial charges and went back to driving again repeatedly. The BMS never gets a chance to sort things out, and uneven heating / discharging could slowly gets the individual cells out of balance with each other. Usually you can correct this by doing a complete full charge and letting the car sit for a while as the BMS figures out what it needs to do and re-balances things. For a really tired old pack some cells may not be able to be recharged to useful state again and the BMS may "write them off" and not try to use them. It all depends on how compartmentalized the system is designed to allow. The Roadster has various "sheets" and such that were expected to work in groups. In the case of the 240,000KM Roadster it may be they could replace one weak "sheet" (say ~10% of the cells) and get the overall health back up a bunch if one sheet was a lot weaker than the others. But in practice, with that many miles, perhaps all the sheets are "tired" now, and there is an assortment of weak and some even "dead" cells mixed around, and it isn't really practical to remove test and replace each from the 6831 total, so a full pack replacement would be the only practical option.
"Out of balance" isn't an all or nothing situation. Basically any pack is going to be "slightly out of balance" to some degree. The problem could be barely noticeable, or so severe that your max range is noticeably less than new/optimal, and the vehicle utility is compromised.
The 85kWh Model S probably has more individual cells than the Roadster, and I don't know if the pack is divided into sections that can be replaced individually or not.
We don't know how good the BMS is at keeping the individual cells balanced and if there are certain charging and/or driving styles that could cause out-of balance situations sooner rather than later. Probably best to discuss with Tesla directly if you were concerned and wanted to use the car in a way best "optimized" to keep the pack healthy as long as possible.
One would like to think that they have improved things to the point where it is smart enough to sort everything out automatically and so the driver doesn't have to think about any sort of "usage protocols". I think it is inevitable that the pack will lose capacity given enough years/miles/kms. Driving habits and charging habits probably have some effect on that aging process, but how far out of your way do you want to go to "baby" your vehicle?
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Actually, it's the other way around: the problem cell gets to 4V first, and you then (in the absence of rebalancing hardware) have to stop charging at that point because you would otherwise destroy that cell by taking it above 4V. So (as you said) you then have one cell fully charged and the rest in the string less than fully charged. The problem cell might not be the weak one: it could be the strongest cell in the pack and it's still at a high voltage because it didn't discharge so far (perhaps it has a lower self-discharge rate), or it could be one that has less capacity than the others due to aging and so fills up more quickly than the others.
Rebalancing normally involves some hardware to let the charging current bypass the problem cell and continue charging the others. Ideally you'd want to switch the problem cell out of the circuit and just charge the others on their own, but that's generally impractical since your switching arrangements would need to handle the full operating current, not just the (smaller) charge current. So what is normally done is to have a bypass circuit in parallel with the cell: this unfortunately means that the voltage across the bypass circuit is the same as the cell voltage, so the bypass circuit dissipates a lot of power: all of the energy that would have gone into charging the cell if it weren't bypassed ends up as heat in the bypass resistor. So you have to balance relatively slowly.
Ideally again, you would balance throughout charging rather than waiting to the end, but you often can't because your cell voltage measurements during fast charging are distorted by cell internal resistance and temperature effects.
Disclaimer: my experience of charging algorithms is with much smaller packs, but the principles should be the same.
AustinPowers
Total Smeghead
But you fail to take into account that not only gasoline and diesel is far more expensive here, but electricity as well.
You don't save that much.
Very simple math for the Model S (for my driving habits) would be:
ICE: 6.5 liter (diesel per 100km) at 1.5 Euro (per liter) times 10k (km a year) equates to 975 Euro in fuel
Model S: 85 kWh (per 425 km / 265 miles) at 0.25 Euro (per kWh) times 10k (km a year) equates to 500 Euro in electricity *
That means at current prices I would save 475 Euro per year. Say I drive my Model S 15 years on its first battery I would save 7.125 Euro in fuel over that amount of time.
I don't think that would cover the price of a new 85 kWh battery, even in fifteen years.
*and that is assuming the battery wouldn't degrade at all over 15 years, every charge would be from zero to full capacity, and every charge would get me the full 265 miles. Being realistic would mean adding at least 10 percent to the electricity costs which in turn would minimize the money saved even further.
As someone once said: "don't buy an EV thinking you could save money in any way".
Our 436 HP corvette easily averages 20 mpg. At a steady 80 mph the engine is loafing at 1400 rpm, and you can get 27 mpg with the A/C on.
GSP
PS. Best to budget for a new battery in 10 years for your 85 kWh model S. Probably 6 years if you get the 40 kWh. If your annual milage is not about 12-15,000 mi, then maybe adjust your timeframe up or down.
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Good advice.
Premium powertrains, and EV range, cost money. How far do you want to go?
GSP
JRP3
Hyperactive Member
NigelM
Recovering Member
Discussion over here: German-article-in-Die-Welt-is-this-verifiable-Model-S-battery-is-different-no
(Mods to merge?)
(Mods to merge?)
Adm
Active Member
In another article from may 5th 2012 it reads he still has 300km of range and he was still happy. I wonder what happened since that article.
http://www.focus.de/auto/news/rekord-im-tesla-200-000-kilometer-mit-strom-statt-sprit_aid_754877.html
http://www.focus.de/auto/news/rekord-im-tesla-200-000-kilometer-mit-strom-statt-sprit_aid_754877.html
bonnie
I play a nice person on twitter.
Under discussion over here German article in Die Welt -- is this verifiable? Model S battery is different no?.
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Ahhh, Nigel beat me to it. Will suggest a merge.
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Ahhh, Nigel beat me to it. Will suggest a merge.
Hansjörg wrote a comment on the German Facebook Tesla Owner Group saying essentially that he is very disappointed of Tesla. Elon personally refused his request to either replace his battery or give him a Model S for free, because of all the advocacy his done in the past for Tesla. It seems like he is not so positive about Tesla anymore and this article looks like it is a result of this dispute.
It also seems that he has refused the offer by the German Tesla team to rebalance his batteries nor to get a heavily discounted refurbished battery replacement.
Personally I don't want to think about the time when I have to replace my batteries for my roadster, but I don't think this is the right way to do it.
It also seems that he has refused the offer by the German Tesla team to rebalance his batteries nor to get a heavily discounted refurbished battery replacement.
Personally I don't want to think about the time when I have to replace my batteries for my roadster, but I don't think this is the right way to do it.
It also seems extremely likely that as the range dropped he started doing range mode charges more frequently, probably exclusively.
I would not be suprised if in the last year every day was a range mode charge. That has to accelerate the battery degradation.
I plan on taking 10+ years to hit 150,000 miles, and I won't need to range mode charge more than 5-10 times per year until my range is under 100 miles.
I would really really like to have a set of logfiles from this car.
bonnie
I play a nice person on twitter.
I want a free Model S!
Seriously, I get really annoyed with this kind of blackmail scenario (let's call it what it is) ... either give me what I want or I'm going to the press. If he'd been reasonable, it looks like he could have gotten a great deal on a refurbished battery. If he'd tried every avenue for resolution (let Tesla look at the battery, get the logs looked at, consider the refurbed battery), then going to the press still would be an option.
Really??? He asked for a FREE Model S?
NigelM
Recovering Member
The tactic never works in any case. The company calls your bluff, you go to the press and a story comes out, the company weathers out the story and your bridges are burnt....now what? The person in question ends up further away from a resolution than they were in the first place.
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