Kevin Sharpe's decreased Roadster range

[stopcrazypp]

I believe this is because the the brick that hits the 0% SOC threshold first effectively limits the entire pack.

Bingo. That's how battery packs work. That why Tesla says the weakest brick is always the one that limits the pack.

 

[woof]

Personally I think this is very significant.

And yet "significant" has a precise mathematical definition (see Statistical significance - Wikipedia, the free encyclopedia). These numbers are not significant, no matter what you personally think.

 

[supersnoop]

In Range mode it charged to est 130 miles, and the computer said ideal range was 171 miles. In Range mode, mind you, not standard mode. In standard mode it is only charging to est 105 miles. I will try to extract the VehicleLogs tonight with some really old, really tiny capacity USBs and hopefully be able to provide some actual information about what is going on.

The only thing I guess I should add is that I've had the hard top on and have been using the A/C lately. Forgot to mention that all along, and it is a relevant data point.

Ignore the estimated range. Ideal range is the only thing we can compare with each other.

 

[stopcrazypp]

The before and after SOC logs show that brick 8 clearly meets the definition of a statistical outlier, being over 6 standard deviations from the mean. Its low capacity is limiting Kevin's range to 94.8% of what it would otherwise be. If brick 8 were not the limiting factor, Kevin's maximum range would be 210 miles.

That's incorrect. What you are saying would only be true if the #8 brick is the only brick that is low. However, that is not true of his pack in the current condition. That is because Kevin's pack also has the #29 brick that is the next weakest, which means the actual limitation directly attributable to #8 is the difference between #29 and #8, which I calculated to be 1.5% relative SOC.

So replacing #8 will only give him 202 miles of range, not 210 miles (or rather 208 miles as that's the best case possible given the #8 brick is only 4.2% below the average brick capacity from his OP showing 129.41Ah for brick #8, vs. 135.11Ah average).

However, Tesla's analysis, is that #8 brick's degradation is still within the envelope of what's considered normal. We already knew previously #8 is 129.41Ah and given the weakest brick determines the capacity, it is what determines the 199 miles ideal he's getting, so that brick is the one that degraded to 81.2%. The average is 135.11Ah and means his average brick have degraded to 84.8%.

 

[stevejust]

Ignore the estimated range. Ideal range is the only thing we can compare with each other.

How are they each calculated/what do they mean?

 

[SteveWest]

That's incorrect. What you are saying would only be true if the #8 brick is the only brick that is low. However, that is not true of his pack in the current condition. That is because Kevin's pack also has the #29 brick that is the next weakest, which means the actual limitation directly attributable to #8 is the difference between #29 and #8, which I calculated to be 1.5% relative SOC.

There are two factors which limit pack capacity: Differing brick capacity, and differing balance. You are observing that brick 29 is the limiting factor due to imbalance. Balance, of course, can easily be corrected.
It's reasonable to use the SOC delta as a proxy for inverse brick capacity. The brick with the greatest delta is the limiting factor, when perfectly balanced. The delta of brick 8 is 74.10, the next smallest delta is brick 98 of 70.24. If brick 8 were performing as well as brick 98 (or better), then the available pack capacity would be 74.1 / 70.24 = 5.5% more.

 

[Kevin Sharpe]

We already knew previously #8 is 129.41Ah and given the weakest brick determines the capacity, it is what determines the 199 miles ideal he's getting

CAC 128.14 this morning...

 

[supersnoop]

How are they each calculated/what do they mean?

ideal is calculated based on the charged capacity divided by an "ideal" consumption of roughly 230wh/mile. Estimated range is based on your recent wh/miles - how you've been driving the car. Estimated range means nothing to anyone else.

 

[Kevin Sharpe]

These numbers are not significant, no matter what you personally think.

The numbers are 'significant' because they directly impact my ability to use the car...

 

[dhrivnak]

The numbers are 'significant' because they directly impact my ability to use the car...

I too have to disagree as significance does have a statistical definition. I too have a low brick and my pack is below the average pack. But I am not significantly lower. In any population half of all bricks, packs and any other measure will be below average.

 

[J1mbo]

The numbers are 'significant' because they directly impact my ability to use the car...

You mean: they are personally significant because they force you to use public charging slightly more often than you would have had to do in the past.

 

[Kevin Sharpe]

You mean: they are personally significant because they force you to use public charging slightly more often than you would have had to do in the past.

I have recently cancelled two electric car speaking engagements because the previous one stop charging strategy is now a two stop charging strategy and I cannot spare the time.

On Sunday I'm sharing a platform with Robert Llewellyn, Ecotricity, and a host of other electric car advocates. This will be the first time in 4 years that questions about Tesla ownership will be difficult to answer.

Please understand that I fully expected and planned for battery degradation. I just didn't expect to deal with the 100,000 mile / 7 Year degradation, at 55,000 mile / 4 years.

 

[thefortunes]

Please understand that I fully expected and planned for battery degradation. I just didn't expect to deal with the 100,000 mile / 7 Year degradation, at 55,000 mile / 4 years.

And you are not.

I have stayed out of this but as has been stated ad infinitum you are down ~ 19%, NOT the 30% that Tesla had provided in their guidance.

Did you expect your degradation to stay at zero until 100,000 miles and then fall off a cliff?

 

[Kevin Sharpe]

Did you expect your degradation to stay at zero until 100,000 miles and then fall off a cliff?

No, I expected my battery to be good on day one (it was not), for the repairs in 2011 to make things better (it did not), and for degradation to be consistent with other UK Roadsters (it is not).

Look again at my OP and the recent graphs I posted... the range is falling off a cliff at 55,000 miles and that in itself is unusual according to the 154 Roadsters in the PiA study.

 

[thefortunes]

No, I expected my battery to be good on day one (it was not), for the repairs in 2011 to make things better (it did not), and for degradation to be consistent with other UK Roadsters (it is not).

Look again at my OP and the recent graphs I posted... the range is falling off a cliff at 55,000 miles and that in itself is unusual according to the 154 Roadsters in the PiA study.

And when did you start your abuse of the battery (specifically clicking through the warning that you would be reducing long-term battery life) and how often relative to others in the study? Oh, that's right, you STILL haven't answered how many times.

I never should have jumped in as you continue to rehash the same sad arguments without taking responsibility for your actions.

 

[deanb2]

You must not have very steep cliffs in Bradford on Avon

 

[Lloyd]

You canceled engagements because it would take you ~15 minutes to charge your lost miles. PLEASE...... I hope the people you were to speak to read this and give their opinion of your actions.

 

[Kevin Sharpe]

And when did you start your abuse of the battery (specifically clicking through the warning that you would be reducing long-term battery life)

My first use of 'range' mode was when driving with a Tesla representative in July 2010. I do not have a definitive answer to your question about how often I've used range mode which is why I can't provide a meaningful answer to your question. I said previously that in 2010 I used it a few times.

how often relative to others in the study?

I have no way of answering that and I suspect every single car has a different charging/driving pattern. If anything I believe the PiA study shows that most cars don't give a damn about the charging/driving pattern although it's possible the 20% battery replacement rate has masked the real failure rate which will become clear now that Tesla are no longer voluntarily repairing packs.

You really need to come to terms with the fact that my battery has always been faulty... once you accept that everything else fits into place... focusing on the results of the battery fault after 4 years and 55,000 miles just allows you to delude yourself (just like Tesla are doing today).

- - - Updated - - -

You canceled engagements because it would take you ~15 minutes to charge your lost miles.

No, I can no longer reach the HPC and would instead be limited to 7kW public charging. I do not have the time to spend charging at 32A just so that I can reach the HPC.

 

[Krugerrand]

Come now, Mr. Sharpe. Just because you can't provide the exact number of range charges (and deep discharges), doesn't mean you can't provide a meaningful answer to that question. You know very well approximately how many times you've ranged charged (and deep discharged) over the years, you just don't want to make that information public because it'll solidify people's opinions against your claim.

 

[bart513]

Kevin,
I'm pretty sure that by pulling the logs from your Roadster you can find out how many times you have charged in standard or range mode. Please correct me if I am wrong on this anyone?