3.0 Battery Longevity

dpeilow · Mar 5, 2018

bolosky said:
And, your CAC hadn't been recalculated for the last 46 days in the log (it is unchanged to four decimal places).

I had a couple of CAC updates since that last log I sent you, but it has not moved by much. It has been down to 211.96 but at the current time is 212.11.

Also, regarding the CAC reset and the 70 days offset, if the battery degraded in that time and if the algorithm is working properly then it should trend down to the capacity of the battery. It is interesting that it hasn't.

Jonathanm · Mar 5, 2018

Add me to the signature...now learnt about repairing PEMs....I guess I should thank Tesla for that...

bolosky · Mar 5, 2018

dpeilow said:
Also, regarding the CAC reset and the 70 days offset, if the battery degraded in that time and if the algorithm is working properly then it should trend down to the capacity of the battery. It is interesting that it hasn't.

My working theory is that the CAC algorithm only gets real information about the battery capacity when it's at very high or very low state of charge. So, range charging and discharging to very low levels tends to affect the CAC (disturbingly, in opposite directions).

Otherwise, it estimates based on time and mileage.

Since you're keeping your battery in a mid-range SOC, all you get is the estimate.

dpeilow · Mar 5, 2018

bolosky said:
Since you're keeping your battery in a mid-range SOC, all you get is the estimate.

Actually I've done a couple of full or close to full range mode drives recently, which seems to be what triggered the change. I may need to do a bit more, as I'm am sure any sensible algorithm will have some hysteresis in it and is keeping the average high. Indeed, this is the kind of thing Tesla needs to tell us that I am requesting above.

Kerios · Mar 5, 2018

And if you remember that situation I had when the car went from showing about 48miles remaining to abruptly dropping to "cannot calcuate range" - you'll recall the data in my log file for that. That was distinctly terrifiyng and subsequently I almost never now use range mode in case I go below some unknown thresehold.

eljf · Mar 5, 2018

David I'll sign this letter. Or whatever you need to help?

hcsharp said:
Waaaaaay too long. If you want to get somebody's attention it needs to be less than one page.

I have 2. Sr & Jr. Nothing beats a nice pair of cans

slcasner said:
Sorry to say, David, my first reaction was the same as Henry's. I suggest that you be very brief in the introduction and limit to just the battery concerns in this letter. If you find traction, then go back for the PEM.

David (can we nickname you Pillow) maybe isn't a lawyer looking at the letter. But I 100% feel what he's getting at. I'm sure many of you had similar experiences in dealing with the manufacturer. From the practical costly PEM/400VC en-bloc replacements, to the more personal sentiments underlying his relationship with the manufacturer in many aspects.

Apart from signing to support my friend and fellow roadster David, I'm happy to know that 'I am not the only one'. I have written several e-mails to the manufacturer with a 2 page saga of "Please help me because I did xxxxx yyyy zzzz to promote you, and sold ## cars."... and "now please help me with xxx yyy zzz" considering that "I didn't do anything wrong because xxx yyy zzz" ......... with green love, signed here.

I totally - no... whole-heartedly - understand where David is coming from. Just bear in mind the nature and policies of the manufacturer.
Even if you can envisage a more eco-friendly way to repair e-cars henceforth, such change is typically top down. No chance bottom up (I'd love to be wrong here).

If this was addressed to my company, I'd spend the time to unpack the letter, and see what this enthusiastic person has to say. But then again, my company is not so big that I'm in the clouds (or outer space). The post reaches my desk here on earth just fine.

I hope he wasn't dismissed when he brought the issue up at the recent session at the West Drayton London event. That would be a shame.

I'd just like to give a shout out to those in Tesla who support the roadster. We are lucky in London to have Julian Smith and Sam Smith working to keep us on the road. Priceless they are.

Best of luck @dpeilow mate.

ggr · Mar 6, 2018

Kerios said:
And if you remember that situation I had when the car went from showing about 48miles remaining to abruptly dropping to "cannot calcuate range" - you'll recall the data in my log file for that. That was distinctly terrifiyng and subsequently I almost never now use range mode in case I go below some unknown thresehold.

Yesterday I drove San Diego - Los Angeles and back on a single charge. Nominally it was 244 miles, but there were a couple of traffic detours in there that probably added a few miles. I got back with no trouble, but got the "cannot calculate" message at about 26 miles remaining (and about 5 miles to go to get home). I did the trip at 75-85 mph except when in traffic, although most of the time I was above 80 mph it was because I was slipstreaming behind some ugly truck

.

dpeilow · Mar 6, 2018

ggr said:
about 26 miles remaining

26 miles ideal or estimated?

thefortunes · Mar 6, 2018

dpeilow said:
The letter will be going shortly, so if people would like to PM me their names and VINs that would be appreciated. It looks better than a TMC username. Thanks.

Paging :-

@Jonathanm
@thefortunes

Done

Curt · Mar 6, 2018

dpeilow said:
The letter will be going shortly, so if people would like to PM me their names and VINs that would be appreciated. It looks better than a TMC username. Thanks.

PM Sent

backmost · Mar 6, 2018

I think this letter to Tesla is a great start, which hopefully will result in them at least looking into this issue. I don't have a Roadster yet, but I would be very skeptical of going the route of spending almost $30,000 (almost half the price of a used Roadster) only to have the battery match the CAC of the original within a few years.

I understand from Tesla's perspective that the Roadster is mostly a decade old car, but McLaren still to this day services and maintains the F1 which is over 25 years old. They even use an old Compaq laptop just to communicate with the car! Of course the Roadster is in no means the level of the F1 in terms of volume and rarity, but it's still the first EV that actually didn't look like a glorified golf cart and rightfully deserves a place in automotive history. It paved the way in funding for Tesla to develop the Model S and eventually the X and the 3.

So would it be too out of question for them to pamper the original Roadster owners with continued support?

shrink · Mar 6, 2018

PM sent in support of this letter. I'm happy to sign.

Great research! These are genuine concerns articulated very well. Thank you. I'm hoping it leads to some action.

ggr · Mar 6, 2018

dpeilow said:
26 miles ideal or estimated?

Estimated. I think it was about 30 ideal when it disappeared.

hallvardr · Mar 6, 2018

Sign me up!

bolosky · Mar 6, 2018

ggr said:
Estimated. I think it was about 30 ideal when it disappeared.

I'd love to see if your CAC dropped a bunch after this happened. I predict that it did.

Care to send me an updated log?

ggr · Mar 6, 2018

bolosky said:
I'd love to see if your CAC dropped a bunch after this happened. I predict that it did.

Care to send me an updated log?

Will do, I just have to get a round tuit. Probably this evening.

dpeilow · Mar 6, 2018

ggr said:
Estimated. I think it was about 30 ideal when it disappeared.

Hmm mine was 26 estimated, but 40 ideal. 26/30 seems a bit low for 80 mph. Maybe check the logs.

dpeilow · Mar 6, 2018

The letter has been sent this morning.

Rolf68 · Mar 7, 2018

dpeilow said:
The letter has been sent this morning.

Thank you !!!

dpeilow · Mar 7, 2018

For the record, here is the cover email and letter that was sent in its final form. I already had an acknowledgement from Tesla and say they will ensure it gets to the correct person.

Dear X & Y,

Many thanks for organising the Clubhouse last Thursday, despite the weather, and thanks for Y for discussing in detail the concerns of the Roadster owners' community regarding a couple of current hot topics after the Q&A.

You may remember that I was the only Roadster owner (I think) present in the room, however I know that others were watching the live stream and were fully supportive of the points I wanted to raise. Still more have been discussing the topics raised for many months in various forums and are keen to get answers from the company about what we are seeing.

As requested, I have put all the issues discussed into writing. I asked the Roadster community to check that I have covered everything accurately and more than 25 owners offered to countersign the letter. It is quite long and detailed, but we hope that it covers the points in enough detail to allow Tesla to investigate and provide us with a satisfactory response.

We would like to again stress that these points are made in the name of constructive feedback - enabling everyone to learn from what it means to run the cars as they age, so that the lessons may be applied to the wider Tesla fleet - and we look forward to hearing from you in due course.

Yours sincerely,

David Peilow