How would you respond if an 80 kwh Roadster pack were available in 2014?

[samcarney]

Additionally I know most of you are saying that you wouldn't roadtrip with the Roadster, but I would absolutely LOVE to be able to roadtrip with it. My wife and I did quite a few group roadtrips in our Miata, and never felt limited by its size. Would I spend a month on the road with it...probably not. But a 5-7 day jaunt would be a blast if you didn't have to worry about charging logistics!

I agree. I have 33k miles with my Roadster, mostly road trips. I do road trip the Model S occasionally. I find the Roadster much more fun although a bit challenging. I meet a lot of interesting people inquiring about " that little car " with the out of state license plates. I would love more range and an HPC at the superchargers.

 

[772]

IMO the ability to roadtrip with the Roadster would differentiate Tesla quite a bit from the other brands and bring it to parity with ICE (although the Model S already does that to an extent, I guess). Still, it would be nice for the brand to be able to say that all of their cars can be used like any ICE. e.g., just because my 911 is a sports car, doesn't mean I can't take it on a 700 mile road trip if I need to. This is why I'd rather see an upgraded charging system on the Roadster, but even a larger battery pack is a nice upgrade.

 

[ItsNotAboutTheMoney]

Extra range is not really an issue for me. Using new cells to give the same range but with less weight (so better acceleration / handling) would be better - after all its a sports car. If you want more range & are not bothered about it being a sports car then trade in the roadster for a Model S.

Well, capacity ~ range ~ performance ~ charge mph ~ 1/discharge rate, so unless the acceleration is limited by the motor or inverter, a higher capacity battery should increase the performance potential.

 

[pharma5]

Based on the responses so far I think it's safe to say there's some segmentation here, with one set of users looking for range (yes, road trips) and one looking more for reduced weight to improve handling/acceleration (including track days for the car).

One side note that I don't see talked about: for the reduced weight case with newer cells, having a lesser count of cells (and maybe lesser count of bricks or sheets) will increase the relative impact of an individual cell failure on the overall system, and perhaps the cell failure rate. With ~~4000 cells rowing together instead of 6831, that might be noticeable.

(I also don't see a lot of comments on smaller pack footprint = bigger trunk!:tongue.

I suspect we may also have a fairly silent third group who just want the most inexpensive battery: same type cells (or cheapest noninferior cell vs. original), same cell count = same weight/handling, and lowest cost.

Obviously this poll is focused on a simple high-range example, but it's good to see the broader types of user preferences as well.

 

[Pantera Dude]

Chances are this upgrade (if battery related) would only work with 2.x vehicles. The 1.5 Roadster uses a significantly different battery and I do not think Tesla would spend the R&D twice to support an additional user base of 500 vehicles. This is probably the sad reality of the situation.

I didn't realize the batteries were different, how so?

 

[pharma5]

Chances are this upgrade (if battery related) would only work with 2.x vehicles. The 1.5 Roadster uses a significantly different battery and I do not think Tesla would spend the R&D twice to support an additional user base of 500 vehicles. This is probably the sad reality of the situation.

I didn't realize the batteries were different, how so?

I don't believe the assertion absent more info. So disagree with conclusion.

1.5 packs may have used different, earlier chemistry. Certain sheets are used for 12V power instead of a separate 12V battery. To my knowledge, same counts of cells, bricks, sheets, total cells 6831. Firmware controls the two configs a bit differently.

So for this poll, the hypo 80 kwh pack again could keep same count and arrangement of cells, bricks, sheets. Certain sheets used for 12V power in 1.5's. Tested with all active firmware, adjusted if needed. What am I missing?

Edit: Even if correct, two groups of owners with prepaid battery replacement plans would still need 'R&D twice'.

 

[PRJIM]

I don't believe the assertion absent more info. So disagree with conclusion.

1.5 packs may have used different, earlier chemistry. Certain sheets are used for 12V power instead of a separate 12V battery. To my knowledge, same counts of cells, bricks, sheets, total cells 6831. Firmware controls the two configs a bit differently.

So for this poll, the hypo 80 kwh pack again could keep same count and arrangement of cells, bricks, sheets. Certain sheets used for 12V power in 1.5's. Tested with all active firmware, adjusted if needed. What am I missing?

Edit: Even if correct, two groups of owners with prepaid battery replacement plans would still need 'R&D twice'.

From my understanding the batteries on the 1.5's are not interchangeable with the 2.x. The PEM and Motor is also different. I read somewhere- in 2010- that some regulation required Tesla to separate the 12v functions from the main HV pack. The prepaid replacement is for 53kwh. This is from memory but I think there were a bunch of T&C's with the replacement:

1. If a replacement is requested before year 7 owner pays 2k/year
2. Owner gets 1k/year after year 8 but before year 10
3. The replacement must be requested after the expiration of the warranty but before the 10 year anniversary of the sale of the vehicle
4. The battery replacement request can only take place after the warranty expires

 

[pharma5]

From my understanding the batteries on the 1.5's are not interchangeable with the 2.x. The PEM and Motor is also different. I read somewhere- in 2010- that some regulation required Tesla to separate the 12v functions from the main HV pack. The prepaid replacement is for 53kwh. This is from memory but I think there were a bunch of T&C's with the replacement:

1. If a replacement is requested before year 7 owner pays 2k/year
2. Owner gets 1k/year after year 8 but before year 10
3. The replacement must be requested after the expiration of the warranty but before the 10 year anniversary of the sale of the vehicle
4. The battery replacement request can only take place after the warranty expires

Thanks. I believe the first part is not to mix and match cells with different mAh, e.g., 2200 mAh with 2400 mAh (or bricks or sheets of such cells). Allows proper balancing and prevents the lower cells from being "preferentially stressed / discharged" during use.

PEM and motor should be no issue i think - firmware controls how they draw from the pack. (Poll does not suggest better performance by drawing more juice.).

Not aware of a Reg behind the move to separate 12V battery, but curious to know if you find it. Maybe hazard lights need to work even if powertrain doesn't?

Prepaid replacement at 53kwh is ok for the poll - that's why it's explicitly an extra cost upgrade in one answer. No cost in the other answer would rely on a decision by TSLA to exceed expectations (like the "40 kwh" Model S - all are software-limited 60 kwh hardware... hey, i think we're onto something here on range/cost:wink.

Those T&C's are not bad:1 and 2 adjust ultimate price for timing (incentive for longer use). 3 is 10-year cap (no lingering commitment). 4 separates replacement obligations from warranty obligations (no picking & choosing).

At least so far, I think the simple 80 kwh scenario of the poll is still in good shape, albeit imperfect for some user segments. (But maybe the lowest-cost segment could get an 80 kwh software-limited to ~53 kwh and save, I dunno, $15k?, upgradeable later...).

 

[hcsharp]

From my understanding the batteries on the 1.5's are not interchangeable with the 2.x. The PEM and Motor is also different. I read somewhere- in 2010- that some regulation required Tesla to separate the 12v functions from the main HV pack.

The differences are minor considering the overall battery management scheme and cell chem which didn't change. But, yeah, they are not interchangeable.

The prepaid replacement is for 53kwh. This is from memory but I think there were a bunch of T&C's with the replacement:

1. If a replacement is requested before year 7 owner pays 2k/year
2. Owner gets 1k/year after year 8 but before year 10
3. The replacement must be requested after the expiration of the warranty but before the 10 year anniversary of the sale of the vehicle
4. The battery replacement request can only take place after the warranty expires

You're close! It's confusing because of how the years are referenced and the contract actually contradicts itself.

1. Owner pays 2k/yr if replaced before year 7. Earliest allowed is year 4 with a 6k payment.
​

2. Refund of 1k/yr after year 7 until the end of year 10. So if you replace on the last day of year 10 you get 3k refund. But here's the catch: Year 10 starts on the 9th anniversary of when you bought the car, and ends the day before the 10th anniversary. Here's the contradiction in the contract: It includes a chart that specifies you have to exercise the option before the 10th anniversary, at which time you will get a replacement ESS and 3k. The language states that you have until "no later than the 10th anniversary" of the delivery date. One day diff.​

Several people have wondered if you get a new ESS or refurbished. The contract states only that you will get a 53 kWh ESS and you have to give Tesla your existing ESS. They only describe it as a "replacement" without specifying new, used, or refurb. Presumably they could replace it with used Model S cells that have degraded to about 70% of their original capacity. In fact I fully expect them to do that. I'm still not sure if that's a good or bad thing for me! And of course they will have upgrades for a price. That's a good thing!

 

[asgard]

The R&D involved in using a different battery type is pretty significant. The charging algorithms may be copied over from the MS but would require significant tuning for all the modes: storage, standard, range. Same goes for battery health monitoring and safety checks. This is not the kind of thing a manufacturer would take lightly since they are liable if bricking occurs for any reason other than owner negligence.

Secondly, the testing and certification of expected mileage will require a lot of runs. A manufacturer would have to stand by any claims of mileage so extensive track and road testing would have performed.

Elon's comment seems like an off-the-cuff remark he just threw out there. I'm not convinced a battery upgrade is what will come of it, though I'd be ecstatic if it did.

 

[Vger]

My perfect outcome would be a combined increase in range and decrease in weight. Having the range extended to even comparable to Model S 85 would be great, but I think a significant decrease in weight would make the car much more suited to its Lotus DNA-- that is, a total blast to fling around the twisties!

 

[PRJIM]

The R&D involved in using a different battery type is pretty significant. The charging algorithms may be copied over from the MS but would require significant tuning for all the modes: storage, standard, range. Same goes for battery health monitoring and safety checks. This is not the kind of thing a manufacturer would take lightly since they are liable if bricking occurs for any reason other than owner negligence.

Secondly, the testing and certification of expected mileage will require a lot of runs. A manufacturer would have to stand by any claims of mileage so extensive track and road testing would have performed.

Elon's comment seems like an off-the-cuff remark he just threw out there. I'm not convinced a battery upgrade is what will come of it, though I'd be ecstatic if it did.

The other question I have is about homologation. Would a change in the battery pack require Tesla to certify the pack by crash/other testing Roadsters? As an OEM I believe this may be the case.

 

[pharma5]

The other question I have is about homologation. Would a change in the battery pack require Tesla to certify the pack by crash/other testing Roadsters? As an OEM I believe this may be the case.

I think it's been suggested that crash testing would not be required for weight-neutral change (<a certain numbers of lbs different) of same architecture (form factor, connections, fixation means, etc.) but would be interested if someone has detail on it. The simple scenario of this poll is essentially weight-neutral (same count of newer cells).

 

[dhrivnak]

I too would prefer less weight and a lower center of gravity. A lighter battery pack would also yield a more balanced car. I can't afford to lose range but 250 miles I can live with.

 

[pharma5]

The R&D involved in using a different battery type is pretty significant. The charging algorithms may be copied over from the MS but would require significant tuning for all the modes: storage, standard, range. Same goes for battery health monitoring and safety checks. This is not the kind of thing a manufacturer would take lightly since they are liable if bricking occurs for any reason other than owner negligence.

Secondly, the testing and certification of expected mileage will require a lot of runs. A manufacturer would have to stand by any claims of mileage so extensive track and road testing would have performed.

Elon's comment seems like an off-the-cuff remark he just threw out there. I'm not convinced a battery upgrade is what will come of it, though I'd be ecstatic if it did.

All good points. Again, this is a hypothetical 80 kwh pack to gauge interest/attitudes on circumstances for swap, timing, and cost (qualitative). No proof it exists.

We have a prior poll question asking what the 2014 "pretty cool" surprise for Roadster owners will be. Most have indicated they think it is (or maybe just want) some type of battery upgrade.

- - - Updated - - -

I too would prefer less weight and a lower center of gravity. A lighter battery pack would also yield a more balanced car. I can't afford to lose range but 250 miles I can live with.

Hey DH! I think you have a lot of company on that. The hypothetical pack in this poll is not really for you then, but would be interested in how you'd respond to it if it's the only one out there.

(I intend to post another question fairly soon about pack upgrade preferences given all the comments on this one... unless people get sick of polls...)

 

[Tesla 940]

same # of cells = MORE weight

The simple scenario of this poll is essentially weight-neutral (same count of newer cells).

I believe the new cells - any new cells - are heavier than the cells used in the original Roadster - therefore the same number of cells would result in a noticeable increase in weight. For the car to remain weight-neutral the number of cells would have to be reduced which would increase range and lower the center gravity.

 

[pharma5]

I believe the new cells - any new cells - are heavier than the cells used in the original Roadster - therefore the same number of cells would result in a noticeable increase in weight. For the car to remain weight-neutral the number of cells would have to be reduced which would increase range and lower the center gravity.

Well, that changes the write-up a bit. Didn't intend absolute weight neutrality (maybe +10-100 lb) but it sounds like we're looking at more than that?

Need to have this straight for any future questions - thanks.

 

[strider]

I've basically given up on trying to "fix" the Roadster since they long-rumored "sub-3-second" car and all the other promised upgrades never materialized. Bring on the P+ version of Gen-3 with AWD which will crush the Roadster in every category and I could even use the phone while driving.

 

[FANGO]

Completely uninterested in 80kwh. Why do I need to go 400 miles? This is total overkill, unnecessary, insane.

I would much prefer a 50kwh pack which is much lighter. This would actually improve range (even though I don't need or want an improvement), but more importantly would improve handling and acceleration. And braking, and tire wear, and efficiency. PLEASE don't give us an enormous pack which weighs the same and has more range than anyone needs. The car is too heavy as it is.

 

[pharma5]

Well, that changes the write-up a bit. Didn't intend absolute weight neutrality (maybe +10-100 lb) but it sounds like we're looking at more than that?

Need to have this straight for any future questions - thanks.

Ok, did a bit of checking on cell weight on Panasonic site to put some back-of-the-envelope, ballpark numbers on this:
http://industrial.panasonic.com/www-cgi/jvcr21pz.cgi?E+BA+4+ACA4001+4++WW

Let me note up front I don't have exact cell models and specs, but I believe the Roadster cells were ~2200 mah and Model S is using something custom at ~3100 mah.

A good comparison might be NCR18650E (2250 mAh typical capacity, 44 g mass) and NCR18650B (3350 mAh typ, 47.5 g), a bit past the Model S cells but not the 4000 mAh that seems to be newest on the market. For ~1.49X multiple on nominal capacity, it's +3.5g per cell. For 6831 Roadster cells, that rounds up to 24 kg or ~53 lbs. For Roadster curb weight of 2723 lbs, adding that weight leads to 2% increase.

I think this is probably ok for what I'd call the "range-first" segment of users, as it's much less than adding an adult passenger with you. Within the realm of current driving experience. And if it lowers dev cost, that was kind of the intent of this poll scenario. (That and potentially making EV history a second time with TSLA's first car -> longest EV range).

Now I totally understand how that does nothing for users in the "handling-first" segment. Crudely flipping the math, maybe (?) a 4600 count of the 3350 mAh cells would give similar nominal capacity as 6831 of 2250 mAh. That would drop 82 kgs or 181 lbs, about 7% of total weight. Useful info for next poll...