Potential battery pack upgrade for Roadster using Model S cells

[VolkerP]

Sorry but I disagree... I want Tesla to give us lots options... some wealthy early adopters will buy on day one and others will buy later.

Yup. Give a 320+ mile range pack to Hans-Jörg von Gemmingen and he will complete the 200k miles within the next 3 months -- he's already beyond 150k miles with his Roadster / 125k miles on the battery pack.

Source: Tesla-Fahrer und -Freunde Forum Forumskilometerzähler...

[Tesla 940]

I would hope that Tesla would have two options:
1) More Range, same pack size/weight
2) Same Range, less weight and that weight set as low as possible in the car.

I thought I read that the new cells, while the same size, weigh more - so "More Range, same pack size..." gets you MORE weight. "Same Range..." gets you slightly less weight but does/should get you a lower COG.

Can't have your cake and eat it too - at least not at this time.

[stopcrazypp]

I thought I read that the new cells, while the same size, weigh more - so "More Range, same pack size..." gets you MORE weight. "Same Range..." gets you slightly less weight but does/should get you a lower COG.

Can't have your cake and eat it too - at least not at this time.

The new cells only weigh 1.5 grams more than the standard lower capacity versions. For 6831 cells, that's 10.2kg/22.5lbs more weight. Hardly noticeable.

On the other hand, a pack with the same capacity as the old Roadster will save ~150lbs in cell weight alone (plus whatever overhead that is removed from having less cells).

[dsm363]

Would people really pay $20k or more for same battery pack capacity but 150lb less weight? You'd be slightly quicker but sounds like they are addressing that with better motor...etc. I think the added range with the other speed upgrades will be a nice upgrade.

[widodh]

Would people really pay $20k or more for same battery pack capacity but 150lb less weight? You'd be slightly quicker but sounds like they are addressing that with better motor...etc. I think the added range with the other speed upgrades will be a nice upgrade.

You never know, I doubt it however.

More range is always better, so yes, that would be nice.

Interesting though, if new packs come out, how long will the car itself survive? Will we see Roadsters driving around in 25 years?

Wonder how the interior and all holds out, I think that will wear out first.

[richkae]

Would people really pay $20k or more for same battery pack capacity but 150lb less weight? You'd be slightly quicker but sounds like they are addressing that with better motor...etc. I think the added range with the other speed upgrades will be a nice upgrade.

A pack made with 3400 mAh cells vs 2200 mAh cells but using 1/3 less will make a pack with about 3% more capacity.
It should weigh 210 pounds less in pure cell weight - but about 250 - 300 pounds less depending on how much they can save by eliminating interconnects and all the other stuff to support connecting, cooling and holding the 2277 missing cells.
( Saving 250-300 pounds will add some range - maybe 5% but likely much more during high performance driving with lots of accelerating )

I assume that an 85+kWh Roadster pack ( made with 6831 of the 3400mAh cells ) would offer more range, but very little additional performance with the current PEM and motor because they can't handle more power.

If they offered the new lighter same power pack today for $20k it would be likely be a no for me, because my pack is within about 2 or 3% of new right now - and that would feel like wasting $20k.

However if my pack needed to be replaced today I would want the lighter one for sure - because I want more performance, not range. My Model S will be my long distance drive car. If you take your Roadster to the racetrack, your time on the track is not limited by your battery size, it is limited by your recharge rate ( ignoring the motor heat issue ). With 85kWh you'd get longer sessions, but then you would be plugged in longer.

From another angle:
If Tesla gave me two options that had the exact same acceleration:
a) 300 pounds lighter
b) same weight, enough additional power to be the same as (a)
But option b was longer range and cost more, I would absolutely choose option a - because 300 pounds lighter will be faster around the track because it will brake better and corner better.

Lastly:
All of this could change if I have a more powerful water cooled PEM and motor in my Roadster. Then additional battery power would not be wasted and I would have to weigh the options again.

[dsm363]

I think a big battery upgrade is really only worth it (for me that is) if it comes with upgraded motor/liquid cooled PEM. Some additional range would be nice too (maybe 225 miles driving at 65mph with AC on) and the added acceleration would be a bonus. Everyone is going to want different things so if two options existed, that would be idea.

[TEG]

With my old Ford Ranger EV, a battery refurbishment business would take old/half-dead packs from out of service vehicles, and "remanufacture" refurbished packs from what cells could be salvaged.
I suppose they could do something like that for Roadster too... Getting bits from various packs that were replaced (for whatever reason) and making some cheap replacement packs that don't have the full capacity of a brand new pack.
That would be useful in the long term for people who are trying to keep a Roadster going on a limited budget.

[dsm363]

A 'price per battery brick' update. That might work too.

[strider]

I'd like more range and performance vs weight savings. I don't track my car and it handles just fine for my driving. But more range and acceleration will always be welcome. But I'll wait until this battery wears down. Have to absorb the cost of a Perf Model S into the vehicle budget soon (and possibly an electric motorcycle) and will need some time to recover :P