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. :biggrin:

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

 

[WarpedOne]

That should be exciting. Given the Model S uses 3100mah vs the 2400mah cells in the Roadster, they can either:
1) Keep the same number of cells and get 1.29x the capacity (72kWh) and power (only useful if they upgrade the firmware/motor/power electronics to use it).
2) Keep the same capacity and use less cells, shaving 22.6% the cell weight (~150lbs) and volume (plus whatever overhead).

No, they can and I am sure they will do some of BOTH i.e. reduce the number of cells for about 10% and still make a pack with a bit higher capacity, power and lower weight. It will have better acceleration, lower average power (less prone to overheating) and better range at lower price than full option 1.

 

[frequencydip]

No, they can and I am sure they will do some of BOTH i.e. reduce the number of cells for about 10% and still make a pack with a bit higher capacity, power and lower weight. It will have better acceleration, lower average power (less prone to overheating) and better range at lower price than full option 1.

I really don't think they are going to produce multiple battery upgrade options. there are 2400 cars and only a small portion will need an upgrade in the next few years, the R&D in one updated pack will already be allot. I'm sure they will again redesign the packs in another 5-10 years with the latest cell tech available. The thing that is unique about the Roadster and hopefully Tesla is the idea of these cars are not disposable, and that they can go on forever. When many of our car interiors are shot I'm sure they will offer a seat upgrade, a dash board upgrade etc. The Roadster is a much simpler car when it comes to parts it so easy to replace anything except the frame.

My personal hopes for a battery upgrade is a little bit of everything, but in the following order.
1) less weight
2) more acceleration
3) more range

The less weight is really important, it effects everything else; acceleration, handeling, range, tire wear, stopping distance etc. Dropping 150lb is huge, I can really feel the difference of the cars abilities when I have a passenger in the car, imaging that difference when basically dropping the weight of the driver...

 

[hcsharp]

I wish Tesla would wait another couple of years, so that battery technology can improve even more. Right now there aren't many Roadsters that need new packs.

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 agree with the option choices. It probably wouldn't be much work to offer it for a lot of money now to those who want it. That won't prevent them from improving it continuously so when the rest of us are ready in a few years, it will be even better and cheaper.

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.

Just curious Kevin, what would be a reasonable price to pay for a 17kw 3-ph charging upgrade on the Roadster?

 

[Kevin Sharpe]

Just curious Kevin, what would be a reasonable price to pay for a 17kw 3-ph charging upgrade on the Roadster?

On it's own I'd probably pay $5k. However, combine it with a significant range increase then I'd pay a lot more.

Dream scenario would be 43k 3 Phase and 320+ miles because I could then drive anywhere in Europe.

 

[Eberhard]

On it's own I'd probably pay $5k. However, combine it with a significant range increase then I'd pay a lot more.

Dream scenario would be 43k 3 Phase and 320+ miles because I could then drive anywhere in Europe.

I fully agree with you Kevin. Even 22kW 3 Phase would be fine or DC charging like Model S (or both) then the current range would be sufficient.

 

[Raffy.Roma]

I wish Tesla would wait another couple of years, so that battery technology can improve even more. Right now there aren't many Roadsters that need new packs.

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 would prefer option 1. But what would happen if somebody gets the second battery replacement option now and then a new battery for Roadster based on Model S cells would come out? Would he get automatically the new battery or should he pay extra money to get it?

 

[pharma5]

The thing that is unique about the Roadster and hopefully Tesla is the idea of these cars are not disposable, and that they can go on forever.

I am definitely in that boat: http://www.teslamotorsclub.com/showthread.php/12697-Roadster-s-Future/page4:biggrin:

If there is a macro upgrade in the works, I am very curious about the possibility of designing in supercharging capability, perhaps at same nominal range with other improvements mentioned on this thread (lower weight via fewer & newer cells, better cooling, effectively better performance...). Would also give faster recharge option (!) + effective range via supercharge network.

All that rolled up with a fresh "powertrain" warranty might snag a nice price tag. But what would it take - a fresh look at ESS, PEM, and motor?

If it's a straight pack upgrade, I vote for max range (e.g., same number of the newest cells). And HPCs at the supercharger sites.

 

[smorgasbord]

With so few cars on the road, I want Tesla to choose carefully what they do. Doing battery upgrade now means just a minor improvement, whereas waiting for Gen-III type batteries should bring cost down and capacity up and, maybe most important of all, reduce the center of gravity so that car handles more like a real Lotus. It's not just the weight, it's the distribution of weight, and in Roadster some of the battery pack is up pretty high.

Water cooled PEM and motor is, of course, something that would be a really big benefit, and I would assume that engineering work could be done now. I recommend that, plus a brake upgrade and then a few years down the road take on the battery.