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Roadster 3.0

scaesare

Well-Known Member
Mar 14, 2013
8,189
12,930
NoVA
No production Roadster is 2.4 Ah.

Has that been officially sourced anywhere?

We KNOW the Roadsters 56kW pack is comprised of 6,831 cells. That's 56,000W / 6831 = 8.2W per cell.

With a nominal voltage of 3.7v, that's 8.2W / 3.7v = 2.2Ah per cell. Even if they used a nominal voltage of 3.6v, that's still only 2.3Ah per cell.

In either case, specifying cells with 31% greater capacity gives you only 2.9 or 3.0 Ah per cell for the new roadster pack. Neither are of the capacity of the Model S cells.
 

dpeilow

Moderator
May 23, 2008
9,151
888
Winchester, UK
So going back to the old efficiency and range graphs, allowing for better aero and rolling resistance we're still looking at speeds under 45 mph for this trip.

The source of 2.4Ah cells was Martin Eberhard. We've been around this many times in the last 6 years.

GSP said:
It looks like the Roadster is using 2400 mAh cells. From Martin Eberhard's blog, in respone to a 17Dec2008 comment by dpeilow:

Martin sez:

Yes, I don’t know where this 2200 mAh number came from. True, in the early days of Tesla, this was state of the art. But my car is built with 2400 mAh cells, and 2600 mAh cells are the jellybean cells today. As you say, higher-capacity cells are already on the market.

Tesla Founders Blog (http://www.teslafounders.com/)
 
Last edited:

AndrewBissell

Member
Apr 16, 2009
645
3
Roadster 3.0 *prototype* confirmed

After Elon's Christmas Day tweet, this blog has just gone up on Tesla's website:

Roadster 3.0 | Blog | Tesla Motors

it confirms some details including a 31% improvement in battery capacity, aero and rolling resistance improvements and a planned 400 mile test run in early 2015.
 

JRP3

Hyperactive Member
Aug 20, 2007
19,432
42,585
Central New York
Over thinking it, but:

We have identified a new cell that has 31% more energy than the original Roadster cell.

The original cell was a 2.2 ah cell, maybe that's what they are comparing it to? And that wording is odd, We have identified a new cell, haven't they been using it all along in the Model S? Is the "new cell" just slightly lower yields of S cells?
 

Johan

Ex got M3 in the divorce, waiting for EU Model Y!
Feb 9, 2012
7,465
9,506
Drammen, Norway
Hmm... The S85 can do 400 miles too, "under certain driving conditions". Just ask dhanson(?) and his son in Florida...

I hope they don't limp from SF to LA. It will look bad...
 

JRP3

Hyperactive Member
Aug 20, 2007
19,432
42,585
Central New York
You should learn to recognize sarcasm

Or you should learn to be more sarcastic. :wink: They seem to be using a cell with close to or under the energy density of the Model S cell. Not sure what's so "new" about that, but yeah, I guess it's an awesome new cell with the same specs as the old Model S cell, or maybe not quite as good.
 

Crowded Mind

Member
Oct 26, 2014
651
1,731
United States
Can't imagine the logic behind doing a run at significantly less than the speed limit and making it a public event. I would be shocked if that was their plan. If real range at normal speeds was only like 340 miles, they would demonstrate that somewhere else instead of limping a performance vehicle through a slightly longer route. My prediction is that the 3.0 will make the drive near the speed limits.
 

dpeilow

Moderator
May 23, 2008
9,151
888
Winchester, UK
If it's the new BF cell with the silicon anode then it has higher power output and less weight than the B version. Maybe that is what they have "identified" and it is needed for the Roadster.

https://www.akkuteile.de/tpl/download/NCR-18650BF.pdf
- - - Updated - - -

Can't imagine the logic behind doing a run at significantly less than the speed limit and making it a public event. I would be shocked if that was their plan. If real range at normal speeds was only like 340 miles, they would demonstrate that somewhere else instead of limping a performance vehicle through a slightly longer route. My prediction is that the 3.0 will make the drive near the speed limits.

Impossible if they need to hit ~180 Wh/mile. It will be limping. At least on Highway 1 it will be closer to normal speed.

Elon's backed himself into a corner with the SF to LA claim.
 
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jdevo2004

Member
May 23, 2012
225
72
Not sure why you think they'd us a Samsung cell when they can get better cells from Panasonic, plus the fact that the cell you specify doesn't meet the posted specs from Tesla.

Tesla also gets its cells from Samsung. The posted specs is 70kWh. 6831cells x 2.85ah x 3.6V = 70kWh. As for aggressiveness with thermal management, maybe that was the wrong word, a better word is responsiveness.
 

Jackyche

Member
Sep 30, 2012
319
2
Seattle
So a new aero kit would involve just the bumper? Cuz if it's anything hood/body panel, that's carbon fiber stuff, that's big bucks. "Just the battery please".
 

scaesare

Well-Known Member
Mar 14, 2013
8,189
12,930
NoVA
The source of 2.4Ah cells was Martin Eberhard. We've been around this many times in the last 6 years.

Well, forgive me for not having been around 6 years ago. And that blog page no longer exists.

So how is it the Roadster has a 56kW pack, yet at nominal 3.6v using 2.4Ah cells = 59kW, and 2.6Ah cells =64kW?

If the voltage is a nominal 3.7v you get either a 61kW or a 66kW pack.

How do the numbers jive for those cell capacities?
 

heems

Member
Jan 10, 2011
309
267
San Diego
Disclaimer - I am not a Roadster owner. Having said that I don't understand the lure of more range with respect this specific car. Looking at the purpose and function of the Roadster, isn't performance the desired attribute? Can one (or would one want to) even sit in the roadster for 5-6 hours nonstop between LA-SF? To me it feels like Tesla is doing a magic trick - distracting with the 400mi talk - while behind the scenes/quietly working on the performance (i.e. acceleration) figures. Is it unreasonable to expect that 3.0 will have awesome/super car 0-60 #s with the new pack and that's the real news?
 

AltPowr

Member
May 21, 2010
262
125
Moorpark, CA
For those of us that do this trip several times a year, the only real way to go is I5. Highway 1 is much longer in miles and time, though a much nicer route.
 

dpeilow

Moderator
May 23, 2008
9,151
888
Winchester, UK
Well, forgive me for not having been around 6 years ago. And that blog page no longer exists.

So how is it the Roadster has a 56kW pack, yet at nominal 3.6v using 2.4Ah cells = 59kW, and 2.6Ah cells =64kW?

If the voltage is a nominal 3.7v you get either a 61kW or a 66kW pack.

How do the numbers jive for those cell capacities?

It's been repeated a few times since and I'm not having a go at you, but it is a pity the same things resurface.

There was much speculation back then that the capacity increased to 59 kWh but usable remained at 53.
 

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