Presumably the current Roadster uses the same battery tech (or worse) than the 40kWh Model S battery, so it's hard to believe it couldn't handle fast discharge.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
LuckyLuke
Model S P90DL
Maybe that assumption is not correct, since most people will charge to full capacity if they know they are going to drive a far stretch.
For myself personally: I usually know at least a day ahead how much distance to travel the next day, so I would always charge using range mode if needed.
PS: Thanks for the numbers, very enlightening.
Last edited:
WhiteKnight
_____ P85 #549 _____ Sig Red / Sig White
WhiteKnight
_____ P85 #549 _____ Sig Red / Sig White
Until the pack is 6-9 years old and then you need them 50 miles apart because you've lost one-third of your battery capacity.
Thanks for all the numbers!
Norbert
TSLA will win
It's the same thing as with supercharging: The fact that the larger packs can more easily support common use, which leads to the longer mileage in the warranty, means that it gives Tesla more space in balancing battery life with how much high-C-rate use they can allow.
Norbert
TSLA will win
Especially since then you'll need to recharge much more frequently which means additional stress for the battery (which has a shorter life and more stress anyway).
As someone pointed out somewhere, the number of cells in the battery will be the main factor that determines how quickly the power can come out. The 40kWh battery will have less of the same cells than the roadster (53-57kWh)...
The Model S is a much bigger, heavier vehicle. Roadster 56kWh pack is 1.4x bigger than 40kWh, so 3.9s turns into 5.5s before thinking about how extra weight will slow you down even more.
(Edit: I see others made the same point while I was working on my post...)
Just to add a bit of math to explain the difference in performance imposed by pack limits.
Roadster is rated at 288hp(215kW)
Using a pack size of 53.75 kWh and 100% efficiency results in a 4C discharge rate.
So Model S power available per pack size at the same C rate is as follows:
40kWh = 214hp (160kW)
60kWh = 322hp (240kW)
85kWh = 456hp (340kW)
Roadster is rated at 288hp(215kW)
Using a pack size of 53.75 kWh and 100% efficiency results in a 4C discharge rate.
So Model S power available per pack size at the same C rate is as follows:
40kWh = 214hp (160kW)
60kWh = 322hp (240kW)
85kWh = 456hp (340kW)
stopcrazypp
Well-Known Member
I figured we would have this issue back in the discussion about Model S horsepower, a couple of months ago:
http://www.teslamotorsclub.com/showthread.php/6421-Horsepower?p=85161&viewfull=1#post85161
I was already wondering how Tesla can maintain the same HP for all three models given the pack size of the base model is relatively low. I assumed maybe the lower weight would help, but I guess not.
Where is that ultra-cap front end buffer when you need it?
Well, I guess the point of the small pack is entry level pricing, so it would probably be cost prohibitive even if technically possible.
I guess they have room in the pack for more cells, so maybe it would have made sense to use more power dense, but less energy dense cells?
I wonder what it would be like if they filled a ModelS tray with A123 cells?
Well, I guess the point of the small pack is entry level pricing, so it would probably be cost prohibitive even if technically possible.
I guess they have room in the pack for more cells, so maybe it would have made sense to use more power dense, but less energy dense cells?
I wonder what it would be like if they filled a ModelS tray with A123 cells?
stopcrazypp
Well-Known Member
The GM Volt has a ~600lbs pack with nominal capacity of 24kWh and accessible capacity of 16kWh. The Volt is $40k, the Cruze is $17k. I attribute $15k to the pack and $8k to the hybrid drive train components.
I figure you can stuff a little more weight into Model S, let's say 800lbs. Nominal capacity would increase to 32kWh, the accessible capacity to 20kWh. Pack cost to $20k That pack could deliver a helluva lot of power, perhaps 600kW, and deal with severe quick charging ~150kW. But the pack is very expensive and range would be around 100 miles.
You get a 100 miler for $50k. That's not the points towards Tesla is engineering their cars.
A123 cells are not for laptops but for cordless tools
smorgasbord
Active Member
Anyone know what the curb weights of the Model S with its various battery packs are? We heard 3825lbs, but that's got to be the 40kWh pack version. What about the 60 and 85 kWh packs?
NigelM
Recovering Member
It's like they took a poll by the Tesla HQ water cooler and summarized the results as "4000 lbs., margin of error 1000 lbs."
WhiteKnight
_____ P85 #549 _____ Sig Red / Sig White
Yes, since the 40 kWh pack has less cells in it that must account for the 3,825 figure and then the "just over 4,000 pounds" comes from Elon.
I think the 40 kWh pack has 2/3 the cells of the 60 kWh pack. If the big pack is 1,200 then the smaller pack is probably 800 for a difference of 400 pounds.
3,825 + 400 = 4,225 which would still be low enough for Elon to say "just over 4,000 pounds."
The 4,900 figure is clearly wrong although it has been mentioned in more than one place. For comparison's sake a BMW 528i weighs 3,814 pounds.
I think the 40 kWh pack has 2/3 the cells of the 60 kWh pack. If the big pack is 1,200 then the smaller pack is probably 800 for a difference of 400 pounds.
3,825 + 400 = 4,225 which would still be low enough for Elon to say "just over 4,000 pounds."
The 4,900 figure is clearly wrong although it has been mentioned in more than one place. For comparison's sake a BMW 528i weighs 3,814 pounds.
Similar threads
