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New Roadster Goodies for 2014
- Thread starter hjr
- Start date
JRP3
Hyperactive Member
JRP3
Hyperactive Member
felixtb
RsEU502,Sp+14274,XpEUSig4
IMHO there's too much IP in the Roadster (as well as dangerous voltages) to encourage people to get their hands dirty for now. Give it 5 years though and I bet we'll have one. I get occasional pages from the service team in the UK as it is cheaper to have me fix the car than to fly someone down. I prefer it that way too frankly... I can now adjust to perfection the windows and the trunk locks plus replace the 12V battery and cooling fans
Buddies in Tesla CA have told me to expect liquid cooling for the PEM and motor, and a sub-3 second 0-60 time, but at a price of $30k. Is that old news? I don't know.
+1 on the battery upgrades. The car is awesome enough and with a reasonably priced new battery with greater range it would feel like new. The same charging electronics as the S would by fantastic (supercharging and 3-phase charging in the EU... oh yeah!).
+1.
dhrivnak
Active Member
The Roadster is no more dangerious than a gasoline car and in all likley hood less dangerious. Yes one must be careful around high voltage but sometimes one wants to buy new lift gate cylinders, or redo the brakes, or rework the hood release latch. They all now require a call to the Rangers who are VERY busy. They do not have to release the details of the PEM and battery but let us at least change our tires or get alignment specifications.
I have had a shop manual for ALL of my cars and the Roadster is the first car I am not able to get such a manual.
I have had a shop manual for ALL of my cars and the Roadster is the first car I am not able to get such a manual.
I'm not sure that the argument that having a lighter battery means greater acceleration is correct.
If you look at what the Roadster does as it accelerates to 60 mph, it's doing two things. Up to about 40mph, it's got constant torque (= constant acceleration) and power that increases linearly with speed. This is limited by the PEM and motor. It's better here in the Roadster Sport than in the base Roadster. At around 40mph (and a little slower for the Sport because of the greater torque) it hits the power limit of the battery pack. From there on out, it has constant power and linearly decreasing torque. (Way above 60 mph this drops superlinearly as inefficiencies in the high-RPM behavior of the motor kick in, but I'm just going to ignore > 60 for now).
The power limit is, roughly, the max power per cell times the number of cells. Hence, if you have more cells, you have more power and the point at which you shift from constant torque to constant power gets higher. This, in turn decreases your 0-60 time. Of course, there's a tradeoff as the mass of the battery is increased, and the acceleration goes inversely with the mass. So the question then becomes whether the increased power can overcome the increased mass.
In the Model S, at least, the tradeoff between increased power and increased mass is firmly on the side of higher power & higher mass. That's why the 85 kWh version accelerates quicker than the 60 kWh version, which in turn is quicker than the 40 kWh would have been had they built it.
So, I don't really understand why everyone here is assuming that it would be opposite for a Roadster with new cells and lower power/lower mass would win. Are people assuming that the PEM/motor can't handle higher power even if the pack could deliver it? That might be the case, but it's not obvious to me that it is so (and even if it is, Tesla might offer upgrades to the rest of the powertrain, too).
If you look at what the Roadster does as it accelerates to 60 mph, it's doing two things. Up to about 40mph, it's got constant torque (= constant acceleration) and power that increases linearly with speed. This is limited by the PEM and motor. It's better here in the Roadster Sport than in the base Roadster. At around 40mph (and a little slower for the Sport because of the greater torque) it hits the power limit of the battery pack. From there on out, it has constant power and linearly decreasing torque. (Way above 60 mph this drops superlinearly as inefficiencies in the high-RPM behavior of the motor kick in, but I'm just going to ignore > 60 for now).
The power limit is, roughly, the max power per cell times the number of cells. Hence, if you have more cells, you have more power and the point at which you shift from constant torque to constant power gets higher. This, in turn decreases your 0-60 time. Of course, there's a tradeoff as the mass of the battery is increased, and the acceleration goes inversely with the mass. So the question then becomes whether the increased power can overcome the increased mass.
In the Model S, at least, the tradeoff between increased power and increased mass is firmly on the side of higher power & higher mass. That's why the 85 kWh version accelerates quicker than the 60 kWh version, which in turn is quicker than the 40 kWh would have been had they built it.
So, I don't really understand why everyone here is assuming that it would be opposite for a Roadster with new cells and lower power/lower mass would win. Are people assuming that the PEM/motor can't handle higher power even if the pack could deliver it? That might be the case, but it's not obvious to me that it is so (and even if it is, Tesla might offer upgrades to the rest of the powertrain, too).
JRP3
Hyperactive Member
If the new cells have greater capacity than the old cells but still have at least the same C rates then each new cell can put out more power than each old cell, so you could get a better power to weight ratio. If the new cells also have a higher C rate as well as greater energy density the power to weight ratio increases even more.
Raffy.Roma
Rome (Italy)
I also would like Tesla taking back the old battery and value them according to their degradation so that the Roadster owner should pay the difference to get the new battery pack.
What do you guys think about this?
JRP3
Hyperactive Member
Raffy.Roma
Rome (Italy)
Most important thing is that Tesla will accept the trade in of the old battery pack for the new battery pack by giving the market value to the old battery pack. Do you think that Tesla will do this?
JRP3
Hyperactive Member
I'd expect them to give something below market value so they can recover handling costs plus make a profit.
Raffy.Roma
Rome (Italy)
Couldn't it also be that an upgraded battery pack will use newer cells than those of the S? E.g. The cells the gen 3 will be using? I think the roadster is kind of a good test bed for newer technology. If something fails it won't hurt Tesla too much if it needs replacing.
Wouldn't such a cell more likely be in the 4000mAh area?
Wouldn't such a cell more likely be in the 4000mAh area?
Raffy.Roma
Rome (Italy)
Good idea
I read that Tesla is developing a new battery pack for Model X based on new cells. So Tesla could do the same thing for the Roadster.
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Agree this is the ideal mix for upgraded pack! But Tesla can damn well give 2400 Roadster owners who helped get the company rolling, free access to use the Supercharger Network! That would cost them close to nothing as most Roadsters probably see at most 2 or 3 long trips in a year.
Raffy.Roma
Rome (Italy)
But I think that is obvious that in case of battery upgrade for the Roadster also Supercharger free access will be available for owners upgrading their Roadster.
True problem is when Supercharger network will be placed in Italy?
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