It's the Batteries, Stupid! - Page 8

malcolm · 01-03-2009, 12:11 PM

Quote:

Originally Posted by Joseph

If the amph if the batteries they are using has risen, why hasn't range also?

The original figure is still far ahead of anything else and they may want to save the announcement of a large jump over previously published figures for Powertrain 2.0.

Particularly as there will probably be a price premium on the new battery pack

dpeilow · 01-03-2009, 01:01 PM

Quote:

Originally Posted by Joseph

If the amph if the batteries they are using has risen, why hasn't range also?

Are they going to be using higher capacity batteries every year?

As GSP mentions above, Martin said to me on his blog that his car is built with 2400mAh cells.

Remember when the production cars first came out, the quoted EPA range went from 224 to 244 miles? Multiply 224 by 24/22 and see what you get. I think this is your improvement in range.

As for higher capacity every year - I guess it depends on what the current 'sweet spot' battery is and how often that is changing.

WarpedOne · 01-03-2009, 02:32 PM

Quote:

Remember when the production cars first came out, the quoted EPA range went from 224 to 244 miles? Multiply 224 by 24/22 and see what you get. I think this is your improvement in range.

I don't think so. Tesla first said that the ESS holds 55kWh then they lowered that number to 53kWh where it is still today. If the increase in range came from better batteries they would probably admit the ESS now holds around 10% more or around 60kWh. But they never have said anything like that. Minimum charging time would also increase by at least 10% but they still claim it to be 3,5h like in the start. On the other hand they still publish old torque curve and old max power. I wish for more up-to-date data.

Cobalt LiIon cells have typical voltage of 3.7 volts. If they are using 2400mAh cells, the ESS now stores up to 6831 * 3,7 V * 2,4Ah = 60 kWh.

JRP3 · 01-03-2009, 03:41 PM

Another possible use of the larger battery would be to extend pack life by having shallower discharges. So if they treat the pack as if it's smaller than it is and keep the range the same then the discharges aren't as damaging.

graham · 01-03-2009, 07:14 PM

Quote:

Originally Posted by JRP3

Another possible use of the larger battery would be to extend pack life by having shallower discharges. So if they treat the pack as if it's smaller than it is and keep the range the same then the discharges aren't as damaging.

Brilliant thought, actually.

Joseph · 01-03-2009, 08:38 PM

"Remember when the production cars first came out, the quoted EPA range went from 224 to 244 miles? Multiply 224 by 24/22 and see what you get. I think this is your improvement in range."

Maybe.

The EPA range first was reduced, but not finalized. That was way back in Martin's blog (Martin was still there!) "range reality." Then, there was a mistake. Wikipedia reminds us, (I checked Wiki's sources.)

"The EPA range of the car was also restated from 245 miles (394 km) down to 221 miles (356 km). The downward revision was attributed to an error in equipment calibration at the laboratory that conducted the original test.[25][3][26]"

And then it was changed once again to the current 244 when the car chagned to powertrain 1.5.

Anyways, back on topic. I don't think the battery change could've been when the range went from 220 something to 244 (that was the powertrain 1.5 change) because Strauble says on the Tesla blogs,

"NO changes to the battery pack"

And I didn't bold the word "no". But you might be right that the batteries were changed during one of the many range figure changes (that we know of).Or the batteries' amph could've gone up but range kept the same to accommodate battery life, as JRP3 said. Questions...

TEG · 01-04-2009, 02:01 AM

With all the recent talk of ESS capacity, it might be worth checking out this old topic:

ESS: 53kWh or 56kWh

GSP · 01-04-2009, 04:03 AM

Quote:

Originally Posted by WarpedOne

On the other hand they still publish old torque curve and old max power. I wish for more up-to-date data.

Cobalt LiIon cells have typical voltage of 3.7 volts. If they are using 2400mAh cells, the ESS now stores up to 6831 * 3,7 V * 2,4Ah = 60 kWh.

I think you are right on the money about Tesla not keeping published specs up to date.

Note that your 60 kWh calculation is very close to the most recent spec of 59 kWh, published in R & T. Tesla probably gave R & T the correct, up to date, value, but doesn't have the manpower to *find* all the specs on their website, much less update them!

GSP

malcolm · 01-04-2009, 06:08 AM

Quote:

Originally Posted by JRP3

Another possible use of the larger battery would be to extend pack life by having shallower discharges. So if they treat the pack as if it's smaller than it is and keep the range the same then the discharges aren't as damaging.

Isn't this already implemented with the option to switch between the Standard recharge and the Max Range and Max Performance settings?

Standard allows a shallower charge/discharge and both Standard and Max Range limit the maximum current draw.

*searches through owner's manual*

Increased capacity would only show up on Max Range anyway

JRP3 · 01-04-2009, 08:14 AM

Sure but even on "Max" settings they are still keeping something in reserve. With the larger pack they can keep more in reserve, so that even on "Max" the pack sees a shallower discharge.