It's the Batteries, Stupid!

[Takumi]

Does anyone know where we can find a timeline of the dominant battery chemistries are?

Or at least give a rough estimate?

[TEG]

History of the Electric Battery
Battery History, Technology, Applications and Development
RadioShack's On-line Battery Guidebook: Battery Timeline

[TEG]

Bill Arnett (Tesla Customer) posted this photos of a real Tesla 18650 next to consumer cells:


Based on the pattern on the positive terminal of the battery, I am guessing Sanyo...

[doug]

What do the Matsushita cells look like?

The guy from Asahi Shimbun asked me for my best guess as which supplier Tesla uses, and I pulled Matsushita out of my err... hat. I said likely Sanyo or Matsu, but ultimately came down on the side of Panny for no particular reason.




.

[dpeilow]

[dpeilow]

I've just noticed something interesting...

Panasonic Industrial Europe GmbH

and

Panasonic Lithium Ion Batteries

max out at 2550mAh, yet

Cylindrical type | Lithium Ion Batteries | Batteries, Power supplies | Panasonic Industrial Solutions Global

lists 2900. Are they not available in the US and EU?


EDIT: A bit of further digging seems to indicate that the 2900mAh are only available to corporate buyers. Some Asus eePC battery packs are reckoned to use them.

[doug]

The photo evidence makes a good case for Sanyo, it seems.

[malcolm]

Thanks David

Panasonic seem to prefer the "It" symbol instead of C Rate, which

Represents "Current" and is defined as follows It(A)= Rated Capacity (Ah) / 1(h).

Looks like it's the same value.

They seem to recommend 0.7 It for charging http://industrial.panasonic.com/www-...ACA4000PE4.pdf

So for a 2900mAh cell that would be about 4.1 A for about 40 minutes (I think in practice you have to charge in pulses with cell balancing stuff in between)

Can't find an acceptable discharge rate range.

[Tim]

Yeah, I couldn't find that either, but the discharge curves available in this old PPT http://download.intel.com/idf/us/docs/PS_EBLS003.pdf give pretty good performance, but only list 0.5C and 1C discharge rates. Something of a mystery battery, since other than that Asus, I haven't seen mention of it used anywhere else. Increasing battery capacity has got to be the easiest way to cut weight and increase performance available to Tesla. With prices so much lower than where they were two years ago, its almost a no brainer. And it would help neutralize those "fat elise" comments that the reviewers like throwing around.

[malcolm]

Well I think the Roadster may be stuck with the "fat Elise" taunt. Reducing battery weight would mean re-designing the pack which would require redoing all the crash tests etc etc. When there's Model S and Bluestar (Model T?) to roll out then maybe Tesla will revisit the Roadster if they reach their 25th Anniversary.

Here's hoping - on both counts.