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Discussion Starter #1
Re: [EVDL] Kokam / lithium 'shelf life'

> They've been round at least 2 years, since that was when I made my first
> enquiries with them.. cliff was already racing round a track with them
> then... you'd think they could extrapolate a curve from 2+ years of
> data...

Hmmm Interesting. My granddaughter is now 6, how would I extrapolate her
life expectancy from just the data I've gathered in the last 6 years?
Assuming of course that I didn't have any other data (like typical life
expectancy for other humans) to base the calculations on?


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Discussion Starter #2
Re: [EVDL] Kokam / lithium 'shelf life'

Your granddaughter doesn't start to decay until she hits ~20 or so,
hopefully. Batteries are quite different, you can measure the rate of
decay and easily extrapolate the expected lifetime. You can also do
accelerated testing to get your results even faster.




Peter VanDerWal <[email protected]> wrote:
> > They've been round at least 2 years, since that was when I made my first
> > enquiries with them.. cliff was already racing round a track with them
> > then... you'd think they could extrapolate a curve from 2+ years of
> > data...
>
> Hmmm Interesting. My granddaughter is now 6, how would I extrapolate her
> life expectancy from just the data I've gathered in the last 6 years?
> Assuming of course that I didn't have any other data (like typical life
> expectancy for other humans) to base the calculations on?
>
>
> --
> If you send email to me, or the EVDL, that has > 4 lines of legalistic
> junk at the end; then you are specifically authorizing me to do whatever I
> wish with the message. By posting the message you agree that your long
> legalistic signature is void.
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
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Discussion Starter #3
Re: [EVDL] Kokam / lithium 'shelf life'

Peter VanDerWal wrote:
>> My granddaughter is now 6. How would I extrapolate her life
>> expectancy from just the data I've gathered in the last 6 years?
>> Assuming of course that I didn't have any other data (like typical
>> life expectancy for other humans) to base the calculations on?

From: Peter Gabrielsson
> Your granddaughter doesn't start to decay until she hits ~20 or so,
> hopefully. Batteries are quite different, you can measure the rate of
> decay and easily extrapolate the expected lifetime. You can also do
> accelerated testing to get your results even faster.

Ah, but you have independent reliable data on how human beings age. For extrapolations and accelerated life tests to mean anything, you need lots of NON-extrapolated and NON-accelerated life test data to base it on. We have this data for older battery types; but *not* for the newer lithium chemistries.

Every time I see a projected life expectancy of a new technology product, it has turned out to be wrong because of failure mechanisms that the authors didn't know about (or that the advertising copy writers left out).

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Discussion Starter #4
Re: [EVDL] Kokam / lithium 'shelf life'

Yes, but lithium battery chemistry isn't some great big unknown where
no man has tread before. The technology has been used in commercial
products for quite a while now and there is plenty of data on how the
cells age. The changes in the chemistry tend to be incremental at this
point, even Altair's nanosafe batteries still use cobalt and manganese
in the cathode.






Lee Hart <[email protected]> wrote:
> Peter VanDerWal wrote:
> >> My granddaughter is now 6. How would I extrapolate her life
> >> expectancy from just the data I've gathered in the last 6 years?
> >> Assuming of course that I didn't have any other data (like typical
> >> life expectancy for other humans) to base the calculations on?
>
> From: Peter Gabrielsson
> > Your granddaughter doesn't start to decay until she hits ~20 or so,
> > hopefully. Batteries are quite different, you can measure the rate of
> > decay and easily extrapolate the expected lifetime. You can also do
> > accelerated testing to get your results even faster.
>
> Ah, but you have independent reliable data on how human beings age. For extrapolations and accelerated life tests to mean anything, you need lots of NON-extrapolated and NON-accelerated life test data to base it on. We have this data for older battery types; but *not* for the newer lithium chemistries.
>
> Every time I see a projected life expectancy of a new technology product, it has turned out to be wrong because of failure mechanisms that the authors didn't know about (or that the advertising copy writers left out).
>
> --
> "Excellence does not require perfection." -- Henry James
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>



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Discussion Starter #5
Re: [EVDL] Kokam / lithium 'shelf life'

And even among cells you have quite nice differences. Estimating the
lifetime is a tricky thing but there is ways to know how and when and what.

For now my opinion is that Lithium Cobalt Oxide cells are best choice
for EVs. Iron Phosphate cells are just too new and they seem to have
really lousy energy density. Barely as good as NiMH cells had. Even wet
lead acid cells have really competitive energy density (if 100% soc
taken out, which is not smart).

Cycle life seems to be extremely high but with Cobalt Oxide cells and
same weight and energy taken out.. we get even better results for the
lifetime and performance.

Sure.. cells I'm testing and using are not the highest quality on
markets but they are cheap enough for EV use.

I've started now to compare various battery manufacturers to find out
why they have what they have. Then CCS profiles will be available for
them too.

-Jukka



Peter Gabrielsson kirjoitti:
> Yes, but lithium battery chemistry isn't some great big unknown where
> no man has tread before. The technology has been used in commercial
> products for quite a while now and there is plenty of data on how the
> cells age. The changes in the chemistry tend to be incremental at this
> point, even Altair's nanosafe batteries still use cobalt and manganese
> in the cathode.
>
>
>
>
>
>
>
Lee Hart <[email protected]> wrote:
>> Peter VanDerWal wrote:
>>>> My granddaughter is now 6. How would I extrapolate her life
>>>> expectancy from just the data I've gathered in the last 6 years?
>>>> Assuming of course that I didn't have any other data (like typical
>>>> life expectancy for other humans) to base the calculations on?
>> From: Peter Gabrielsson
>>> Your granddaughter doesn't start to decay until she hits ~20 or so,
>>> hopefully. Batteries are quite different, you can measure the rate of
>>> decay and easily extrapolate the expected lifetime. You can also do
>>> accelerated testing to get your results even faster.
>> Ah, but you have independent reliable data on how human beings age. For extrapolations and accelerated life tests to mean anything, you need lots of NON-extrapolated and NON-accelerated life test data to base it on. We have this data for older battery types; but *not* for the newer lithium chemistries.
>>
>> Every time I see a projected life expectancy of a new technology product, it has turned out to be wrong because of failure mechanisms that the authors didn't know about (or that the advertising copy writers left out).
>>
>> --
>> "Excellence does not require perfection." -- Henry James
>> --
>> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net
>>
>>
>> _______________________________________________
>> For subscription options, see
>> http://lists.sjsu.edu/mailman/listinfo/ev
>>
>
>
>

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