[ausev] Battery choices

[Rob H]

This is great!  It's nice to have a better info than the rule of thumb that
I'd been working on.

Please be sure we factor in the costs of the charging system.

On Mon, Jul 7, 2008 at 7:42 AM, Mike Seningen <mseningen at austin.rr.com>
wrote:

>  Thank you Brian --
>
> if what you say is correct that one would need 1/2 the battery energy of
> the AGMs
> (and I have no reason to doubt you), at ~$2 cell, that make these LiFePO4
> very competitive.
>
> That puts it at  1.5x-2x the cost, with 1/5-1/6 the weight.
>
> Granted this is a manufacturer direct, Chineese supplier -- but still very
> interesting.....
>
> http://www.fuzing.com/vli/0005509cd235/Li_ion-battery
>
> The same type of cell was tested here:
>
> http://zeva.com.au/tech/headway/
>
> will continue to do some more homework,
>
> Mike
>
>
> Brian Lasseter wrote:
>
> On Mon, Jul 7, 2008 at 12:23 AM, Mike Seningen <mseningen at austin.rr.com> <mseningen at austin.rr.com> wrote:
>
>
>  12v 20 Hr Rate AH = 100  -- so is this a 100AH battery at 12v -- or 1200AH at 12v?
>
> Li-ion 3.7v @1.7AH -- to get 100AH @ 12v is roughly 190cells?  (100/1.7)*(12/3.7)
>
>
>
> Volts X Amp_Hours = Watt_Hours
>
> 12V x 100AH = 1200wh of energy for your AGM.
> 3.7V x 1.7AH = 6.29wh of energy for your Li-ion cell.
>
> Your final count of 190 li-ion cells would give you the same energy though.
>
> However, just to confuse you more, the peukert exponent comes into
> play here.  Long story short... the li-ion cell can use nearly 100% of
> it's energy, while the AGM cell will likely only be able to use 50% of
> it's energy at the high rate of energy depletion used in electric cars
> (depending on what it's peukert exponent is).
>
> So... 95 li-ion cells should suffice to give you the same amount of
> "useable" energy.  If you know the peukert exponents for each battery,
> then you could calculate an exact number.
> http://en.wikipedia.org/wiki/Peukert%27s_lawhttp://www.smartgauge.co.uk/peukert_depth.html
>
>
> --
> TTFN,
> Brian "Lasso" Lasseter
>
> · (512)736-1677 · AIM:digininja · ICQ:2238123 · MSN:azoreg ·
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>
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-- 
Rob
____________
Rob Hirschfeld
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