This is great! It's nice to have a better info than the rule of thumb that I'd been working on.<br><br>Please be sure we factor in the costs of the charging system.<br><br><div class="gmail_quote">On Mon, Jul 7, 2008 at 7:42 AM, Mike Seningen <<a href="mailto:mseningen@austin.rr.com">mseningen@austin.rr.com</a>> wrote:<br>
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Thank you Brian -- <br>
<br>
if what you say is correct that one would need 1/2 the battery energy
of the AGMs<br>
(and I have no reason to doubt you), at ~$2 cell, that make these
LiFePO4 very competitive.<br>
<br>
That puts it at 1.5x-2x the cost, with 1/5-1/6 the weight.<br>
<br>
Granted this is a manufacturer direct, Chineese supplier -- but still
very interesting.....<br>
<br>
<a href="http://www.fuzing.com/vli/0005509cd235/Li_ion-battery" target="_blank">http://www.fuzing.com/vli/0005509cd235/Li_ion-battery</a><br>
<br>
The same type of cell was tested here:<br>
<br>
<a href="http://zeva.com.au/tech/headway/" target="_blank">http://zeva.com.au/tech/headway/</a><br>
<br>
will continue to do some more homework,<br>
<br>
Mike<br>
<br>
<br>
Brian Lasseter wrote:
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<pre>On Mon, Jul 7, 2008 at 12:23 AM, Mike Seningen <a href="mailto:mseningen@austin.rr.com" target="_blank"><mseningen@austin.rr.com></a> wrote:
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<pre>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)
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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.
<a href="http://en.wikipedia.org/wiki/Peukert%27s_law" target="_blank">http://en.wikipedia.org/wiki/Peukert%27s_law</a>
<a href="http://www.smartgauge.co.uk/peukert_depth.html" target="_blank">http://www.smartgauge.co.uk/peukert_depth.html</a></div></div>
--
TTFN,
Brian "Lasso" Lasseter
· (512)736-1677 · AIM:digininja · ICQ:2238123 · MSN:azoreg ·
"No Sane man will dance." -Cicero (106-43 B.C.)
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