I think you hit 2 of the 3 points when I was talking to you, no worries. Thanks for the info Willie!<br><br>-Paul<br><br><br><div class="gmail_quote">On Sat, Mar 14, 2009 at 6:09 PM, Willie McKemie <span dir="ltr"><<a href="mailto:mckemie@spamcop.net">mckemie@spamcop.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">I enjoyed my second AustinEV meeting today.<br>
<br>
I was chatting with someone about the advantages of using large LFP<br>
cells and did not come up with the points I wished to make.<br>
Befuddlement, be gone. Here are the points:<br>
1) large (>=200ah) TS LFP cells have an advertised life of 3000 cycles<br>
at 80% discharge and 4000 cycles at 70%. Smaller cells are 2000 and<br>
3000 cycles.<br>
2) For a given application, the large cells can be discharged and<br>
charged at lower relative rates. I infrequently demand more than .5C<br>
and never more than 2C. The low rates are supposed to lead to<br>
longevity.<br>
3) For a given voltage and given average trip length, the large cells<br>
will be discharged to a higher SOC than smaller cells. That, also,<br>
leads to longevity.<br>
So, that is the "triple whammy" that makes large cells more attractive<br>
with respect to longevity.<br>
<br>
I am frequently asked about the cost of TS cells. I always get to talk<br>
about:<br>
1) I paid $1.50/ah (about $400/cell and about $18K for my 45 cell<br>
pack).<br>
2) They might be bought now for $1.30/ah.<br>
However, I don't always get around to mentioning the other expenses:<br>
1) Shipping. As I recall, about $1.3K from China to Houston by ship.<br>
2) Shipping insurance - 1%<br>
3) Import broker fees. These were modest, about $300, as I recall.<br>
4) Import duty. 3%, again, as I recall.<br>
5) Shipping from Houston to Kansas was supposed to be about $700, but<br>
ended up more like $200.<br>
All the above were applied to 77 TS-LFP260 cells. Only 45 of those<br>
cells are in the Hyundai.<br>
I paid EV-Power of Australia $3.5K Australian dollars for<br>
2 TBS meters, 2 EV-Power control units, and 77 EV-Power cell modules.<br>
I believe a AuD is worth about $.75 USD. The cost of the BMS and TBS<br>
meter for a 45 cell pack would then be about $1400 US.<br>
<br>
<a href="http://www.evalbum.com/2314" target="_blank">http://www.evalbum.com/2314</a><br>
<font color="#888888"><br>
--<br>
Willie, ONWARD! Through the fog!<br>
<a href="http://counter.li.org" target="_blank">http://counter.li.org</a> Linux registered user #228836 since 1995<br>
Debian3.1/GNU/Linux system uptime 455 days 12 hours 26 minutes<br>
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</font></blockquote></div><br>