Take a close look at the actual spec sheet and discharge rate charts. You'll see that the typical operating voltage is around 3.2v rather than the 4.25 you (and they) mention. This will require proportionately more cells to achieve the voltage you'd like to run at.
Russ K1HOP
--- In electricboats@
>
> On Wed, Dec 23, 2009 at 2:42 AM, Eric <ewdysar@...
>
> >
> >
> > Rick,
> >
> > When people ask my opinion of almost anything about what is the best
> > answer, I typically answer "It depends."
> >
> > Good answer.
>
> I was planning on AGMs for my conversion but you've got me thinking about
> LiFePO4s again. I'm wondering your source for those batts at 40% over AGMs?
> As an example I had 4x 4D AGMs in the budget, available here:
>
> http://www.factorie
>
> They're $1238 (plus $150 shipping) for the four of them. Second option was
> group 31 from here:
>
> http://www.batteryc
>
> I'd need 8 to have that some 200 ah pack , so about $1320.
>
> Just doing a quick search the best price on LiFePO4s I can find, again,
> setting up a 48v 200 ah pack are these:
>
> http://www.evcompon
>
> They're 4.25 V so I'd need about 12 of them, totaling at $2640. That's
> almost exactly 2x the cost.
>
> I know you mentioned 'quality' AGMs but from what I can discern the
> industrial batteries are every bit as good if not better than the consumer
> retail batteries.
>
> I agree that given the potentially longer life and greater depth of
> discharge of the lithium batteries and especially if weight is a huge
> concern (its a concern for me but I'm in a 32' monohull, not exactly weight
> senative like a cat or tri.)
>
> One must remember that we've all got different priorities when picking
> > battery types. Another advantage to LiFePO4 batteries is that they are half
> > the volume and 40% the weight of wet cells or AGM for the same rated
> > capacity. In the case of the converted trimaran that has been discussed on
> > this board, the weight savings are well worth the 40% premium in cost over
> > quality AGM alternatives. And with a lifespan of more than 2000 80% DOD
> > cycles, they are could be considerably cheaper per mile. Of course, if one
> > has the room and extra payload capacity, AGMs are often a good answer.
> >
> > Fair winds,
> > Eric
> > Marina del Rey
> >
> >
> > --- In electricboats@
> > Rick Campos <rick_1211@> wrote:
> > >
> > > To Date: there is no superior battery for this application other than AGM
> > type. The variable of lifespan vs. initial cost far out guns all others.
> > YES...even lithium based.
> > >
> >
> >
> >
>
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