Dave;
One often overlooked benefit of the LIFEPO4 batteries is that they are much less sensitive to the perkert effect, SO when using then for propulsion, with it’s higher amp draws, you will get more juice out of the batteries. I have seen no scientific comparisons, but I seem to remember reading that the effect was about 20% of what you might see with wet or agm cells.
Chris
On 12/23/09 2:25 PM, "David Goldsmith" <suntreader@gmail.
I'm sorry, I hit 'send' accidentally before I was finished.
I was saying that the lithium batteries make a lot of sense when weight is a major concern but probably not in my case.
I'm wondering about the durability and charability of AGMs vs LiFePO4s. I've heard about both types they are temperamental and easy to destroy with poor charging practices. I've also heard about both types they are durable and able to handle all kinds of abuse, just pour the power in and suck it out with impunity. So what's the deal?
With a charger designed for each and with a solar controller designed for each type what could go wrong?
I'm going to look into this some more, the new tech batteries sure look to me like the wave of the future, but there is something somehow reassuring about half a ton of lead and acid holding all that energy too.
David
On Wed, Dec 23, 2009 at 2:20 PM, David Goldsmith <suntreader@gmail.com > wrote:
On Wed, Dec 23, 2009 at 2:42 AM, Eric <ewdysar@yahoo.com > wrote:
Good answer.
Rick,
When people ask my opinion of almost anything about what is the best answer, I typically answer "It depends."
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.factoriesonline.com/ ProductInfo. aspx?id=5767609
They're $1238 (plus $150 shipping) for the four of them. Second option was group 31 from here:
http://www.batteryconcepts.net/ yuasa/ub121100. html
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.evcomponents.com/ ProductDetails. asp?ProductCode= TS-LFP200AHA
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@yahoogroups. <mailto:electricboatcom s%40yahoogroups. > , Rick Campos <rick_1211@..com .> 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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