I have 251 cycles on my lithium bank, and at the rate I use the boat, I'll probably be at the manufacturer's rated 2000 cycles in another 7 1/2 years.
Calendar life is another concern. I've read of a ten year lifespan for the cells, but there was nothing to back up this claim. Anybody have credible info?
I intend to operate this boat for decades, so it will be interesting to see how the battery life plays out.
-Tom
--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> Hi Tom,
>
> That is an additional consideration. My post was to point out that Ah ratings on different battery types don't mean the same thing in use, so the math for "usable Ah" is more complicated than just looking at the 20hr rating.
>
> One needs to know a detailed use case including expected distance and speed, "watts to knots" for your specific boat, charging capabilities, extended case scenarios (not exactly worst case) to make sure that you've got capacity for adverse conditions or longer trips. Then factor in the Peukert's calcs that I mentioned before and you are getting closer to knowing your "usable Ah" that you can factor against cost.
>
> I do know some EV folks with close to 1000 cycles to more than 60% discharge on their LiFePO4 batteries, they are still operating to the manufacturer specs. These same people would wear out a set of T-105s (400+ cycles) in 18 months or less. My battery bank in my boat is still in the tens of cycles after more than a year. I expect my batteries to die of old age rather than cycle life. That is true for every battery that I've had on a boat, including house batteries. I was lucky to get 3 years out of a deep cycle FLA battery, much less than 100 cycles, I usually killed them by not keeping them charged. I find that my Lithium batteries are better equipped for that kind of treatment.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
>
> --- In electricboats@yahoogroups.com, "Tom" <boat_works@> wrote:
> >
> >
> >
> > Another consideration (at least for those who run their EP system frequently) is how many usable Ah/$ will you be getting over the lifespan of the bank. Or perhaps more importantly, how many Ah/$ over the duration you own the boat.
> >
> > Cycle life specs vary widely among the various battery types. I don't think anybody really knows what to expect from a well cared for LiFepo4 bank in the real world, they haven't been in use long enough.
> >
> > -Tom
> >
>
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