Hi Pat,
I agree. I know that my Lithium cells will die of old age before I get close to 1000 cycles. I'm hoping that they last 10 years. Considering that I typically had to replace my deep cycle batteries every 3 years, I'm ok with the tradeoff. I know that I killed my old house batteries through non-use, sulfation would reduce their capacity too much. I know that it was my fault, and that I could have gotten more life from them if I had been more diligent in my charging regimen when I wasn't using my boat, but it just didn't happen. One advantage to LiFePO4 is a very low self-discharge. After storing my cells unattended for a year while my boat was being worked on, they were still above 80% charged. Try that with lead acid batteries (actually don't, because it's not good for the batteries).
That's why for boats, I never try to factor in the rated cycle life into my justifications. I've never had a boat battery die from too many cycles.
On the other hand, for EVs that do deep daily discharges, cycle life is more applicable. You can actually run batteries through their entire cycle life. That's where Trojan T-105s ended up being a better deal than cheaper deep cycle alternatives. I experienced this personally when I was converting cars to electric back in the early 1990's.
Fair winds,
Eric
--- In electricboats@yahoogroups.com, "greenpjs04" <greenpjs@...> wrote:
>
> Both Eric and Charlie have provided valid useful numbers. However, other data must be considered as well. I use my boat about once per week during the roughly 25 week season. So, even at 2000 cycles for the LFP batteries, I will be 140 years old when the batteries have used up their cycles. Does anyone know a typical life for these battery chemistries in years? Do they really last for their rated cycles even if it takes 80 years to do that many cycles?
>
> I am currently using AGM, so I will only be 92 when 800 cycles are complete. (For those not good at math, I am currently 60.)
>
> Pat
>
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