Hi Tom,
I noticed that too. My Chinese (Thundersky) LiFePO4 cells are holding up well, though I don't have too many cycles through them yet. I've had no failures or reduced capacity issues.
On the topic of low self-discharge, the batteries are pretty amazing. But I did read that to maximize LiFePO4 cell life, they should not be stored charged above 90% capacity. It seems that somewhere around the 65-75% charge is optimal for long term storage. So I have started leaving my batteries discharged after the day's sail and I then charge at the dock while I'm preparing to leave. For my set-up, 30% of my 8kWh is 2.4kWh. from 70% full, it takes my shore charger about 90 minutes to charge above 95% full. For most day sails, I use much less than 2.4kWh, so I don't worry about topping them off because I want them back down to 70-75% by the time I get back.
Of course, with any L/A battery, leaving them discharged like that is a sure recipe for early battery death because of sulfation. Regular flooded batteries self discharge at up to 4% per week, so leaving them alone for a month after a full charge will drop them to 85% and sulfation will start to set in. It becomes obvious why flooded cells should be left on maintenance chargers. AGM are better with only 3% discharge per month. With AGM, sulfation won't get bad if left alone after a full charge for 3-4 months. The Lithium cells will only lose 10%, from 75-65%, in 4-5 months.
For years, I was able to kill off many flooded house batteries long before their time by leaving them unattended. Batteries that lasted 3 years were uncommon. For someone like me, AGM are well worth any price premium based on their self-discharge rate alone. And my Lithium cells have already provided great service, I'm guessing that I would already be on my second set of FLA had I gone that way for my conversion. Yes, I know that it would be my fault that the FLAs died, but knowing myself, the first set would most likely be dead.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "Tom" <boat_works@...> wrote:
>
> I find it interesting that the author of this article, who cautions against purchasing Chinese lithium cells, is apparently an Australian distributor of cells which are made in Taiwan.
>
> -Tom (who is using Chinese cells)
>
> --- In electricboats@yahoogroups.com, "DRHitch" <drhitch@> wrote:
> >
> > I came across a good article by a electric marine distributor that gives a pretty good, recent exploratory on Lithium iron battery technology as it applies to electric marine applications:
> >
> > http://www.ddmotorsystems.com/ElectricBoats.php
> >
> > They are a distributor of EV sub-systems for marine and land-based vehicles.
> >
> > Thx,
> > Doug
> >
>
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