Outside of a small batch of bad cells 10 years ago from one vendor (that no longer exists), I have never seen on any forum a LiFePo bank ever dying of age or cycles. And all of the original car conversion from 10 years ago are still going strong, even in the Ford EV Rangers which where famous for eating Lead and Nickel banks, The first batch of Fords are still doing good and the oldest Ford EV Ranger conversion is going on eight years.
So I have little doubt about the life or the cycles living up to the manufactures declared cycle life's. But you don't have to rely on real world reports on internet forums The US government commissioned a few studies of different cells here is one:
And this test was done to 100% discharge and at various C-rates and at C-rates (2C) that would be typical (or a little high) for boats even to 100% DOD for a 100 cycles the LifePo cells still had around 80% capacity. Which is around what most of the manufactures quote as well.
The only deaths I see on all the forums I watch are always imbalance or very high C-rate related deaths. Or the occasional short from a dropped wrench or bad BMS. (Some of those result in fires!)
One the other hand in cars lead deaths from cycle life are inevitable I have never even seen a car make it three year with a lead pack. 100% death by cycle life.
As we are now at the ten year mark it is no longer a guessing game that Lithium can make it ten years, there are quit a few Lithium conversion on the internet that can be referenced. And a big bubble of cars conversions starting around 8 years ago that was the first big wave all are still doing well. It will be interesting to see when we start seeing the first wave of age or cycle related deaths. If it even happens. Either way value wise as far as cars go Lithium or Sulfur are the only sane choices.
The secrete with Lithium is keeping the C-rate as low as possible and the cells balanced. 80-90% DOD at 2C and you should have 80% capacity in ten years.
On Sep 7, 2012, at 5:54 AM, GNHBus@aol.com wrote:
Both questions are valid, however I would address each product separately regarding cycle potential.
Has anyone seen valid data from a Lith Supplier that shows a Life Cycle Test Result ?
I would imagine this data would come from the EV world, but I just have not seen anyone demonstrate theproof. I have seen evidence of Lith Batts turning into "bricks" , (Death Cycle) so validating the (Life Cycle) only seemsappropriate to validate the Investment Cost.
Geo
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