Hi All,
It is my understanding that LiFePO4 cells should not be float charged.
I think it is an electroplating issue. (probably all lithium cells)

I use a bank of LiFePO4s on a daily basis
http://users.adam.com.au/marick/IMGP2225cut.jpg
The datasheet for these cells suggests 3000 cycles if the Depth of=20
Discharge DOD
is not greater than 70% of their capacity. (2000 for 80%)
The standard charge is 0.3C so for these cells 100Ah would be 30Amps
We charge at 10A. The car has now travelled > 30 000Km on this battery
approx 750 cycles

Most charging algorithms have a constant current until a cut off voltage
then a constant voltage until the current drops to 5% of the CC value.
The fully charged voltage is 3.65v for these cells.

Pulse charging may be a way around the float problem, one circuit that I=20
have
used in the past is the mini maximiser.
http://www.voltscommissar.net/minimax/minimax.htm

I have also been told that cells should be stored at 80% of their capacity
not full, and definitely not flat.
A  low load /light charge  might appear to the cell as a period of storage.

Sorry for rambling on... Trevor

> I have an MSP430 project here at home that runs off a single LiFePO4
> cell and I'd like to charge it off a solar panel.
>
> Capacity is not important to me, or efficiency, I just want the cell to
> survive as many cycles as possible and not spend much effort with any
> fancy charging methods.
>
> I was hoping to be able to float it at some safe voltage, if there is
> one. My maximum charge current is less than 0.1C.
>
> My best guess is that somewhere below 3.4 volts is probably safe since
> that's where a fully charged cell settles after a few days.
>
> Any LiFePO4 experience out there?
>
> Thanks!
>
> Bob
>
> PS My experience with LiFePO4 so far: I also have a Philips brand solar
> light that I purchased a couple of years ago, it has a single LiFePO4
> cell and kills them after 100 days, so I know that you can't just
> trickle into them and expect many cycles!

--=20
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