Lifepo4 AA test results

[gravityz]

Finally got my UF-139 charger in
i also orderd those diodes from KD to lower the voltage so that this charger can be used to charge the lifepo4 AA's
KD however could not provide them so i decided to do some tests myself

Setup
UF-139 charger
1N4007 diode (tested several but these seem to work the best)
lifepo4 14500 cell form KD
Fenix L1DcE Q5 head

First i tested charging current because 450ma is a bit to much
it turned out my charger is charging at 300-350ma so this is ok
do not know if this is the case with every charger or that it has something to do with the internal resistance of the lifepo4 14500

when charging the voltage rises to 3.3 volt and stays these for a while(approx 1 hour i think)
after that the voltage is rising steadily
voltage just before the charger turns green it is around 3.89 volt.
after that the battery drops to 3.6 volts

Runtime

Turbo:26 minutes (current is 0.9 amps)
high:57 minutes
did not test med and low but they work as they should be.
so these figures show that the actual capacity is 900x(26/60)=390Mah

on several occasions i charge a cell with 4,15 volts
also i forgot one time that i was testing and depleted the battery completely
voltage after this was 1 volt and it refused to charge.
after letting it rest for an hour it was back up to 2 volts and i could charge it again. Amazingly the cell does not seem to suffer from this.

so compared to a 1.2 volt 2500NimH cell this cell gives you half the runtime on high.

i really hope that fenix will make a aw14500 compatible L1DCE
they need to correct both the 14500 suport as well as a tube which needs to be 2 mm longer.

 

[Fallingwater]

What's the voltage under load?

 

[gravityz]

What's the voltage under load?

if you mean voltage during charging

3.3 volts for lets say an hour and than slowly increasing to 3.87

i did not measure the voltage while it was in use on turbo but the output was the same as with 2x AA so basically you have a L2DCE in a L1DCE format(with low battery duration)

i must say however that de capacity difference between these cells and the 3.7 v14500's is better than a factor 2

eg
if you calculate that the aw14500 pulls 0,67Amps in turbo and has a duration of around 50 minutes you come to these numbers

AW14500 670ma x50/60=558mah
lifepo4 900ma x 26/60=390mah