and compiled as many if not all of AW's info about their LifePO4 R123 batteries
These are what AW said or agreed on. Minor text adjustments was done. But do take note that they are still Lithium Ion batteries which must be respected and treated well.
AW's Lithium Iron Phosphate Rechargeable 123 size batteryThese are new generation R123 with safe chemistry that will not vent with flames (explode). The key to this safety feature is that no oxygen will be released from the oxide structure of the cell composition even under abused conditions. No oxygen means no pressure built up and fuel for combustion. Can be used in series on multi-cell applications.
Specifications :
Nominal Voltage : 3.2V
Capacity : 500mAH
Lowest Discharge Voltage : 2.0V
Standard Charge : CC 250mA CV 3.6V
Cycle Life : > 500 cycles
Weight : 16.5g
Specifications for charger (Ultrafire WF-138):
- 2 Bay independent charging channel
- 250mA charging rate for each channel
- intelligient IC control with full auto-stop
- 4.2V / 3.6V selector for charging 3.7V and 3.0V LiIon cells (the recessed switch is designed so you won't accidentially move the setting, you'll have to use a ball point pen or paper clip to change the setting manually)
- 100-240V worldwide voltage auto-switch CE and PSE approved
More about these LifePO4 123 size batteries:Do not discharge below 2V. Cells will be damaged when discharged below 2V.
These cells can be used without any protection circuit like NIMH cells. Even if they are overdischarged, they won't be hazardous.
If you accidentially go lower than 2V and it recovers after rest, they are still good. I have tried draining them down to 1.5V and they still recover OK. I drained one further down to 0.5V and it was dead and wouldn't accept charge.
Off the 3.6V charger, it reads 3.6V and will settle down to 3.37V (fully charged). Nominal voltage is 3.2V under load.
I have tried charging these PO4 cells using the 4.2V setting up to 4.2V. The voltage will gradually settle down to 3.37V in about an hour. These cells will not be overcharged, however, routinely charging them above the recommended voltage will reduce their rated cycles.
These cells will hold their charge like normal LiIon cells.
I haven't tried the nail test myself but I believe these cells won't explode with the LiFePO4 chemistry.
The RC people have been discharging LiFePo4 cells for 10C without any problem. However, you won't see much runtime out of these 500mAH cells under such a high load.
These cells don't need protection and they behave just like NiMH batteries. I tried discharging them down to 1.0V and they still can be recharged safely back to full capacity.
You may have to trick the smart charger to charge the cell though because they won't charge a cell with a voltage below 1.2V. I charge the PO4 cell first by hooking it up to a regular 4.2V LiIon cell for a minute or so to bring up its voltage to about 1.5V and then put in into the charger.
I have put these LiFePO4 cells into a BBQ pit with burning charcoal and they did 'pop' but the intensity was lower than a NiMH AAA cell - (DO NOT try this).
As long as you don't leave them on over discharged state (below 2v) for too long (days), they'll come back fine because the LiFePO4 chemistry is quite robust and will take some reasonable abuse well.
It is OK to use them just a little, then recharge.
Safe chemistry R123 don't need a pcb. You won't find protected LiFePO4 R123s anywhere.
They can go 1000+ cycles if not abused. The spec says they have about 5 years of service life but the ones from 2006 that I am using myself are still going strong with no signs of degrade.
AW's post taken from Wikipedia:
LiFePO4 is an intrinsically safer cathode material than LiCoO2. The Fe-P-O bond is stronger than the Co-O bond so that when abused, (short-circuited, overheated, etc.) the oxygen atoms are much harder to remove. This stabilization of the redox energies also helps fast ion migration. Only under extreme heating (generally over 800°C) does breakdown occur, which prevents the thermal runaway that LiCoO2 is prone to.
As lithium migrates out of the cathode in a LiCoO2 cell, the CoO2 undergoes non-linear expansion, which affects the structural integrity of the cell. The fully lithiated and unlithiated states of LiFePO4 are structurally similar, which means that LiFePO4 cells are more structurally stable than LiCoO2 cells.
No lithium remains in the cathode of a fully charged LiFePO4 cell — in a LiCoO2 cell, approximately 50% remains in the cathode. LiFePO4 is highly resilient during oxygen loss, which typically results in an exothermic reaction in other lithium cells.[2]
Other LifePO4 sizes info:The LiFePO4 18650s already exist but the capacity is only 1200-1300mAH. I have samples of the 4000mAH D long cells which is capable of 20A discharge and still maintains 80% capacity with a very flat discharge curve. I 'll see the demand before I do anything.
AA size LiFePO4 cells are available but they 'll need a charger. You can as well use the R123 LiFePO4 charger but you 'll have to rig them up for charging. The charging algorithm is the same for R123 and AA cells with the same chemistry. A good LiFePO4 charger I am looking for is CC/CV charging to 3.65V which will fully charge the cells.
Regarding WF-138 Charger:The charger is a CC/CV charger.
The charger will charge regular protected/unprotected LiIon cells including my 750mAH protected R123 as well as RCR2s (need 8mm spacer).
Set the switch to 3.0V for the LiFePO4 cells which will charge them to to 3.6V.
Regular LiIon cell will require the 3.6V setting which will charge them to 4.2V.
Regular 3.7V cells will come off the charger at around 4.15-4.2V at the 3.6V setting on the WF-138 charger.
The WF-138 charger for LiFePO4 R123s does not trickle charge. It will stop charging after 1 hour when the LED turns green.
The charging current will not exceed 450mA for the WF-139 / 250mA for the WF-138.
Other than the WF-138, you can use RC chargers with LiFePO4 setting. Many are available.
Sale thread info @
http://www.cpfmarketplace.com/mp/showthread.php?t=125353Discharge graph from 1C (0.5A) to 10C (5A):
Mar 13 2010, 11:50 AM
Quote
i'll stick to my Lummi Wee [ 100 ] and Raw [ 20/200 ].....more unique/exclusive than quark cr2 in a way....
can use LifePo4....safer and rechargeable too! 
These are what AW said or agreed on. Minor text adjustments was done. But do take note that they are still Lithium Ion batteries which must be respected and treated well. 
cheers.
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