LiFePO4 battery

[ChocolateLab33]

I know this has probably been asked many times, so please forgive me. Does the LiFePO4 battery provide as much power as other RCR123 batteries? I heard the runtime is not as long as other RCR123's, but is the output the same? (I want my lights as bright as possible)
Thanks for your help.

 

[PhotonAddict]

I believe the nominal voltage for LiFePO4 is 3.2V as compared to 3.7V for LiIons. They are usually charged to approx. 3.6V as compared to the max. recommended 4.2V for LiIons.

 

[barkingmad]

I know this has probably been asked many times, so please forgive me. Does the LiFePO4 battery provide as much power as other RCR123 batteries? I heard the runtime is not as long as other RCR123's, but is the output the same? (I want my lights as bright as possible)
Thanks for your help.

It also depends on your light - if it has a regulated circuit then quite probably - but they tend to have slightly lower capacities so also slightly shorter runtime?

 

[ChocolateLab33]

I'm pretty sure the run time is shorter for the LiFePO4 but I keep plenty of them charged and on hand, I just don't want to sacrifice output by using them.

 

[PhotonAddict]

As barkingmad said it may not matter much if your light is regulated except that it will drop out of regulation sooner due to the reduced capacity (mAh rating).

If your light has a buck driver and needs the Vf of the led to be lower than the battery voltage to stay in regulation you may notice a difference if the Vf of the led(s) is high enough (ie., practically the same as the battery voltage). Likewise for LDO drivers like the Flupic.

With boost drivers the output should be the same unless the battery voltage is low enough that it encounters the maximum input current of the driver. You are more likely to encounter this situation if led Vf is high and/or the led is being driven pretty hard (high current).

 

[LuxLuthor]

Besides the lower 3.2V of AW's R123 (& 3.3V of the A123 brand of Saphion larger size cells), he lists them as 500 mAh, but you really need to see ratings curve (in post #2) at various loads to know anything about how his battery compares to others in your application. You also need special chargers with these chemistries.

 

[rizky_p]

RCR123 always confuses me, 3v one is the most confusing well at least to me :thinking: not to mention battery and charger matching.

 

[LuxLuthor]

Yeah, there is a lot of confusingly similar battery names involving "123" & "a"

Silverfox did a nice shootout of 3V CR123a non-rechargeable Lithium "disposable" cells here. Surefire calls their 3V version, SF123a just to be special.

Then there are the rechargeable Lithium Cobalt Ion versions called RCR123a, some of which have a typical 3.7V (look about half-way down page), but others such as this "Powerizer" version described as 3.0V (not sure what chemistry it uses)

Then AW has his reduced explosion risk RCR123a using LiFePO4 (Lithium Ferrous Phosphate) which are 3.2V here.

There is also the "A123 BATTERY COMPANY" that makes the safe Nano-Phosphate Lithium "Saphion" larger (26mm x 66mm) 3.3V batteries.

So I can't imagine why anyone would have any confusion about cells with the "123a" or "A123" names!!!! :huh:

 

[juplin]

but others such as this "Powerizer" version described as 3.0V (not sure what chemistry it uses)

"Powerizer" version may be regulated cell according to two clues.
First clue is the 4.5V charging voltage that can be recognized from the bottom view of this cell's dedicated charger.
Second clue is the statement "Peak voltage of 3.0V Li-Ion will be 3.85V after fully charged. Once loaded, cell's voltage will drap to 3.5 - 3.0V".