Special rechargeables for LEDs?

svenh · Aug 11, 2008

Are there special restrictions on rechargeable batteries to be used with LEDs? If so, why?

I need batteries that last longer for commuting on a road racer during winter. I have Fenix P3D, (https://www.fenix-store.com/product_info.php?cPath=22&products_id=409) that I would like to be able to use in turbo mode 160 lumens, instead of general mode 90 lumens.

My current batteries are Vanson CR123A Li-Ion, 600 mAh. Are there suitable batteries with more energy? I have looked at Olympus batteries att eurobatteries.com (http://shop.eurobatteries.com/product_info.php?products_id=2292&osCsid=hm0iiaup4blepmabev44qven83), but it says "Not suitable to power LEDs" - why?

Grateful for info, links to tutorials etc,
/Sven

PhantomPhoton · Aug 11, 2008

There are a number of things to comment on here.

First in general there is no reason a quality Lithium rechargeable cell cannot power most LEDs. Quality being the key word.

Specification:

Click to expand...

Li-Ion,
3v,
1200 mAh,
17.1 x 34.5 mm

These specifications given are outright lies. The best RCR123 cells (which are generally claimed to be 750mAh to 900mAh actually only seem to deliver 600+ mAh if memory serves.

One would guess that because it lists them as 3V and not 3.7V that they have a circuit attached inside the cell packaging that kicks on and drops the voltage down. Thus they waste power from right there. Usually these types of cells do not have the ability to deliver very much current, so this is my guess why they're not recommended for flashlights and such.

In my humble opinion, if you want to stick with your P3D and not buy a new light, yet want to have a better performing cell you should look into buying a 17670 Li-Ion. It is one 3.7V cell that is twice the length of RCR123. They generally have better capacities than two RCR123s in series from my experience and from what other members here have stated as well. I think, though someone will hopefully chime in and confirm, that most 17670 cells will fit into a P3D.

:grin2:

svenh · Aug 11, 2008

Thanks PhantomPhoton for your info!

If it turns out that I need to buy "special type"/expensive batteries/charger to get the performance I want, it might be cheaper to get a better LED that I can feed with standard/off the shelf batteries. I would appreciate that kind of suggestions as well. If so, I am interested in a light that is easily mounted on the bike and that doesn't need a separate battery pack.

yellow · Aug 11, 2008

1. there is no better led (in the sense You consider it)
2. if one gets a very small light, that still kicks large lights in output, there inevitably are drawbacks - here its runtime
3. its not the "high power led", its the circuit that should be considered when using different than designed batts
4. if there is no time to stop and change the batts at 1:45 hours, there are two options:
--> 1. dont use Turbo
--> 2. mod the P3D to be fed with an external battery pack (2-cell Li-Ion)

... try to get a light running on a single 18650 Li-Ion.
Same size than 2 pc. CR123a but runtime about 2:30 hours (when led gets full power)

PS: if one does not have a decent charger for AAs, then getting one for Li-Ion cells + the cells is way cheaper than just the Ni-Mh-version
PPS: dont forget to use "protected" Li-Ions! (the ones in the link above dont seem to be protected)

TONY M · Aug 11, 2008

yellow said:
--> 2. mod the P3D to be fed with an external battery pack (2-cell Li-Ion)

+1 Someone here did that last year and it worked very well using x4 AA cells.

The L2D is better for a bikelight than the P3D. RCR123's in the P3D do not last as long as NIMH in the L2D.

If you plan to use lithium primaries then they can get very expensive, so an external battery pack may be the way to go and it is not too difficult a mod to try.

svenh · Aug 11, 2008

yellow said:
4. if there is no time to stop and change the batts at 1:45 hours, there are two options:
--> 1. dont use Turbo
--> 2. mod the P3D to be fed with an external battery pack (2-cell Li-Ion)

1:45 hours!

I only get some 30-40 minutes! Part of the problem is that I bike in temperatures slightly above freezing point, but also: I probably don't use the best batteries currently. I would be happy if I find batteries that give me one hour of turbo mode during my temperatures.

Would you please post link(s) to good batteries?

svenh · Aug 11, 2008

Anyone tried these?

http://www.batteryjunction.com/rc390reliba.html

Gunner12 · Aug 11, 2008

Re: Anyone tried these?

If a LED light can or can't accept rechargeables depends a lot on the driver that it uses. White LEDs run at around 3.5-3.7v so the 6v of 2 CR123s has to be lowered or the LED could fry. The buck circuit in the Fenix that lowers the voltage can handle up to 16v so you can use 2 RCR123s(full charge voltage is 4.2v for Li-ion ones) without problem.

But since you want 1 hour 45 minutes, RCR123 batteries for the P3D-CE won't have enough capacity to last that long. If you use a L2D-CE Q5 and use 2 good NiMh batteries, then you'll get around the same output out the front on turbo and have around your needed runtime(this is with 2650 mAh NiMh batteries 2 Lithium AAs give over 2 hours of runtime on turbo).

LukeA · Aug 11, 2008

svenh said:
Are there special restrictions on rechargeable batteries to be used with LEDs? If so, why?

I need batteries that last longer for commuting on a road racer during winter. I have Fenix P3D, (https://www.fenix-store.com/product_info.php?cPath=22&products_id=409) that I would like to be able to use in turbo mode 160 lumens, instead of general mode 90 lumens.

My current batteries are Vanson CR123A Li-Ion, 600 mAh. Are there suitable batteries with more energy? I have looked at Olympus batteries att eurobatteries.com (http://shop.eurobatteries.com/product_info.php?products_id=2292&osCsid=hm0iiaup4blepmabev44qven83), but it says "Not suitable to power LEDs" - why?

Grateful for info, links to tutorials etc,
/Sven

The restriction is not with LEDs, it's with high-draw devices (as mentioned above). The page says not to use the cells with any flashlight, because these cells can't handle the draw.

PhantomPhoton · Aug 12, 2008

Re: Anyone tried these?

svenh said:
http://www.batteryjunction.com/rc390reliba.html

No, not those either, essentially the same thing you asked about to begin with. These can not run some of my LED flashlights as well. They're not bad, but definitely not for high power lights. They do work in my P3D but won't give better runtime, the 900mAh rating on these aren't accurate, especially when drawing higher currents.

Here is a link to sales of a well regarded 17670 cell that should fit into the P3D that you already have. BUT... someone else needs to confirm that it will fit into a P3D first. (I dont have any to try in my P3D).
Runtime will be better but only a bit.

Getting a light that will take 2AA or an 18650 will extend runtime even more. When you can spare the money I'd definitely recommend either of these setups if you want runtime on max power (while keeping it handlebar friendly/ no external bat pack).

yellow · Aug 12, 2008

yellow said:
4. if there is no time to stop and change the batts at 1:45 hours, there are two options:
--> 1. dont use Turbo
--> 2. mod the P3D to be fed with an external battery pack (2-cell Li-Ion)

svenh said:
1:45 hours!

I only get some 30-40 minutes!

Gunner12; said:
But since you want 1 hour 45 minutes, RCR123 batteries for the P3D-CE won't have enough capacity to last that long.

Gunner is right on th e L2D offering the runtime.

A P3D should be around 1:30 hours, when batts are ok
lets calculate:
say one CR has the Voltage needed to power one led
say the P3D gives 800 mAh to the led
...
a draw of 800 mA divided by 2 (for 2 pieces of CR123) makes 400.
Most any rechargeable Li-Ion should be around 600, even at low temps.

Now with a bit of "hope" such cells should give 1 hour and some 15-20 mins AT LEAST, at any temperature.
(+ get heated a bit by the led. Maybe try to put some isolating sleeve around the light at very low temps,when the metal feels brutally cold otherwise)

Considering Your 40 mins "best", my guess is:
these are not protected and have already been gone too low at the very 1st use.
Now are damaged (Li-ions are immediately damaged when under 2.7-2.5 Volts. A modern step-down driver might still draw current then)

Therefore: protected cells!!!
(con: when these get down enough in voltage, the inside circuit cuts power and the light is OFF suddenly. No "fading away" emergency light. Dont ride when that end-of-runtime is near)

PS: do a test to check Your cells.
have the P3D run for 10 mins (to heat up a bit), then measure current from the batts at turbo.
Now You know what the light draws and can calculate the real mA of Your cells

olrac · Aug 12, 2008

PhantomPhoton said:
In my humble opinion, if you want to stick with your P3D and not buy a new light, yet want to have a better performing cell you should look into buying a 17670 Li-Ion. It is one 3.7V cell that is twice the length of RCR123. They generally have better capacities than two RCR123s in series from my experience and from what other members here have stated as well. I think, though someone will hopefully chime in and confirm, that most 17670 cells will fit into a P3D.

Yes they do in mine, I am using a AW 17670

Special rechargeables for LEDs?

svenh

Newly Enlightened

PhantomPhoton

Flashlight Enthusiast

svenh

Newly Enlightened

yellow

Flashlight Enthusiast

TONY M

Flashlight Enthusiast

svenh

Newly Enlightened

svenh

Newly Enlightened

Gunner12

Flashaholic

LukeA

Flashlight Enthusiast

PhantomPhoton

Flashlight Enthusiast

yellow

Flashlight Enthusiast

olrac

Flashlight Enthusiast

Similar threads

Latest posts