any rcr123 the same diameter as a surefire cr123?

[overkill]

first off, I've tried to search but could not find an answer. . I have the Romisen n-3 cree q5 led flashlight. With it comes an extension tube that will hold two AA batteries in case you do not want to use a single crt123. With the tube screwed on it is the correct length for three cr123 batteries. I had a friend "turn out the ID of the tube so that the cr123's will fit and the light output is amazing.

Now, I recently purchased the battery station rcr123's and it's charger, but the battery diameter is too large. Is there any rcr123 out there with the same diameter as say the SUREFIRE CR123? Thanks.

 

[Black Rose]

I'm surprised you didn't fry the circuitry running it with 9 volts.
It's only designed to handle just over 4.0 volts.

To answer your question, AW's 16340/RCR123 cells are almost the same diameter as a Surefire SF123A cell.

The official specs for the AW cell indicate a diameter of 16.62mm +/- 0.1mm.

I just measured the diameter of the AW 16340 cell I received last week with my calipers.
The AW 16340 is 16.53mm and a SureFire SF123A is 16.42mm.

So about 0.09mm difference in diameter.

 

[Marduke]

Diameters are usually spot on. Lengths are another issue...

BTW, Running you light as such is very dangerous. I too am surprise you didn't let the magic smoke out.

 

[mdocod]

first off, I've tried to search but could not find an answer. .

Welcome to CPF!
The answers are coming overkill...

I have the Romisen n-3 cree q5 led flashlight. With it comes an extension tube that will hold two AA batteries in case you do not want to use a single crt123.

Light designs that involve a single CR123 or 1xAA or 2xAA configuration have boost regulators and should not be used with a power source that exceeds the Vf of the LED.

With the tube screwed on it is the correct length for three cr123 batteries. I had a friend "turn out the ID of the tube so that the cr123's will fit and the light output is amazing.

I'm actually amazed to hear that you are getting any output at all. The LED should have fried already, undoubtedly you have already done permanent irreversible damage to the LED and possibly the electronics. The Vf of an LED is around 3.5V give or take a few tenths, when flashlights are designed around these LEDs, they generally either boost a lower voltage source up to the voltage needed for the LED, or buck down the voltage from a higher voltage source. There are no production flashlights in existence at this time that can properly boost from ~3V or buck from ~9V and work properly either way. You have to choose either boost or buck in most circumstances. In your case, you have a boost regulator.

Now, I recently purchased the battery station rcr123's and it's charger, but the battery diameter is too large. Is there any rcr123 out there with the same diameter as say the SUREFIRE CR123? Thanks.

If you did manage to fit 3 RCR123s in there, it would be the end of the flashlight for sure. I don't know how or why you haven't already smoked it with 3 CR123s, but if anything you are lucky you weren't able to fit those cells in there.

Lets say, by some weird miracle, that the LED survived long enough for it to be a useful configuration on 3xRCR123s (it wouldn't), I can guarantee that it would be drawing far more current than what is safe for the cells anyways.

....


Now, to actually answer your question:
Most RCR123s are a few tenths of a mm fatter than regular CR123s, but some are closer than others. *Most* flashlight tubes designed for CR123s have enough wiggle room to fit these variations but not all. AWs new LiMn chemistry IMR16340s are probably the closest to the size of a regular CR123 of any RCR123 cell on the market, but I warn you, installing 3 of them into the light will instantly destroy the LED or electronics or both.

-Eric

 

[overkill]

First off, I want to thank everyone for their input. I'm am by no means a flashaholic, but I do enjoy very bright lights. They come in handy for my line of work. As far as damaging/destroying my light , it was my understanding that the cree q5 drop in module was rated at 4.7-18v. This is the info I went off of. Having said that, when I have 3 cr123's in there, like I said it' brighter than the sun, and have never had any problems.. yet. Could someone verify the input of my led?

 

[Marduke]

That light is only 2-4.2v. Running it on 3xCR123 WILL burn out the circuit.

 

[mdocod]

Hello Overkill,

If the circuitry in your light was designed to operate from 3.7-18V, how would it work on 1xCR123 or 2xAA cells? (both configurations peaking ~3V)... hehe.

-Eric

 

[overkill]

Once again, thanks for all your input! I do not pretend to know much about led's and such, because I dont!!! and now to stick my foot in my mouth. I knew that there was a risk using more juice than the flashlight was intended for could possible damage or destroy it, but for such a low price I knew I would not be out a lot of money. Now, is it common for the circuitry to last this long? I do know that when I had the light on for about 4-5 minnutes, the housing did get quite warm

Also, the specs said that the LED was rated at 210 lumens, and after running it on 1 cr123, I knew that it was no where near the maximum lumen rating. This was another reason why I thought it would be safe to use the additional batteries.

 

[mdocod]

As we have said, we are totally in shock that the light survived it for even a moment. The LED should have already fried. The saving grace must be some other factor here. My guess is that the circuit has a point of high resistance in the design that is acting as your LEDs buffer from the real onslaught of destruction that otherwise would certainly be.

If you had a DMM and could measure the current across where the tail-cap would be that would be a fun little experiment to see how much you are overdriving the light.

To give an idea of why we are so amazed: LEDs do not conduct like regular resistive loads. They operate across a very narrow voltage band. Below ~3V they have very high resistance and very little current flows across them. at ~3.3-3.8V they are operating at their recommended drive range (~usually 350-1200mA), the effective resistance of an LED drops dramatically as the voltage is increased even in just small increments through it's operating range. All LEDs vary from one unit to the next, and there will be some variation in how much voltage is required to achieve certain amounts of current flow, but one thing is pretty absolute: not many are going to handle ~4V or much higher without frying, they would go into thermal runaway. Your configuration is probably running upwards of 3 amps or higher across the LED, with the cells sagging to ~2V per cell under the load, and some small wire connections in the circuit and leading to the LED actually protecting the LED from complete destruction immediately by dramatically reducing the effective voltage that the LED would be seeing under this configuration if the wiring were up to the task of carrying the load that's trying to flow.

-Eric