ultrafire with 4x18650?

[vwarner]

Hi all great forum!
i have a flashlight as attached and wanted to add a couple extension tubes and run 4x18650 batteries in it.
has anyone tried this? thoughts?
cheers

as a new member i cant post pics, these are links to the light.
cheers all


http://www.ebay.ca/itm/UltraFire-26...3525416?pt=US_Flashlights&hash=item3a98e93ca8

or

http://www.ebay.ca/itm/UltraFire-26...8895070?pt=US_Flashlights&hash=item5afd6de7de

 

[JasonJ]

Are you sure the emitter can handle the additional voltage OK? I'm not sure if it will work or not, but that would be the first thing I'd check, whether double the working voltage will be accepted or if it will fry the LED.

 

[RMM]

Are you sure the emitter can handle the additional voltage OK? I'm not sure if it will work or not, but that would be the first thing I'd check, whether double the working voltage will be accepted or if it will fry the LED.

Since that light can already take 2x18650, it already has a buck driver which steps down the voltage to the LED. The question is what the maximum input voltage rating is on that driver. Often times in a cheap light the only way to know is to try it (obviously risking the LED in the process).

 

[tandem]

I think we'll soon see a light, or light user (hope not), turn into

To the OP, unless your light specifies 4xlithium-ion voltages (4x3.7V nominal = 14.4V), don't do it.

Chances are the driver in the light was not designed for for 14V+. Currently it operates on 6xAAA (6x1.5V max = 9V albeit not for very long) or 2xlithium-ion (2x3.7V = 7.2V).

Secondly... multi-cell lithium ion lights need to be managed properly to be safe - from charging to using the cells. Adding even more cells to the mix just raises the stakes. Be sure you've got your safety bases covered before running even a 2xlithium-ion powered light.

 

[Chicken Drumstick]

The other question is why?

Running 4x18650 won't make it brighter. If it can handle it, it should increase runtime, but I'm not convinced it's worth it, as the buck driver will just have to work harder to shed voltage. Which I'm guessing would make it less efficient.

If it's runtime you are after and it already runs on 2x18650. Get yourself one of those small plastic 18650 holders and carry two spares along.