Fewer batteries than needed?

[silentlurker]

Are there flashlights that can use fewer batteries than they were designed to use? For example, if you put only 2xAA into an LD40 would you get half as much light, half as much run time, or nothing at all out of the light? I'm interested in the general answer, not just for Fenix lights. Thanks!

 

[Lynx_Arc]

Are there flashlights that can use fewer batteries than they were designed to use? For example, if you put only 2xAA into an LD40 would you get half as much light, half as much run time, or nothing at all out of the light? I'm interested in the general answer, not just for Fenix lights. Thanks!

There are lights that you can lego with other tubes that will run on fewer batteries. I have a dorcy 2AA that will light up with one battery if you use a dummy cell with it but mostly the problem is making up for connections that the other batteries provide and some lights will stop working when the voltage gets too low even if the batteries are not even half depleted. My advice is to look for a light that had a driver that works from 1.5-4.2v and has options to buy battery tubes for 123, 2AA, and 1AA. A 2AA light with a 1AA tube could run normally with reduced runtime off a 3v CR14505 cell (primary lithium).

 

[LEDninja]

If you put 2AA into a LD40 you will get no light, or just a dim glow. Buck drivers in that type of light prefer at least 4V to work properly.

The Fenix TK40 and TK45 are designed for 4 cell operation. The battery holder can take 8 batteries in 4 series 2 parallel to allow use of low amperage capacity (alkaline and some NiMH). If you use Eneloops you can use just 4.

Check the voltage range of the flashlight head.
The Quark AA an 2AA both use a 0.9V to 4.2V head. So if you have a Quark 2AA you can buy a 1AA body.
The Quark 123² uses a 3V to 9V head. The Quark 123 uses a 0.9V to 4.2V head. I do not recommend using a Quark 123 body on the Quark 123² head. While in theory a 3V CR123 or 3.6V RCR 123 is within the 3V to 9V range buck circuits operate best at 4+V.

A number of lights come with extension tubes. You can use more batteries with the tubes or less batteries without them. Just remember the lights will be a lot dimmer without the extensions. (Some 1AA/2AA lights can take 1*14500 which brings the brightness back)
The top light in the picture below is an example.

I shrunk the length a little more by switching the head to a body without a click switch.

 

[shane45_1911]

EDIT.

Oops, TK 40 already mentioned above. :)

 

[blah9]

Can you actually use only four batteries in a TK45? I was under the impression that they're all in series, unlike the TK40, and using only 4 would not work.

 

[angelofwar]

Here's the few from Surefire that will function on "less than required" Batteries (using a different body or a battery spacer)

-Any 3 Cell model using the KX3/KX4 head can also function properly (less runtime) on 2 Cells
-The 3rd and 4th gen KL1 heads found on the <2007 E2L's/E1L's (Domed optic) will run on 1, two, or THREE CR123's
-The Lux-V 2 Cell Surefires (L4/U2/L2) will run at half out-put on a single CR123 or about 70% output on a single RCR123 (search "TW4"), although the first method is really inefficient, but it will work.
-2007-2010 LED Models featuring the P60L will work on 2 or 3 Cells at full capacity.
-The Kroma will work on 1 Cell (CR123/RCR123), again, not in full output, except maybe the red and blue LED rings, and also at reduced runtimes.
-The Old KL3's will function at full out put on 2 or 3 cells.

I think that's it on the SF Models...

 

[gladis]

As a general rule many lights from reputable manufacturers who have a 1 or 2-cell variety will have a common head, which means you can interchange (ie lego) them. This also means that in a pinch, you can use one cell and complete the pathway by using something metal (ie a wad of aluminum foil, or paper clip bent into shape).

But as always check the manufacturer's page to make sure the head's designed to accept a 1-2 cell voltage.

Lights of the DX variety will sometimes have drivers that take a very wide range of voltages, and in those you can mix any combination of batteries.