3 C Cells in a 2D Mag?

Will 3 C cells fit in a 2D mag body? Do any modifications need to be done? I think Im going to make a LuxIII direct drive off 3 C cells in a 2D mag body with a Hotlips sink. Id really rather use liths, but Id have to use a circuit.

I believe that they will fit if you cut the sping in the end cap so that it will fit down in the cap and remove some of the anodizing to get a good connection between the spring and the cap.

Use some 1" pvc to make a battery tube to hold the 3 C cells. Cut the spring down do that it fits all the way into the end cap. I use Red Devil lye (a drain cleaner) to remove the anodizing for a good contact. If you use the lye, don't let it sit too long. That stuff will eat the aluminum.

This seems like a very sensible mod. Lots of light, lots of throw, lots of run-time, reasonably small flashlight.

I just did this mod over the weekend. Works great. I also did one with a BB750 at the same time. Which is better? I don't know, different design philosophies for driving the 3 watt luxeon.

I did cut down the tailcap spring (using Dremel tool) so that it would fit down into the tailcap bottom. I cut off the top (narrow coils) and most of the bottom, so that spring tension of the wider coils holds it in place in the bottom of the tailcap. I did have to bend the narrow coils for sure contact with the C-cells (using pliers).

Also, I used the Dremel to sand the anodizing from the floor and sides of the tailcap, so that the spring made good electrical contact.

With kinda worn alkaline C cells, it pushes the luxeon 3 at about 400 mA. The light is good, but not outstanding. With NiCads (much less internal resistance), it pushes about 750 mA (same as the BB750) and is indistinguishable side-by-side from its twin with the BB750.

I highly recommend this simple and inexpensive mod. Also, the Hotlips heatsinks are a joy to work with.

Kerry

Prometheid, what bin was your Lux III. Forward voltage?

Bill

Prometheid,
Are you sure about that current? Are you using 3 C cells? I get over an amp on fresh batts. The direct drive light should be brighter than the BB750 setup on fresh batteries. My batts have to be near dead for the current to get down to 400mA. I change the batts way before this.

There might be something in your current path adding resistance.

You don't really need to cut the spring at both ends. Just the back end and only enough for the spring to fit down into the end cap.

With 3 fresh Eveready Gold alkalines and 0.5 ohms in series with a SV1J, mine draws 1.2 amps on the 20 A scale of a DMM. So, considering test lead length and the shunt resistor in the DMM, it's a little higher than 1.2A. But it does drop off rather quickly.
Rob

Chop, when u change out the C cells, are they pretty much completely drained, or do they still have juice? I dont want to have a bunch of partially drained C cells lying around.

Take a look at this new 3C LS3 light ($50) from Elektrolumens
FT-3C

And check out this EL thread. Something's funny, because different guys are getting quite different current flows from the same configuration.
FT-3C thread

MTFD,
You can run 'em down as much as you want. You can run 'em almost completely dead. It's just a matter of how dim you wanna let your light get. I don't often need full brightness, I just like to keep it that way. I buy cheap C cells whenever they're on sale and don't worry about it.