Need a 4AA body w/ good heat dissipation

I'd like to run 5.0v 1.5A 7.5watt xenon lamp designed specifically for 4 cell NiMH/NiCd use in a 4AA body.

The 2.5Ah NiMH have no problem sustaining 1.5A for at least an hour after reviewing battery specs.

Obviously, alkaline wouldn't be able to drive it, but I'm only going to use NiMH.

I have a cheap Eveaready 4AA thing, but if I put a 7.5W lamp in that thing, I'm fairly certain things are going to start melting.

What kind of 4AA PR lamp body can handle the heat from a 7.5W lamp without resulting in the lamp base solder melting or plastic melting?

Adjustable focus is a big plus.

PrincetonTec has the Tec40 which is a 4AA PR-based light. I think it should be able to handle 7.5W without problem. No adjustable focus though.

5.0V, 1.5A bulb will be underdriven in 4AA flashlight.
Bulb won't get more than 4.5 volt.

fivemega said:

5.0V, 1.5A bulb will be underdriven in 4AA flashlight.
Bulb won't get more than 4.5 volt.

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Wrong. I researched the NiMH discharge characteristic and it can indeed maintain around 1.25v/cell nominal at C/1.8 rate.

As I said, this is intended to be used with NiMH and ONLY NiMH.

A high quality plastic light like the Brightstar Responder 4AA should hold up to that kind of heat, since it's made for firemen who tend to be around a lot of heat. Focusable, too.

Considering a 6D Mag is ~7w and uses a plastic lens and a plastic reflector that touches hot metal bits on the pedestal, plastic may be OK.

bfg9000 said:

A high quality plastic light like the Brightstar Responder 4AA should hold up to that kind of heat, since it's made for firemen who tend to be around a lot of heat. Focusable, too.

Considering a 6D Mag is ~7w and uses a plastic lens and a plastic reflector that touches hot metal bits on the pedestal, plastic may be OK.

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The Princeton Tec surge, which is 7.7watt (8AA, 4AA x 2 parallel) in its earlier version had issues with the solder in lamp socket melting.

If the body isn't made of metal, I would imagine its hard for the internal heat to get out.

Handlobraesing said:

Wrong. I researched the NiMH discharge characteristic and it can indeed maintain around 1.25v/cell nominal at C/1.8 rate.

As I said, this is intended to be used with NiMH and ONLY NiMH.

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You missed resistance of battery connectors and switch.
You will not get 5 volt (1.25x4) to bulb.

One of the nice things about the Tec40 -- no switch

There may be some issues with the connectors in the bottom of the light though. I absent-mindedly tried to take a flash-amps reading of all 4 cells while installed and not sure if there is a purposely fusible link down there, but I melted something. Well, duh. A robust copper "bus bar" can easily be fashioned and laid over the springs to ensure a good connection. I fashioned some 1/8 inch copper tubing into a spiral-"S" to make the bridge.

You definitely won't be over-driving that bulb though. I'm getting 5 watts and a satisfying white by overdriving 3-cell mag bulbs. I ran across this bulb which seems like might take it up to 6 watts and still a reasonable overdrive for whiteness

http://atlantalightbulbs.com/ecart/nw012104/KPR130.htm

You could always sleeve a 3D M*g for 4AA. I have one setup that way, as it's brighter and safer to run a 3 cell bulb on NimH. Also makes the M*g feel empty.

Or use a 2D M*g and a 6AA holder and a dummy cell.

Nothing terribly wrong with the TEC 40, but it's fine with 4AA NimH and a 3 cell Whitestar.

I guess solder melting would depend on the melting point of the solder used (including the PR bulb itself). I am running over 7w without issue in a Duracell Explorer that is not only plastic, but entirely rubber encased as well. Unlike LEDs, incans don't mind operating at high temperatures at all.

Since most of the mod parts are for Mag, may I suggest a 1D Mag like this one: https://www.candlepowerforums.com/threads/80436

The group buys are over, but there is a 1D for sale in B/S/T. Don't know if it is still PR.

bfg9000 said:

I guess solder melting would depend on the melting point of the solder used (including the PR bulb itself). I am running over 7w without issue in a Duracell Explorer that is not only plastic, but entirely rubber encased as well. Unlike LEDs, incans don't mind operating at high temperatures at all.

Since most of the mod parts are for Mag, may I suggest a 1D Mag like this one: https://www.candlepowerforums.com/threads/80436

The group buys are over, but there is a 1D for sale in B/S/T. Don't know if it is still PR.

Click to expand...

But if the heat isn't dissipated well enough, the body can melt.

Much as there are many different types of solder, plastics have many different melting temperatures too. Polycarbonate, for example, melts above 480F.

Very little heat is actually transferred from a flashlight body to the air because there is insufficient airflow. Most of it is removed by directly conducting into the hand holding it.