Madmax Q's. Updated: my new battery vampire.

I have a MadmaxLite WO and MadmaxPlus WO on order want to get a better idea of how or even if they will work for the following:

KL1 Surefire head
Luxeon III Red/orange emitter (2.10Vf @ 200ma / 2.95Vf @ 1400ma typical)
Battery: single CR123

The idea for the light is to mainly run used up primary cells that have dimmed on P60 lamps. Howerver, I'd like to be able to use fresh cells also.

Will fresh cells run the emitter in direct drive? If so, will the Madmax handle the current? At what point might the converter take over and semi-regulate the output? How well will this setup work to finish off the near dead cells? Or should I ask, what kind of current will the Madmax be able to get out of a cell when it's below 2.5V open voltage?

Re: Madmax Q's. How will this setup behave?

The bypass diode in the Madmax when in DD is only rated for 1A. If the battery voltage overdrive exceeds this drive current you may be ok, but, it would be beyond the parts specification and not recommended.

A fresh cell CR123 under a 1A load will drop 0.4V or so. This might make it safe and regulate when the battery voltage drops below the Vf of the LED. I believe for a short while a fresh battery will be in DD mode.

The Madmax will be in regulation when the LED current drops to 1A draw from the battery side.

Wayne

Re: Madmax Q's. How will this setup behave?

Thanks for the quick response, Wayne. I'll go ahead with it. Hopefully I don't get an emitter with below average Vf. I'll post results in a few days.

Re: Madmax Q's. How will this setup behave?

My Madmax boards arrived yesterday and I promptly got to work this morning. I had been running the light in direct drive on a single CR123. It worked pretty well. A fresh cell would only show ~700ma at the tail and by 2.6V it would only push the Lux3 @ 6 or 7ma. With the Madmax Lite, I'm now getting about 29 or 30ma from a cell at 2.6V. The light has usuable brigtness until the cells has about 2V resting. I let it run one cell until the light went out and resting voltage of the cell was in the 1.2V range. Im really happy with this little "vampire".