A19 XR-E Aleph Mod

Anyone,

I want to modify my A19 to be driven at around 350 ma to give it very long runtime and I would like to be able to have a low of around 40 to 80 ma.

I am very new to the game when it comes to modifying lights so I will need real help on this.

I want to be able to run the light with 1 x R123, 1 x CR123, 1 x 17650 or 2 x CR123.

What I am wanting to know is what I need to buy to do this.

Thank you.

-Goatee (Future Modder and Builder)

You will need to replace the downboy driver in the light engine with a Downboy400 (closest you will get to 350mA without getting a custom one)

I don't know if the new Cree light engines are potted or not, if they are you will probably have to buy a LE kit and the Downboy converter and make up a new one.

Once you have the light engine built with a Downboy 400 then you can change the guts of the two stage tailcap to ones with a resistor value to yield to low level your after.

You only need the Downboy if you want to use 2 cells, if you stick with single cell setups then you will have more choices in different drivers.

The 2x123 is kind of a showstopper. The other cell configurations can be had with a buck/boost converter like Wiz2 or GD converter. The bias resistor has to be modified to get the desired 350mA. Not hard to do with the right equipment (tweezers, fine tip iron, maybe a 10x eye loup, and of course, the ability to work with fine pitch parts)

I really like the idea of dialing down the bias for very long runtimes. With the lumen efficiency of the Cree, this is now feasible. In fact, something maybe even lower than 350mA would be good. I wonder what the efficiency of the above converters would be at say, 200mA-250mA. Probably the only way to tell is to modify a GD or Wiz2 and do a runtime test.

I have been simply putting a 17670 into my unmodified 2x123 A19 XR-E.
Somewhat lower light level after the battery has run down a little than the usual 2-cell configuration, but still very bright.

Considerably lower low.

Still going at 2 hours on high, though now noticeably less bright than
a fresh A19 XR-E, so it must have fell out of regulation at some point.
Even the low is still too bright to look at.
Still going at 2:25, but the battery voltage was down to almost 3 volts so I terminated the test.

I have been pulling the battery out and checking open-circuit voltage periodically:

0:00 4.17v (DSD's idea of a full charge)
0:30 3.88
1:00 3.77
1:30 3.70
1:45 3.66
2:00 3.51
2:05 3.43
2:10 3.30
2:15 3.24
2:20 3.13
2:25 3.02

The light was still going, but I didn't want to run the battery down any lower.