I'l like to present something here that is of general interest.
The LED flashlights that one gets for free from Harbor Freight
have 9 LEDs , in paralled, run by three AAA cells with no
current limiting resistor.
The current draw is in the neighborhood of 160 ma.....
I fabricated a piece that can be inserted into the back
of the flashlight without modification of the original unit.
It is a piece of double sided G-10 board, approx the size
of a dime, with the copper trimmed slighly away from the edges to
keep copper on each side from shorting to the case of the light.
A small notch is cut, and a 100 ohm resistor is inserted so that
the current will flow from one side, thru the resistor, to the
The "coin" is then inserted into the BACK of the flashlight
and the back cap screwed back on...
This effectively inserts a 100 ohm resistor between the negative
terminal of the battery and the negative terminal of the flashlite
--- a current limiting resistor....
The resultant current is 16 mils (approx) to the nine LED
The light output decreases, but still puts out enough to
read by, or find one's way in the dark. My guess is about
1/3 or the original, by eyeball only......
The batteries are no longer working into a short circuit, but
only supplying about 1/10 of the original current, and should last at
10 times a long as before....
If one wants to restore full brightness, one has only to remove
the "coin" insert....
I've done this with about a dozen LED flashlights that I keep
in the car, house, pocket, garage, etc.... It works well..
Give it a try. If you have a more simply, or more innovative way
to accomplish this, I'd be most interested in learning about it...
Andy in Eureka, Texas P.E.