I modded a Streamlight SL20 today. Well, I built a custom drop-in is more like it. The person who I did it for wanted the light to be able to be returned to stock at any time. There was not a lot of room to work with, so everything I added had to be cut, filed and shoehorned to fit. On with the slide show...
Here's my clamp meter zeroed at the LED leads and a DMM ready to take a tail-cap consumption measurement. I'm not sure how much charge the battery had on it at this point:
Here's the owner's previous drop-in, an MC-E based Terralux TLE-110. What a power hog. Check out the tailcap measurement.
Here's my "drop-in". Same pack, same unknown charge. 2.8A output, and far less consumption measured at the tail.
Even after trimming down the reflector and base, I still couldn't make everything fit without one reversible "mod". I replaced the pan-head screw with a countersink screw of the same thread, and dropped the plastic shroud about 2mm. To return to stock, the original screw can be reinstalled and the plastic returned to its stock position.
Here's the original drop in with the stock polycarb lens:
Here's the custom XML mod with a 54mm AR coated glass lens:
And now for the requisite beamshots. All camera settings at the same F stop, ISO and shutter speed, but the white balance was on auto for the TLE drop-in and forced to something else for the other two shots, so ignore the "tint":
control, lights on:
Custom XML drop-in:
Notes for the owner:
1) The driver will strobe when the battery pack is low. I ran it for 12 constant minutes on the charge that was on it before that happened. I verified this was not a thermal event causing the strobing by allowing the light to cool and then observing the same thing almost immediately at the next power-on. Immediately after that, I charged the battery for a few minutes put a little more charge on the battery and was then able to run it a few minutes more with no strobing. After 1-2 minutes, I shut it off instead of waiting for the battery to sag again.
2) The battery pack is the OEM pack from Streamlight, but I'm not sure how old it is or how much charge was on it when I received it. Also, I don't know if you keep the light off the charger how badly it will self discharge. You might want to consider replacing/upgrading to an aftermarket NiMH pack that works with your light and charger. Batteryjunction has one for $25, which isn't much more than the standard NiCd variety.
3) Avoid unassembling the light. Things really are shoehorned in there. To reassemble properly, the wires must be carefully tucked inside the switch compartment area with forceps or needle nose pliers and coiled just right to make sure they're not pinched anywhere. If curiosity gets the better of you, or the glass lens ever breaks and you have to reinstall it, make sure you mind the color coding of the switch leads that connect to the driver. I used a red and black sharpie markers on each set to label the pos and neg. (Red to red, black to black.) If the Sharpie wears off, then hopefully you'll dig up this thread to reference that the driver's input wires are green for pos and white for neg. I'm pretty sure the driver does not have reverse polarity protection and it will die if the leads (or battery pack) are reversed.
4) I hope you like it. I am very pleased with the improvements to throw, brightness and power consumption. Hopefully, it will be more reliable than the Terralux modules that gave you so much trouble. I don't know anything about them other than the troubles you described and the power consumption that I observed. Based on that, I'd guess that they were overheating internally, causing the first to fail and the second to perform flaky the way it did/does. I still can't understand why they chose the little 34mm Fraen microfaceted plastic reflector when they could have fit a much larger metal reflector to tighten the beam and distribute the heat to the head.