That is some awesome work. I’m stalled about halfway through a very similar build. This is some great motivation to get back after it. I really like what you did with the pill… I may have to incorporate some at least one of your ideas - adding copper on top to raise the LED seems much better than trying to file the lip on the pill down to get it to screw in further.
I’ve got a few cut pieces of pipe press fit into the pill already… but it never occurred to me to drill holes in the aluminum to solder a copper spacer on top to the copper below. Nice work!
I did some tailcap current measuring and got some numbers that don’t make sense to me.
From 2x freshly charged old sanyo’s (1s2p) led pulled 3,70 A (batteries are old and I didn’t expect them to go as high as this)
From 1x freshly charged old sanyo (1s1p) led pulled 2,93 A - this is what I don’t get. According to this, two batteries should “give” around 6A when connected parallel.
Similar thing with shitty ultrafires:
1s2p - 4,4 A
1s1p - 3,8 A
Forgive my ignorance but could someone help me understand this. Thanks.
I agree with dentillozie that it is probably voltage sag. 2 cells will sag less than 1, but not by much. You could have some resistance, but it doesn't look like it. Probably have an emitter with a high Vf. If you can measure the voltage accross the emitter, that would give you some good info. Here is a chart djozz made when he tested an xml2 on copper some time ago. Link to thread in picture.
The only real resistence left that I can see is the contact plate maybe?
You could drill threw and solder the driver directly to a fitting copper-sealing under it propably ? That would take care of that.
If that doesn’t work WarHawg made a contact plate for it (don’t know if tested): Link to OSHpark .
Yeah, that is pretty high. If you look at djozz's chart above, his older XM-L2 had a Vf of about 4.65 3.65 at 4.4amps. Decent cells will sag to 3.9 volts under even at just a 1 amp load. Sounds like you identified your issue. High emitter Vf and cell voltage sag.
Bet you're even happier to have some 25R's on the way now. Please report what they do tail current wise. I'm curious.
Yes, it looks that way. Take a look at the picture 28. The pill is around 2mm below the wire. I had to move those wires as far as I could to get clerance from reflector bottom since it is sitting on the MCPCB. That’s why I sanded the edge of the pill down.
That explains everything, thanks.
Don’t get me wrong, I couldn’t tell the difference in amount of light emitted between 4.5A and 3.8A. Maybe that’s only my inexperience . This thing throws like crazy even at lower currents. Although it would be nice if numbers were like they supposed to be. Hope that 25R’s will help. Can’t wait .
. . . I couldn’t tell the difference in amount of light emitted between 4.5A and 3.8A. . . .
I think that is normal due to our perception of light and our ability to adjust to different levels of light. Where I have noticed a difference the most is in throwy beams. I have some lights that have some obnoxiously close modes. The extra current makes a difference when I'm trying to see on object far out towards the edge of the usable beam. I need, however, to switch between modes to see the difference. Well, I can also see the difference close up in the intensity of the hot spot when switching between high-level closely spaced modes, but I don't like doing that.