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.
Some of what you did is time consuming pain-staking work, you made it LOOK easy! Nice job!
The new high Vf makes it more difficult to pull high current, BUT they make more using less.
To my findings they’ll typically do about 2A less at the limits, but only lose about 200 lumens. Very similar output, much less current draw. Efficiency working hard to give you longer run times.
You should see more from the 25R’s but don’t expect a lot more, what you’ll see though is a little more and it lasting longer as the higher quality cell maintains during the current draw.