Hello friends,
I have an old Convoy C8 host (bought in 2014), the one with the aluminum pill and the retaining ring for the board.
I have installed an XP-L Hi on a DTP cooper star and a 12 x 7135 105c driver (I have added the extra 4 7135s).
The thing is that I will only get a ~2.9A tailcap reading. I use thick DMM leads which have read 4+ amps on other lights.
Also I have the LED+ spring bypassed with copper braided wire.
Before the XP-L HI, I had an XP-G2 installed in the star and I would get 2.8A (the lower amperage is probably to the high Vf of the LED).
The driver has been tested for continuity on all of the 7135 legs and everything is fine.
At first I thought that maybe the driver had gone bad so I tested with another nanjg driver with 10 x 7135 and this time I only got ~2.3A.
Both drivers had their wires changed with 20AWG ones but no change in draw.
I have come to a dead end.Maybe the 16mm dtp copper pill is causing the problem?
Any suggestions are highly appreciated.
- remove the driver and LED (or use other XPL led if you have spare one) from the flashlight and connect them directly (outside of the flashlight)
if you have clamp meter use that to measure amperage supplied to the LED (you are measuring between the driver and the led, not between the battery and driver)
(or use regular DMM that you have just connect the LED through it if you don’t have clamp meter).
-report readings…
Nanjg with 12xAMC should supply about 4.1-4.3A measured between the driver and LED (that is what I get but with XML2, not XPL)…
You didn’t mention the cell you are using… Some cells just aren’t capable of pushing that much current (old blue-wrap UltraFire 18650 I received as part of a combo from the Jolly Green Dino years back…)
Reseat everything. Might’ve happened that taking it out to add the 7135s and then putting it back added some resistance somewhere (eg, grounding it to the case).
Also, force-feed the cell to 100% (4.2V) and see if that makes a diff. 7135s drop at least 0.1V when saturated, so you’ll have to overcome the Vf of the LED and that 0.1V from the 7135. Forgot the Vf of the XP-L, but it shouldn’t be that high.
If you have the skillz, you can poke your meter throughout the circuit to see what the summed voltages are:
Vbatt, total
Vf of the LED
VCE of the 7135s
and see what’s the hangup. If everything seems “normal”, then it’s something in the connections, eg, between the LED and the driver, or the driver’s ground to the cell’s ground, etc.
Quick example, someone’s car-stereo was acting up. Proper system voltage (~14.5V on startup), only ~9V at the stereo. Measuring resistance from (-) at the battery and ground at the stereo showed lowlowlow resistance! (With almost no current, aha!) Turned out corrosion in the chassis increased the “low” resistance significantly that when full current was going through, that raised the voltage diffs between the grounds by a few volts!
Could be that a soldered wire broke most except 1-2 thin strands from being moved, etc.
Should’ve also mentioned… try a different cell anyway. Never know if there’s something wonky with it, that it might be sagging under load for whatever reason.
