Now it's arrived, and it's fairly bright, but nothing Earth-shattering. On batteries delivering 6.74V under load, it was drawing 1.44A, for an underwhelming total of 9.71W (minus losses).
So what's the likely story here? Fake XHP70.2? Deliberately under-driven? Faulty?
Is there anything I can do (within sensible budgetary constraints) to significantly improve it?
I’m surprised to see that this is actually a genuine XHP70.2.
1.44A is not much for the XHP70.2 which is specified for at least 5A. If you feel comfortable with soldering SMD resistors you could try to replace or stack resistors on the four R200 resistors. If you lower the resistance of those you should get more current.
Good call - for some reason the voltage didn’t seem all that low to me. After I took the measurements I discharged them and they gave up over 3000mAh, so I assumed they had been in pretty decent shape, albeit with an internal resistance of ~190mΩ. After a full charge the brightness is better, but still not awesome. When I get a chance I’ll pop it on a bench supply and measure the current through the LED itself.
Sounds like a plan - I’ll give it a go once I rule out bad cells using a bench supply. Was wondering if there’s something to be done to alter the gate voltage for the dual MOSFET package, but I’m no EE, so I’m not even clear on how this driver circuit functions, let alone how to alter it. But reducing series resistance is something I can wrap my head around reasonably easily
Yeah, I forgot to take a look while I had the head apart, but although most of the seals seem pretty good, there’s a reasonably direct mechanical connection between the external button and the internal switch, so I’ll apply my standard AliExpress water resistance conversion:
“Splashproof” - will not (immediately) explode when splashed with water
“Water resistant to 10ft” - splashproof
“Water resistant to 200ft” - water resistant to 10ft.
You’re doing the right thing by first taking tailcap current measurements and trying to baseline things. Might also want to cycle the batteries. Take temperature measurements of the host, noting the time durations. Repeat with different batteries too if you have some.
x2 on the R200 resistor mods. This is a common upgrade to the Convoy L6 and other lights too. I dont have first hand experience on it though since my L6 remains stock. Note though that this will also brighten your low modes too. That may not be to your liking.
I have no idea how to tell a fake XHP70.2 from a real one. so if other members think its authentic I would agree with that. But the difficult question then becomes what flux BIN is it?
You could also bypass the springs with copper braid wire.
Curious how is the PWM on low modes? How do you like the battery charge level indicator feature?
Looks like a nice host, good luck!!
Haven’t noticed any flicker at all on any setting. Also haven’t seen the power indicator show anything but green yet. Takes a second for the indicator to come on after you switch the torch on, which is a mild annoyance.
They’re…blue. No idea what make, they were supplied with the torch, and took 5223mAh and 5336mAh after an initial discharge. Internal resistance is around 190mΩ.
190 mililliohms for those 26650’s? How are you measuring those? That’s way too high internal resistance. It tells me those cells are either junk or faulty. Normal quality 26650’s are between 15 and 20 milihoms. Get some good quality 26650 and that thing will come alive I bet. The 6v xhp70.2 can be driven really hard.
Quick test mode on an Opus BT-C3100. Not sure how much I trust it - the results vary between slots, and come down with a little extra pressure applied. I’ve seen one result as low as 63.
HJK’s testing showed that charger to have pretty accurate resistance measuring (not being 4 wire), and I bet those cells really do suck. It could have came from the cells not being balanced in series properly? diff. voltages under load for example. I know I may have been guilty of that at one point.
I recommend this pair of Shocklis - They do quite well in all my lights. Not the absolute highest-current 26650, but very high current without sacrificing capacity.
Any idea how thick the shelf is under that LED? Also if you want some quick testing you can do the old pencil trick to those R200s.
Might give the pencil trick a go if I end up looking to mod it, though decent batteries might be the main fix I need. Not sure about the thickness - maybe 2-3mm, check the photo below where the black wire runs through it and you can see the red wire behind.
