No, I haven’t yet.
I mentioned this in another thread, but when you all say measure tailcap current, is the tailcap actually in the circuit?
What I mean is that when I measured current, I connected from:
the tail end threads of the light
=> meter
=> - end of battery =battery + end of battery
=> (the spring on the) driver in head
i.e., the tailcap was not actually in the circuit.
When you measure “tailcap current” do you connect it differently than above?
Thanks,
Jim
garry,
I was about to try another white wall shot, and checked that the light was on high mode, and, just looking at the screen (I was using the camera from my tablet), I could see the lines… kind of like when you look at a TV through a camera.
Weird!!
Jim
Hi,
Tried the current measurement both ways:
- The way I described above (no tailcap in circuit): ~1.57 amps
- With tailcap in circuit: ~.8 amps
Edit: So does this mean the tailcap switch is ~5 ohms (V/I = ~4 / .77 = ~5.19 ohms?
Is that high? Or low? Or normal?
FYI, the host was a SolarForce “Blue” L2x with the default forward clicky switch.
Jim
Hi,
I think that what you said earlier may be correct, that there’s PWM when in high mode with that original driver. When I was measuring the current, I could see the meter reading fluctuating all over the place.
I think the driver is from this drop-in:
http://www.fasttech.com/p/1179700
Why would they design the driver this way, usng PWM in high mode? Are they trying purposely to reduce its visible performance in high mode?
Edit: I just found this:
If you check the comments for “FandyFire A10B XM-L”, it says:
I think that the same thing may be happening with the driver from that drop-in.
Hey Jim sorry for the late response. Yes it sounds like your seeing a driver with PWM in high mode (I don't think that's common, but as you found they are out there). Yes, measuring tailcap current is generally without a switch in the circuit - one meter probe in the (-) end of battery and the other probe on the threads or flashlight body to complete the circuit. The drop you measured across your switch sounds awfully high, but others would have to chime in on that. The 1.57A sounds like it should be okay for the XP-E (your not overdriving it that much, although I'm not real sure of an XP-E's "true" limit).
-Garry
I was “on a roll”, so I did tailcap current measurements on a number of the lights that I have. Recall that all of my lights are “out-of-box” from commercial vendors, i.e., no mods yet. Anyway, when I did all of those tests, all of them measured ~1.0V - ~1.5V. I guess that I wasn’t so much surprised, but a little disappointed, at those results.
Thinking about it though, I was wondering if, maybe, manufacturers are more conservative with their designs, and because of that, when they design/build lights, they purposely don’t drive their lights very hard?
Does anyone know if that’s the case?
I take it you mean 1amp - 1.5amps. Yes, that is pretty typical. Sometimes even lower.
Sorry about that. Yes, I meant “amps” not “volts” :(…
And thanks for confirming that this is typical.
But, I wonder is that even the case like with the “stock” Kaidomain C8s? I’m assuming that vendors like Kaidomain mod some OEM C8 (or whatever host) with new drivers, in order to be able to claim 2.8 amps, and lights like that would actually show current that’s higher than the 1 - 1.5 amp range?
I should add more. Many stock lights out there go higher. Sometimes, you don’t get the same current due to batteries with high resistance or resistance within the flashlight. Also, your DMM’s leads may have a lot of resistance.
Hopefully, someone with more experience in this area can give you some input.
What lights did you test?
before you get all het up, I assume you have a 2.8 or 3 amp nanjg on the way.
If not, get one on the way asap, with this, build a drop in or c8 pill then use this to confirm your meter will read 2.8/3.0 amp reliably. If your using a cheap meter you may have to make up some low resistance/high current test leads.
I would generally hope to be getting 2a or so to an xm-l, although I’m regularly disappointed in this respect and now count on most lights being “hosts” as the emitter tint,modes and drive current will not be what I want. This is the beauty of modding, getting what you find most usefull in a light.
Hi,
Let’s see:
- Several different C8s (a couple fromAmazon and one from Tmart (actually a “G4-MCU”, but it sure looks a C8 to me))
- Several different P60 lights, with SolarForce and FastTech drop-ins
- Crelant 7G6CS
- Niteye TF20 and 25
There may’ve been others… can’t recall them all at this point. All had ~1.0 amp - ~1.5 amps
Jim
Hi,
I might try that, but it might be awhile, as got some stuff at work that’ll tie me up some this week.
Tailcap readings don’t really tell you anything unless you’re running direct drive or an AMC driver.
The Crelant and the Niteyes probably run buck drivers, which means that the battery current will be less than the LED current.
The only way to know the current at the LED is to measure the current at the LED, not the tail cap.
Hi,
I wanted to let you all know, esp. for those of you who were encouraging, that I happened to also have an “Cree XP-E, 16mm Star MCPCB, R2, WG tint”, and I ended up putting that on the drop-in, instead of the 10mm Nichia PCB, and it was EASY (like some of you already said… ok, ok).
I was just outside with an L2P with the “new” pill, and while it’s not as bright as the original XM-L emitter, it was really able to throw… a very narrow, bright beam that was able to reach across to a stand of trees, about 150 yards. Hardly any spill though :(…
Thanks for all of the help.
Jim
Thanks for the update. It always to good to recover a light up to at least some level of functionality. Thanks for the beam info. I haven’t owned or used an xpe yet.