A17DD-L Drawing Only 2.75a?

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joediese
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A17DD-L Drawing Only 2.75a?

Hello enlightened ones, bear with me here, long time listener, first time caller!

Recently fitted a A17DD-L driver into one of my lights, excited by FET power and was frankly expecting more amps, more bright!

Only drawing a paltry 2.75a at the tailcap, measured by two decent meters and some and some solid-core household wiring for leads.

Set up as it currently is: XinTd V5, A17DD driver with bypassed Pos spring, XPG2 emitter, 30Q battery.

Consistently only pulls ~2.75a which is about the same as the Nanjg 105c which was in the light before. Same battery in different lights pulls 6a no problems.
In all honesty I was expecting to pop the emitter when I turned her on…

Any tips as to where to look? Duff driver? Set something wrong in Config menu? Unable to access turbo? Not enough solder between driver ground and pill?

Tried many searches of all the key terms on the webs, but no joy.

What say you guys?

Edited by: joediese on 12/06/2019 - 08:36
Yokiamy
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How are you measuring?
The resistance of your DMM leads will have significant influence of your reading.

Better to use a clamp meter

joediese
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I’ve been measuring current on both a Fluke and my work-issued meter using quality leads, and also re-measured with solid-core wiring I’ve made into leads on the same meters.

The results of the current draw checks on other lights all sit roughly where they ought to, so believe that the issue lies with this light not producing enough amperage.

I have a clamp meter but haven’t had time to make up a piece of copper plate as per what’s used in Djozz’s video.

Hikelite
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Maybe the Vf of the emitter is that high that it can only draw 2.75A in direct drive.

joediese
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Hikelite wrote:
Maybe the Vf of the emitter is that high that it can only draw 2.75A in direct drive.

I believe this emitter (XP-G2 S4 2B) should be okay up to six amps, although only needs to be driven up to five amps to deliver most of its output.

I could be wrong though…

EasyB
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It’s not that your ammeter is inaccurate. It’s that the ammeter itself has significant resistance (not just the leads) that affects how much current flows. So the current might be different when the light is actually assembled.

However, the XPG2 does have a high Vf which will limit the current. In my experience about 4.5A flows with a good battery and all springs bypassed.

Try the clamp meter method. This will be more accurate. But again the current might be less with the light all assembled because of the added resistance of the tailswitch and spring (if not bypassed).

joediese
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I will knock up a copper piece to use with my clamp meter this weekend and retest ASAP, I would like to know what the correct draw on turbo is…and then try to increase this.

I have some 20 AWG that I will replace the emitter wires with once I have a decent reading.

I’m coming around to the fact it’s probably the Vf of this LED and my testing methods giving me such low amps: I managed to blow the tail switch last night whilst trying to adjust the reflector height!

chops728
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Which driver UI —- are you sure it’s going into Turbo —— even with IFFY leads you should be measuring more than that —- try Bi-Passing the driver by putting ground lead on neg of LED to see what it reads

joediese
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Bistro.

I would have assumed that it would have pulled more than 2.75 amps on my meter setup.

My old PD35 shows 3a with the same set up, an S2+ is pulling 2.80a, and my D4 pulls more than 6a with the same meter and leads also.

I was sure a FET driver would draw at least mid 4a in this light, the old 8×7135 driver it replaced drew 2.75 with no bypassed springs…

chops728
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Make sure you’re not in Simple mode —- high is about 50%

joediese
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chops728 wrote:
Make sure you’re not in Simple mode —- high is about 50%

Pretty sure I’m not in Simple as I have access to all options in the Config mode, whereas Simple mode only gives you the option to exit Simple when you are in Config mode.

I need to throw a new switch in the tail tomorrow, then I’ll factory reset the UI, just to rule this out.

joediese
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There was an increase in current measured using my clamp meter and a piece of thick copper wiring.

The greatest increase in current came after filing off the anodising on the base of the battery tube, so the switch retaining ring could contact the base of the battery tube better.

The light may have been getting as much current before filing, only through the unanodised threads as opposed to through the cross section of the battery tube, but it certain makes getting a consistent reading on the meter easier.

I was then drawing 4.2a on the clamp meter, and could really notice an increase in intensity in the spot.

Not satisfied this was enough I desoldered the driver and replace the emitter leads with a heavier gauge wire, although unfortunately once soldered on the heavier wires merely ripped the traces clean off of the driver whilst reinstalling!

Still awaiting a replacement tail switch after I accidentally blew the trace off of the switch board last week.

New driver and switch en route, the saga continues!

mattlward
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Lots of things going on here… that is a fairly high Vf led, this will reduce current. Your tail switch and board may be in question… try an Omten 1288 switch and this board. You may want to get some good silicone wire for the leds, use the very find stranded wire for good flex and think 18 gauge if it will fit. If not go to 22 gauge or 20 gauge. Also, your springs can be as big a problem as any other part here. The gen 3 Bluesword springs are wonderful for current draw. You can also set a small spring inside a larger spring for more current. Bypasses can sometimes be difficult and when they fail they can cause nasty shorts in places you do not want to have one.

When measuring current, I use a good clamp and about 6 inches of 10 gauge ultra fine braided wire with a silicone jacket. This allows one to center it in the clamp and makes sure that your test lead is not a source of limited current.

The quest for every last amp and become frustrating. Please remember that you can hit a point of diminishing returns where more amps actually reduces output and damages leds.

EDC rotation:
KR4, SST-20 FA3 4000k (favorite!)
FW3A, Nichia 4000k sw40 r9080 (second favorite)
FW1A, LH351D 3500k (third favorite)
FW1A, XP-L Hi 3A
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
Emisar D4V2, brass E21A 3500k (night light of choice)

joediese
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mattlward wrote:
Lots of things going on here… that is a fairly high Vf led, this will reduce current. Your tail switch and board may be in question… try an Omten 1288 switch and this board. You may want to get some good silicone wire for the leds, use the very find stranded wire for good flex and think 18 gauge if it will fit. If not go to 22 gauge or 20 gauge. Also, your springs can be as big a problem as any other part here. The gen 3 Bluesword springs are wonderful for current draw. You can also set a small spring inside a larger spring for more current. Bypasses can sometimes be difficult and when they fail they can cause nasty shorts in places you do not want to have one.

When measuring current, I use a good clamp and about 6 inches of 10 gauge ultra fine braided wire with a silicone jacket. This allows one to center it in the clamp and makes sure that your test lead is not a source of limited current.

The quest for every last amp and become frustrating. Please remember that you can hit a point of diminishing returns where more amps actually reduces output and damages leds.

Thanks for the reply bud, a lot of good info there.

The switch PCB was a definite bottleneck, which is why it failed when I accidentally shorted the emitter POS to the reflector. The OshPark board is 17mm, I’ll see if there is a 20mm which would be compatible with my tailcap.

The springs were bypassed internally, and I haven’t had one like that fail before, but I may give double springs a go with the new switch/driver.

I am using solid core household wiring in my clamp meter at the moment, less ideal than stranded heavy-gauge wire, but it was all I had on hand.

I hope to get this light up and running again in the next week and see if any tweaks pull more amps, I’m aiming for 4.75a as a guess, I think this LED will go about 6a, but gives no more output above 5a.