A17DD from BG in an L2 - low amps

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gchart
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A17DD from BG in an L2 - low amps

I just assembled a Convoy L2 with an XP-L HI (V2 3D) on Noctigon from Richard and the A17DD FET+1 driver from Banggood (which I’m beginning to question). Using a King Kong 26650, also from Richard.

I did copper wick spring bypasses, put everything together and fired it up. I’ll say, I’m quite disappointed. I put it side-by-side with my Convoy C8 with an XP-L HI and 3A QLite driver and could hardly tell a difference (besides a somewhat tighter hotspot). So I got out the multitester (a decent Craftsman-branded one) and measured amps at the tail at only 3 amps. I was hoping for more like 5-6 amps.

Is there anything else I can/should check? I’m feeling like I shouldn’t have cheaped out… shoulda just picked up the FET+1 driver from Richard while I was getting the other components.

Andrew2007
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sixty545
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The resistance in the multimeter and its leads will greatly influence the measurement.
Try thicker leads.

comfychair
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Trying to nail down an issue like this an accurate absolute measurement isn't all that important, a relative measurement is fine. Compare the amp draw to the known-good C8, see what the difference is.

gchart
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Thanks for the replies, guys. I’m pretty sure I’m hitting turbo, I’ve seen it do the 45 sec step down.

And the C8 with its 3A QLite driver measures around 2.6A.

djburkes
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Where did you get the L2 host from?

gchart
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Banggood. It’s the earlier run of the new L2. Single cell, block style tube.

djburkes
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Gotcha, just make sure you have that retaining ring really tight. I’ve built several lights using those drivers and they seem to perform as good as other fets. I recently purchased an L2 host from BG and a zener modded 17mm fet grow mtn for an MT-G2 build and I was getting low and no voltage until I really cranked the driver retaining ring down.

gchart
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Thanks, I’ll give that a shot. I was concerned that the retaining ring might be causing issues, so I put a blob of solder connecting the ring and the driver, but it’s certainly worth another look.

gchart
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OK, I just cranked down the retaining ring and did another reading – 3.8A now.

My meter leads were about 3 ft each of 18ga so I made makeshift ones about 9” long of 16ga. Got the same reading, about 3.8A.

Visually looks a little brighter than my C8, but not quite what I was hoping for.

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One thing I've noticed is that there are usually a lot of residual film left over by coolant during the machining process. Sometimes it appears to cause surface oxidation when it's been there long enough. The bare aluminum surfaces need to be scuffed really good with red scotch brite and/or a clean stainless steel wire brush and cleaned with alcohol or acetone. Remove the switch and scuff the threads of the tail cap and the retaining ring threads and the surface that contacts the switch pcb.

Same for where the tube and head screw together. Also scuff out the little shelf that the driver sits on and the retaining ring just like on the switch. 

I always apply a light coat of corrosion x to everything before assembly and electrical grease on the threads, nyogel 760. 

All the scuffing and cleaning and treating has made huge differences for me. 

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comfychair wrote:

Trying to nail down an issue like this an accurate absolute measurement isn’t all that important, a relative measurement is fine. Compare the amp draw to the known-good C8, see what the difference is.


I think he said the C8 has a regulating driver. If the C8 is in regulation, then the ratio of currents with the leads and meter in the circuit is not representative of that without them. The C8 might be a steady 3 amps. with or without the leads, if it stays in regulation, but the FET driver does not regulate, so the current may be much different.

Flashlight designers should look at lighthouses and pottery.
这些谁设计的手电筒应该看灯塔,以及在陶器。

Andrew2007
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Ballpark figure.

DB Custom
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Double check the switch end, make sure ground connections are clean and tight, also clean the ground contact ring on the pcb as well as the switch retaining ring. You should be getting more than that.

I built a new FET+1 today with a trial Vishay SIR404DP MOSFET, put it in an Eagle Eye X6 with full bypasses and have an XP-L V6 1D on a 20mm SinkPAD up top. 1783 lumens at a 5.94A draw from a new Samsung 30Q. The V6 should make more than your V2, but still, you should see well up in the 4A range. Assuming that the King Kong is up to it. Sometimes they aren’t.

gchart
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Is there any way to test the battery’s capacity to push that many amps? I don’t really have another battery to try (I’m pretty new to li-ions), my only other cell is a standard pana 18650.

I’ve cleaned most of the threads with a brass brush and rubbing alcohol, per RotorHeads comment. Still need to hit the retaining ring threads though.

Swib
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Would cleaning the board and the points of contact with DeoxIT or similar contact cleaner help improve current? Been thinking of trying it out but unsure if it’s just wishful thinking.

If you don’t like what it looks like on the wall, take it outside.

DB Custom
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I’ve seen a light have horribly low current draw and after checking EVERYTHING,,, the switch pcb ground ring was dirty as was the retaining ring it contacted.

Sometimes it’s the littlest things…

comfychair
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To bypass the driver with everything else in place, find some way to connect LED- to GND. If the current isn't much higher it's probably a battery issue.

gchart
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Well, I’m not sure what to think now. I put another XP-L HI in a C8 head, firmly taped short 16ga leads to battery, and ran a circuit that was just led, battery, and tester. Getting around 3.5A even without the host and driver being involved.

Richard says this cell should be good for a constant 8A. Should I question this particular cell? Or did I skip something important in the test above?

And thanks everyone for throwing ideas out there, I still have a lot to learn!

Andrew2007
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Frustrating. Facepalm

The only other thing would be the charge in the battery, measure the voltage with your multimeter.

gchart
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Freshly charged it yesterday. Just tested it at 4.02V

comfychair
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4.02v vs. 4.20v will result in a huge difference in current. You have a junk charger if it says it's finished when the cell is only at 4 volts.

gchart
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Using a Xtar MC1 Plus. Just recharged the cell and measured 4.19V. Put it in the flashlight and measured 4.1A.

That’s a bit closer to what I was hoping for (5A out so). Perhaps disassembling it and a more thorough cleaning will help close the gap.