YLP Panda 2M CRI: A (very) brief subjective review & a warning

Other Types of Lights LED Headlamps
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I bought the Panda 2M CRI mid-2019 based mostly on bmengineer's most excellent review. I link to it here for the tech details:

Let me say from the start, I like this headlight. A lot. It ticks all the boxes for me:

- Three-strap retention that offers plenty of adjustment to fit over a heavy wool winter toboggan, as well as my bare noggin. I don't like single-strap headbands. At all. They're a deal-killer for me.

- Extremely flexible UI. Many hidden adjustments that could add value & flexibility. I've used the Panda 2M CRI for many hours exclusively with the native UI as it comes out of the box.

- The warm tint, useful flood & great CRI is very pleasing & hugely useful to me. YLP hit a home run with this headlight at a fair price.

The Panda 2M CRI was extremely useful during a recent interior painting project. White ceiling, light grey walls, white trim. Not a lot of contrast between the light grey wall color and the white of the trim and ceiling. The Panda 2M CRI allowed me to clearly see the corners where the wall met the ceiling and trim, making neat, straight cut-in much, much easier using paint that didn't have much contrast when up-close, especially when wet. No amount of additional workspace lighting of any kind was nearly as effective. The workspace floor or stand lights were either always in the wrong place, shining into my eyes from the sides causing glare, making me work in my own shadow unless I constantly re-positioned them or, just didn't have the spectrum to clearly see the subtle color differences easily.

The Panda 2M CRI solved all of those problems. No shadows. No glare. Subtle differences in color plainly visible at any angle.

I'm not a pro painter by any stretch, just a DIY homeowner. The resulting cut-in between wall & ceiling, and wall and trim is straight & sharp. I couldn't have done it without the Panda 2M CRI.

Now, on to the problem, and a warning.

Glossary:

Tailcap = positive (+) end cap w/magnet.

Headcap = negative (-) end cap without magnet. Also supplies mechanical lockout.

Unscrewing the tailcap with a cell in the tube while both caps are in place can break the positive conductor off of the tailcap board. Here we see the tailcap board inverted, spring up. The (+) lead in the tube is next to it's broken solder joint on the tailcap board.

An 18650 cell is apparently to be placed in the tube by unscrewing only the headcap, inserting the positive end first, toward the tailcap.

Both caps have fairly stout springs.

If the tailcap is unscrewed while a cell is in place, the tailcap board that has both the (+) spring and the (+) lead from the tailcap board to the driver board soldered to it can spin along with the tailcap. The tailcap board is not keyed to the tube in any way, just sort of a snug-ish fit into a very shallow shelf cutout at the end of the tube. On mine, unscrewing the tailcap while the cell was in place broke the tiny wire that is the (+) conductor from the tailcap board to the driver board because the tailcap board spun at the same time. The break happened at the solder joint where the (+) wire that runs from the tailcap board to the driver board is attached. The (+) lead runs from the tailcap board to the driver along a groove machined into the inside of the tube.

The directions in the manual clearly state the Panda 2M CRI can be mechanically locked out by unscrewing either tubecap. I believe that's an error, as the tailcap itself does not appear to be part of the cell circuit; the tailcap board serves that function. See highlighted text top left.

It was an easy enough fix:

Remove the lens cover (four T-6 Torx screws).

Unsolder the (+) lead from the driver board. The (+) lead is easily accessed once the lens cover is removed. The hardest part was finding insulated wire small enough to fit the groove in the side of the tube. I sourced a length of wire from a low voltage pin connector harness out of a dead UPS.

The tiny centering rings on each LED are not glued down or captive in any way; I looked for five minutes before I found one that got away.

There was a tiny dab of what might be glue on the tailcap threads. It wasn't enough to keep the tailcap from rotating when I grasped both caps to unscrew one in order to change the cell. I applied a dab of blue Locktite to the tailcap threads when I reassembled.

I also placed a small disk of very thin, stiff plastic (cell insulator used for shipping) between the inside surface of the tailcap and the tailcap board, to help break the stiction between them if the tailcap is ever rotated again.

Hope this helps keep another user from experiencing the same problem with the (+) tailcap conductor.

If YLP sees this, I'd like to suggest:

1) Key the tailcap board much more securely to the tube to keep it from rotating with the tailcap.

2) Correct the lockout instructions.

3) Glue the tailcap in place more securely.

slmjim

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Thank You

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Thanks for this update! Interesting because I can’t even remove the opposite cap on mine.

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Thank you, slmjim, I will forward your comment to YLP.
Usually cap with the magnet is completely sealed, and user cannot unscrew it.
I will ask YLP to check this batch for sealing.

Why? Usually “Tailcap” means the negative contact, or it’s even more correct to say “where the battery is inserted”

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"Head" and "tail" were ambiguous meanings when I wrote the OP. That's why I precisely defined each, for clarity. Relative position becomes less important and, nomenclature becomes less precise when dealing with a T-shape headlamp, because there is no conventional head-end (reflector) or tail (usually for cell access, often including magnet). Hence my decision to offer definitions. I do agree that "tailcap" is generally the removable negative end. Except when it's not, a la FW3A.

I chose the define "tailcap" as the one that has the magnet in it only because a magnet is almost universally a feature of tailcaps AFAIK.

We can see good pics of the negative end in maukka's excellent review linked below.

In the 14th pic from the top, a tag is clearly visible inside the tube indicating the (+) end of the cell should be inserted first, toward the cap with the magnet.

In the 16th pic from the top we see the (+) lead entering the driver cavity through a hole at the left & soldered to a pad identified as (+) on the surface of the driver. The other end of that wire is soldered to the edge of board that is under the (+) tube cap that has the magnet. That's where it broke on mine.

18th pic is of the owners manual. At top left ti clearly reads "...untwist the tailcap or the head.." to achieve lockout. I suspect that's a carryover from another, conventional handheld light. At any rate, it's an error for the Panda 2M CRI.

https://budgetlightforum.com/t/-/55413

Now lets look at an illustration of the Panda 2M (not the CRI version) on the YLP site itself. Same light but with a pair of XP-G3's this time. The (-) end cap clearly indicates it's the one to be removed. That curved-arrow graphic doesn't appear on the 2M CRI. Instead, there is simply text that reads "HI CRI. Which cap is to be removed then becomes ambiguous to an observer.

https://ylplight.com/en/katalog/1/nalobnye-fonari/panda-2m/

It had been many months since I'd first installed a cell in my 2M CRI. I didn't remember which cap to remove, so I simply grasped a cap in each hand & twisted. I must have tightened the (-) cap fairly tight the first time months before and, the light's body had heated & cooled a few times during use, perhaps effectively tightening the (-) cap a little further. At any rate, there was insufficient glue on the threads of the (+) cap to keep it from turning.

slmjim