Tuesday, 21 June 2016

Convoy S2+ mod for Keeppower 18350 cell

From an earlier electronics project, I had a nice Keeppower 18350 protected cell left over. These are great little cells, although the capacity is not outstanding at 900mAh. It would have been a shame not to put that cell to a good use, so I looked for a suitable single cell lamp.
I found a good quality Convoy S2+ that looked nice and should be compatible with 18350 cells. It also was within my budget.
I intentionally choose the warm white XML2 T6-4C LED because I when hiking and camping, I find the cold/neutral white a bit too "harsh" and unpleasant for reading.
I already have an "eagle eyes" branded light for 18650 cells that I quite like. Some of my cells would not fit into that light.
Bits'n pieces
So I ran into the same problem. My cell doesn't fit:
The strip for the protection circuit adds a few 10ths
The bulge is not that wide, so a groove in the anodized aluminium tube should do the trick.
The bulge is just 4mm wide
So it's off to the workshop...
Not too much pressure and a pair of protective pads!
... to file it down a bit. To get smooth ends, I needed a bit of fine grained sand paper.

And sure enough:
The battery now fits nicely
This works, of course:
Ain't she a beauty?
I was pleasantly surprised by the moderate power requirements of the Convoy (XML2 T6-4C):
(And: No, the battery is not the limiting factor here.)

Low: 57 mA
Mid: 430mA
High: 1049mA

As opposed to my similar looking (different driver, though) Eagle Eye X2 (with a XM-L T6 U2-1A) emitter. (That I use with a 3100mAh 18650 cell.)

Low: 254mA
Mid: 1224mA
High: 1980mA (no wonder this thing gets hot!)

Bottom line: The combination of this LED and driver seems great for the small cell. I especially like the low light mode, which should last for about 15 hours with the 900mAh cell The XML2's improved efficiency over the older XML is very well used in this scenario.

PS: The Convoy  S2+ also works great with a CR123 cell.
PPS: To change between 3 and 5 modes (incl. strobe / SOS), switch the light off briefly after it has flickered in low-power mode.

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