On 18650’s its 2S, not sure how it runs the 6x123’s.
Got my bench setup swapped out with a proper copper mounted xml2, it’s reading 4.78, I think the 6A+ reading before it died was runaway.
Every solder connection in this light is way over loaded with the solder, I’m going to clean up all the connections and swap the 20AWG wire for 18, if I can get 5A I’ll be happy for now while I look for a lower resistance SOIC FET. So is the 8A rating just a joke or what’s the deal with that?
Edited to add: hmm, the driver no longer has low, still has the hidden strobe tho (double click from on)
The current rating in the spec sheet is for running a load that's not dependent on voltage like a LED is. Since more voltage = more current, resistance in the FET lowers the voltage which also lowers the current. A different kind of load like a DC motor or a straight resistive load doesn't work like that.
Losing modes is pretty common when bridging resistors on a lot of drivers. It'll need at least some small amount of resistance there to go back to working again. A better FET will let you use a reasonable sense resistor and still get more output current. The 4468 is something like 23-25mOhms (for comparison, the Vishay 70N02 is 4.5mOhms).
see here: http://www.digikey.com/product-detail/en/IRF8734TRPBF/IRF8734TRPBFCT-ND/2096660
I just received my SR51 yesterday. Really like the beam pattern, but the UI and modes suck. Really high low and not much mode spacing between High and Low. After reading this, I may just going to swap out the whole driver.
Nice to know how to resister mod the stock driver though. Thanks for this thread.
comfychair wrote:
What's the battery config on this light? I checked the Olight site and can't figure how you get a light that uses either six CR123s or two 18650s.
The 18650 holder is 2S. The CR123 holder is 3P2S.
EDIT: Unfortunately, the battery tube can't take 3 18650's and it's too thin walled to bore out. What a shame, there is plenty of vertical room to rig up a 3S carrier in there.
Don’t overlook the stock MCPCB, while it’s really nice looking all copper clad and huge it’s not direct bond, after getting it all back together and measuring lux it didn’t even make it threw the 10sec reading lol. Beam started out nice and neutral and almost instantly there was a major blue shift followed by instant death.
Would it be possible to get any gains from leaving the big bar sense resistor but swapping in a better FET so it would retain factory modes?
Now that I’ve got a new U2 1A dedomed on a XM20 it’s doing 134kcd, I’m happy now and gonna leave it alone but I’m still wondering about the question above.
Yes, that was what I was suggesting earlier. With the high resistance FET and very low sense resistor, it was already running near wide open in stock form. Swapping that around, a low resistance FET and maybe even a higher sense resistor would net you more output while leaving more safety margin.
Man that driver looks complicated. I like the idea of swapping out the FET and also replacing the MCU. Won't be touching the light until after I finish my scratch build though.
If you get a chance, it would be nice to see some beam shots. I think your the first to install dedomed emitter in this light.
So it turns out there is a low still, its just barely dimmer than high lol, its not useful at all and its such a small difference out in the open I couldnt even tell, only when I went into a tunnel was I able to notice.
I just tried and 3 17650’s do fit but 17650’s suck. It wouldn’t be worth it to do 3p 17650’s over 2p 18650’s. The only possible reason I can imagine to use 3x 17650 is if it was 3s.
3p 1600mAh 17650’s is >30% less WH than 2p 3400mAh 18650’s, even using high drain 2500mAh 18650’s 3x 17650 is still ~25% less than that.
I knew I'd seen some higher capacity skinny cells recently. It turns out they weren't 17650. They were 16650. HKJ has reviews of 3 different ones on his site, here are Keeppower's protected Sanyo cells. They still only make sense when in series, but I thought I'd throw that out there while we were on the topic.
Dissapointing news, the driver has been out of the light (replaced with a 17DD) for awhile now but I’m looking at using it for my 2D to 6AA maglight mod since the input voltage off 6sAA will be right so I finally got around to swapping out that FET (and swapping back to the stock sense resistor) and it runs at the exact same 3.4A to the emitter.
Bummer. For shits and giggles, you should take those DMM leads with the alligator clips out of the equation. Just jam the emitter and driver leads directly into the DMM. You could use wood skewers or dowels to wedge the wires in tight. May not make a difference in this case, but it's the best way to roll. Well, maybe the best, but the easiest best I know of.
