The L8 is definitely my favorite single cell sbt90 Light. I like everything about it, but the biggest drawback is the limited compatibility of a single 26800 / 26900. They're just not great cells for high amp sbt90 lights. I'd much rather the L8 head / Reflector with single 21700, 21700 in series or even 26800 in series if need be, and the appropriate buck driver of course (Side switch only). But, i still use the L8 daily and own two of them. One for each hand, of course.
As someone mentioned above, at 18A, it should be pulling about 4.5A per cell, which may cause sag in an NCR18650GA, but should be well within its capabilities. Probably less at most voltages since it’s a buck converter and the vF is close to 3v, so at higher cell voltages, it should be pulling less than 4.5A for the driver to deliver 18A @ 3v.
Even at 25A it’s only 6.25A per battery, which should also be ok for Sanyos. Sbt90.2 is about 3.6V on 25A if extrapolating from diagram. And GA’s drop to 3,8V at 7A current draw.
I didn’t know the regulator was linear, touché. Still, worst case is 4 - 6A draw per cell. Voltage sag may still be the culprit, but well within the cells’ capabilities. Only way to know for sure would be to test with different cells and compare I suppose.
About 70~80mV higher with 30Q at 5A at high SOC, not a big difference but it can help a bit.
More importantly the 180mV drop across the sense resistor doesn’t help.
With 30Qs and a more reasonable 50mV Vsense, 0.2V would be saved, that’s significant.
Although today is not my birthday, I still want to thank you all. :partying_face:
There’s an interesting thing in there. China has a lunar calendar and a solar calendar. Actually my birthday is counted according to the lunar calendar.