This is more complicated than it seems. There are two parts in a protected battery. The battery itself, which you want to make sure it made by a reputable manufacturer. The NCR18650B clearly meets that criteria. The second part is the protection PCB. The rub is the protection PCB is ‘aftermarket’. That means it was provided by and integrated into the battery assembly by one or more third parties. Panasonic, Sony, Samsung etc. do not make protected batteries.
The only real question is whether or not the NCR18650B is the best battery for you intended use. It is not a high current battery, so if the intended use is going to draw more than about 3.5 amps, you might want to look at battery with higher current capability such as NCR18650BD, and if you need really high current such used in portable power tools, then you want a true IMR battery such as a Samsung or Sony. These very high current batteries in generally are not available with protection. The upper limit on protection PCB’s typically about 7 amps. However the IMR battery chemistry is much more tolerant of abuse than ICR batteries, so protection is generally not needed.
So the real issue becomes are you buying a protected battery from a reputable source who really did use a quality cell like a Panasonic and did they use a quality PCB and packaging to add the protection to the cell. That’s a much more difficult question to answer.
Yeah you are asking for cake and the eating of said cake. If you want the highest lumen output you’ll need to go with good quality unprotected hi drain cells. If you want the best protected cells that will still give good output I’d check out mountain electronics. Richard carries high quality protected and unprotected and knows the cells he sells and will give you good advice and a good price so don’t think twice. Take my advice. Shrimp fried rice. Ok I went a little too far there. Sorry. The rest is serious though. :bigsmile:
At the days I was starting people were considering protected cell as a holy grail, and must for safe use.
No one recommended me unprotected cell saying: "Stay away from unprotected cells", "you will overcharge", "you will over-discharge", "keep your eyes and ears wide open if you use unprotected one", "you will be worried all the time and you'll not have piece of mind.
I recommend LG18650D1 protected. It will be suffiecient for all factory lights and moderate modded ones.You can't go wrong with protected cell(or you can cause it may not fit to each light or charger). If protection dies you can always unwrap it and have unprotected one.
Gregor - If you have good charger with "overcharge protection" (you do) and good light with "low voltage protection" (A6 does) - then you can use anything.
Look at Dale's chart in the OP of the A6. Even the cheap Sanyo laptop salvage and Samsung 26F (both not the high drain) do very well :)
Gregor, whathever you choose out of good brand cells you won't see big (if any) difference with naked eyes since human eyes are adaptive. If it would pull more current it would heat up more, have bigger voltage drop and give less light in a short time. So it's not worth to hunt for highest lumens output just by choosing batteries and you even can't notice the difference.