Best 18650 for Astrolux MF02

Hi there, just bought an Astrolux MF02 light with some Samsung 30Q 18650's for it, heard that these were a good battery for this light but these are only 3000mah. I don't know much about these yet but I see there are some 3400 and 3500mah 18650's, the Nitecore NL1835 3500mah one of them. Can I use these 3500mah batteries in the Astrolux, or any other light for that matter? As long as they're button top? Yes, I'm new with all of this,I guess my more basic question is - Is there a limit as to what mah rating you can put in these lights? I also have a couple of Blitzwolf BW-T1's that I got with my MF02, can any 18650 go in these?

Yes you can. I would not care to change out the battery. The mAh tells just how mutch energy it can store. Compare it with the petrol tank of a car. How many gallons it can hold. Now if you got a drag racing car, you dont want to put a regular car petrol tank in it, with a regular thin petrol hoze. It wont be able to give the amont of fuel the engine needs on full throttle. Same with batteries, so dont only look at the mAh ratings. Max discarge current is only 4A on the 3500mAh nitecore. Samsung 30Q max discarge current 15A. So one gives you better preformance and can deliver all the Amps any light will ever need, and the other slightly longer runtimes. So even if the nitecores are bigger in terms of mAh, it will give less light output on those biggest hi drain lights.

Thanks for reminding me about the max discharge rate, I see there's even 5000mah batteries out there but I'll be looking closer at that discharge rate as well. Other than cost, are there any other factors that you consider when buying a good battery?

For 18650 there is no reason to buy other than Sanyo, LG, Samsung, Panasonic, and Sony. Some companies build in protection circuits on top of these and these are worth buying as well, examples: Orbtronic and Keeppower. The nitecore you are looking at probably repackaged one of these manufacturers.

The highest capacity legitimate 18650 is 3600mAh which both Samsung and Panasonic make but these are not high drain cells. While there are some decent 3500mAh 18650 such as LG MJ1, Samsung 35E and Sony VC7, I am not sure it is worth repurchasing a whole new set of cells just for a little more capacity.