What batteries for XM-L U2 in SF L2P host?

[Bauer]

Right now I am running it on 2x ultrafire 16340's and was wondering if there is a better option for better performance. I think it is a 9v max, and it runs much brighter on the 16340's vs surefire 123's. Is there a higher voltage option that will fit without modification? Would higher voltage increase the output enough to be worth it?

I was also looking at the 18350's and was wondering if they make them protected?

 

[kosPap]

there are trustfire (orange flames) 18350 batteries with protections (seeFasttech.com) but i do not know anything about performance

Another option is to get a 1cell abttery extender from solarforce and use AW 18500s

 

[Bauer]

Ok, so i am new to batteries and such. My U2 is the SF high output version, so how much does the mah of a battery effect output?

 

[kosPap]

it is not an issue of battery capacity (mAh) it is an issue of battery performance under load.

Check HKJ's post here and in hiw website to understand