I bought a light with a CREE XML T6, and i want to buy a Li-ion 18650 protected battery for it. I need it to last me at least 3 hours on High setting.
I am planning on getting some Generic Batteries with Panasonic cells and 3100mAh capacity, wonder if they will last me 3 hours and how much more would i get out of the 3400mAh capacity? I've seen the 3100mAh for about $8/each shipped and for the 3400mAh is a little over $10/each shipped.
Thanks
Hi,
I'm a Laser engineer and a flashaholic. I have about 50 various LED flashlights of every size, configuration and battery type.
That being said, a T6 LED draws about 3A (3000mA) of power per hour to operate on high beam. That's 3 amps per hour of draw (battery drain). A 3100mAh 18650 battery, depending on its quality, operates in a range from 4.2V (fully charged) to around 2.7-3.2V (discharged or automatic shut-off if it has a PCB, or if the flashlight has a PCB to protect the battery from over-discharge). So a good quality 18650 3100mAh battery gives you a "usable" 1.75-2Ah of energy at its nominal 3.6-3.7V of output. So you can calculate that you'll get about 30-40 minutes of high-beam usage before the flashlight goes dark. A 3400mAh Panasonic NCR18650B (a very good quality, high capacity, affordable Li-ion battery) will give you just over an hour of runtime.
Also, keep in mind that the flashlight's beam will get weaker as the battery is drained down from 4.2V to let's say 3V, i.e. it'll get dimmer.
My favorite everyday-carry flashlight has a T6 emitter and uses a 26650 Battery. I prefer the KeepPower IMR26650 5200mAh battery. Very good quality, affordable and a much longer runtime.
I do not sell or work for any battery or flashlight company. All my knowledge just comes from years of trial and error
experimentation.
Anyway, just make sure you get a "CREE" LED, a good quality flashlight, and the best high capacity batteries you can buy. It's pretty hard to go wrong if you do.
Have fun!