Hi, just wondering what would be the recommended protected 18650 battery for SRT7.
Specifically, considering how some flashlights can stay relatively brighter for longer with 2600mAh battery, as opposed to 3400mAh battery, does the similar observation apply to SRT7 too?
Say for example, between Sanyo 2600mAh Protected (Red) and Panasonic 3400mAh Protected (Green), which will be recommended for better overall performance?
Thank you very much!
Are you likely to run them all the way down to 3.2volts? I use mine a lot and start to charge mine once they hit 50% (3.8V) just in case.
You can get the Sanyos if you are more likely to use it in high (or I guess 80% or higher in the SRT7) because it holds voltage better.
But if you’re more likely to use the light at lower levels, the Panasonic will win. Once the Panasonic starts to fall behind the Sanyo at the higher levels because it can’t hold the voltage, if you had a runtime test at lower levels the Panasonic would win since it has a higher overall capacity.
So basically it comes down to, do you want a higher run time at maximum brightness or higher run time at a lower brightness?
Just in case you weren't aware. The SRT7 requires button top batteries and will not work with flat top. This is due to the nature of the spring loaded shock absorption battery carrier mechanism.
Thank you Slewflash. As I am still inexperience with Li-Ion in general, may I also ask how would you normally measure the remaining voltage of battery inside flashlight? Does it involve removing the whole battery from flashlight and make contact with Positive and Negative end of the battery with both leads of meter? Or is there some other method like, removing the tail cap, and place the Red lead on the bottom of battery, and the Black lead on the flashlight body?
Yeah you can just do this, and then divide the voltage by the number of batteries. I take the batteries out just because I’m used to it, but you can do it this way if you want.
Thank you CalvinIS. May I ask, if this special design apply to all the SRT- series? Or is it common among many other models and different manufacturers too?
Thank you. Also, I posted a question related to Aussie buyers in separate thread, not sure if you could help sharing some experiences and advice too?
Preferred purchase options (overseas vs. domestic) for Aussie buyers?
There are a few other manufacturers that also have a similar design. For the SRT series this affects the SRT6 and SRT7 that I'm aware of, I do not have any SRT5s yet. The SRT3 has a modified design but should not cause any problems since CR123 and AA/14500s only seem to come in button top form.
Thank you for the detailed response. The upcoming SRT5 does seem interesting. On paper the SRT5 seems to be in same league as with F’s PD35… (but noticed that PD35 is not offered on IS, so I would refrain from asking too many ‘comparison’ questions here) 
To be quite frank, even with the step down on the P25 from 800+ lumens down to around 500, it’s barely perceptible. Any dip in performance from a panasonic battery compared to sanyos would be fairly miniscule and imperceptible to the eye. After the P25 steps down after 20 minutes it’s only driven at around 1.4A, a Panasonic battery should have no problems at all maintaining optimum performance at that level.
I took 3400mAh batteries… At 3A the Sanyo are better, but as already said, alle Nitecore Single 18650 will step down to about 500 Lumens and then only 1.4A is used. With that, the panasonic should last longer! Also the P25 e.g. will show 50% indicator at 3.6 and 10% low power at 3.2V (I asked for that at nitecore directly). This also is better for panasonic.