I still think the KP 3400's are the best protected cells around - great match for these lights, but other quality protected cells should work just as well - probably best to use 3400's because even 3400's won't last too long. The Pana PD's I used were unprotected - I know there are protected versions around, not sure where to get them.
Wow! That was some haul of fish!
Can I suggest Sanyo UR18650FM 2600mAh cells? They suffer less voltage sag at pretty much all levels but is more pronounced at around 2A and higher, which is what this light will demand.
Less voltage sag means the light will run on high (which is probably what you will be using) for longer. On lower levels the KP3400mAh are better but for 2A+ applications the Sanyo 2600mAh all the way!
You could be right about the Sanyo's, but I'm not seeing much of a difference in these lights with different cells - KP's, Pana PD's, Samsung 20Q's all the same output. Because you have a high qual buck driver and a high qual carrier, doesn't seem to make much of a difference. Of course I'm only checking for a minute or 2...
Oh I know they can all handle the output well enough, but I’m talking about run time.
When you take it out you want to minimise battery changes and maximise run time. The Sanyo 2600mAh will get you maximal run time if run on high mode. And the fact that they are like $10-11 a pair makes it even sweeter.
really made my day! Glad you’re up and about enjoying life and furthermore with your son!
Hey thanks.
My back is still not the best. But I’m trying to live with it.
I figured I better go fishing with him before he leaves for college. He went again to day. He ask me to go, but I told him I had to get things done today.
Will post once I get mine from the group buy - got a tracking # but all it says is "Origin Post is Preparing Shipment" with no date.
ill post my readings once i get it too
but those sanyos wont last nearly as long as the pana’s since its 2600 vs 3400 right?
are any of these the pana pds? all i see are ncr
http://www.fasttech.com/category/1420/batteries/MTI1PTE4NjUwfDE4Mz1Qcm90ZWN0ZWReUmVjaGFyZ2VhYmxl/
FT don’t have protected Pana PD , so must untick filter for protected.
Int’l outdoor, callieskustoms have protected Pana PD
May be because it is high drain that usually with minimum resistance, so not many sell protected one.
The 3400mAh Panasonics do have a higher capacity, but only at low current draws. In a light like the TN31 nodded which needs significantly higher current the Sanyo 18650 2600mAh has less voltage sag which translates to longer run time.
To put it simply, the Sanyo just handles high currents better which is why it lasts longer.
It seems like he’s saying the Pana capacity is less than the Sanyos at 3+ amp draw rate; it’s not but I don’t think that is what he is telling us.
Looking at the Battery Comparator (awesome tool) it looks to me like the Panas’ lower and faster voltage drop (or sag, as described above) will have us wanting to pop in fresh batteries before you use all of their capacity. And the light won’t be as bright from the start.
For a situation where you want all the juice available at the lower and dimmer voltage (especially when you don’t have spares and need light), then the Panas will run longer in that dimmer state.
The Sanyos let the light stay in the high mode for longer. If you ran a light at 3A with both cells, you’d find the Panasonic would indeed last longer, but it would also be the first to dim. That’s basically what I’m trying to say.
That’s only true for linear driving.In case of switching driver better is battery with higher energy content (Wh) at required current.And current remains constant until batteries are empty(if it is a good driver).
Not sure about that . . first, the curves appear to be based on constant current with voltage dropping. But even if the juice is sucked out faster with an increasing current to maintain near constant output, then the curve will drop faster (or the driver may simply shut down early when voltage isn’t high enough to maintain current).
The Panas show more capacity left but when you look at the curve and note it’s only available @ <3v running 5A . . then it’s pretty much shut down time for a lot of lights (and the way many of us use our Lion cells). Personally, I try not to run mine below about 3.1-3.2v and frequently change them out before then, even if the spec is 2.75 on some cells.
ok after reading slewflash and gottazooms explanations, i think the sanyos will suit me better, as i know already know that i will be using these for mainly on turbo mode for the tom e super shocker and vinhs k40 thrower.
so are these the ones your talking about?
http://www.fasttech.com/products/1420/10001901/1143802-sanyo-ur18650f-18650-2600mah-protected-rechargeabl
can anyone confirm that these will fit the battery carrier for the btu shocker and k40?
Not sure about the K40, but it’ll fit the Shocker well.
If the K40 battery carrier is the same as the TN31 then it would fit in the K40 battery carrier. Also something to note, The Sanyos will have a much harder time fitting in the TN30. It fits, but it’s pretty tight. It’s not hard to get out because of the way the carrier is designed, but it requires a little effort trying to get them in.
EDIT: And yes, the ones you linked are the protected Sanyo 2600mAh cells (UR18650FM).
Yes they do fit the K40 quite well. I’m using these protected Sanyos for my K40. 
thanks for the fit confirmation fellas. time to order me some sanyos