I would recommend avoiding Basen cells for use in series. There are far too many reported variations in those cells.
+1 those 40A Efest cells are quite nice for flashlight use.
liionwholesales' new 2016 Efest's are 35A, where can I get the 40A in the US?
I purchased mine because of a highly respected BLF member that recommended them to me. I’m not mentioning his name out of respect for his privacy unless he wants me to. I got mine from http://liionwholesale.com/
I voted other I use Keeppower ICR26650 5200mAh 3.7v Protected Rechargeable Li-ion Battery.
Ordered a pair from Banggood on May 10 2016 before I knew about the max lenght issue, when they arrived it was the short version.
I might be late, but couple of threads say LiitoKala’s $5 battery could be the best high drain 26650 available.
https://budgetlightforum.com/t/-/39541
https://budgetlightforum.com/t/-/39804
If I have read correctly the test here,Test of EnerPower 26650 4500mAh (Dark blue) ,I see this.
“Conclusion.
This battery looks like a good 26650 battery, it can easily handle a 7A load.
It is the best 26650 I have tested until now”.
The link will not work for me. Is it correct???
Thank you……… :+1:
That review by HKJ was done in December 2012:
Test / Review: EnerPower 26650 4500mAh (Dark blue)
https://budgetlightforum.com/t/-/13536
Best Regards,
George
Just some FYI since these questions keep popping up about the L6 and S70 batteries.
I decided to do some tests on the drivers as they should be constant current, which means basically any battery will work.
I hooked them up to my bench power supply and started playing with the voltage while watching the current and wattage figures.
From 8.4V down to 7.9v everything is very consistent, wattage sits right around ~38 watts for both drivers (L6 higher by about .5-1w).
At 7.8V input there is an odd jump in wattage on both drivers, you can also hear the PWM kick in a bit, no idea why. But wattage on both drivers jumps up to ~40-41 watts. By 7.6V it is back down to 38 watts and holds that until ~7 volts. Somewhere in the high 6 volt range is where it started really dropping wattage, forgot the exact number.
During this time the current that the driver pulls from the batteries / power supply varies in order to keep the wattage the same, so at 8.4V it pulls ~4.5A and at 7V it pulls around 5.4A. Both are the same wattage and brightness though.
The exception if it you just happen to hit that magic spot at 7.6 - 7.8 ish volts where wattage jumps along with current, then brightness does increase because the LED is getting more power.
It was an interesting test and basically showed that the S70 and L6 are almost identical from a driver standpoint, although the L6 driver has way better modes and a very slight bump in power.
This is made up for by what appears to be a lower bin emitter though, so it actually outputs slightly less lumens in stock form.
The long and short of that is that it doesn’t really matter what batteries you use in either the L6 or S70, any 26650 I have seen will easily handle the ~5 amp draw needed and voltage won’t sag low enough to cause a loss of lumens unless the battery is low.
I personally have some keeppower 4200mah unprotected cells that work great along with some LiitoKala’s that work equally well but obiously net you longer run times.
Based on bang for the buck, I would go with the LiitoKala for sure, why pay more if you won’t get anything out of it?
Also while posting a mini-review of the 2 lights, I saw someone ask about mass difference between them. The S70 head only is exactly 1 pound (454 grams), the L6 was 384g. So the S70 does have a bit more mass but the beam profile, modes and look of the L6 makes it my go to “big boy” light.
Now to mod them both for more output, think I am going to up them to around 6.5-7A and see how things go.
Thank’s for posting Texas_Ace, that is some good info!
I also like the L6 & the LiitoKala’s best for the same reasons you mentioned. 
I have read mixed results on the LiitoKala batteries fitting the L7; my batteries have yet to arrive to verify my own use.
I do not have and am not familiar with the L7, but they do fit just fine in my L6.
My only wish about the LiitoKala’s, and it is no big deal; is that the positive flat top was a bit higher so they would work in series without a Battery Series Connector or some other modification.
Otherwise, so far; I love them & the price is surely right……. :+1: ……
Edit: Oh yeah, it has been reported by some that their LiitoKala 26650’s will work in series as they receive them… without any modification. However, I have 8 at this point and none of them will.
I have 4 more on the way, so I’ll be interested to see if they will work in series. Time will tell…….
Typo, I meant to write L6.
Anyway, the L6 is more specific about the overall length of two cells in series. I use both protected and non-protected but I do try to keep the same over all battery length.
I don’t worry about it personally, the springs are stiff enough to handle a fair amount of variance. I only use un-protected personally, the chances of having an issues with 2 unprotected cells that are even reasonably matched, in a single discharge cycle is virtually nill.
Any mismatch is balanced out as soon as you recharge them. Mismatched cells are a larger issue in things where they are never removed from the series.
+1
+2
Good, I thought I had missed something or was “loosing it”.
I only have two 26650 Liitokalas but they fit perfectly snugly inside the L7. No way they can be used in series without a magnet or the Convoy connector though. True flat tops. They are just a bit fatter than the 4500 mAh protected Keeppowers, 26.64 vs. 26.53 mm at their widest part.