Some key info on chargers
Avery important but overlooked item when it comes to charging is the off load start voltage. Sadly this aspect is also an often overlooked one. When it comes to Lithium-Ion batts of all types overcharging them seriously hurts the cell. In the case of a 3.7v batt, anything over 4.25v is going to hurt the batt long term. This where what kind of LIB cell comes into play. I'm going to use my other item's batts as an example...
There are two types of batts that it can use, one is an unprotected high drain imr batt the other a protected LIB batt. Using the trustfire charger the protected batt will come off at 4.21v +/- 0.01v hot off the charger, the imr batt 4.25 +/- 0.1v. While this extra voltage gives you slightly more run time out of the batt, it also will potentially lead to a shorter lifespan of the imr. Using a pila charger (which is the highest quality charger for LIB I've come accross) the same two batts will come off at 4.18 +/- 0.1v for the protected batt, and 4.22 +/- 0.1v for the imr. Which leads us to the Vapor4Life batts and chargers.
I took four batts and did 10 charging cycles of each using the 3 different chargers. 2 of them are from the vapor king line (one manual, one auto), and 2 are from the new line (one stealth, one king diamond). As soon as the light turned green or blue (depending on the charger) took them off and tested them without load (no carto) to see what voltage they were at.
Vapor king auto shorty:
Wall charger (WC)- 4.23 avg. Highest I saw was 4.24, lowest 4.22.
USB charger- 4.24 avg. Lowest was 4.23, highest 4.25.
Slim line (SL)- 4.18 avg. Lowest was 4.16, highest was 4.20.
Manual regular vapor king:
WC- 4.21 avg. Highest was 4.23, lowest 4.20
USB- 4.23 avg. Highest was 4.25, lowest 4.21
SL- 4.18avg. Highest was 4.19, lowest 4.16
King diamond Shorty:
WC- 4.25 avg. Lowest was 4.24, highest 4.26
USB- 4.26 avg. Lowest was 4.24, highest was 4.27
SL- 4.22 avg. Highest was 4.23, lowest was 4.20
WC- 4.25 avg. Lowest was 4.23, highest was 4.26
USB- 4.26avg. Highest again was 4.27, lowest was 4.25
SL- 4.21 avg. Highest was 4.23, lowest 4.20
What this tells me is the newer batts use a lower internal resistance batt (which also explains why they hold their voltage longer than any previous batts on the market). Would highly suggest if you want as long of a lifespan as possible from your king diamond and stealth series batts using the slim line charger. Currently working on another set of complete life cycle tests using two fresh king diamond batts and the slim charger to see just how many more cycles you can expect from using the SL charger exclusively. Will be a bit before those numbers are posted (those tests take a few months, do apologize). Hope someone finds this useful.