Are you sure to take this Batteryholder?
Once i was loading any Batteries in a similar holder.
The springs has been so very hot that the holder has been damaged.
This is not the only disadvantage of these types of battery-holders, i also use one of them (6er) for my prototype-lamp. i only drive in the city, but there i have problems with the contacts -> the leds flickers at every bigger bumb (bodenwelle). but it need some time until this phenomenon happens, an new holder will work some weeks.
i think he is charging the akkus outside of the holder in a normal charger. ?


. Bei meiner Version mit 28mm Kupferendkappen sind die 1,5mm Dicke der Kühlplatine sogar notwendig um die led im richtigen Abstand zu montieren. Ich habe diese Methode dann einfach bei den späteren Modellen fortgeführt. Mir gings wahrscheinlich darum die Kontakte vor dem Abbrechen zu schützen.