The flash has 4 contacts, 2 make an internal Minus to PLus cross connection... so the battery pack is acting as 4cells in series to make 6VDC.
The charger also has the same 4 contacts, with 2 internal formning a cross connection, but is charging with only 2 so the batteries are charging as 4 cells in series.
Now here is the hitch... the battery pack is keyed, it can be inserted in 2 directions, rotated 180°, so the terminals will still be the same polarity in pairs on both sides. ^=direction
internal cross jumper is at the back of both the flash n charger.
So where do you put the thermistor since both ends can be the front or back, none are end cells?
So if you have one of these packs, can you crack it open n tell me where it makes the connection? I'm not looking for therory, I need to know exactly where it physically solders to.