TP4056 18650 Charging Board... Series Out?

Noobian:
Wrong, you're talking about these first version of the TP4056 modules, OP has posted the second version with battery protection features. Please read the Original post before replying to any of the later posts. :stuck_out_tongue:

Fair point, although the original post has now been edited.

However, a cut of voltage of 2.5V is way too low. Not a good idea to let the batteries discharge that low on a regular basis.