For those that want to "parallel" two 10440 batteries, please considerate that the hosts that unscrew in the middle, sometimes have not enough space for left you use the pack with the connections in place (also using flat strips of copper as wires, instead round wires) ..... the ones that have the body with only the end caps unscrewing for insert batteries, instead, have a lot of space, and you can easily build them.
Just take some strips of copper foil (like, from the shielding of old PSU switching transformers, if you cannot find them elsewhere) ..... solder them to the poles that go together, place a disk of fiberglass or hard thin cardboard between the poles, bend the strips, from opposite sides, to the corresponding pole of the other battery, solder them and cover all with insulating tape (kapton tape is the best, but also a pair of layers of common adhesicve tape are ok for a test).
Like in the attached draw ..... only one advice, to follow categorically, if you want that your cells last for a decent time ..... choose cells
from the same production lot, and possible new ones ..... the production lot is usually a string of numbers printed in "dot matrix" on the body of the cells, near the other details ..... if you use two cells from the same production lot, there's more possibility that the electrical, internal resistance and chemical characteristics are the more equal possible ..... (i already had a blowed cell from a parallel, using two AA cells from different producers, once that i had nothing other around
)
