Batteries

For 4s1p - shrinking tube should be 90mm - 21700 is 21mm*4

Good sources:

To solder 18650 or 21700 batteries, ideally, you need a spot welder, on amazon, they cost arround 50€.

You also need balance leads and positive/negative leads.

Buy option:

Series lipos:

example for 2S (1S added to another 1S):

If we take two batteries of 3.7v, 2000mah each, and connect them in series, you will get a new battery of 7.4v, 2200mah's.

3.7 v is the storage voltage, for a lipo, if charged, it would be 4.2volts and 2200mah's

We keep the amount of mah's.

Paralell

Notes