How and when you connect batteries in series or parallel

How and when you connect batteries in series or parallel.

Before some key recommendations:

Safety first, then very carefully.

Never use thinner cables than those that are normally used with the batteries involved. If you can use a little thicker the better, can increase resistance and cause a little loss, but safety is guaranteed.
Always use identical batteries in the process.

Make sure that the motor and esc are suitable for the configuration of battery that is to be fitted.

Let's go.

When using in parallel?

When it is necessary that the battery lasts longer. In this situation the voltage (V) is not changed. Example of parallel connection:
Two batteries 3S (11.1 V) 1800 mAh connected in parallel act as a 3S battery (11.1 V) of 3600 mAh.

When using series?

When you need to increase the battery voltage. In this case the duration of load is not modified. Example of series connection:
Two batteries of 2S (7.4 V) 1000 mAh connected in series act as a 4S battery (14.8 V) of 1000 mAh.

Diagram of connections:

Thank you for your attention and your time.