The popular Tamiya Connectors are a user friendly and safe choice for e.g. batteries or chargers. The most common model in airsoft guns and batteries.
Note! The male and female sides of Tamiya connectors have been named in a way that is different from the common standard. Normally, connectors are named according to the metal contact pins, but in the case of the Tamiya connectors, a connector with a female plastic body and male contact pins is often referred to as the female connector. Keep this in mind when choosing your connectors.