Hello everyone.
The included charger is 12V/2A, that means it can output 2A/2000mA per hour. The Ronin S battery is 2400mAh, so why does it need "2 and a half hour" to charge?

The battery is 14.4v (4s) and is charged to around 16.7v.
The charger also ramps up the amps in the beginning and ramps down when the voltage gets close to max. It also performs cell balancing, so it will charge the individual cells diffrently.
Charging this "slow" also prolongs the life of the battery pack.

Hi Haxorious, the Ronin-S has already adopted the quick-charge technology, its operating time is up to 12 hours, StianGel explained very well, please refer to his post, thank you.