This depends on how many amperes you set it to charge. Generally, 1A current can fully charge a 1000MA battery in one hour, 5000MA takes 5 hours to charge with 1A, 2 hours with 2.5A, and 1 hour with 5A (these are theoretical values, and the actual values may differ slightly, due to different remaining battery power and different battery packs).
Regarding the charger setting charging A number, for example, the B6 charger is 50w. The battery you want to charge is a 12.6v battery that is fully charged in 3s, which is 50w÷12.6v=3.9A. When setting the charging voltage, do not exceed 3.9v. Similarly, the charging voltage for 4s should not exceed 2.8A, 5s should not exceed 2.2A, and 6s should not exceed 1.9A. If you do not set it according to the formula, the charger will automatically restart or power off. If you need high current charging, please purchase a high-power charger with a large w number!