The battery charger is designed with LED indicators, it is a 4-bay charger that can charge Ni-MH, Ni-Cd batteries. Each individual slot recharges a battery independently. It's also equipped with USB output function that can be used as a power bank to charge your cell phone, iPad and other electronic devices. Protection Function The internal microchip can monitor the charging current and battery voltage in real time： *Short circuit protection *Over discharge protection *Over charge protection *Reverse polarity protection *USB short circuit protection *USB output overcharge protection Features To charge batteries, connect AC adaptor to a power source, place batteries into the charger, the charger will stop charging automatically when batteries are fully charged. Compatible with: Cylindrical AA / AAA Ni-MH, Ni-Cd batteries. If an electronic device is connected to the charger during charging process, the charging time may be extended. USB output function: When the A⁺ charger is connected to a power source, the USB output will also begin to work, if batteries are inserted at the same time the charger will prioritize the USB output function to charge any connected electronic device. The charger will then charge the batteries when the electronic device is fully charged or removed. Warning: 1)Please read the manual carefully before use. 2)Confirm the battery specifications before use. The battery inserted must be compatible with the battery charger. Misuse can cause damage to the battery, charger, or user. Please do not attempt to charge incompatible batteries, misuse may result in explosion, leakage, fire and possibly burn the charger or things around it. 3)Do not use this charger in wet, flammable or explosive environments. 4)Please make sure the charger is dry at all times, keep the charger away from water or any other liquids.