Important notes and safety precautions about charging your 510 battery:
DO NOT OVERTIGHTEN THE BATTERIES ON THE CHARGER. Over-tightening the battery in the USB charger can cause the charger or battery to malfunction. Turn the battery slowly only until the light on the battery flashes, or (if your charger has a light) the light turns from green to red.
Always plug the USB charger in before the 510 battery. Ensure the light on the USB charger is green before charging the battery.
Do not leave a charging battery unattended.
Do not leave a charged battery on the charger for an extended period of time