When to charge rechargeable batteries?
In general there is no major difference whether you charge the batteries before or after use. However, if you use your rechargeable batteries infrequently, e.g. only once a month, you may forget whether or not the batteries are already charged. In this case, be careful not to overcharge them. It is recommended to charge a rechargeable battery when about 70% to 75% of the capacity has been consumed. Rechargeable batteries are damaged by over-discharging them, which will have its impact on the service life of the batteries and could cause leakage. In order to avoid this, Panasonic urges its customers to charge their batteries when 70% of the battery capacity has been used.