NIKON:
DMNEN4 , DNK004 , EN-4 ,
Do not short-circuit the nikon battery.Accidental short-circuiting can occur when a metaillic object such as a coin,clip,or pen causes direct connection of the positive(+) and negative(-) terminals of the en-4 battery.(These look like metal strips on the nikon en-4).This might happen,for example,wehn you carry a spare digital camera battery in your pocket or purse.Short-circuiting the terminals may damage the battery or the connecing object.
Keep the nikon en-4 battery contacts clean: Clean your battery's metal contacts every couple of months with a cloth moistened with rubbing alcohol. This keeps the transfer of power from your EN4 battery pack more efficient.
If a replacement en-4 battery is being used for the first time or if the nikon en-4 battery has not been used for a prolonged period.it may be necessary to connect the nikon en-4 battery charger and then disconnect and reconnect it to start the charging.