This really is a clever & hugely versatile battery charger that will recharge up to 4 x AA and/or AAA rechargeable batteries or even a mixture of the two at any one time thanks to its independent charging feature. The batteries dont even have to be the same brand as the Powerchimp 4A will charge any make or model of rechargeable AA or AAA battery simultaneously. The Powerchimp comes with 4 x AA rechargeable batteries that can be inserted straight into the unit, if you are using AAAs then you will need to fit the included adaptor that is stored in the base of the unit. However if you want to charge AAs & AAAs at the same time you can use the AAA adaptor tubes & insert them straight into the battery tray in any of the slots. You dont even have to have a battery in every slot, the versatile Powerchimp 4A independent charging feature means that it will only supply power to the slot in use. Full charge is achieved in Approx. 8 hours & can be charged via USB (Universal Serial Bus) cable from your computer or via any other Powertraveller chargers. Input power is via micro USB (Universal Serial Bus) & output is via USB (Universal Serial Bus). When the unit is charging all 4 of LEDs at the top of the unit will light up red, & then as the Powerchimp 4A works out which slots are in use, the lights will stay or go off accordingly. Once the battery inside is fully charged, the relevant LED with turn green. Now you are ready to use all that power, using the included USB (Universal Serial Bus) cable you can charge up any compatible 5V device. The Powerchimp 4A will work with: iPhone Smartphone Mobile phone iPod MP3/MP4 players Sat Nav GPS Head torches What you get in the box Powerchimp 4A charger unit 4 x Powertraveller rechargeable batteries 2 x AAA adaptor tubes AAA 4 way adaptor USB (Universal Serial Bus) to micro USB (Universal Serial Bus) connection cable Micro USB (Universal Serial Bus) to female USB (Universal Serial Bus) output cable User guide