The USBCELL is a Ni-MH (Nickel-metal Hydride) battery. Due to this they can be charged up even when the battery has not been fully discharged, without affecting the lifetime of the battery. The USBCELL battery is a 1.2v 1300mAh AA battery. When charging these batteries in a USB port they should take around 5 hours to reach 90% fully charged, of course this may be achieved in less time if the battery was not fully discharged first.
These rechargeable batteries offer more freedom than average rechargeable batteries which require a battery charger, as these can be charged through USB ports. USB ports can be found on most laptops and computers. The USBCELL battery can then be charged while you are out and about from your laptops power.
The USBCELL batteries can also be charged through a Ni-MH battery charger. To charge them through a USB port you just flip down the lid covering the USB plug which is located at the positive end of the battery. When the USBCELL is plugged in a small green light will turn on near the USB plug part of the battery to show that the battery is charging.
Via: Enviro Gadget