Chicago (IL) – Moixa Energy has developed rechargeable AA batteries with a twist: the batteries are recharged simply by plugging them into an USB port.

The batteries, called USBCell, do not look different than a regular Ni-MH AA battery at first sight. However, the top part of the device is a cover that not only contains the cathode of the battery, but also, when opened, exposes the USB connector. The battery can be plugged into any USB host to be recharged.

At this time, there are only AA types of the technology available, but the manufacturer promises to follow up with 9V blocks and cellphone batteries in the near future.

The convenience of the recharging process (assumed you have a USB host, such as a notebook) put aside, there are a few downsides. The integration of the USB connector requires a reduction of the electrolyte. As a result, the available capacity is much lower than a typical Ni-MH battery, which are commonly selling in variants ranging from 1400 mah to about 2400 mah. The 1.2 volt AA USBCell provides a maximum of only 1300 mah, which means that it won’t be able to provide as much juice than regular rechargeable AA batteries.

The weight reduction that results from trading electrolyte for a USB connector is marginal: The USBCell weighs about 22 grams compared to the 23 grams of a regular AA battery.

Also, the charging time appears to be quite long, as the manufacturer noted on his webpage that a 90% charge is reached after a charging time of about 320 minutes.

A 2-pack of USBCell batteries is currently selling for just under $17.