People keep bringing up the lipo voltage compared to the 4 cell voltage. No one has researched to find out if these ithium cells can be changed to produce a different voltage. Here is a link that explains how a cells voltage is determined.
http://www.powerstream.com/BPD.htm
http://www.machinedesign.com/BDE/Ele...bdeee7_10.html
One shows current battery voltage and output readings for given type of cells, the other goes into giving a brief summary of how batteries work and how changing the cathode and anode affect the battery. It also shows that lithum cells can be designed to produce different voltages. In the example it shows that a cathode of FeS2(Iron disulfide) could be used to make them comparable to sub-c cells in certain configurations(5 cell sub-c and 4 cell Li-Sef2). The doors are open to more than just the 3.7 volt lithium ion cells currently designed. There are more choices than people are actually aware of.