Lithium Ion or Lithium Polymer batteries are quite new to the market, but they are showing early on that they promise great things, especially in the realm of electric indoor flight.

Unlike NiCd rechargeable battery and NiMH cells, the Li-Po cell has a nominal voltage of 3.6V. Typically these cells would be used in 1, 2, or 3-cell packs giving voltages of 3.6, 7.2, and 10.8 volts respectively. This limits the selection a bit when compared to the other batteries which offer combinations in 1.2V increments for wider voltage possibilities. The advantage comes in their energy density or energy to weight ratio as much as four-fold over a typical NiCd battery. Modelers who have adapted these batteries for indoor and park flyers have found they can get long run times compared to using NiCd and NiMH packs.

Self-discharge for the Lithium Polymer battery is very slight compared to either the NiCd or NiMH. It is generally negligible and one need not be concerned with topping up the cell before use.

Unlike NiCd and NiMH cells, the characteristics of the Lithium Polymer batteries remain relatively constant over many cycles. The internal resistance increases only marginally, the capacity decreases only marginally, and the self-discharge is still negligible. Unlike NiCd and NiMH cells, the Lithium Polymer battery exhibits no memory. One can charge or discharge the pack partially or fully and still retain the long term capacity of the unit. This means that cycling with a battery exerciser is not required to maintain functionality. Lithium Polymer batteries are considered low maintenance as opposed to the NiCd and NiMH which are high-maintenance batteries.

Everything seems perfectly rosy and the lifepo4 batteries are the cats-meow. There are some disadvantages, however, and also some cautions to take when using the Li-Po technology. As the technology improves and it is changing quickly, these will undoubtedly become less of a concern.