What Are Lithium Polymer (LiPo) Batteries, and Are They Better Than Nimh Batteries?

[Batfish]

First, for 2s/3s/4s - the "s" means "series". This is the amount of cells the pack has that add to the total voltage. Each cell is 3.7 volts nominal, so 2s=7.4v, 3s=11.1v, 4s=14.8v, etc... Nimh packs are cells in series, so you could draw a comparison by calling a 6-cell nimh pack a 6s pack of nimh.

Next, 2s2p, the "p" means "parallel". Unlike traditional nimh packs, lipos are commonly run in parallel in addition to series. This "p" number is the amount of cells in parallel the pack has, which adds to the total capacity. Each "p" adds the capacity equal to one individual cell capacity in the pack. This concept can get a little tough to understand for the first time, so I'll try to explain more.
For example, let's take my FMA BalancePro 2s2p 7.4v 6400mah pack. The pack is made with cells that are 3.7v (same for all lipo) and 3200mah. 2s means TWO cells in SERIES, so 3.7v*2=7.4 volts. 2p means TWO MORE cells in PARALLEL with the first two, adding capacity equal to one cell's capacity in the pack, so 3200mah+3200mah=6400mah.
Therefore, 2s=7.4volts and 2p=6400mah.

Packs can be added together to increase voltage, similar to the way we add two nimh 6-cell packs together in an E-Maxx to make 14.4 volts. Two 2s1p LiPo packs connected in series would provide 14.8 volts. When attaching packs in series OR parallel, it is important to make sure they begin at the same voltage so neither pack is discharged more than the other. Remember; over-discharging can permanently damage the batteries' capacity and performance.

Please note that this information is intended to provide you with basic information in regards to Lithium Polymer batteries and is NOT a replacement for manufacturers instructions and guidelines for usage of their LiPo batteries/chargers.

PLEASE FOLLOW THE MANUFACTURERS INSTRUCTIONS FOR CARE AND MAINTENANCE OF LITHIUM POLYMER BATTERIES.