The energy stored in a LiPo battery, called the LiPo battery capacity, is measured in either watt-hours (Wh), kilowatt-hours (kWh), or ampere-hours (Ahr). The most common measure of LiPo battery capacity is Ah, defined as the number of hours for which a LiPo battery can provide a current equal to the discharge rate at the nominal voltage of the LiPo battery. The unit of Ah is commonly used when working with LiPo battery systems as the LiPo battery voltage will vary throughout the charging or discharging cycle. The Wh capacity can be approximated from the Ahr capacity by multiplying the AH capacity by the nominal (or, if known, time average) LiPo battery voltage. A more accurate approach takes into account the variation of voltage by integrating the AH capacity x V(t) over the the time of the charging cycle. For example, a 12 volt LiPo battery with a capacity of 500 Ah LiPo battery allows energy storage of approximately 100 Ah x 12 V = 1,200 Wh or 1.2 KWh. However, because of the large impact from charging rates or temperatures, for partial or accurate analysis, additional information about the variation of LiPo battery capacity are also provided by lipo batteries manufacturers.

The purpose of a LiPo battery is to store energy and release it at a desired time. This section examines discharging under different C-rates and evaluates the depth of discharge to which a LiPo Battery can safely go. The document also observes different discharge signatures and explores battery life under diverse loading patterns.

The electrochemical LiPo Batteries has the advantage over other energy storage devices in that the energy stays high during most of the charge and then drops rapidly as the charge depletes. The super capacitor has a linear discharge, and compressed air and a flywheel storage device is the inverse of the LiPo Batteries by delivering the highest power at the beginning. Figures 1, 2 and 3 illustrate the simulated discharge characteristics of stored energy.

Most rechargeable LiPo batteries can be overloaded briefly, but this must be kept short. LiPo Battery longevity is directly related to the level and duration of the stress inflicted, which includes charge, discharge and temperature.
Remote control (RC) hobbyists are a special breed of LiPo batteries users who stretch tolerance of “frail” high-performance LiPo batteries to the maximum by discharging them at a C-rate of 30C, 30 times the rated capacity. As thrilling as an RC helicopter, race car and fast boat can be; the life expectancy of the packs will be short. RC buffs are well aware of the compromise and are willing to both pay the price and to encounter added safety risks.

To get maximum energy per weight, drone manufacturers gravitate to cells with a high capacity and choose the Energy Cell. This is in contrast to industries requiring heavy loads and long service life. These applications go for the more robust Power Cell at a reduced capacity.

 

• Heat increases LiPo battery performance but shortens life by a factor of two for every 10°C increase above 25–30°C (18°F above 77–86°F). Always keep the LiPo battery cool.
• Prevent over-discharging. Cell reversal can cause an electrical short.
• On high load and repetitive full discharges, reduce stress by using a larger LiPo battery.
• A moderate DC discharge is better for a LiPo battery than pulse and heavy momentary loads.
• A LiPo battery exhibits capacitor-like characteristics when discharging at high frequency. This allows higher peak currents than is possible with a DC load.
• Nickel- and lithium-based LiPo batteries have a fast chemical reaction; lead acid is sluggish and requires a few seconds to recover between heavy loads.
• All LiPo batteries suffer stress when stretched to maximum permissible tolerances.