Lithium Polymer Batteries
Overview
The Lithium Polymer (LiPo) battery is a rechargeable battery widely used in RC aircraft. LiPo batteries offer several advantages over other rechargeable batteries (like NiCad and NiMh), including:
- Lightweight design
- Versatility in shape and size
- Large capacity
- High discharge rates
- Ability to be charged over 100 times without significant performance loss
Understanding how to read and interpret the information about your aircraft’s LiPo battery is crucial for safe piloting and successful missions.
Objectives
- Learn the composition and terminology of LiPo batteries.
- Understand the importance of battery voltage and safety measures.
- Gain knowledge on how to interpret battery specifications.
LiPo Composition
- A LiPo battery consists of one or more cells connected to provide specific voltage and current capacity.
- Common connectors include Deans, featuring a red (+) and black (-) lead, along with a Cell Balancer Connection.
- Each cell is rated at 3.7 volts and requires a charging voltage of 4.20 volts.
- Critical Voltage: Do not allow any cell to drop below 3.2 volts to avoid damage.
LiPo Terminology
A typical LiPo data imprint might look like this: 14.8V 5000mAh 4S/1P 20C 4C charge. Here’s what each term means:
- (V): Voltage of the LiPo. For example, a 4S pack has a voltage of (4 \times 3.7V = 14.8V).
- (S): Series value indicating the number of cells in series (e.g., 4S means 4 cells).
- (P): Parallel value indicating the number of cells in parallel, affecting current capacity.
- mAh: Milli-Amp-hour, indicating battery capacity. A 5000mAh pack can output 5A for 1 hour.
- ©: C Value, indicating discharge and charge rates. For example, at 1C, the battery discharges in 1 hour.
LiPo Safety
Proper handling of LiPo batteries is essential to prevent accidents. Here are key safety rules:
- Charging: Use a charger designed for LiPo batteries. Always verify settings for cell count and charge rate.
- Transporting: Use non-flammable containers and avoid sharp objects that could puncture the battery.
- Handling Damaged Batteries: Never touch damaged batteries with bare hands. If leakage occurs, wash immediately.
- Water Safety: Protect LiPo batteries from water exposure and ensure correct lead connections.
- Storage: Store batteries in a cool, dry place, away from children and flammable materials. Do not store dead or damaged batteries.
Emergency Procedures
- For dead or damaged batteries, discharge them and place in a covered container of salt water for 2 weeks before disposal.
- If a battery is ballooned or visibly damaged, skip the discharging step and submerge it directly in salt water.
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