Battery Chargers

by Kurt Gornek
 

Disclaimer:

I’ll state it up front for everyone’s benefit and for my peace of mind: USE CAUTION and BE RESPONSIBLE when charging and handling batteries. Few people have the electrical, electronics and chemistry knowledge to design a charger that doesn’t ruin or explode batteries, so when you think you can safely use a charger not specifically designed for the battery type you are charging…you’re wrong. Injury, property damage and even loss of life have been attributed to improper charging and handling of high-current battery packs such as the ones we use in RC flight. Please be careful and responsible when charging batteries. Never leave them unattended or charge them overnight. Li-Pos specifically can experience aggressive thermal runaway and result in violent combustion.

2 Brothers Hobby does not recommend charging your batteries by any other method than that which is specified by the manufacturer of the battery and the battery charger. The information contained in this article is for educational purposes only and is not intended to provide information suggesting or recommending how to charge, discharge, handle, or dispose of any rechargeable battery. Always refer to the manufacturer’s instructions and consult your local battery recycling center or visit the Environmental Protection Agency’s website on matters regarding the proper disposal of any battery or electronic device.

Additionally, some Li-Po manufacturers are suggesting higher charging rates for their batteries. ALWAYS consult your manufacturer’s specifications and charging instructions BEFORE attempting to charge any Li-Po battery at rates higher than 1C/C1.
 

For help in making your battery and charging calculations
check out our Battery Calculators
in the Tools section.

Overview

The most common batteries used today in RC flight are Lithium-ion Polymer (Li-Po), Nickel-metal Hydride (NiMH) and Nickel-Cadmium (NiCad). Another cell chemistry that is gaining ground is LiFePO4 or A123 cells. LiFePO4 packs are primarily used for receiver power in electric flight and not for main motor power due to lower discharge rates and lower cell voltage.

Some other cells you may encounter are Sealed Lead Acid (SLA) and Lithium-ion (Li-ion). Although these batteries are widely popular in many of today’s electronics and power equipment, they are not as commonly used in electric RC flight as the four previously mentioned. SLA batteries however are commonly used as a field-recharging power source for electric enthusiasts and are a staple with gas or glow flyers as a power source for their glow igniters, fuel pumps, and starters.

For the purpose of learning about chargers and to familiarize you with the types of situations you may encounter, we’ll cover charging as it applies to the following battery types:

  • Nickel-Cadmium (NiCad)
  • Nickel-metal Hydride (NiMH)
  • Lithium-ion (Li-ion)
  • Lithium-ion Polymer (Li-Po)
  • Lithium-iron Phosphate (LiFePO4/A123)
  • Sealed Lead Acid (pb/SLA)

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