Part of the Fuel-Powered RC Airplanes Center
I do not judge a receiver or ignition battery by whether it fits in the airplane. I care about whether the complete power path—battery, wiring, connectors, switch, regulator, and any distribution system—can maintain the required voltage while the servos and ignition are actually working. A small battery or connector can cause a very large problem, so capacity, voltage, current capability, charging, and installation all matter.
This guide’s primary home is the Radio & Receiver Setup Center. For a complete receiver, servo, and ignition power plan for larger models, see the large-airplane receiver power guide.
Receiver Battery vs. Ignition Battery
The receiver battery powers the receiver and servos when the airplane does not use an ESC/BEC for that job. A gasoline ignition battery powers the electronic ignition module. Some installations use separate batteries and switches; others use manufacturer-approved regulators or shared arrangements. Follow the receiver, servo, ignition, and engine instructions rather than assuming every system accepts the same voltage.
Voltage Compatibility Comes First
Check the allowable voltage for every connected component. A battery’s nominal voltage is not the whole story: fully charged voltage can be higher, and voltage can sag under servo or ignition load. Regulators, power distribution systems, and switches must also be rated for the expected current.
Capacity and Current
Capacity tells you how much energy the pack stores, but it does not guarantee that the pack, wiring, connector, or switch can supply high current without a voltage drop. Large digital servos moving together can produce brief loads much higher than a simple bench test with one unloaded servo.
Choose capacity using the airplane’s servo count and type, expected flight time, number of flights, telemetry data when available, and a conservative reserve. Establish actual consumption by recording how much charge goes back into the pack after known flight time.
Connectors, Switches, and Redundancy
A reliable battery attached through a worn switch or loose connector is still an unreliable system. Secure plugs against vibration, provide strain relief, and inspect contacts for heat, looseness, corrosion, or damaged wire. Larger airplanes may benefit from dual batteries, dual inputs, or a purpose-built power distribution system, but redundancy must be wired so one failure cannot disable both paths.
For the broader subject, read receiver power, brownouts, and redundancy.
Installation
- Mount packs securely with protection from vibration and sharp structure.
- Keep them away from exhaust heat, fuel leaks, and ignition high-tension wiring.
- Do not let heavy batteries pull directly on connectors.
- Provide access for inspection and charging without disturbing the installation.
- Recheck the airplane’s center of gravity after changing battery type or position.
Charging and Preflight Checks
Use a charger program that matches the battery chemistry and series-cell count. Before flying, confirm charge state using a method appropriate for the chemistry, then test the system under realistic load. Moving several servos together while watching receiver voltage or telemetry is more useful than an unloaded voltage reading alone. We once repaired a Katana overnight after a crash, then flew it again the next day without recharging the receiver battery. It crashed again. The repair got our attention, but the battery did not—and that is exactly why charging belongs on the written preflight routine after every long shop session or repair.