A 4.8V receiver battery can save weight in a radio-controlled (RC) model; a 6V pack can give compatible servos more speed and torque. Choose between them using the voltage and current requirements of your receiver, every servo, and any other connected equipment. Use a five-cell 6V NiMH/NiCd pack only when the complete system accepts that battery type, including its higher freshly charged voltage.
This guide is about the battery powering the receiver and servos in an RC airplane, car, or boat—not the transmitter battery or an electric model’s propulsion pack.
Based on Dave Thacker’s original Radical RC receiver-battery Q&A. Technical guidance updated .
What is the difference between a 4.8V and 6V receiver pack?
With NiMH or NiCd cells, 4.8V means four nominal 1.2V cells in series; 6V means five. Adding a fifth matching cell increases voltage, weight, and stored energy. It does not increase the pack’s amp-hour capacity: four 700mAh cells in series and five 700mAh cells in series both make a 700mAh pack.
| What you are comparing | 4.8V pack | 6V pack |
|---|---|---|
| Cells in series | 4 | 5 |
| Weight, using the same cells | One cell lighter | One extra cell |
| Servo performance | Check the servo’s 4.8V rating | Often faster and stronger if rated for 6V |
| Capacity in mAh | Set by the cells used | Not increased just by adding a cell |
| Main decision | Does it meet the system’s voltage and load requirements? | Can every component accept a fully charged five-cell pack? |
Nominal voltage is a label, not a maximum. A freshly charged NiMH pack starts above its nominal voltage, and its voltage changes with load and discharge. The Energizer NiMH handbook explains this behavior. Do not assume that an absolute 6.0V equipment limit automatically permits an unregulated “6V” battery pack.
Will 6V make my RC servos faster or stronger?
It can, when the servo is designed for that voltage. For example, Futaba rates its S-U306 at 0.23 seconds per 60° and 7.1 kgf·cm at 4.8V, compared with 0.18 seconds per 60° and 8.9 kgf·cm at 6.0V. A smaller travel-time figure means a faster servo. These are specifications for that servo, not a guaranteed percentage improvement for every model. See the Futaba S-U306 specifications.
In an RC airplane, the difference may be noticeable in control-surface response and the servo’s ability to resist aerodynamic loads. It does not fix binding linkages, an undersized servo, excessive control throws, or a weak power supply. Follow the voltage ratings for the actual servos installed—including an older throttle or retract servo you may have forgotten.
Will a 6V receiver battery give longer flight time or more range?
Voltage alone does not predict flight time. Usable capacity, servo load, flying style, battery condition, and wiring losses all matter. At the same mAh rating, a five-cell pack stores more nominal energy, but higher-voltage servo operation can also change power consumption. There is no fixed runtime penalty or gain that applies to every RC model.
Do not choose 6V as a radio-range upgrade. A sound power supply helps the receiver keep operating; it is not a substitute for correct antenna installation and the radio manufacturer’s range test. Low voltage under load can cause a receiver brownout. The Spektrum AR631 manual identifies the battery, regulator or BEC, switches, leads, and connectors as parts of the receiver power system that need checking.
Does a fifth cell provide backup power if a cell fails?
No. A five-cell receiver pack is still one series-connected battery, not a redundant power system. An extra cell does not make a faulty pack safe to keep using. A shorted cell is a battery fault, and an open circuit can interrupt the entire supply.
For a model that needs backup receiver power, use a manufacturer-approved redundant system. For example, Spektrum’s PowerSafe manual describes two independent, isolated battery inputs. That is a different arrangement from adding a fifth cell or simply joining two packs together.
What should I check before changing an RC receiver battery?
- Check every voltage rating. Read the receiver, servo, gyro, retract, switch, and regulator instructions. Confirm approved cell count and battery chemistry, not just a nominal voltage printed on a pack.
- Check current capacity and connections. The pack, switch harness, plugs, and leads must handle the combined servo demand. Use our RC connector and wire chart to help identify what is installed.
- Test voltage at the receiver under load. Follow the radio manufacturer’s ground-test procedure with the engine stopped and propulsion disabled. Check for voltage sag during simultaneous servo movement; do not hold servos stalled.
- Confirm fit and balance. Check pack dimensions, mounting, lead length, connector polarity, and the airplane’s center of gravity. The receiver battery configuration chart helps compare pack shapes.
- Investigate glitches before operating the model. Jitter, receiver resets, overheating, or a suspect cell are reasons to stop and find the cause. Do not dismiss jitter after charging as normal. See our battery inspection and charging guide.
What if my model uses an ESC/BEC, LiPo, or LiFe battery?
Many electric RC models power the receiver through a battery eliminator circuit (BEC) in the electronic speed control, or through a separate regulator. In that setup, the BEC’s output voltage and current capability are what the receiver and servos see. Follow the ESC/BEC instructions before adding a separate receiver pack or changing the supply arrangement.
A two-cell lithium pack is not an automatic replacement for a four- or five-cell nickel pack. A standard 2S LiPo reaches 8.4V fully charged. LiFe has different voltage and charging requirements again. Confirm compatibility or use an appropriately rated regulator; use a charger intended for the pack’s chemistry. Horizon Hobby’s guide to replacing old RC receiver batteries discusses these choices.
How did Dave choose receiver packs for his airplanes?
Dave’s original Q&A put the practical tradeoff this way:
“For most of my smaller and normal-sized ships I am chasing weight savings, so I use 4.8V.”
Dave Thacker, Radical RC
He also described using 6V in a combat model and favoring it for larger models. Keep that experience in context: the right supply depends on the equipment in your particular airplane. Modern receivers, digital servos, and power-distribution systems can have different requirements from the equipment discussed in the original exchange.
Compare receiver battery packs for your RC model
These matching 700mAh examples show the difference between a four-cell and five-cell flat pack. Select capacity and current capability for your installation; these examples are not a recommendation for every model.
Browse NiMH receiver battery packs or read the Radical RC battery FAQs. For other chemistries, see A123 and LiFe battery options after checking your system’s compatibility. If you need help choosing a pack, contact Radical RC with your receiver model, servo models, available space, and existing connector.