3.7V 550mAh LiPo Upgrade Battery Spare Pack for FX9503 F6F Hellcat RC Airplane

End Mid-Air Voltage Drops, Recover Instant Stunt Burst Power, and Extend Your Warbird Flight Window

When piloting a high-performance warbird like the brushless FX9503 F6F Hellcat, executing high-load maneuvers like 360° extreme stunts, vertical climbs, and inverted loops demands sustained, aggressive current delivery. Over consecutive charging cycles, standard stock cells suffer from internal chemical degradation, resulting in premature voltage sagging that triggers the low-voltage cutoff midway through an aerial run, or dropping cell punch entirely when you open the throttle for a stunt. For this brushless scale model, an underpowered or swollen cell limits the high-RPM output of the motor, causing sluggish aerodynamic response and risky stalls. Swapping in this premium factory-spec 3.7V 550mAh 25C lithium pack eliminates battery fade, stabilizes delivery throughout your flight window, and delivers the instantaneous high-discharge burst needed to pull off flawless aerobatic loops with confidence.  Ships worldwide.

Product Highlights

• High-Rate 25C Continuous Discharge Matrix: Specially formulated to deliver a steady 3.7V flow with a 25C peak burst output, maintaining continuous throttle response even during sudden high-amp stunt maneuvers.

• Optimized Size-to-Capacity Footprint: Packed with a dense 550mAh / 2.04Wh payload into an exact form-fitting shell measuring precisely 42mm in length, 21mm in width, and 8mm in thickness to maintain the plane's center of gravity.

• Pre-Assembled Low-Resistance Pin Harness: Comes fitted with a flexible dual-insulated wire run leading to a standard white micro plug connector for a direct, drop-in link to your plane's main board tray.

• Robust Thermal-Shielded Cell Wrapping: Encased in a durable, heat-resistant silver protective foil matrix designed to regulate heat build-up during fast charging and intensive aerobatic discharge cycles.

Compatibility

For the FX9503 F6F Hellcat RC Airplane only.
Full model page (specs & photos):

https://www.kidstoylover.com/products/fx9503-f6f-hellcat-rc-airplane-brushless

What’s in the Box

• 1 x  FX9503 3.7V  550mAh Battery

Install Tips

• Accessing and Seating the Fuel Module: Unlatch the underbelly battery compartment door on your EPP foam fuselage skin; slide the old drained cell out from the inner cavity slot, checking that the foam interior walls remain clear of debris.

• Connector Orientation and Channel Protection: Align the white plastic terminal block connector with the matching socket receiver prong on the ESC wire; push gently until it clicks flush, routing the flexible red and black lead wires cleanly into the side channel path so they do not pinch when shutting the hatch cover.

• Center of Gravity and Hatch Locking: Push the 42mm long cell body completely forward into its structural seating pocket to ensure the nose-heavy balance point aligns with factory tracking parameters; click the hatch lock button shut to prevent the power block from shifting during inverted stunts.

• Safe Handling and Multi-Pack Balance Care: Always allow the high-output core cell to cool down for 10-15 minutes after landing before attaching it to your USB charging station adapter; if storing the warbird for more than 7 days, discharge or charge the unit to a stable nominal range to maintain the chemical health of the core lithium layers.

Support & Warranty

• 3-month warranty on manufacturing defects
• Ships worldwide