Choosing FPV radios & batteries starts with a fork: are you adding a receiver to a model, or buying power for the model? Even within the receiver group, channel and output needs can matter more than a familiar product name, while a battery decision turns on voltage and connector fit. The four choices below cover those different jobs, so the useful payoff is a quick match between your build and the part-not a one-size-fits-all pick.
Quick take
Three entries are RadioMaster ExpressLRS receivers, while the HRB entry is a battery pack. Receiver shoppers can focus on the ER4, ER8, and RP3 V2; battery shoppers should start with the HRB pack. Compare the receivers by channel count or receiver design, then assess the battery separately by its electrical and connector details. The receiver prices sit in a different range from the battery, making the price comparison useful alongside the fit and feature differences.
Listed-price comparison
Prices run from $17.49 to $93.99, an absolute spread of $76.50. The bars are a visual aid for the price position of each item, not a performance ranking.
| Product | Price | Price bar |
|---|---|---|
| RadioMaster ER4 ExpressLRS (ELRS) 2.4GHz 4-Channel Receiver \[RM-HP0157.RX-ER4 | $17.49 | |
| RadioMaster ER8 ExpressLRS (ELRS) 2.4GHz 8 Channel Receiver \[RM-HP0157.RX-ER8 | $40.99 | |
| RadioMaster RP3 V2 ExpressLRS (ELRS) 2.4Ghz Receiver \[RM-HP0157.RX-RP3-V2 | $22.49 | |
| 2pcs HRB XT90 4000mAh 6S Lipo Battery 100C 22.2V for RC Drone Helicopter Car FPV | $93.99 |
Decision matrix
- Four PWM channels needed: Choose the RadioMaster ER4, whose product name and specifications identify four-channel PWM support.
- Eight servo outputs needed: Choose the RadioMaster ER8, which is identified with eight channels and support for eight servos.
- WiFi firmware updates wanted: Choose the RadioMaster RP3 V2, which supports updates through WiFi using ExpressLRS firmware.
- Two battery packs wanted: Choose the HRB 2pcs pack, whose title specifies a two-piece battery format.
Product notes
RadioMaster ER4 ExpressLRS (ELRS) 2.4GHz 4-Channel Receiver [RM-HP0157.RX-ER4
The ER4 is aimed at small aircraft, boats, cars, and other models where a lightweight receiver matters. ExpressLRS operation, 2.4GHz frequency, high-speed response, flexible configuration, and ultra-long-range capability give it a clear reason to enter a compact-model build. Its concrete limitation is the four-channel ceiling: a setup needing more than four simultaneous PWM outputs will need a different receiver. The ER4 makes sense when the model's control-output plan fits four channels. Its $17.49 price also gives receiver shoppers a straightforward entry point, but it should not be selected as a substitute for the HRB battery, since the two items serve different jobs.
RadioMaster ER8 ExpressLRS (ELRS) 2.4GHz 8 Channel Receiver [RM-HP0157.RX-ER8
The ER8 brings a fixed-wing-oriented format, a 20cm high-sensitivity antenna, and a stated DC 4.5-8.4V supply. Its 16.5g weight and 43x30x15mm size add concrete planning details for a build where those parameters matter. The eight-channel phrase in its product name is the main reason to choose it when extra servo outputs are part of the plan. The limitation is the $40.99 price, which sits above the ER4 and RP3 receiver prices. That makes the ER8 a less natural fit for a smaller setup that does not need the added channel capacity, even though fixed-wing use is specifically named.
RadioMaster RP3 V2 ExpressLRS (ELRS) 2.4Ghz Receiver [RM-HP0157.RX-RP3-V2
RP3 V2 is the receiver to consider when antenna diversity and signal-stability features drive the decision. It also includes a built-in TCXO, LNA, PA, two antennas, and WiFi-based firmware updates through ExpressLRS. The frequency range is 2.404-2.479 GHz, the maximum receive refresh rate is 500Hz / F1000Hz, and working voltage is DC 5V. That 5V requirement is the key limitation: the electrical setup needs to match it. At $22.49, RP3 V2 sits nearer the ER4 than the ER8 in the price comparison. Choose it for its receiver-specific design features, not for the battery job handled by HRB.
2pcs HRB XT90 4000mAh 6S Lipo Battery 100C 22.2V for RC Drone Helicopter Car FPV
The HRB pack is the battery-focused choice, with two packs in the product title and 4000mAh, 6S, and 22.2V specifications. Its Amass XT90 female plug and 7PINS JST-XH balance connector are important selection details, while the named compatibility list covers large multirotors, EDF jets, helicopters, cars, boats, planes, and quads when voltage, dimensions, and plug match. The concrete limitation is the $93.99 price plus those fit conditions; the pack cannot be treated as a universal match. Choose it when the model calls for this electrical and connector combination. Its 100C continuous discharge and 200C burst-rate figures are included as listed specifications, not a reason to assume a particular setup outcome.
Final recommendations by use case
- Lowest-priced receiver path: Choose the RadioMaster ER4 ExpressLRS (ELRS) 2.4GHz 4-Channel Receiver when the $17.49 price and compact-model use align.
- Fixed-wing setup: Choose the RadioMaster ER8 ExpressLRS (ELRS) 2.4GHz 8 Channel Receiver when its fixed-wing orientation matches the build.
- Signal-stability-focused receiver: Choose the RadioMaster RP3 V2 ExpressLRS (ELRS) 2.4Ghz Receiver for antenna diversity and its receiver-focused design.
- 6S battery setup: Choose the 2pcs HRB XT90 4000mAh 6S Lipo Battery when the 22.2V, XT90, and JST-XH requirements match.
The $76.50 spread matters because the comparison does not put interchangeable parts on the same job. Start with receiver versus battery, then narrow the receiver choice by outputs or design features and the battery choice by voltage and connector fit.
