Choosing among FPV radios & batteries starts with a simple problem: are you trying to control a model, power it, or charge the batteries? A receiver, a 6S LiPo pack, an AC adapter, and a charging hub can appear in the same search while solving completely different gaps. Identify that gap first, then compare the explicit channel, connector, voltage, and charging-role details.
Quick take
Start with the job, not the product category:
- Model control: RadioMaster ER4 ExpressLRS receiver.
- Flight power: 2pcs HRB XT90 4000mAh 6S Lipo Battery.
- Charging expansion: Genuine DJI FPV Battery Charging Hub.
- AC charging: Genuine DJI FPV Drone Battery Charger AC Power Adapter CDX170-90.
Listed-price comparison
The listed prices run from $17.49 to $93.99, a $76.50 difference between the endpoints. The spread reflects four different roles: the receiver is the lowest-priced item, the HRB battery two-pack is the highest, and the DJI charging accessories sit between them. Read the prices as a way to budget for the job you need, not as a ranking across unlike hardware.
| Product | Listed price | Price bar |
|---|---|---|
| DJI FPV Battery Charging Hub | USD 36.80 | |
| DJI FPV Drone Battery Charger AC Power Adapter CDX170-90 | USD 29.99 | |
| 2pcs HRB XT90 4000mAh 6S Lipo Battery | USD 93.99 | |
| RadioMaster ER4 ExpressLRS Receiver | USD 17.49 |
Decision matrix
- Need a control component? The RadioMaster ER4 ExpressLRS receiver is the relevant choice.
- Need more charging capacity around DJI FPV batteries? The DJI FPV Battery Charging Hub is the relevant accessory.
- Need the adapter and charger role? The DJI FPV Drone Battery Charger AC Power Adapter CDX170-90 addresses that job.
- Need a two-pack of flight batteries? The HRB XT90 4000mAh 6S battery addresses that format.
Product notes
Genuine DJI FPV Battery Charging Hub Multiple Battery Charger Manager
Choose this hub when the missing piece is charging expansion for a DJI FPV setup. When connected to a DJI FPV charger, it can charge three additional batteries in sequence, with an approximate 55-minute charging time subject to temperature. That makes its role distinct from a flight pack or AC adapter. The limitation is dependence on the DJI FPV charger: it is an expansion accessory, not the power adapter itself. Its condition is open box, so shoppers who specifically want a new condition may prefer the separate CDX170-90 charger instead. The black color is also explicitly listed.
Genuine DJI FPV Drone Battery Charger AC Power Adapter CDX170-90 25.2V 3.4A 86W
This adapter suits the shopper whose missing part is the AC charging role for a DJI FPV battery setup. The CDX170-90 model carries 25.2V, 3.4A, and 86W specifications, and a power cord is included. Those specifics give you a focused way to compare it with the hub, which expands an existing charger rather than serving as the adapter. Its limitation is packaging: it comes in bulk, non-retail packaging, so it is less suited to someone who specifically wants retail presentation. The condition is new, and the item serves as a charger and AC power adapter.
2pcs HRB XT90 4000mAh 6S Lipo Battery 100C 22.2V for RC Drone Helicopter Car FPV
The HRB pack is the flight-power choice for a build calling for the listed two-piece, 4000mAh, 6S configuration. It has an XT90 female plug and a 7-pin JST-XH balance connector, giving you concrete connection details to compare with your model. Fit depends on matching the voltage, dimensions, and plug, so the pack should not be treated as universal. Its size is 135 × 42 × 49 mm and its weight is 590g, both relevant when space or weight matters. Choose it for the two-pack format and the stated connector arrangement when those physical requirements align.
RadioMaster ER4 ExpressLRS (ELRS) 2.4GHz 4-Channel Receiver
Pick the RadioMaster ER4 when your model needs an ExpressLRS receiver with four simultaneous PWM channels. It is intended for small aircraft, boats, cars, and other models, with flexible configuration and ultra-long-range capability. The limitation is the channel count: a model requiring more than four channels would need a different specification, so the long-range wording alone is not enough to establish a match. The model reference is RM-HP0157.RX-ER4, and the condition is new. This receiver is the control component in the comparison; it does not serve the battery or charging roles covered by the other three choices.
Final recommendation by use case
- For control: Choose the RadioMaster ER4 ExpressLRS receiver when the four-channel receiver role matches your model.
- For charging expansion: Choose the DJI FPV Battery Charging Hub when you already have the DJI FPV charger it requires.
- For the AC adapter role: Choose the CDX170-90 charger when its 25.2V, 3.4A, and 86W configuration and included power cord are what you need.
- For flight power: Choose the HRB 2pcs XT90 battery when the 6S configuration, connector, and physical dimensions line up.
The simplest shopping rule is to avoid comparing the receiver against the battery on price alone: first identify the job, then match the explicit electrical and physical details. The listed range from $17.49 to $93.99 reflects that mix of roles, while the title phrases make the intended use clear.
