| 25KG·CM STALL | 0.070S/60° NO-LOAD | 8.4V RATED |
| 65G WEIGHT | StainlessGEARTRAIN | 360°TRAVELCustomizable |
Overview
The BLS325 is a low-profile brushless servo: 41 × 20.5 × 28.5 mm, 65 g, 25 kg·cm at 8.4 V. The 20.5 mm thickness is the point of the design — it fits where a standard 20 mm-tall case plus horn will not clear a canopy or a frame rail.
A brushless motor drives a stainless steel geartrain on two ball bearings, with a 25T-φ5.96 mm spline and a POM horn. There is no mechanical stop on the output, and the case is a CNC aluminium block with fins cut into the sides rather than a plastic shell with a heatsink sticker.
This page covers the PWM build: a standard 50–333 Hz pulse input, 1500 µs neutral and a 3–4 µs dead band. It is the version to pick when the servo hangs off a receiver or a flight controller and you want nothing between the two.
Performance at each supply voltage
| Supply | No-load speed | Peak stall torque | Idle current | Stall current |
|---|---|---|---|---|
| 6.0 V | 0.120 s/60° (500 °/s) | 17.5 kg·cm (1.72 N·m / 243 oz·in) | 190 mA | 3.5 A |
| 7.4 V | 0.090 s/60° (667 °/s) | 22 kg·cm (2.16 N·m / 306 oz·in) | 220 mA | 4 A |
| 8.4 V | 0.070 s/60° (857 °/s) | 25 kg·cm (2.45 N·m / 347 oz·in) | 250 mA | 5 A |
Control specification
| Item | Specification |
|---|---|
| Command signal | PWM |
| Amplifier | Digital controller |
| Pulse width range | 700–2300 µs |
| Neutral position | 1500 µs |
| Dead band | 2 µs |
| Rotating direction | CCW (1000–2000 µs) |
| Travel | 360°, customizable |
Mechanical specification
| Item | Specification | Item | Specification |
|---|---|---|---|
| Dimensions | 41 × 20.5 × 28.5 mm | Case material | Aluminium, CNC |
| Weight | 65 g | Geartrain | Stainless steel |
| Bearings | 2 × ball bearing | Motor | Brushless |
| Output spline | 25T-φ5.96 mm | Horn | Plastic, POM |
| Lead / connector | 300 mm, 3-wire | Mechanical limit | No limit |
| Operating temperature | −15 °C to 65 °C | Storage temperature | −20 °C to 70 °C |
| Ingress protection | Splash resistant (customizable) | Travel | 360°, customizable |
What’s in the box
- 1 × XQ-BLS325 servo
- 1 × POM horn set
- 1 × mounting screw pack
Optional: metal horn, sold separately.
How to size it
Torque tracks the rail: 17.5 kg·cm at 6.0 V, 22 at 7.4 V and 25 at 8.4 V. A 2S LiPo sits near 7.4 V for most of its discharge, so plan around 22 kg·cm and treat 25 as the fresh-pack number.
Stall current is 5 A at 8.4 V against 250 mA no-load. A shared BEC that also feeds four of these needs 20 A of headroom on stall — check the BEC before blaming the servo for brownouts.
FAQ
What makes it low-profile?
The case is 20.5 mm thick instead of the usual 28–30 mm, so the servo sits flatter on the mounting surface. That is what lets it fit under a canopy or inside a narrow fuselage.
Does it fit a standard 25T horn?
Yes — 25T spline, φ5.96 mm centre. A POM horn set ships in the box; aluminium horns are a separate item.
What pulse range does it accept?
The inspection sheet specifies a 500–2500 µs window (800–2200 µs on the 9130/9150) with 1500 µs neutral, both customizable at order. Feeding it outside that window is out of spec.
Can I drive it from a normal receiver?
Signal-wise yes, but check the supply. This servo wants 8.4–16.8 V, not a 6 V receiver pack, so the power rail has to be separate from the receiver’s.
Other interfaces
Downloads
- XQ-BLS325 inspection specification (PDF, 387 KB)
Torque, speed and current at each supply voltage, mechanical data, control specification, mounting dimensions. - 2D dimension drawing (image)
Mounting hole positions, case depth and overall height; the same drawing is inside the datasheet.
