| 85KG·CM STALL | 0.110S/60° NO-LOAD | 8.4V RATED |
| 92G WEIGHT | StainlessGEARTRAIN | 360°TRAVELCustomizable |
Overview
The BLS8185D is the 85 kg·cm low-voltage build: 20 × 40 × 44 mm, 92 g, and the same 25T-φ7.96 mm output as the 8175D one step down. It reaches its full 85 kg·cm at 8.4 V, which is what makes it a 2S part rather than a 4S one.
Stainless steel geartrain on two ball bearings, CNC aluminium case, and a 7075 aluminium CNC horn in the box — at this torque a POM horn is not the right default. The output has no mechanical stop, so travel is set entirely by the controller, and the 360° running degree is a real option rather than a customization that needs a different part.
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 | 0.170 s/60° (353 °/s) | 42 kg·cm (4.12 N·m / 583 oz·in) | 320 mA | 4.0 A |
| 7.4 V | 0.140 s/60° (429 °/s) | 75 kg·cm (7.36 N·m / 1042 oz·in) | 370 mA | 5.0 A |
| 8.4 V | 0.110 s/60° (545 °/s) | 85 kg·cm (8.34 N·m / 1180 oz·in) | 440 mA | 6.0 A |
Control specification
| Item | Specification |
|---|---|
| Command signal | PWM |
| Amplifier | Digital controller |
| Pulse width range | 800–2200 µs, customizable |
| Neutral position | 1500 µs |
| Dead band | 2 µs |
| Rotating direction | CCW (1000–2000 µs) |
| Travel | 360°, customizable |
Mechanical specification
| Item | Specification | Item | Specification |
|---|---|---|---|
| Dimensions | 20 × 40 × 44 mm | Case material | Aluminium, CNC |
| Weight | 92 g | Geartrain | Stainless steel |
| Bearings | 2 × ball bearing | Motor | Brushless |
| Output spline | 25T-φ7.96 mm | Horn | 7075 aluminium, CNC |
| 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-BLS8185D servo
- 1 × 7075 aluminium horn
- 1 × mounting screw pack
How to size it
Torque is 42 kg·cm at 6.0 V, 75 at 7.4 V and 85 at 8.4 V, at 0.17, 0.14 and 0.11 s/60°. The step from 6.0 V to 7.4 V is unusually large on this winding — on a 2S pack that sits near 7.4 V under load, the honest working figure is 75, not 85.
Stall current runs 4.0 A at 6.0 V, 5.0 A at 7.4 V and 6.0 A at 8.4 V. Two of these on one rail is 12 A at stall. If the receiver resets during a hard manoeuvre, add a servo rail before changing the servo.
FAQ
BLS8185D or BLS8185HV?
Same case, same geartrain, same 92 g — different winding. The low-voltage build gives 85 kg·cm at 8.4 V and is meant for 2S. The HV build gives the same 85 kg·cm at 16.8 V and only 42 kg·cm at 8.4 V. Pick by the pack you already run, not by the headline torque.
Will my 25T horns fit?
Check the centre diameter — this is a φ7.96 mm spline, the same as the 8175D, not the φ5.94 mm used on the 8135D and 8145D. A φ5.94 horn will not seat, even though both are called 25T.
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-BLS8185D inspection specification (PDF, 807 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.
