Maestro compatibility with Hitec brushless servos

Support Servo controllers and servos
1

I am considering upgrading my robot to use Hitec’s brushless servos (such as the HSB-9360TH or others in the 9000 series). The servos use regenerative braking that puts a backflow current into the power system when the motors are slowing down in order to increase efficiency (like a Prius). Their web site warns that this may be incompatible with some electrical systems and I am wondering if anybody has verified whether or not they work with Maestro controllers. Has anybody tried this?

FYI, the following paragraph is from Hitec’s web page:

While compatible with most radio control devices, the regenerative braking feature of the HSB-9XXX series servos may cause a problem if the device cannot accept a backflow of current. The types of devices that cannot accept this backflow are: Voltage Regulators, Power Safe Receivers and certain BEC circuits whether stand alone or integrated within an Electronic Speed Control. Check with the manufacturer or the Hitec website for a list of compatible models. If your device cannot accept a current backflow, then you must install a PAD (Power Absorbing Device - Hitec PN# 55756) as described in this manual. A PAD is included with every Hitec brushless servo.

2

Hello.

I am not familiar with the regenerative braking on that servo, but the warning is almost certainly referring to the power lines and not the signal line. The Maestro’s servo power rail is not connected to anything else on the board by default, so the Maestro should not be affected by a black-flow of current on the servo power rail. If you choose to connect the servo power rail to the Maestro’s VIN pin in order to power everything from one power supply, that might also be OK because the Maestro’s regulator can handle voltages as high as 16 V.

You can find more information about the powering options for the Maestro by referring to the “Powering the Maestro” section of the Maestro user’s guide.

However, it sounds like a power absorbing device is included with all of the Hitec brushless servos (based on the paragraph you quoted), so you might consider using it as an extra precaution.

-Brandon