JimDrew

My Feedback: (16)

FenderBean, then perhaps you are not aware of what the problem actually is? The problem is not related to battery system, it is related to powering a string of servos from a single connection. Servos can pull a lot more current than most people realize. Servos also do not draw their highest current in a stalled condition. Servos typically draw anywhere from 2-5 times their stall current during a direction change, which is when the servo is moving one direction and told to move the other way. To get those super fast transient times, servos don't just stop the motor before reversing directions. Instead, they reverse the motor voltage against the moving gear train. The result is a massive current spike that greatly exceeds the stall current. For example - I have a 33% Hangar 9 Extra 260. It has 7 of the JR8711 servos on it - 2 on each wing, 1 on each elevator half, and 1 on the rudder. It's an electric powered plane, so it doesn't have any other servos (for throttle or choke). Sitting idle on the ground, the current draw is around 150mA. While flying I see anywhere from 1A to 8A doing normal pattern stuff. However, on a snap to snap maneuver, it pulls a little bit over 60A of peak current. It's not a long peak (a bit more than 25ms) and tapers off into the high single digits after another 1/4 of a second, but it certainly occurs. A servo connector is technically only good for 5A. With SBUS (or any other serial stream protocols) you are relying on a single wire (with a known 5A limitation) to power all of the servos on the bus. Because it's physically impossible to draw more current than a wire and connector will handle something has to give, and that is the voltage that is being carried on the wire, which results in a brown out. The level of brownout can be anything from significantly reduced holding force of the servo(s) to the rebooting of the receiver. By plugging each of your SBUS servos individually into a bus with huge power handling capabilities (like the X24 provides), you completely eliminate any potential brown out conditions.

The Emcotec system is a lower current version of what is built into the X24, so thanks for pointing that out - I had not seen their system. The X24 can handle 100A per battery input - which is really just a marketing hype thing. In reality, the servo pins will all burn off long before you reached the max capability of the system.