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Background: I'm building a quadrocopter. In such RC models, usually brushless engines are being used and these require ESCs (Electronic Speed Controllers) to work properly. Most ESCs are equipped with a BEC (Battery Eliminator Circuit), which converts (for instance) +14.8V from battery to +5V and allows powering up whatever is using the engine (Radio receiver or, in case of quadrocopter, the flight controller board).

I'll be using KK 2.1.5 FC board, which looks like the following:

Front Back

The board is powered from the BECs - there are no separate pins for power input.

My ESCs have linear BEC with output +5V, 3A.

Question: Is it safe to connect all ESCs to the FC? Or should I remove the +5V cable from all but one ESC?

FC's and Rx's power requirements oscilate around 0.1A.

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up vote 3 down vote accepted

Only connect one supply voltage.

Some LDOs are designed to be paralleled. But I don't think you should rely on this, as you can easily meet the power demand with only one regulator.

Connecting them in parallel could cause instabilities and/or non-equal power distribution due to thermal runaway and so on.

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ESC are basically a FET that accepts a PWM signal from the FC and regulates power from the BEC to the motor. Some ESC have the feature to provide 5V to power all other boards, such as the FC. It is generally a bad idea to short circuit the outputs of voltage regulators so, as you suggested, just connect only one of the 5V outputs of the ESC to the FC.

Hope this helps.

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