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Telemetry & RMG Winches


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I finally pensioned off my 30 year old JR PCM10 and bought a new transmitter.  One of the major reasons for doing this was to have telemetry i.e. show information about the state of the receiver battery and the received signal strength.  Exactly what information you get depends on the receiver you use but usually battery voltage is the supply fed to the receiver. (It definitely is for a Fkysky IA6B)  Now if you use an RMG (or other winches where the battery is connected to the winch rather than the receiver), the voltage you will monitor is not the raw battery but rather the output from a voltage regulator (or BEC) and hence is of very little use, as it will stay constant until the battery is completely flat.

The 'proper' way round this is to use an additional sensor such as:


However you could do a little re-wiring to measure the battery voltage directly.  The reason that RMG winches (and some others) include a BEC is that the winch can operate from a supply up to about 9V (and has better performance if you do) but most servos are only spec'd to 6V (until recently at least).  Receivers on the other hand contain their own voltage regulators and 99.9% will be happy to run off 9V.  So you can connect the receiver to say a 2-cell LiPo without fear.  For servos it is the current that will kill them not the voltage, so they will be fine on a 2-cell LiPo - as long as you don't leave them stalled for any length of time!  So if you are happy to run your rudder servo at the higher voltage then you can get the actual battery voltage by re-wiring as shown in the second diagram below.  If you are concerned about your rudder servo then use the third one.

Note the diagrams show the logical wiring.  The best way to actually implement the second diagram is to wire an additional Futaba plug across the battery connector and plug this into the receiver battery connection.  Rather than cut a wire in the RMG plug, use a short extension and cut the red wire in that.

Telemetry Wiring.jpg

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