An onboard switch when battery low

[Christopher Morris 2]

Hi, was wondering if there was a way to trip a switch/relay when my main battery falls below a certain voltage on an electric plain. I tried using one of the low voltage alarms, but unfortunately my hearing is not great on this type of tone. So, i was thinking about using some strobes connected to this same alarm & on some testing, seems to be ok. But is there another way using a DX8 or 6 to do this without going to the expense of onboard telemetry. 

[Dad_flyer]

On board telemetry is not necessarily expensive, that depends on the radio system. 

 

Otherwise, if you have been able to connect a strobe to the voltage checker the same method could drive a relay or electronic switch instead of the light.

 

[Kim Taylor]

As an example, using Spektrum, the AR620 has built in 'fly by' telemetry for rx voltage (assuming that your tx does telemetry). So you'd get a warning on your tx if the rx voltage was to go low. Cost about £35 I think (unless they've gone up recently).

Kim

[Frank Skilbeck]

The Low Voltage Cut off on your ESC should do this, you might want to check the settings on the ESC to see if you can increase the shutdown voltage, on some ESCs you can also set the shutdown mode to either reduce power or completely shutdown.

[David Ashby - Moderator]

If you're worried about the model falling from the sky and/or the Rx being starved of power then you could try one of these. It's a small 2S LiPo that kicks in to supply the Rx if normal Rx power is lost from an ESC/RX battery etc. You can buy an optional LED for it that provides a visual indication when the unit has been triggered. 

 

I've seen these fitted to high-end helis and have some in my more valuable models for peace of mind. 

[SIMON CRAGG]

I generally fit a 1100mah 2s Life pack (switched) to the RX, and only use the main Lipo for the motor.

[Robin Colbourne]

Christopher, the XH-M609 appears to do what you are asking. 
The desired cut-off voltage is programmed in using the buttons and LED display, then the relay cuts the power when the battery drops to this level.  Its pretty cheap at under £4, although size may be an issue at 55x40x15mm or 2.16"x1.57"x0.59''.  As far as I can see, the weight is between 1 & 2 ounces.

XH-M609 Lithium Battery Cut-off Switch on Ebay

 

 

Edited May 31, 2021 by Robin Colbourne
Grammar

[leccyflyer]

For a normal model, just fit an appropriate power supply - whether that is an ESC with BEC, a separate U-BEC or a conventional receiver pack, then just go and fly the model. Most models really do not need the added complexity or redundancy of a complete back-up power supply. 

[cymaz]

I have a Jomar Ultimate Battery Backer in my big Cap. It’s always tested as part of my set up / pre flight checks. Works without a hitch.