Quadcopter build - KK2.0 voltage alarm setup

by eluminerRC | May 1, 2013 | (8) Posted in Projects

This is 7th video in this quadcopter build series and it's about battery voltage alarm setup on KK2.0 flight control board. This is optional step, but it's highly recommended.

We all know the importance of proper handling a LiPo battery. One important thing is not to discharge a LiPo battery under around 3.3V per cell. In air RC we don't like LiPo cut-off feature because, while it saves the battery from excessive discharge, means crashing your craft (and the battery). So, we like alarms. Something that will warn us when to land, but it won't force us to do so.
KK2.0 board has a voltage alarm feature although it's not all that obvious. This video will show you how to properly setup this feature.

In order to alarm you when your battery is about to die, board needs to know what is the battery voltage at all times. By default, this is not possible since only power source connected to the board is constant 5V BEC. So, you need to connect positive and negative wire from the battery directly to the board. In this video you'll see how to do this neatly and safely and where to find those connection points on the board.

Biggest advantage of using KK's voltage alarm instead of separate/external voltage alarm is reducing weight and saving space. Also, besides the fact that the board will alarm you when your battery reaches set voltage, it will also beep faster as the voltage drops lower.


1. While you're doing this, you might as well solder one more female JST connector so you'll have easy access to battery voltage (3S/4S) if you'll need one in the future. I know I will so I've soldered one more JST connector to other terminal on PCB board.
2. As I said in many previous videos, on JST connector 2 means positive (+), and 1 means negative (-). So make sure you do this correctly.


1. Despite the fact that this is highly recommended and simple modification, you have to be aware that you are handling very sensitive electronics and that excessive heat will damage components on the board or/and the board itself. So, try to solder this as quickly and carefully as possible to ensure you won't damage anything.
2. Using black wire for both positive and negative is NOT recommended. You could confuse them later and create some damage. Use red wire for positive instead! Only reason why I'm using black wire for both is look. This quadcopter will be black and white and red wires are not an option for me. As long as you understand the risks involved, you can do the same.

You need:

KK2.0 flight control board

JST male connectors

JST female connectors

Servo wire (26 AWG)

Crimping tool

Soldering Paste

Soldering Iron (30W)

Solder (60/40)

Third/helping hand tool

Precision Knife

Wire cutters


Enjoy RC as much as I do! :)


apache64 on May 2, 2013
Another beautifully shot video, although I have seen this done elsewhere it is still compelling to watch. I am still amazed you can recognise which wire is positive, when both polarities are dyed black :-)... Keep them coming, I can't wait till you get to the good stuff, I.e. KK2 tuning etc..
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eluminerRC on May 2, 2013
Thanks. As I said numerous times, I don't recommend dyeing wires black. However, it's actually not that big of a problem because once you solder the wires correctly and put the pins in the connector the right way you can't plug it wrong later because it goes only one way. So, basically you have to be careful only when you doing/building this, not when you using it later.
Yeah, I can't wait for the good stuff either, but I must do everything right and I want to have my own videos for things like voltage alarm setup, battery connector soldering and similar stuff. I know that people have done it, but I always liked the YouTube channels where I could find everything in one place so I try to do that as well.
This part of the build is just something that it has to be done and it's not very interesting. Cool stuff will come after the build. ;)
Stay tuned I thank you for your support!

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thinc2 on May 2, 2013
Thank you for this series of videos - very useful and greatly appreciated!
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Sirglider on July 23, 2013
Thank you for your whole video serie. I built a tricopter, but some of your videos were usefull and very well presented. Concerning the low voltage alarm. I tried it, but when my copter flies, I almost cannot hear the low voltage beep. So I went back to Mr Windestal solution. Plug a low voltage alarm (http://www.hobbyking.com/hobbyking/store/__18987__On_Board_Lipoly_Low_Voltage_Alarm_2s_4s_.html?strSearch=low%20voltage) directly on the balance plug of the battery. You cannot not hear that alarm then!
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Quadcopter build - KK2.0 voltage alarm setup