Discussions

Hello people!

I'm having problems with my Attopilot 180A voltage and current sensor.

I know people had similar problems but can't find any solution.

Here is my story:

I have 1.000 mm octocopter (6S 16.000 mAh), around 50 A at hover, Pixhawk.

I've installed Attopilot 180A voltage and current sensor in order to have voltage, current, but most importantly for me, mAh reading to be as safe as possible when flying. I also have Futaba 14SG with telemetry so I'm also tracking my battery status (voltage) on the transmitter.

The problem is that Attopilot doesn't seem to have linear voltage (nor current) output under load. I've ruled out everything else because I did the following:

1. I've calibrated the voltage reading with handheld voltmeter and fully charged 6S. The voltage info on the OSD/MP is absolutely correct without load.

2. When I start to draw about 10-20 A, voltage on the OSD/MP drops too much, 0.4-0.5 V under actual value (measured with inline watt meter and handheld voltmeter)

3. Interestingly enough, when I connect 4S pack, without any load the reading is perfect. So, conclusion is that when current starts to flow shit start to happen.

4. Now, to rule out the Pixhawk, I've measured the output on the Attopilot alone and compare that to the voltmeter. Here is what I get: 24,87 V (no load) -> 1,579 V; 24,67 V (around 7A) -> 1,559 V; 24,49 V (around 10 A) -> 1,546 V; 24,41 V (around 20 A) -> 1,537 V

If you start doing the math you will see that Attopilots voltage drops too much when under load. So, if I calibrate the voltage reading with no load, then the reading will be inaccurate when under load. If I calibrate it under 10 A load, then it will be inaccurate without the load and under different load (50 A).

Since these Attopilot board are very simple devices I don't know why is this happening. Should I try to buy another Attopilot 180A board (or any alternative if something like that exists) or I can fix this somehow

Thanks a lot!!