Powerbrick readings in Mission Planner help

Cube Autopilot
#1

Hi,
I have a Cube Orange Standard Set (ADS-B Carrier Board) with ArduRover 4.0.0 and Mission Planner 1.3.74
I’m having trouble configuring the Current readings from the two Cube Power Brick Minis I have connected to POWER1 and POWER2.
I have looked at the doco here The Cube User Manual V1.0 - CubePilot
and tried to follow that but only seem to get stable voltage results when I configure things slightly differently.
For the first battery
here is what works for me under SETUP > OPTIONAL HARDWARE > BATTERY MONITOR
Monitor = Analogue Voltage and Current
Sensor = 0:Other
HW Version = blank, no entry at all.
Then to calibrate I measure the battery voltage with my Multimeter and put that value into “1. Measured battery voltage”.
that results in pretty accurate voltage measurements in Mission Planner, I totally understand that a bit of error (say +/- 0.2v) is to be expected.
I did also look in the CONFIG > FULL PARAMETER TREE > BATT >
where BATT_CURR_PIN = 15 Cube Orange
and BATT_VOLT_PIN = 14 Cube Orange
can’t recall if I sett both of those myself.

For the second battery
here is what works for me under SETUP > OPTIONAL HARDWARE > BATTERY MONITOR 2
Monitor = Analogue Voltage and Current
Volt Pin = Pixhawk2_PM2/CubeOrange_PM2
Current Pin = CubeOrange_PM2
Then to calibrate I measure the battery voltage with my Multimeter and put that value into “1. Measured battery voltage”.
again thats giving me a pretty good voltage reading.

I did also look in the CONFIG > FULL PARAMETER TREE > BATT2 >
where BATT_CURR_PIN = 4 CubeOrange_PM2
and BATT_VOLT_PIN = 13 Pixhawk2_PM2/CubeOrange_PM2
can’t recall if I sett both of those myself.

The questions I have are around getting the current readings correctly from those two Power Bricks.
Battery 1 (12-13v SLA) has nothing other than the Power Brick connected, and that is in turn connected to Cube POWER1. So my understanding is the Cube will be selecting that as its internal power source and drawing up to 0.5A depending on the situation. With my multi meter I can see that current (bouncing around 0.2 - 0.4A) but in Mission Planner I see 0.0A??
Battery 2 (12.8v LiFePo) is connected to the 2nd Power Brick which is in turn connected to the Cube POWER2 and also via the bricks downstream XT60 connector to my ESC and motor.
When my motor is not running, Mission Planner is showing about 0.15A current for Batt2 which makes sense as the ESC has a BEC and so I guess a little current is in use. But when I throttle up my motor, which I know is drawing about 1A (I have another power monitor inline) the current for Batt2 in Mission Planner just stays at the 0.15A???
I’m pretty new to all of this so any suggestions welcome :slight_smile:
Thanks,
Paul

#2

Just re checked the doco
https://docs.cubepilot.org/user-guides/autopilot/the-cube-user-manual#battery-monitor-calibration
and noticed for BATT2_CURR_PIN should be 14, so I set that and rebooted. Now It’s showing 16A for BATT2 in Mission Planner. My independent current meter is telling me its actually close to zero in reality!
What am I doing wrong?
Thanks,
Paul

#3

Cube doesn’t draw power from both power sources at the same time. See
https://docs.cubepilot.org/user-guides/autopilot/the-cube-module-overview#multiple-power-sources

#4

Hi @Alvin ,
Yeah I’m aware of that, but that doesn’t really have anything to do with the questions I asked does it?
What I’m asking is what is the correct config for my Cube Orange running ArduPilot Rover to correctly read the current from two of your Power Brick Mini’s, when attached to POWER1 and POWER2?
Thanks,
Paul

#5

Have you setup these extra parameters for POWER2 battery sense?

https://docs.cubepilot.org/user-guides/autopilot/the-cube-user-manual#battery-monitor-2-calibration

#6

Hi @Alivin,

I’m not sure if you have read my posts, yes I have made those settings and as I reported above.

“Just re checked the doco
https://docs.cubepilot.org/user-guides/autopilot/the-cube-user-manual#battery-monitor-calibration
and noticed for BATT2_CURR_PIN should be 14, so I set that and rebooted. Now It’s showing 16A for BATT2 in Mission Planner. My independent current meter is telling me its actually close to zero in reality!”

Also, I noticed in

That the default BATT2_CURR_PIN is 4, not 14 as described in your doc?

When I set BATT2_CURR_PIN = 4 Mission Planner does show BATT2_Current as approx 0.3A, which is not exactly right, but a lot closer than 16A. But, when I run my motor from BATT2 and it draws about 1A (from independent meter) BATT2_current just stays at 0.3A???

Which information is correct, should BATT2_CURR_PIN = 4 or 14?

What are the specs of your Power Brick Mini, should it be able to accurately measure currents less than a few Amps or is it aimed at higher currents only?
Can you point me to the documentation or specifications for it please?

Thanks,
Paul

#7

Part of the problem is the conventional current sensors used in the normal power bricks dont have any resolution below about 3 amps or so. You would need to draw about 5 amps or more to calibrate remotely accurate readings better than the default amps per volt value.
After using a good amount of battery you can compare the logged current draw total with whatever your charger puts back into the battery, and adjust amps per volt.
If you’re always going to have low current draw then you’ll need to get a 50amp Mauch current sensor, or similar hall effect device.

#8

I think I have misunderstood part of you question.
What I was telling you is most likely the software troubleshooting but you may have met the hardware limitation.
However, the powerbrick mini we provided in standard package is not an ideal solution if you need very accurate current sensing. We usually recommend people using it on small vehicles only.
Although the guide tells you to set up Analog Voltage and Current, the ‘current’ part usually doesn’t work ideally. We recommend replacing the power brick mini with Mauch's product, if you need current sensing.