Proper way to set parameter for power module of pixhawk cube orange?

Cube Autopilot
1

Hello. now I’m suffering from power module parameter setup of my quad(pixhawk orange).

[A]EXPLANATION OF MY CIRCUMSTANCES :
my copter uses this power setup :

my setup
my setup782×248 30.8 KB

I’m using 2 * LIPO 6S battery. it is parallel connected to my TBS discovery frame’s power solder points. before I upload the similar question and someone suspected my copter didn’t wired up correctly, but I wired up correctly.

my copter need to done CompassMot calibration. to do CompassMot calibration, I need to setup current sensor correctly. it is necessary thing to me now.

but now in my log I found current oscilliation like below photo :

current oscilliation
current oscilliation1891×975 194 KB

this copter battery is total 5.2Ah.(2.6Ah * 2) it fly about 20 minutes. so total current would be about (under)15A. so current should be 5~6A each power module.
the current is stable when the BATT_AMP_PERVLT is 39.877(recommended value for this module), but with BATT_AMP_PERVLT 39.877, “current total” is invalid.(total current is very smaller than actual)
so I adjusted BATT_AMP_PERVLT to about 120 and now current total value is correct, but there are current oscilliastion.(see red graph line.)

“battery 0” is CubePilot Power Brick Mini came with original pixhawk, and red line graph.
“battery 1” is power module from aliexpress. green line graph. output total current well.
CubePilot Power Brick Mini have problem now.(default value 39.877 doesn’t print correct total current value.)

if I set BATT_PER_AMPVLT from 39.877 to 120 value, although current oscilliates, current total value become good like below picture.

total current
total current1917×1012 148 KB

It is my parameter file :
20230208 parameters before autotune.zip (5.3 KB)

[B]QUESTION :
[1]I don’t know whether if I should select “cube HV power module” in mission planner “battery monitor” screen.
I selected “cube HV power module” and BATT_PER_AMPVLT automatically set(39.877). and the log result total current was bad. so I changed to “other” module and adjusted BATT_PER_AMPVLT as formula.( NEW_AMPS_PER_VOLT = OLD_AMPS_PER_VOLT * CHARGED_MAH / LOGGED_MAH)

[2]in this link(https://docs.cubepilot.org/user-guides/autopilot/the-cube-user-manual#the-cube-power-module-voltage-calibration) they are saying battery 2 monitor should set to “Monitor Analog Voltage Only”.

so, only battery 0 in the log indicates the total current?
is battery 0 current the total current?
I thought if sum of two battery consumption is 4Ah, total current of battery monitor 1,2 should be 2Ah each.(2+2 = 4)
but regarding that document, if sum of two battery consumption is 4Ah, total current of battery monitor 1,2, should be 4Ah?

if I can’t find solution with this article, I’m planning to change my power module.

2

measured_current
measured_current1491×698 141 KB

If I set pixhawk power brick mini BATT_PER_AMPVLT as 39.877, the measured current grape shape is nearly same with two different power module(power brick mini / aliexpress module). but pixhawk power brick mini’s value is too much small.(red graph.) so I think it is the problem of parameter value(about the scailing), not the sensor itself.

as I said above, this copter battery is total 5.2Ah.(2.6Ah * 2) it fly about 20 minutes. so total current would be about (under)15A. so current should be 5~6A each power module.
but with default value 39.877, I see the cureent is 0~3A which is totally incorrect.

anybody experienced this? I want to know the reason why this phenomenon happens.

3

I think what people most often do is have the two batteries connected through one power module, meaning BATT parameters will be providing total voltage and current.
Then BATT2 is the backup power supply for the Cube and probably only reads voltage since it’s not passing any current - It is just a BEC essentially.

The way you have it wired is good but obviously the two different power modules require different BATT_AMP_PERVLT as you have found, and probably BATT_VOLT_MULT too.
So definitely put in the correct AMP_PERVLT values for each of the power modules (and their correct VOLT_MULT) based on the procedure below, and actual voltage measurement for VOLT_MULT.
Ideally you would probably want two identical high quality power modules.
Or you could just get a Mauch voltage/current sensor and BEC and run both batteries through that.

To get the two current values summed and voltages averaged
Set this
BATT_MONITOR,10 → Sum Of Selected Monitors
then reboot the FC and reconnect to MissionPlanner, then you can set this
BATT_SUM_MASK,3 → bitmask, Current will be summed and voltages averaged

Definitely set
BATT_FS_CRT_ACT,1
BATT_FS_LOW_ACT,2 or 3
It’s highly advisable to have both of these set and for different actions. There was a related bug, since fixed, but better to be safe than sorry.

Here’s how to adjust your Amps Per Volt

  • Plug in a fresh battery and do a hover flight for 5 minutes or until you’ve used a significant amount of battery capacity
  • Immediately unplug the battery and charge it, note how many mah’s it took to charge. Let’s say that was 1,500 mah
  • Download your log and look at maximum CurrTot. Let’s say it was 1,300 mah
  • Get your existing BATT_AMP_PERVOLT setting from Mission Planner
  • NEW_AMPS_PER_VOLT = OLD_AMPS_PER_VOLT x CHARGED_MAH / LOGGED_MAH
    With my example numbers, you’d get
    NEW_AMPS_PER_VOLT = 17 x 1,500 / 1,300 = 19.61
  • Set the new value in the BATT_AMP_PERVOLT parameter and save to your copter
  • Fly to check, repeat until you’re happy the new value gives consistent readings
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