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Problem getting battery current and mAh reports via telemetry

Posted by Bob Anderson on May 24, 2011 at 8:36pm
I am running APM 2.12

I added a current sensor (details later).

When I run APM terminal and invoke test] current I get good numbers reported for battery voltage, current and mAh keeps climbing.

When I switch to telemetry and HK GS, battery voltage is reported correctly, but battery current is zero and mAh does not change.

Furthermore, when I look at HK's serial diagnostics which interpret the MAVlink packets, the only one that I can see that includes battery information looks like this:

WP#0,Dist=0,Battery=10.795,Mode=,Throttle=0.2

Note the missing Mode value. APM terminal reports battery mode is 4 (as it should be).

There is no current info or mAh info that I can find in the serial streams.

The current sensor that I added is NOT the standard one. It is a Pololu 0 to 30A sensor. I attached it to one the expansion ports on the IMU shield and made the followings changes in the code:

#define CURRENT_PIN_1 6 // in defines.h (AN6)

In APM_config.h I added:

#define CURR_AMP_PER_VOLT 7.52 // Pololu ACS715 is 0-30A 113mv per amp
#define CURR_AMPS_OFFSET 0.454 // Pololu ACS715 has nominal 500mv offset (measured 454mv)

While that installation is non-standard, I don't think that that is where the problem is because APM terminal is returning good readings.

I'm stuck and need to be pointed gently in the right direction.

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Replies

  • Ravi May 27, 2011 at 8:31pm
    i am having the same problem. the current shows in the CLI but does not comes to the serial data in HK GCS. i think it has to be defined to go to serial 3. I am using attopilot current and voltage sensor. the voltage  is showing on the HK GCS. but current is zero on HK GCS.
  • Developer
    Doug Weibel May 24, 2011 at 8:47pm
    HK-GCS is not compatible with current and mAh usage reporting from APM at this time.  Mavlink has no spot for current, which HK-GCS wants.  It does have a spot for % of battery capacity remaining, which HK-GCS does not use.  It is just a mismatch at present between what can be transmitted with the protocol and what HK-GCS uses.  We have requested that current be added in Mavlink somewhere, but that might be a while before it is implemented.  I do not know what Paul intends in this matter for HK-GCS.
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