In-flight monitoring of total battery voltage and individual cell voltage is important for accurately estimating flight time. Monitoring the cell voltages during flight and operating load conditions help to predict battery health and cell degradation. 
We designed a battery monitor board to interface with pixhawk to read the cell voltages of flight battery. We will be doing a 50 piece production run of the boards in the second week of march,2018. Anyone interested in the board, please PM me.
Currently available battery monitors drain over 20mA and will drain the battery if left connected and very few monitors currently support over 6 cells. 
The specs for our monitor are:
Max cell count: 10

Active current drain: <5mA
Total sleep current: < 20uA
Sleep current drain per cell: <1uA

Interface with autopilot: i2c , UART (will implement other protocols if there is interest)

Pics of first version monitor



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  • @David, 
    Please PM me your requirements.

  • Hi, I'm extremely interested. Are they any still available or when will you be doing another manufacturing run. Also, any news on the CAN integration?? 

  • @Edward, Sure, will update when there is CAN version.

  • Im in for sure when there is a can version. Anything but i2c. Start plotting large amounts of data and see what type of noise creeps in through i2c. Just a bad interface. Uart is much better if those are the only options but with something having batteries connected directly to it and the magnetic levels surrounding that. Thing about a quick implementation of something else. You could write a uavcan node via libcanard pretty quickly. Just use an stm f103 and there are quite a few examples. Not only less headache but will be in line with something a bit more forward headed. Then I’m totally in. 

  • @Edward, We have tested the board for several hours in flight on multirotors without any issue from i2c. But you are right that i2c isn't the ideal protocol for this. We have also not tested it with data lines longer than a 1 ft.

    The CAN version will be for later revisions.

  • Totally interested except a few unanswered things. What type of testing and support have you done in the firmware side, i2c really is not the way to go on this. Too many problems and with current and magnetic interference going around so that’s not a good idea. As for uart. That would work except going to have to get tricky if running a second gps so maybe offer a breakout cable for the uart to split to the extra pins or even better use the can port and putting something on there to run uavcan so it’s modern. If so I’m in for 5-10 sets. Price depending but I don’t suspect this should be much.
  • @Guy: not yet . But we will be working on stackable modules if there is interest
    @Hugues: it will communicate over i2c or uart . There will be a firmware update to read the cell's voltage
  • MR60

    Nice idea. How will the cell voltages be communicated to Ardupilot and/or displayed on mision planner ?

  • Any plans for higher cell count?? like 28s ??

  • There are other already available inline battery current monitors which connect to APM. We can look at this in a future version. 

    Its based on battery monitor chip. If there are enough contributors to the project, we would open source the project. 

    Yes, it has I2C. 

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