LiFePO4 House Battery Monitor

Monitor use and charge state of a RV or boat house battery

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Available battery monitors are designed for lead-acid or electric vehicle use, are overpriced, and don't include all the features I want. This one will be optimized for my 260 Ah LiFePO4 battery bank charged by solar that I use for almost all my electric power needs. It will do long-term logging and display output on a web page.

Current into or out of the LiFePO4 battery will be monitored by an INA219. This will be connected to a Raspberry Pi Zero via I2C for logging and display. Additional sensors may be added for temperature and individual cell voltages. It may also monitor the starting battery. Control outputs will be used to turn off the Converter/Charger and control the "solenoid" connecting the two batteries.

  • 1 × INA219B Power Management ICs / Power Supply Support
  • 1 × Raspberry Pi Zero
  • 1 × Sense Resistor 300A 75mV used as 160A 40mV. See discussion.
  • 1 × USB ethernet adaptor.
  • 1 × Switching power supply 11-15V input, 5v output.

  • Hardware Prototype started

    Blars Blarson01/15/2017 at 21:50 0 comments

    After long delays, I got a Raspberry Pi Zero and have wired up some hardware for testing. A pl2303 usb-serial converter gives me a console, and a usb-ethernet adapter is hooked up through a otg cable. A clone of the adafruit ina219 breakout is monitoring the "12v" input to the dc-dc converter powering the pi. An example python program is giving reasonable results, so I'll need to figure out why my perl code isn't.

    Current plans are to switch to an Orange Pi Zero with built in Ethernet and Wifi, multiple USB, and multiple serial ports. Unless I do my own PCB, I'll use one of the ina219 breakouts with the R100 resistor removed.

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Greg Sadowy wrote 10/29/2016 at 17:26 point

I am interested in following your progress. I am working on a similar project:

  Are you sure? yes | no

Blars Blarson wrote 02/22/2016 at 19:40 point

On Ebay, sense resistors are usually rated by maximum current and voltage rather than resistance and power.  By ohms law, a 300A 75mV one could be used to sense 160A at 40mV.  Ones at Digi-Key are listed by resistance and power, are more acturate, and are much more expensive.

  Are you sure? yes | no

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