Battery Capacity /Fuel Gauge

This topic has 4 replies, 2 voices, and was last updated 2023-11-27 at 12:22 PM by neilh20.

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- 2020-11-19 at 2:33 PM #14846
  neilh20
  Participant
  Just wondering if anybody has looked at algorithms for battery capacity.
  
  For logging reliability, when a LiIon battery is low in available energy, it would be nice to reserve the available energy for just the core logging functions (ie no high powered radio transmission).
  
  I mentioned some work I’m doing in this thread https://www.envirodiy.org/topic/monitoring-power-consumption/
  
  Another possible method of measuring available power is to use a Fuel Gauge Adafruit LC709203F LiPoly / LiIon Fuel Gauge and Battery Monitor https://www.adafruit.com/product/4712.
  
  That is LiIon battery to Adafruit-4712, then pwr cable to Mayfly, I2C cable to Mayfly. Then of course for safety could use some shrink wrap tubing round the Adafruit-4712.
  
  I’ve prototyped the driver on a Mayfly and pretty simple. It does measure the LiIon battery voltage accurately. It does allow a battery capacity to be plugged in (0.5AHr , 1AHr, 2AHr, 3AHr) and then gives a percentage Fuel Gauge. The fuel gauge is pretty squiggy, but possibly good enough to say stop wireless transmission below 60% capacity.
- 2020-11-25 at 3:26 PM #14862
  Matt Barney
  Participant
  Interesting -thanks Neil. I may try that fuel gauge as well.
  
  Matt
- 2020-11-25 at 7:37 PM #14863
  neilh20
  Participant
  Hi Matt – well been watching the output of the LC709203F with some other testing. It does work for the accurate battery voltage measurement.
  
  However the LC709203F “%” capacity could be challenging to use. There is a lot of technical discussion about battery fuel gauges and what works and doesn’t. Another device that I got was the Seeed LTC2941 which only measures coulombs/mAHrs .
  
  https://www.seeedstudio.com/Grove-Coulomb-Counter-3-3V-to-5V-LTC2941.html
  
  I’m figuring out it needs to be accurate battery voltage ~ for basic battery “gauge” status, and also measure mAhrs to be able to characterize activity (or field monitor) while awake. My test system with Xbee S6, periodically goes into some sort of lock up and consumes current, and the only way to recover is to unplug the battery. For the Xbee LTE carrier board it can be turned off if this happened.
  
  The LTC2942 does coulombs and battery voltage – except no cheap board with it that I’ve found.
  
  An fun link about “orchestrating power” from some work being done at CMU on dealing with power – https://youtu.be/eAhVdSCdv08
  
  Wishing you a good safe thanksgiving – great time of year for giving thanks 🙂
- 2021-03-10 at 8:37 PM #15235
  neilh20
  Participant
  Just a note, I’ve switched to an STC3100 “Battery monitor IC with Coulomb counter“. The LTC2942 became unavailable and turned out to be more expensive.
  
  I’ve got the basic driver here – the device driver reading the registers is here —https://github.com/neilh10/STC3100arduino
  
  A device manager that can provide power consumed in mAhrs is still wip.
  
  I’m using it with an enhanced RS485 power board that supplies power directly to the 4V to 12V booster – and it can supply a continuous 1.9W.
  
  https://github.com/neilh10/SensorModbusMaster/blob/release1/hardware/knh002-MayflyWingShield/rev6/knh002r6_rs485schematic.pdf
  
  This a new board, and if anybody wants one they should let me know this week so can be included in a manufacturing build.
- 2023-11-27 at 12:22 PM #18187
  neilh20
  Participant
  An update – I’ve found I2C bugs in some of the ST3100’s devices – that I couldn’t get a work around. It may be to do with the AVR I2C master. Some other engineers are using it with an STM32 / ARM system that they aren’t seeing the same problem https://github.com/neilh10/STC3100arduino/issues/1
  
  From using the STC3100 – https://monitormywatershed.org/sites/TUCA_PO03/ I’ve come to the conclusion better to have an IC that also includes a battery capacity algorithm.
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