I'm currently trying to figure out the best way to make use of my gas gauge LTC2943-1 in conjunction with my pack of NiMH batteries. I am aware that voltage alone is not a sufficient measure of the SoC of a battery, so I am trying to make use of the gauge's coulomb counting ability. Unfortunately I am not clear on a couple of things.

1) When should the fuel gauge be set? From my understanding, it should be set after a full charge has completed. Does this need to be reset every time a full charge has occurred though? Because batteries are dynamic, and don't necessarily accept the same amount of charge all the time, and because batteries tend to lose capacity over time, is resetting the gauge after each full charge the best way to get an accurate read of SoC?

2) What is the best way to calculate/figure out the "low end" of my gauge? Currently I've just been waiting for my device to reach a state where it can just power on, and then capturing the coulomb count at that point. The value attained for one unit, may not necessarily be applicable though to other units as their full charge counts could be different. As such, what is the best method for determining this value?


1 Answer 1


The best way to determine a new capacity is learned by cycling the battery. One needs a non-vol memory register to save these parameters.

Read about the demo board and consider using it as it has some nice software. http://www.linear.com/docs/44117 Although this software compares only a stored profile of the Panasonic LiPo cell.

  • \$\begingroup\$ Is this how it is done when devices are mass produced? Each battery is cycled? Or are the initial battery state of charge generally known? \$\endgroup\$
    – JimJammer
    Mar 7, 2018 at 20:12
  • \$\begingroup\$ Initially they would be known, but some older BIOS options had this feature to recalibrate the fuel guage for Laptops> I had this in an older Asus unit. \$\endgroup\$ Mar 7, 2018 at 20:42

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