On many Sparfun boards there is an integrated circuit Max17048 to monitor the charge status of the battery. Also on my logger board. There are also breakout boards from Adafruit for a few dollars or from other manufacturers.
This Ic is much more accurate than using resistors on AD converters and calculating your own curve. Would it be possible to have this IC as a component for Flowcode?
on the Sparfun board or as breakout board Info about
The MAX17048/MAX17049 ICs are tiny, micropower current fuel gauges for lithium-ion (Li+) batteries in handheld
and portable equipment. The MAX17048 operates with
a single lithium cell and the MAX17049 with two lithium
cells in series.
The ICs use the sophisticated Li+ battery-modeling algorithm ModelGauge™ to track the battery relative state-ofcharge (SOC) continuously over widely varying charge
and discharge conditions. The ModelGauge algorithm
eliminates current-sense resistor and battery-learn cycles
required in traditional fuel gauges. Temperature compensation is implemented using the system microcontroller.