Other Parts Discussed in Thread: BQ27510-G3
Tool/software:
We're using a BQ27510-G3 as gas gauge for a battery powered Android device. We have a test that checks the charging current draw (while powered by DC supply) by querying the gas gauge with a 50% and 100% state of charge simulated battery connected. These two conditions are measured sequentially, first the 50% SoC charging current is measured, and then the 100% SoC charging current is measured. We expect the gauge gauge to report 0 mA current when 100% SoC simulated battery is connected.
On a handful of units, the gas gauge reports a very small discharge (about 5000 uA) when the 100% SoC condition is measured. After about 60 seconds, the gauge reports 0 uA, which we expect.
Our terminal charging voltage is 4.1V, and it was found that the battery simulator was incorrectly set to 4.127V for 100% SoC. Setting this to 4.1V seems to have fixed the problem.
I can re-create the reported small discharge by quickly switching from 50% SoC (about 3.7V open circuit), to 100% SoC (4.1V open circuit) and the querying the gas gauge. We're using the circuit design from the datasheet/technical documentation, and I do not see the expected -50uV across the 0.01 ohm sense resistor when the gauge reports -5000 uA. When the gauge settles to 0 uA, there is no obvious change in voltage across the sense resistor.
We're using "/sys/class/power_supply/bq27510g3-0/current_now" to query the gas gauge.
Can anyone explain what might bet happening?
