I'm fine tuning the control algorithms for NiMH batteries on a new charger we're about to put into production and have observed a strange behavior of the TI bq2060 fuel gauge (yes not the bq2060A) that's in the battery being charged.
For the low current used to top off charge in this battery, the charger controls per the Average current parameter from the bq2060. I log both the average current and immediate current parameters while this low (~50mA) charge current is running and observe an offset between the center of the immediate current noise band and the average current (see attached plot). I've seen a similar offset in higher current charge as well, but it doesn't matter as much in that mode.
We really need tight current control in this mode because if the current is too high, charging continues and the battery may over-heat. The 50mA was selected to just offset self-discharge in this battery.
Given this offset, I must decide whether the center of the immediate current noise band, or the computed average current better reflects the actual current into the cell array.
I don't see anything in the bq2060 to bq2060A changes about this, so I assume it's not a defect in the bq2060 that's been fixed.
Our customer requires use of the bq2060 instead of the "A" part because this is a medical product and they don't want to requalify the battery with the bq2060A.
Any info would be appreciated.
