Hi TI folks,
We have a strange issue with a BQ40Z80 monitored battery. See below image:
This is in a UAV application with two identical batteries powering both the avionics and motor. The two batteries are in a redundant setup using an ideal diode oring (LTC4359).
The above graph comes from a flight log and shows the following: dark blue (closely matching the green line) is bat1 voltage, green is bat2 voltage. Red is bat1 remaining charge, light blue is bat2 remaining charge.
As you can see at about 1200sec, something happens on bat1 with a 0mAh reading of remaning charge and a drop of about 2.5V. Right after the event, the voltage goes back to normal and the remaning charge indications partially restores but with around 700mAh of offset compared to the second battery.
I have not plotted the current readings as not to clutter the graph, however they both remain nominal and similar on both batteries during the event.
The event duration is around 2sec, the log resolution is 0.1s. This phenomenon has happened multiple times, although I am not able to tell if it was always on the same battery or not.
Would you have any idea as to what could cause such readings? It does not appear that there has been a short of any kind (plus that should not instantly drop the remaning charge indication to 0). Could this originate from a program error on the gauge? A lose cell balancing cable?
Thanks!
