RI battery charger fails when left over night.

[dlech]

Describe the bug
What is the problem?

I left a Robot Inventor hub running over night with the USB plugged in to test some code changes. In the morning, the battery charger light was yellow, indicating that there is a problem with the charger. The battery voltage is currently 7.2V, so either the battery did not charge all the way or it did charge and has been discharging for a while.

This is at least the second time this has happened.

To reproduce
Steps to reproduce the behavior:

1. Start an infinite program running (no motors) on the Robot inventor hub.
2. Go to bed.
3. Wake up.
4. Check the hub.

Expected behavior
What did you expect to happen instead?

Battery charger should charge the battery all the way an not fail.

[dlech]

Revisiting the data sheet, we can see that this means we have likely triggered the safety timer (yellow light is triggered by oscillating CHGOK signal).

So I guess the question is if this is working "as designed" or if we should stop charging when the battery is full to avoid triggering the fault.

[dlech]

I left this running a bit longer to confirm it was indeed discharging (now at 7.1V). Then unplugged and plugged the USB back in to clear the fault and start charging again.

[dlech]

Closing as duplicate of #647.