Does the B80 actually charge the AC60

After connecting a B80 to a (nearly) empty AC60, does the B80 actually charge the AC60? That would be neat to protect the AC60 battery.

Or is the the capacity of the B80 just available through the AC60?

Just the capacity is available. There would be significant efficiency losses if the extra battery was used to charge another battery through the built in charging system of the AC60

Many thanks. When the B80 is connected to the AC60 do they discharge in an equal percentage? That is, if the AC60 is discharged to 60%, is the B80 also discharged to 60%?

The discharge rates don’t match each other exactly they will cycle back and forth somewhat through the discharge cycle but will even out when they get to 0%