Saab 9-3: Battery Charge Warning Despite Healthy Alternator And Battery

My Saab recently started to throw a warning when first starting the car: To clear the warning, I had to turn the ignition off and on again - the warning didn't fire the second time. The warning itself is triggered by the battery's voltage dipping too low under the demand of the starter. Just occasionally this led to a failed start and I'd need to jump the car to be able to get it started.…