Q: battery saver mode came on again after replacing battery and alternator

As you probably know, the battery saver mode will come on when there is a problem in the charging system. If the charging system isn’t working, with a new battery you can drive the car for several hours and a couple of dozen re-starts before the voltage gets low enough to cause a problem. My guess is that even though you replaced the alternator, the charging system is still not working. You didn’t mention where you bought your alternator, but if it was not a dealer replacement and came from one of the big retail parts chains, it’s not too unlikely that it is defective. But there are a number of other reasons that the charging system might not be working, so before you go back to the store and fuss at your parts man, contact Your Mechanic to have a technician come out to your home or office to check out your charging system and let you know what it is going to take to fix it.