Lights dimming at 750rpm idle is not "normal", just mentioning that because I often see people saying it is, lol.
No car maker would spec an alternator that didn't have enough output at idle to run factory equipment.
Just for future use a $15 volt/ohm meter can save you hundreds of dollars down the road.
A good battery will show above 12.4volts with engine off.
After startup recharging, good alternator will show 13.5volts(at battery) with engine at idle.
With engine at 2,500rpm(approx.) voltage should go up and then drop down to 13.5v again.
At idle with 13.5v showing as you turn on lights, fan, radio, ect.....voltage should drop and then come back up to 13.5v.
1.1volts above battery voltage is the maintenance voltage, this doesn't charge the battery or allow battery to be drained.
If your battery voltage is 12.6v then at idle you would see 13.7v, 1.1v above battery voltage.
Just after startup battery is drained, alternator will then run at 2volts above battery voltage to recharge battery, so 14.4 to 14.8volts would be normal.
This should only last for a few minutes, if it lasts longer battery will start to "cook", fluid inside evaporates, yes even on "sealed" batteries, and battery life will be cut short.