Iirc alt is told what to do via a pwm signal.
In your case I would be checking the earth strap as it is a common fail point, have a google, it is underneath the engine.
@gstuart might have some pics.
More likely to be camshaft bearing shifted causing massive loss of oil pressure, and as you drove it for a few miles with little to no oil pressure I would say investigation might just be a waste of your money.
So long as roughly the same then no worries, unless they are all amazingly low!
I would say maybe get injectors reconned and leave it at that on the engine health front.