Mr. Spree,

I wish your dad a full speedy recovery.

Although the brushes are not worn down, the regulator may be faulty. Most regulators fail due to worn brushes but the electronic or soldered components can fail and cause the alt to not charge.

now that your car is home, top up the water level and charge the battery.

Re install the regulator (with battery disconnected) then get a voltmeter (multimeter), If you don't have one get a friend to come over with one and help you out.

Check battery voltage - should be 12 volts or more. Now start the engine, the battery voltage should now read 13 to 13.5 or 14 volts.

If the battery voltage stays the same as with the engine off (12v) that indicates the regulator is faulty and should be replaced. Given that all connections are clean and tight.

Please note that when my regulator went bad, I was able to gently tap it with a screwdriver handle and it would kick in and work so I could drive the car to get a replacement, of course this was specific to the problem with my regulator at that time but it is something to consider for anyone in that situation.

I suggest this test but replace the regulator with a new one.

About the battery test, call ahead to see if they can do it, I know Canadian Tire or Part Source have the right equipment and offer free diagnosis. The battery must be fully charged prior to being tested and they should have the proper tool to put the required electrical load on it for testing as well as looking for shorted cells.
Good luck with it,
Acky