Input!!! Charging System quit at -24F.

Yesterday the temps were -36F. Today -24F. Today the charging system quite. I havn't looked at it yet other than to confirm the belt is still on. A slight squeel was heard while driving it.

My first concern is to tow it home and get it on a charger before the battery freezes. (I drove it several blocks to get me to work and a WARM, SAFE place, so an uncharged optima battery is in. Do optimas freeze?)

Does anyone have any experience with alternators in the cold? Regulators? I am kinda electrically challenged, so any input would be appreciated.

BTW, recently I tightened the belt, the alternator would squeel when lights, defroster, radio and charging were all taking place. I eliminated the squeel, I don't think I overtightened the belt, very dificult with the OBA and the homemade brackets and idlers.