Bad alternator but its new ?

Run your rippums to 1400, see if your voltage spikes.

But yes, entirely possible the brand new alternator is bad

Might be lucky and you just didnt tighten the pully bolt hard enough/not tension the alternator

 

Get a digital multimeter and check voltage between alternator positive and the alternator case. If its 14-ish, check the batteries. If batteries are not within about 0.5 volts of the 14-ish volts the alternator should be producing then you have a wiring issue somewhere in the charging circuit.

 

It should be 14.5

 

Does it have an external regulator?

 

It is entirely possible to have a 'brand new' alternator that is bad out of the box. It's not common, but does happen. It has happened to me twice (4 wheeler) that I can remember over the years. If there is some way to get the alternator tested, that would be my next step. I can't speak to what voltage levels should be coming out of the alternator in a semi. For an older 4 wheeler, anywhere between 13.8 volts to 14.2 volts is the usual, depending upon brand and model. These new cars have alot more computer control on all the systems and unsure how that effects things like alternator voltage.

 

Does it need to be field flashed?

 

Probably should be bic flicked in a field. That should take care of any computer related problems.