If there's enough juice to power a fuel pump, ignition coil, etc there should definitely be enough to excite the alternator. Old alternators' excitation termina

If there's enough juice to power a fuel pump, ignition coil, etc there should definitely be enough to excite the alternator. Old alternators' excitation terminal used to be powered through the "battery charge" indicator lamp so very little current would get through (and indeed the wire gauge was very thin).