Re: 2005 Diesel F250 Battery Light
Perhaps the new alternator is rated at a less amp/hr rating than the old one, which can cause the charge light to come on. Glow plugs use some power to operate. Be sure that the fan setting is either OFF, or NOT in a defrost position, as it'll run the air conditioning compressor and create added load on the engine when starting.
I'd phone the shop to see what amp rating the alternator they installed was rated for, and compare it with the stock alternator (check owners manual).
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!