My 2007 1/2 dually wouldn't start yesterday or today. Few minutes on charger yesterday and it fired right up and started many times throughout the whole day. This morning wouldn't start. Again, few minutes on charger it fired up, drove it for an hour, let it sit an hour then wouldn't start again. Shop replaced my two Gold 8-year batteries that were only 2 years old (both completely dead). Took alternator out and had it checked; all was fine.
Any ideas on what could be draining my batteries since the alternator checks out fine??? Any thoughts would be greatly appreciated.

 

A good shop and use its equipment to trace an electrical drain. You can also use an amp meter to check voltage drain