Does Leaving Bluetooth On Drain Car Battery. This only pertains to leaving the fob in close proximity to the vehicle which is not something the OP has consistently done. G in the garage.
To figure out whether youre going to use the USB on your laptop or an Ethernet port youll need to know your vehicles. The access key may be locked inside the vehicle or the battery may discharge rapidly. Dont do it.
But Bluetooth was designed from the start to minimize battery usage and it has only gotten better over time.
The answer is maybe or more correctly probably. But to answer your headline question - a plugin USB charger by itself shouldnt drain your battery if its not actively charging anything. If your alternator has a bad diode it will cause your battery to drain. Not by any appreciable amount if its not actively connected to a handsfree device.
