What is the proper method to charge 2, 12volt batteries in a hooked in a series? Do I need to charge each seperatly or can I charge them while hooked together? Thank you

Two 12volt batteries in series makes 24volt make sure you charge with 24volt charger across the outside terminals. Other wise disconnect and charge each separately on 12volt

Yes, things like electric wheel chairs, or scooters use two 12 vt in a series, or as noted they operate off 24 vts. And require a 24 vt charger.

The two batteries can be unplugged from each other and each charged on a 12 vt charger.

Thanks so much for the help!
Mike