I considered this safe to use, but you might decide otherwise. I have powered up the phone when connected to mains.
Motorola 8500X Vintage Retro Vintage Mobile Phone - NO CHARGER - Made In USA
Motorola 8500X Vintage Retro Vintage Mobile Phone
Motorola 8500X Vintage Retro Vintage Mobile Phone Brick untested spares/repairs
Motorola MR30 Vintage Retro Mobile Phone with Charger and Original Box
Motorola MR30 Vintage Retro Mobile Phone