The cable needs to be long enough to connect the vehicle with the intended outlet from where it's parked (you cannot use extension cords. Portable Level 2 EV chargers have a wide range of readouts they can give you. Some offer rich LCD readout displays with charging data. Some only offer a green light to confirm it's. Portable Level 2 EV chargers are expensive. Many of the companies selling them are new and not particularly name-brand. Some chargers can come with one or multiple-year warranties to offer some peace of mind. Most portable EV chargers are designed to work with the J1772 outlet used by most manufacturers. Tesla owners need to use an adapter. Also, note that there's no universal standard. Odds are that if you're using a portable EV charger, it may be outside. Dust can still be a concern, even if you live outside an area with wet.