He forgot to tell you to disconnect the batteries before charging. You can charge each battery independently with a 12 volt charger but disaconnect them completely.
You will likely either find two 12volt batteries or four 6volt batteries. Typically the charging systems charge 12volts. I would suggest checking your owners manual to discern how it is wired before proceeding. Great question.
What cables need to be removed before charging from a 12 volt system? Do you advise removing the grounded cable (on the left in the video) before I begin charging? And how can I save the data in all the control modules? Details, details, of course. Just want to make sure I don't make things worse. Thanks for your help.
a 24v system uses 2 12v batteries wired in series together to achieve 24v. if you want to charge using a 12v you must only charge one battery at a time. they are wired basically: ground to negative on battery one, battery one positive to battery 2 negative, battery 2 positive to vehicle. to isolate one battery simply disconnect from the system. example: battery one would be disconnected from battery two. if in doubt, disconnect both wires of the battery being charged. ensure the wires don't touch anything they aren't supposed to. hope that helps.
I don’t understand your question. Are you saying that you have different wires on your batteries ? Ideally it is best to disconnect the batteries before charging, but the video shows how I charged my batteries while connected due to being in a hurry to get on the road. If you disconnect, make sure you reconnect the same as they were initially wired. Wiring or charging wrong can be dangerous.