Alternators are suited to the electrical needs of the truck. Asking them for even another 1 KW is not practical. Charging a hybrid truck's lithium batter at 1

Alternators are suited to the electrical needs of the truck. Asking them for even another 1 KW is not practical. Charging a hybrid truck's lithium batter at 1 KW is nowhere near enough power to be useful. If you want to have the diesel engine charge the battery that means a total redesign if the truck, its engine, and its power train.