have just bought and fitted a split charge system only £14.
have'nt tried it yet, but am told it will only start to charge leisure batt once it detects van batt is running at optimum voltage aprox 13.4 volts, then this charger will open and allow voltage to flow to leisure batt.
Will let you know how it is, when fitted leisure batt which arrives 2mora, had to order a special one to fit in compartment in wall of van, Dispatch.
Goochie.