Three Sterling Power battery-to-battery chargers: BB123670 taking 12V and giving 36V, 70A in and 23A out; BB124870 taking 12V and giving 48V, 70A in and 17A out; and BB1248120 taking 12V or 24V and giving 48V, 120A in and 30A out.
Size the install on the input figure. These units are rated by what they draw as much as by what they deliver: 70A or 120A has to come down the cable from the starter battery, so fuse, cable cross-section and alternator capacity are set by the input side, while the output current is what reaches the 36V or 48V bank.
The BB1248120 is the flexible one, since it accepts either 12V or 24V on the input.
