I have a boat where I am installing Victron Smart Lithium batteries ( 2 x 200 Ah). I have a Smart BMS CL 12/100 to manage the charge sources ( MPPT 100-50 + and Phoenix IP43) plus loads ( Smart battery protect 12-220)
In all diagrams, input of the BMS is connected to the alternator and the starter battery. However, in my case, the output of the alternator is connected to a MOSFET battery splitter ( Cristec that came with the boat) , which feeds the service battery, the starter battery and the bow thruster battery from three separate outputs.
Since BMS CL 12-100 takes its power from the input port where the alternator output is connected, due to the battery splitter, it is not connected to the starter battery, therefore if the alternator is nor running, BMS will not get its power and it will not enable the chargers and the loads.
My solution is to have a cable from lithium batteries connected to the alternator input of the BMS with a diode. This configuration did work in my test setup. But I need to get a confirmation that it will not cause any issue before wiring the boat.
I understand that the reason to have the starter battery and the alternator output to be connected to the BMS is to ensure not to have any transient voltage spikes when the BMS shuts down the alternator, bur since the alternator is connected to other two batteries ( starter and bow thruster) this should not cause an issue. And since the diode will ensure that BMS input is always at least 0.6V higher than its output, this should also not cause an issue.
Am I correct, or should I disconnect the starter battery from the splitter and connect it to the input of the BMS ? I really don’t want to do this to be able to have a separate charger for the starter battery which is Lead-Acid.
