I have a Multiplus II 48/10000/140, which provides two M8 positive and two M8 negative terminals for battery connection (terminals K and L, as shown above).
While the manual doesn’t explicitly state it, this design suggests that the full 140A current should ideally be split across two cables for both positive and negative sides.
My battery setup consists of two 16-cell LiFePO₄ batteries in parallel, each with its own BMS (cascaded). Each battery is currently connected directly to one of the Multiplus’s M8 terminals, effectively splitting the load between them.
I now want to install a Victron SmartShunt to accurately monitor the real State of Charge (SoC). However, the SmartShunt only has a single M8 terminal for the battery connection.
My question is: Can I safely combine the negative terminals of both batteries into a single cable connected to the SmartShunt and then to Multiplus, without compromising the efficiency, safety, or electrical performance of the Multiplus II?
You can, but will it fit through the hole in the body of the inverter and be the correct cross section?
You will be lug stacking in the battery side now?. You may as well do it to both.
Essentiallly all you are doing is cutting the negatives adding lugs and adding the shunt in.
{Am going to add in here, i am not a fan of the idea, i would add some little correctly amp rated bus bars, but also recognise sometimes…} In any case you will end up doing so if you plan on adding solar
That’s what I thought, and unfortunately, you’re right. But properly splitting the load across a busbar can be a real headache. Considering that the 140A will be divided between two circuits, even a 0.01Ω difference between the connections could introduce up to 700mV in a DC circuit carrying 70A.
I guess this will be my next challenge: how to assemble the bus bar properly.
