1. Thanks, I was wondering about that.1. If you use the temperature sensor that comes with the Multiplus on the Cerbo GX you can use the Cerbo GX to control a fan. That allows you to skip adding a separate thermostat.
2. Assuming the worst case scenario that you pull a full 150 amps out of the BMS @ 12 volts (that voltage is bit low, but we tend to use that as it's worst case) and have a round trip distance of 8' (4' one way x 2) then 4 awg is the smallest wire you should run. It gives you just under a 3% voltage drop. But like Chris said above, bigger is better. I'm using 2/0 for a 120 amp BMS.
3. The Multiplus 12/3000 has two posts for each DC leg. That means you can run two 2/0 positive cables and two 2/0 negative cables. That gives you a very safe set of cables.
4. The 300 amp bus bar between the BMS and the shunt isn't necessary or is simply in the wrong position. The bus bar should be located downstream of the shunt. You can easily double up 2/0 lugs on the shunt. That's how I did my initial install. In the picture below, I put copper flat bar on the input side of the shunt to give my cables a better mounting surface.
View attachment 101700
5. Similarly, your positive bus bar should be downstream of the switch and fuse. Battery->BMS->Fuse->Switch->Bus Bar.
6. All connections are then made on the common bus bars. Inverter, solar charge controller, Trailer DC distribution panel, Cerbo GX, etc.
7. Your solar charge controller and the Multiplus will both have separate ground (not negative) connections. I put in a separate ground bus bar that those tie into and then there is a cable that goes from the ground bus bar to the chassis/frame.
8. You also need to decide what you're going to do with the 12 volt charge coming in from the 7-pin cable.
2. Sounds like I will just go 2/0 on everything from the batteries. The one question I have is that between the negative terminal and the BMS. It looks like you used 3x4awg?? Current connected sells the 2x6AWG kit for the BMS I found a formula on another post and it looks like that would support the 198A value I got for 2400W (divided by 2 for 2p) at 10V (low voltage disconnect). 2x4AWG should give me ~250A which should be more than sufficient for that portion?
I've established that I want to carry the load in my system with 2/0 awg wire. It's 24 volt 280ah and I want to be able to use a 3000 watt inverter. The JBD BMS I got already has 4 awg wires and lugs attached for two negative leads. I'm wondering if I should replace these with 2/0 awg as well...
3. Sounds good. So I will run 2 x 2/0 from bus bars to the inverter just to be safe.
4. Good idea. looks simple enough.
5. Thanks, will change that.
6. Makes sense
7. I have a separate ground bus bar in the trailer already. I will likely need to evaluate the size of that (and cabling size). Assuming this is similar to what I need for the bus bars on the DC side of the circuit. Will plan for 2/0 cabling and 300A bus bar. What did you do?
8. Planning on using the victron DC-DC converter 12/12-18 I think. I don't think the 7pin wiring in my truck can handle much more than that. What did you use?