That directional MCB is no good as it is wired. It will only protect for internal faults and will burn out if you trip it whilst the battery is on load or for an external fault. To make it bi-directional, you need to wire one of the legs ( + or - ) the wrong way through the MCB. That way at least 1 of the poles will break the arc.
I enjoy following your build process and progress, so thank you for sharing. After building a smaller version for my RV, I too do not understand your rationale for the placement of the MCB, or intended function? The T-class fuse ahead of your battery disconnect is your main protection and cutoff. The BMS also serves to hopefully not let things get too out of hand. The DC MCB is something normally used as a disconnect for the solar PV input, and seems unnecessary as configured.Thank you for the info! I am going to have external protection on the inverters as well, so I may rethink it and come up with a different solution. I'm still betting the BMS will shut down long before I trip the breaker.
I don't disagree with you. But in my configuration, the Class T is ONLY there for a direct short really. A real major "oops" moment - and the Class T has the AIC rating to take care of it. They are far too expensive to be there for the primary overcurrent protection. Thus, they are sized large (400A). I don't want them to blow ever, but if they do, I'll be very happy I spent the money on them.I enjoy following your build process and progress, so thank you for sharing. After building a smaller version for my RV, I too do not understand your rationale for the placement of the MCB, or intended function? The T-class fuse ahead of your battery disconnect is your main protection and cutoff. The BMS also serves to hopefully not let things get too out of hand. The DC MCB is something normally used as a disconnect for the solar PV input, and seems unnecessary as configured.
Nothing wrong with that, having multiple points of protection. It certainly doesn't hurt anything. CheersI don't disagree with you. But in my configuration, the Class T is ONLY there for a direct short really. A real major "oops" moment - and the Class T has the AIC rating to take care of it. They are far too expensive to be there for the primary overcurrent protection. Thus, they are sized large (400A). I don't want them to blow ever, but if they do, I'll be very happy I spent the money on them.
I'm personally very hyper aware of the incredible amount of energy that is contained in one of these boxes, and I'm overcompensating by putting in more protection than needed. Class T, Circuit Breakers, Cut off switch, Anderson Connectors. If something screws up, I have lots of protection. Single points of failure and single points of protection are not in my nature.
is the dual MCB necessary on both the (-) and (+) ? just curious, my general take is to minimize the number of junctions/connections. Also, does the BMS have temperature sensing ? thank you for sharing your build
Not really. There should never be any heat build up there under normal conditions. The dual breaker allows another way to remove both poles of the battery from the system (Anderson connector being the other). I had a 2 pole breaker on the v1 battery, but was told I would need to run one of the poles the opposite way through it to make it work correctly. Solution was to use 2 1-pole breakers together.post #30 concepts are well taken, but unless the usage of double pole on the DC is to increase the breaker combined trip point, there are an extra 2x mating contacts increasing total resistance. It's really a very minor point. Is there a temperature concern with the modules packed next to each other ?
Do you remember which size wire lug was needed to fit both of the BMS wires into?
Do you remember which size wire lug was needed to fit both of the BMS wires into?
CorrectThat’s for the jk?