I’d like some input and or advice on wiring for installation of a 12/12/30 isolated charger going in truck camper. Do you see any problems with wiring this? Sorry for any confusion with the drawing, I’m a machinist not an electrician. Appreciate any and all feedback Thanks
The ONLY thing that should be connected to the battery side of the smart shunt is the battery negative. All other negative connections need to go to the system side of the shunt. Otherwise the current that flows in/out of those connections made directly to the battery will not be counted by the shunt. The way you have it drawn, only current from the converter or to your loads will change the shunt's state of charge value. The DC-DC charger's current won't increase the state of charge!
The point you bond the system negative to the chassis should also be on the system side of the shunt, so repeating my original statement: the only connection to the shunt's battery connection is the house battery bank negative.
Disconnects are typically placed in the positive connection from the battery but a cutoff in the negative lead AFTER the shunt would be acceptable. Placing the disconnect before the shunt will cause the shunt to power off with the disconnect. Doing so will loose the current SOC value requiring the batteries to reach the absorption voltage before the SOC is shown. Power consumption of the stunt is minimal.
Breakers and fuses are there mainly to protect wiring. So the breaker you show at the output of the DC-DC charger is not protecting the wiring to the battery positive connection. Should a short in this wire occur the full available battery current will flow in the wire up to the fault point. Place the breaker as close as practical to the battery. The reason the DC-DC charger does not need a breaker at it's output is because it's maximum current is limited internally so should a fault occur in the wire, only about 30 amps (in this case) will flow after the breaker near the battery trips.
Take all connections from the house batteries off the same positive and the same negative. And make the positive connections to one battery and the negative connections to the other. This way the currents in/out of each battery will be balanced. Taking positive and negative off the same battery will exhaust this battery first due to the voltage drop in the jumper wires to the other battery.
Make sure you use heavy gauge wire from the truck battery to the DC-DC charger input. Voltage drop in these wires can make it difficult to set the voltage-based startup/shutdown logic to function properly.
