To fix this, move the shunt away from the positive cable (not ideal). Or consider not using shunt at all but use smart batteries that generate their own sate of charge or use the VE.Bus battery monitor.
4.7 Parallel and/or 3 phase system DC wiring
In a system with more than one inverter/charger who are connected in a parallel and/or in 3-phase configuration it is essential that each unit has the same DC path from battery bank to each unit, or from the busbar to each unit. The reason why this is important is, that if there was a difference in cable thickness and length, the resistance between each unit will differ. The internal resistance of an inverter/charger is very low, so a difference in resistance will cause the DC path for one unit, to be much higher or lower than the path of the other unit. Different resistance means different voltages and currents for each unit in the system. Inverter/charger overload is directly related to current. The result will be that, the unit that has more current running through it than the other units, will go into overload before the other units do. The total inverter power of the system will be reduced. As soon as one unit goes into overload, the whole system stops working. The unit with the bad wiring will determine the performance of the whole system. To achieve a balanced system, you will need to use the same cable type, cross section and cable length to each unit from the battery bank or from the busbars. We highly recommend for you to consider using bus-bars or power-posts before and after the inverter/chargers. A parallel and/or in 3-phase system needs to connect to a single battery bank. It is not allowed to connect the individual units of a 3 phase and/or parallel system to individual batteries.
To check if a system is correctly wired or to trouble shoot wiring follow these steps: • Load the system to maximum load. • Current clamp the DC wires to each unit. • Compare the current readings, each unit should have similar DC currents. Alternatively, you can measure the voltage on the busbar or battery bank and compare this with the voltages you measure at each unit’s battery terminals. These voltages should all be the same.
Powered by FlippingBook