russellvanlife avatar image
russellvanlife asked

Adding MultiPlus Compact Causes Circuit Voltage Drop

Description of failure:

I was adding the MultiPlus Compact into my DC system. Without the MultiPlus, my circuit looks great and the multi-meter reads 13.13v throughout the system.

When connecting the MultiPlus to the bus åbars and ground and throwing the master switch, the circuit experiences a voltage drop from 13.13v to ~3.0v. My battery monitor connected to the shunt dies. When I turn the master switch back off, the battery monitor remains down and the voltage to it remains at ~3.0v.

I tried to be incredibly careful with my wiring and configuration. I used 2/0 AWG cabling from MultiPlus posts to bus bars. The positive connection is fused with a 300A fuse. Ground uses a 4 AWG wire to the vehicle chassis. I have a single, 100Ah battery connected to the system for testing due to the manufacturer stating that all batteries needed to be charge-leveled before hooking them all together. I'll have three in series. I was hoping to use the MultiPlus to charge them all up to full capacity individually before hooking them all together.


  • What are the potential causes of the voltage drop?
  • Though the manual says 350Ah minimum recommended capacity connected to the system, can I still charge each battery individually, initially?



campervanvoltage drop
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1 Answer
derrick thomas avatar image
derrick thomas answered ·

You probably need a pre-charge resistor. The inverter is drawing more at startup than the single battery BMS is capable of providing.

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