This explains and shows with pictures how the wiring / washer / lock washer order should be when connecting your battery
Can you ensure its set up like this:
Place the following on the bolt in order: Lock washer - > Washer -> Meter/charger wire -> Thickest wire (inverter wire) See examples below:
The washer and lock washer need to be ON TOP of the wire, not on the bottom of it.
