I have 2 leisure (house) batteries, 1 under each front seat of my van, connected in parallel. My positive comes off LB1 under the drivers seat and goes to my fuse box, which is earthed to a seat stud bolt. My -ve comes off LB2 -ve under the passenger seat, and goes to a seat stud bolt under that seat. When I place the shunt under the passenger seat, do I have to reroute the -ve from the fuse box so it also goes to the shunt? Thanks.......