You mean like this
Just my opinion FWIW but I would
not attach the amp wiring to the Smiths voltmeter. All the accessory current flows through those wires on the ammeter from the battery source and the fuse assembly, check Blas's SPF wiring diagram for review. Those large ammeter wires need to the carefully and thoroughly soldered together and
very securely shrink tubing isolated from anything else and zip tied carefully in a secure safe place. The tiny terminal on the voltmeter is not sufficient purchase for such heaving wiring to be positioned and connected there. Attach a "key-on" 12v + source to the positive side of the voltmeter, such as the wire that goes to your lighter or similar, other side of the voltmeter to ground. That's how I did it, works fine
