Deve,not sure how you have the system wired, but the battery is the real threat in case of short circuit. It is capable of much more than the 150 amps and is not controlled. Most would put a fusible link at the starter and connect wire from there to the ammeter or to the fuse panel, depending on whether an ammeter or volt meter is used. Use of volt meter does not eliminate the concern of a short to ground causing a fire.
