Voltmeter ?

[Shorty]

I will be installing oil pressure & water temp gauges this spring. I presently only have idiot lights on my 1985 Yanmar 3GMF. The questions is, while at it, should I install a voltmeter? I have a Link 10 @ the electrical panel below to monitor battery health. Will the voltmeter tell me anything while running that the idiot light would not? Do alternators sometimes fail slowly, dropping in voltage?

[Hud3]

The Link 10 will give you a voltage readout for the alternator output. My boat came with an analog voltmeter wired in at the DC panel, but it was redundant after I installed the Link 10.

[S/V Illusion]

It is redundant, however, it depends on whether or not you want some indicator at the helm which presumably the battery monitor is not. How often do you want to go below?

[Shorty]

Yes, Illusion has the question. Will I have better info at the helm? I normally check the link 10 in the AM after letting the batteries settle down overnight. Do alternators generally fail precipitously therefore triggering the alarm & idiot light? Or might I foresee a gradual failure through a decline in voltage while running?

[Hud3]

My helm-mounted B&G Wind instrument had the ability to display system voltage by pushing a button on the display head. It read a tenth or two below what the Link showed due to voltage drop on the wires, but would give a good indication of the progress in charging the house bank. Check to see if yours has that feature.

Alternators usually either work or not, although there are some situations where the output can be diminished, like when they overheat.

[Shorty]

So here's a new rub. I asked my parts guy what amperage fuse to use as the VDO wiring diagram shows a fuse in line on the hot lead. He sez I have never heard of fusing gauges not to say it couldn't be something new. So whadyathink, fuse them or not?

[CharlieJ]

Every conductor on a boat, with the exception of the engine starting circuit or circuits, should be protected with a fuse or circuit breaker. This includes instrumentation.

FWIW, this requirement is part of the ABYC Standards but it also makes very good sense, IMO.

Best regards,
Charlie