The car starts, and/or bright lights

A voltmeter would will work reasonably well at alerting the driver of a charging issue from the drivers seat.

 

Just test the output of the alternator at the alternator when you first install it. If the battery goes down later, then check the output of the alternator again. How many times has your battery run down because the alternator went south?

 

A voltmeter read potential, an ammeter reads charge and discharge. To tell the driver what the charging system is currently (no pun intended) doing, you need an ammeter. Yes, a voltmeter reads a chaging voltage, usually around 16 to 18 volts, and without any voltage being generated by an alternator, you would read 12 or less. So, to tell the systems operation, you need to add a voltmeter. This seems to be missing in the 'simple' change over. The meter's installation and hook-up I'll leave to your imagination.
Jim

 

There is a reason why ammeters are not used in modern cars. When a ammeter is in place all of the electricity that the car uses and / or produces must go through the meter. (exclusive of power drawn by the starter motor). In the old days, when cars had few electrical accesories, and 30 amps of charging capability, there was not a whole lot of juice going through these ammeters. With all of the electrical stuff on cars now days, it is neither practical or safe for this kind of energy to be passing through the little ammeter in the dash.

I do not know of any vehicle made in the last 20 or 30 years that does not use a volt meter in place of an ammeter. Frankly, I do not see the need for an ammeter anyway, as todays charging systems are really quite reliable. If a person is watching his or her guages, a defective charging system shows up right away on a voltmeter. Once that sucker gets close to 12 volts or below there is usually a charging issue.

EDIT<<< I guess what I am really saying is that IMO ammeters suck >>>

 

Yeah, all restomodders know to use volt meters.

 

Right, you gave someone part of the info about a one wire system, but left out a critical part, an indicator. Would you drive on the street with out gauges? I don't think so. My point is you should have stated that the generator idiot light is not going to work - at the least. Then given an alternative, a voltage indicator and how to hook it up. Placement isat the owners pleasure.
Jim