Friday, October 12, 2012

Volkswagen (VW) Beetle Basics: Additional Gauges- Voltmeter and Ammeter

Additional Gauges- Voltmeter and Ammeter:

In addition to the Oil Temperature gauge and the Oil Pressure Gauge I mentioned in my previous posts (VW Beetle Basics: Additional Gauges- Oil Temperature GaugeVW Beetle Basics: Additional Gauge- Oil Pressure Gauge) here are two other additional and related gauges I added to my VW beetle:
VDO-190031 Ammeter, 60AMP

VDO-332041 Voltmeter, 8-16V

Voltmeters measure voltage, whereas ammeters measure current. Both are based on the galvanometer which is a device used to detect small currents. Galvanometers that are calibrated to measure currents of different amounts are called ammeters. When they are modified to measure voltages, they are called voltmeters.


These are the additional gauges in my 1973 VW Beetle
The upper two are the Oil Temperature and the Oil Pressure Gauges while the bottom one is the Voltmeter

A voltmeter gauge, unlike the ammeter, is very inexpensive. It allows at a glance an assessment of the bug’s electrical/charging system performance. The voltmeter shows you the condition and function of the entire electrical system which includes the charging system and that of the battery. It is also handy in monitoring the function of the other electrical accessories such as the lights, signals, wipers, etc.
A 14-14.5 volts from your charging system (generator/alternator) is ideal to get your battery to charge correctly. A voltmeter will give you this information. If the reading is in the 13.5 to 14.5 volts range it indicates that the battery is fully charged and that the generator/alternator output is matching system demands. If over 15 volts your generator/alternator is probably over charging and you are going to get smoke soon... If under 12.5 volts with the engine not running, battery may be weak; if the engine is running, it’s indicates that the generator system may be failing.
A volt meter is much easier to install. All that is required is to connect it to ground and to a "hot" line that is switched by the ignition key. No massive power is involved which may not cause a big problem if the circuit fails.


An Ammeter gauge measures the flow of current to the battery. It is a very good indication of the function of the charging system as well as the draw that various accessories put on the battery. If you want to know how far your house battery is down and how long it might take to charge, an ammeter would help. It gives you a better idea of your battery’s ability to hold a charge. It will also tell you if something is draining your battery when everything is off.

This gauge though must pass all of the current to the battery which means that the wiring to and from it must be heavy- 8 gauge or better. With the gauge in the dash of your Beetle, it means that you must run a length of this heavy wire all the way from the battery to the dash and back. With an ammeter gauge, be aware of the wiring requirements. The current path must be very solid making sure that the connections to the gauge are protected from shorts.

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