48

Congrats on earning your wings! Because ammeters measure the flow of current (positive or negative) they can immediately show when the alternator is no longer providing power and the battery is discharging instead. In a voltmeter, like most modern automobiles have, you would have to wait to see the charge level on the battery drop, and by that point, several ...


22

Because it displays how much current, and thus how much power, your electrical system is consuming. This provides a quick reference for diagnosing problems. Negative values can indicate a malfunctioning alternator and large power draws can indicate a short circuit somewhere in the system.


19

The more unpleasant a failure of some system is, the more tools you get to prevent, diagnose and mitigate the failure. An ordinary passenger car can stop in a middle of nowhere because the alternator failed and the battery depleted. Quite unpleasant, but rarely fatal - and modern cars tend to be reliable enough anyway. An offroad rig with winches, extra ...


7

The reason ammeters were dropped in cars is they were (and are as used in airplanes) wired to the battery and only show the current flow into or out of the battery. The battery's nominal voltage is 12, but the system operating voltage is about 14, and the voltage regulator varies the alternator field to keep roughly 14 volts in the system so that the ...


3

Some history from the automotive side, and a bit of information from the electrical engineering side. To measure amps, you need to have the meter in series with the load. Earlier systems had the amp meter directly in line, so all the power of the vehicle ran through the ammeter. This could be dangerous if something went wrong, as you had 30+ amps running ...


1

... cars did away with them years ago ... I'm working in car electronics sector and I know that your assumption is wrong: Modern (combustion motor) cars use a so called "battery management device", a computer which measures the voltage and the current of the battery; in some cases it even measures multiple voltages inside the battery and multiple ...


1

Yes a voltmeter indicates state of charge with some provisos. It shows issues like insufficient charge and excessive load by implication. Simply put, an analogue meter needs offset and expanded scale to show much detail, and responds to charge anomalies more slowly. It needs to be accurate. An ammeter in the battery line indicates charging or discharging ...


1

Yes, you can safely plug in a 6A load. Possibly a circuit breaker will pop out after some time. That depends on the rating of the circuit breaker serving the outlet and if there are any other loads on that circuit breaker. But it is completely safe to try it.


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