Re: Ammeter vs. Voltmeter
Not to be argumentative - it's mostly a matter of preference - and shoe leather.
The purpose of either a voltmeter or ammeter is to monitor the electrical system's performance and give early warning of failure - as early a warning as possible.
IF - and that's a big word - IF the ammeter is properly wired like automotive systems have been since the 20's:
The ammeter is placed between the battery and everything else. The alternator or generator first feeds the entire electrical load (does not go through the ammeter,) then whatever's left over goes through the ammeter to the battery. So the ammeter only reads, and passes, the current going to the battery to recharge it - a (+) reading. The only time the entire load goes through the ammeter is if the battery is having to provide the energy to the load -- a (-) reading like the alternator quit.
Whenever you get a (-) reading you need to know it - that's the early warning that you'll be walking soon.
The ammeter movement is far greater than a voltmeter's is and is noticable much sooner.
If the alternator quits charging and you are watching a voltmeter the meter deflection between 13.6 and 13.4 is slight. By the time the battery has discharged enough for you to notice it, it's getting so low you are probably getting ready to start walking.
Notice most all automotive ammeters only show +/- 30 amps, if the entire load went through it, it would need to go higher.
And - yes, ammeter is not misspelled - it's either ammeter or amp meter - 2 words.
Alternator, generator, or nuclear reactor - recharging the the battery is still the same.