Quote:
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Originally Posted by derb
LB,
I thought 14.something was close enough 
With a bad alternator wouldn't the engine quit if you pulled of the + battery terminal off? A double check? |
It's NEVER a good idea to pull a terminal off the battery of a running car. The alternator uses the battery to 'absorb' natural voltage spikes which occur.
To disconnect the battery with the car running can introduce a large voltage spike in the electrical system that may damage electronic modules and/or the charging system, including the alternator itself. These spikes can range from 20-40 volts!
Back in the day, this was a check when cars used electro-mechanical regulators, and it's stuck around. Not because it works, but because people have never adapted to solid state technology. You'll find lots of people still using it and praising it. Some get by with it, or think they do, because they blow one of the three pairs of diodes and the alternator still
seems to work, but in reality, it's output current has been cut by a third. For others, doing the test actually blows the alternator, so they mistakenly believe the test confirmed their results, when in fact, it caused them.
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