Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

Trending News

Promoted
"DOZER"
Lv 4
"DOZER" asked in Cars & TransportationMaintenance & Repairs · 1 decade ago

Can an alternator charge, and drain the battery?

The answer is YES. But do you know why?

Not many people know this.

3 Answers

Relevance
  • Mr. KnowItAll
    Lv 7
    1 decade ago
    Favorite Answer

    Inside the alternator are a pair of rectifiers (big diodes) that turn the alternating current AC made by the "alternator" into DC direct current.

    If one of the rectifiers goes bad, it will charge the battery while the engine is running,

    but as soon as the alternator is no longer turning, it creates a direct short to ground through the bad rectifier.

    10 points.....

  • Andy
    Lv 7
    1 decade ago

    Mr Know It All is right.A bad diode will cause that.A diode is basically like a switch that only allows current to flow one direction.When it goes bad it lets current flow both ways(a short) killing the battery.

  • bandit_60
    Lv 7
    1 decade ago

    sure if it has a short in the alternator. also did you know a overcharged battery is the same as a dead battery?

Still have questions? Get your answers by asking now.