Rectifier?

[guywithboat]

What is a rectifier and what does it do?


[colour=red]***I apologize if this is a duplicate post, it said this post did not exist after posting it the first time.***[/colour]

 

[xtraham]

Re: Rectifier?

http://en.wikipedia.org/wiki/Rectifier

 

[guywithboat]

Re: Rectifier?

Interesting. Never new that the starting current is AC. Thanks.

 

[Silvertip]

Re: Rectifier?

Starting current is not AC -- it is DC. The battery supplies 12V DC to the starter motor to spin the engine. Once running, the battery receives charging voltage from the rectifier. The rectifier has as its input, AC voltage from the stator located under the flywheel. Magnets in the flywheel spinning past the stator creates this AC voltage. The job of the rectifier is to convert that AC voltage (which is a sine wave) into a DC voltage. Other windings in the stator provide the voltage to actually run the engine. A battery is not required for the engine to run, but the rectifier will fry if you try to do this.

 

[jtexas]

Re: Rectifier?

An "alternator" is called an "alternator" because it generates alternating current. Technically it's a "generator", but when cars first started using alternators they needed to distinguish them from the older "generators", which generate DC.

 

[swist]

Re: Rectifier?

Engines and associated boat/car devices use DC power. Way back car engines had generators which produced DC power directly, but generators have brushes which wear out, cause all kinds of static noise, and as you can imagine are not a great thing to have in a closed marine bilge. It is simpler and safer to produce AC with an alternator and then rectify it to DC with solid state devices (diodes).

 

[Silvertip]

Re: Rectifier?

Alternators have brushes too. The difference is that they run on slip rings rather than a segmented commutator and are smaller.

 

[swist]

Re: Rectifier?

The alternator slip rings are use to supply the field winding (much lower current than the alternator output). The primary output (where all the noise/sparking is produced on a generator) is brushless.

 

[Chris1956]

Re: Rectifier?

Swist, The alternators used on outboards are pemanent magnets rotating around fixed coils of wire. No brushes or sparks in this setup. Also outboard starter's field are permanent magnets. More recently, the starters used on I/O motors my GM V-6 for example, have permanent maget fields. As far as I know, the alternators used on the I/Os still have field coils.

 

[swist]

Re: Rectifier?

Swist, The alternators used on outboards are pemanent magnets rotating around fixed coils of wire. No brushes or sparks in this setup.

Right. I was talking about auto-style alternators.