using an alternator

[Thunderchild]

I have an alternator i would like to fix up how do I do this ? I think there should be a neg and pos conections to "exite" the alternator I have a picture here any suggestions welcome

 

[ericgibbs]

I have an alternator i would like to fix up how do I do this ? I think there should be a neg and pos conections to "exite" the alternator I have a picture here any suggestions welcome

hi,
Look at this RE site:

TheBackShed.com - Alternator Rectifier

 

[Thunderchild]

hm that tells me about reusing the rectifier I want to use the whole alternator not take the rectifier out does that site also deal with connectingthe whole alternator ? I'll have a look round it later

 

[RODALCO]

Alternator

Normally the alternator gets it's 12V excitation via the charging light on the dash to one of the two small terminals at the back of the alternator.
The other terminal is often the negative.
These terminals are connected to the sliprings and internally connected to the voltage regulator.

As soon the alternator is up to speed the built in regulator will take over the excitation and will keep the output voltage at a constant 14.4 volts.

The output current is taken from the big M6 terminal at the back and a good ground is the negative to the accu from the alternator housing.

Clamp your alternator in a vice safely without distorting the housing and see if you can turn it around via a belt driven from an other motor.

I have used a few car alternators as fast accu chargers in the Netherlands to charge tractor accu's in winter when the first attemps to start a cold diesel engine failed. By using a 1Ø or 3Ø motor with pulleys to get the alternator up to around 4000 revs a very powerfull charger can be built which easily puts out 40 to 60 Ampères, depending upon the RPM speed.

Regards, Raymond

 

[Thunderchild]

thanks I'll see if i can do anything so basically I need to connect 12 V to the "extra" terminals to start it up then just draw current from the outputs

 

[stevez]

Some alternators have built in circuitry that adjusts the field current as the demand on the regulator changes - or as the RPM of the alternator changes. Others do this with circuitry that is separate from the alternator. If you have the type that has a separate regulator then you'd have to provide current for the field. I could be mistaken but if you were to deliver full power to the field and the current demand was not high, the output voltage could rise to a level that is harmful.

I've seen various regulation schemes in amateur radio publications - amateurs quite often employ and alternator and spare gasoline engine for emergency service.

 

[Ubergeek63]

Some alternators have built in circuitry that adjusts the field current as the demand on the regulator changes - or as the RPM of the alternator changes. Others do this with circuitry that is separate from the alternator. If you have the type that has a separate regulator then you'd have to provide current for the field. I could be mistaken but if you were to deliver full power to the field and the current demand was not high, the output voltage could rise to a level that is harmful.

I've seen various regulation schemes in amateur radio publications - amateurs quite often employ and alternator and spare gasoline engine for emergency service.

Yes and no. The voltage out of an alternator is directly proportional to field current and shaft speed minus the diode drop and the current times the armature resistance.

The regulator will increase the field current slightly as the current increases, but varies it wildly with rotor speed to maintain the output voltage.

 

[Thunderchild]

well as there are the minimal conections I would think that its a self regulator

 

[Diver300]

The negative terminal is the body on just about all alternators.

The two large terminals are usually connected together inside the alternator. If not, both should be connected together and to the battery.

You need to connect a bulb of about 2W between the battery and the smaller terminal. Without that, the alternator will not have any field current, so it will not generate a voltage. Once the alternator has started generating voltage, the alternator provides its own field current, and the light goes out and isn't needed any more.

Car alternators are rated to about 15000 rpm and will produce full output from about 4000 rpm upwards. They are usually geared to run at about twice engine speed.

 

[Thunderchild]

thanks its starting to look easier now