RPM is not enough

[jare]

Hi: I have this car alternator (CS144 140Amp) running with this 3000 rpm motor using same size pulley on both and belt. I don't have an amperimeter yet, but the voltimeter said the output is just 2v. Some says that it just need about 1500rpm to start working (are they right?).

Do I need more rpm?

What is the average rpm for a car alternator?

Thanks in advance

JARE

[johnlm]

If the motor is running at 3000 rpm and you have the same size pullys on both the motor and the alternator then the alternator is running at 3000 rpm - plenty fast.  It sounds as if you do not have the field connected up to a 12 v source (battery or battery charger or whatever).  Most car alternators in their stock condition will put out 12V around 700-800 rpm with the field running with a continuous 12v input.  Car alternators will not generate an output without the electromagnetic field activated (which usually consumes 20-30 watts) that is why people who want to use car alternators for windchargers usually convert the armature (field) to permanent magnets and usually rewind them (with more turns of a somewhat smaller wire guage) to get the 12V output at a lower rpm than 700 or so.  

[jare]

Thanks Johnlm

Do you know where I can find how to convert it to permanent magnets and rewind them.

Is that simple and cheap or complicated and expensive?

Another thing, the alternator also have this plug with two wires( red and white) what I supose to do with them?

Pardon my ignorance :/

Thanks a lot

Jare

[hiker]

on my alt you wire those two wires togeather--then hook them up to the positive

lug on the alt .you can hook up a on and off switch if you want..turns the field on

and off [ the big electric mag inside the alt.]

for battery hook up--the neg. goes to the grd. on alt --plus goes to batt. lug on alt..   just do it........

[hiker]

heres mine

[johnlm]

try this web site

http://members.1stconnect.com/anozira/SiteTops/energy/Alternator/alternator.htm

johnlm