what is the correct output of a cosworth alternator? the last time i checked mine it was 13.8v but heard people have over 14v.

i'm thinking of getting mine reconded if its a little low.

 

13.8 volt is not too low. In my experience anything between 13.6 and 14.4 is o.k.
Measure with engine idling and consumers on (front and rear window heaters, lights). Whats the voltage then? And with 2000 rpm?

 

i willl give it a test

 

13.8V is perfectly normal and nothing to worry about, so long as under load it does not drop below 13V it's ok.

Martin

 

There is a slight variation in voltages, even different makes regulators can give different readings, some(older) vaux's run up to 15.5V.
A extra new wire from the alt to the battery direct will make a bit of an increase over 20+ year old wiring, more so under load.
tabetha

 

I get 14.6v at the battery and 13.9v at the secs monitor

 

since as tabetha recommends, i put a new wire from the alternator to the battery, my battery voltage via secs monitor peaks at 13.7. but when under load itis still dropping to 12 volts with everything on. when the fans alone kick in the voltage goes down to 13 volts. i have had my alternator reconned last year and had it checks 6 month ago when i started having the voltage probs. plus the battery is only 2 years old and i charged it 4 weeks ago to see if that wasthe lowvoltage prob.

is it my regulator?, and also were is the regulator? is it the small wire going into the alternator that is next to the alternator/battery wire. i also checked the earth and it is fine.

 

Have you measured the battery voltage directly as a test?

Before rushing out for an alternator check all earths are good, particularly the engine earth strap, otherwise from what you describe it does sound as your alt may be struggling under load.

The regulator is integral to the alternator it is fixed to the back with two screws. The thin blue wire excites the field windings. There is also a suppressor mounted in the back with a small black wire.

Martin