another alternator question

[midnightrider1818]

alright. put a new alternator on and new volt reg. got current going to both field terminals on alternator. with engine running and lights and **** off testing at batt it is reading around 13.2 v. so it is charging. turn the lights on and test it again it reading around 12.3 v. is this right. it seems it should stay right at 13.2. when i turn my lights on shouldnt it put more of a field to my alt and make it put out more amperage. ????

 

[bean bandit]

Hi midnightrider,
All alternators have an output curve that increases with rpm. In other words, your alternator can not provide as many amps at idle as it can at higher speeds.
If your car demands more power than the alternator can supply at idle, the remaining amps must come from the battery, thus a decrease in voltage results.

So you have to do a system check with an engine rpm of aprox. 1500 rpm. (accourding to a Powermaster manual).

And it's sayinig the following:

With battery fully charged and engine running at 1500rpm, measure the voltage at battery positive post (+) and the ground post (-). Voltage should be 13.8~14.5VDC. Readings above 15.5VDC indicate a defective alternator and readings below 12.7VDC indicate that the alternator is not functioning or cannot supply the current amperage needs of the vehicle at this engine speed.

This is not completey true though, because if you have a defective voltage regulator, the battery is not charging either.

I have a voltage meter in my car. And have the following readings:
~ 12VDC - with contact on WITHOUT running engine
All with running engine:
~ 14VDC - battery fully charged or low engine rpm (sitting at a traffic light)
~ 16VDC - battery is charging

I hope this helps you.

Cheers,
Remco

 

[midnightrider1818]

Hi midnightrider,
All alternators have an output curve that increases with rpm. In other words, your alternator can not provide as many amps at idle as it can at higher speeds.
If your car demands more power than the alternator can supply at idle, the remaining amps must come from the battery, thus a decrease in voltage results.

So you have to do a system check with an engine rpm of aprox. 1500 rpm. (accourding to a Powermaster manual).

And it's sayinig the following:


This is not completey true though, because if you have a defective voltage regulator, the battery is not charging either.

I have a voltage meter in my car. And have the following readings:
~ 12VDC - with contact on WITHOUT running engine
All with running engine:
~ 14VDC - battery fully charged or low engine rpm (sitting at a traffic light)
~ 16VDC - battery is charging

I hope this helps you.

Cheers,
Remco

thank you bean bandit. yep, i increased rpm with the same result. also has a new volt reg and and even tried another one to be sure. still same result. i have a msd igntion. whats the amp pull on them. my alt is a 60 amp