Ok, Here is the story. I am building an FC race car and I completely stripped out the entire car and rewired the entire car manually. Everything has gone as planned except one part: My alternator is charging very strangely.

This is what I'm seeing:

1) Before I start the car, battery volts is at about 12.1 volts per my multimeter

2) I start the car and the volts drop down to about 11.8 volts and do not increase much past 12 volts.

3) If I rev up to about 2,000 rpms and back down to idle, the volts jumps up dramatically. a) at the alternator post it is 15.3 volts. b) at battery it is 14.8-14.9 volts c) at the switch panel on the dash it is 14.9 volts.

What I don't understand:

* Why I am not seeing 14.7 volts anywhere in the system at idle.
* Why it jumps up above 15 volts as soon as I rev it up and back down to idle.

How do I have it wired?

* + battery to alternator post
* S plug lead to 12 v ignition
* L plug lead to nothing

What have I tested?

* I've replaced the alternator (both tested fine at store)
* I've checked voltage drop on the positive and negative circuits and both are only .1 volts.
* I've run as a test jumper cables to the battery to the alt post on both the positive and negative side to eliminate any grounding issues.

The only thing I can think of is that this is perfectly normal, but below 14 volts at idle initially and above 15 volts after a rev scares me with all of the electronics.

Any ideas?

Any help is appreciated!

 

What pulley is on the alternator?

 

Both alternators had the stock pulley on it.

Is it possible that this is a battery problem? I hear the battery wheezing after running a few minutes like it is being over charged. I just don't see how a battery could put out more than 12 volts and how two different alternators are putting out more than 14.7 volts.

It has to be something on the car or lack of on the car given that I re-wired the car manually.