brand new alt and im getting a really high voltage. i even tried tweaking the bac and im still getting the high volatge. so far ive

Cleaned the bac
made sure it actually works

so im not sure what else to do

 

Definately make sure as others have said, if it bumps up to 15.5v I would shut the car off. 15 is pretty boarder line internal voltage regulator failure... You could just have a really low battery, but even so I would watch out... There are many things that don't like such high voltages...

Honestly If you lose a fuse I would take the alt back and get another. 14.5 is about all I see with an FD alternator.

Is it a custom alternator with an external regulator? I know of some Jeep alternators that people have custom made that will put out higher voltages and amperages to handle the winches/welders etc.... but our little cars don't need such things. Even with a large stereo.

 

You guys shouldn't be posting about topics you know nothing about. 15V is neither great, fine or sweet. It's getting dangerously close to frying stuff.

alwayssideways, take the alternator back and have the faulty voltage regulator fixed.

 

well as for testing it or reading voltage i have a electronic read out on my turbo timer and a analog gauge that is reading from my battery and on my S-afc. all read about the same .. Its a reman s5 alt. but it looks like i ll be getting a new one today i hope .. it should still be covered by warrenty. cuz i have pulled over 15 v. i knew it was high . i liked the 14.5 though . heheh ,, ill swapp it out today

 

AGREED.

14.5VDC is your target.
Going over that is not recommended but still "okay".
Hitting 15.0VDC or higher is asking for trouble.
15.0VDC is like the safety border - don't even think about going over it.

One of the biggest dangers is overcharging the battery.
In extreme cases, the battery can explode.
Overcharging at 15VDC+ would most likely cause the battery to leak...acid.


-Ted

 

Analog meters can be off a volt, but digital meters are usually pretty close.

As Mark & Ted say, better to swap it before the warranty or you car expires.

 

well ill solve all the problems right now!!. i have 3 gauges testing the voltage . one greddy turbo timer. readling about 15 vs at idle. the analog aftermaket peice was no more than .5 v's off what the turbo timer was saying, then the Safc 2 was agreeing with what the other 2 were saying. if any different no more than .1-.2 v's off. here is the thing. the safc is running off the ecu voltage , the analog running off voltage comming straight from the battery and the timer off the ignition.

with that said there was def a problem. so since i work at a shop and i know the parts guys who sold me the alt pretty well they sent me a new alt no questions asked. put it in . now im pulling 15.5 v's at idle. so im like wtf . (a little history) i have a s4 and i did the swap over to a s5 alt with the harness. well i guess i should have known better to double check my work and to re read the how to(as confusing as it is since its the easier conversion i have ever done) i had the signal wire plugged into the wrong part of the "T" swapped that now getting a nice 14.5 v's at idle . and like 14 v's under load. which was exactly what i was searching for. sorry to have started a little controversy but it was a simple mistake and cost me nothing as the alt was under warrenty. go figuire

 

I'm at 12v on idle and about 14v driving. Could be wrong on the driving part. I always had the assumption that my battery needed charging since it was at 12v and 14v. I assumed that it always needed to be at 16v. Glad I didn't do anything to my battery.

 

NZ, you're always telling everybody to read the FSM, and you're not even following your own advice...

14.4 to 15v is in the book... The FSM... For the S4...Look it up

15 volts shouldn't fry anything on the car. I'll bet a day's pay that all of the electronics on the car were designed for at least 18 volt surges during engineering and testing before they were ever OK'd by Mazda to be installed on the car. I know for a fact that the boost sensor is rated for up to an 18v input (research done a long time ago on the little thingy that makes the output, lol).

Having said all of that, 15.5v would be freaking me out a bit...

 

Glad to hear you got everything fixed!
Those numbers sound spot on a healthy electrical charging system.
Congrads!


-Ted

 

On the contrary, I do know what the FSM says. But the FSM is certainly not my only source of info and nor do I take everything in it at face value.