What voltage should be on 130 amp alt.....

[Darek78]

hi guys i need to know what voltage should be on idle on a 130 amp alt 3G
and what it shows when you idle araund 2000 rpm should be the same as idle or should it pick up???????????
because i just went to 2 alt with charging abaut 13.4 to 13.5 on idle or if i idle more then 2 k is this a good ???????
or is it on the low side????????
can any one help out??????
Can a low charging alt can make my gauge go crazy????????

Thanks again Derek.N

 

[HISSIN50]

A bad power cable connection can make the gauge go crazy.

With no load and an otherwise full battery, something around 13.5 volts at idle is decent. If the alt(s) is/are running at max capacity at idle, the volts will likely go up at a given RPM (like 2000) because of the increased spin rate. But if the alt is not overwhelmed at idle, the volts should stay near the same.

Good luck.

 

[Darek78]

so you say that 13.5 is what it should be ?
but my gauge only shows in NORMAL on O" and when i start the car in thje morning it shoew araund M or litlle past that and after worms up i goes down and if i put my radio on the Volts drop below 13.5 even if i rev the car
but the funny thing is that dosen't matter if i idle the car or rev the car charge does not change i was told that with the RPM up i should charge a little better then 13.5 it should be araund 14 volts

Derek.N

 

[HISSIN50]

Derek, I have no idea what the letters on the stock guage correlate to, so I cant comment on that part. Sorry bud.

13.5 volts at idle is pretty darn decent. I might like to see a little more, but not much.

Here is the thing: the alt charges the battery as much as the battery needs charging/replenishing (while accomodating the electrical draw at the time). If your just took your battery off the charger before starting it, the alt would be able to take it easy, needing only to break even, and then charge the battery back up from the cranking it had to do.
But if someone jump starts a dead battery (for instance), that is about the hardest thing one can do to an alternator - the alt will work at max trying to charge the battery. So just the state of the battery is important.

The key is that ~12.6 volts is break-even (with some gel cell batts, it is a little higher). Below that and you are discharging, above that and you are charging. And DON'T forget about voltage drops. Some voltmeters (in the car) read a volt or more less than what the voltage is at the battery. This can skew diagnostics.

With a non-topped-up battery, charge voltage can reach 14.5 volts or so. And yeah, normally volts go up with revs. Some of the newer aftermarket 3G's+, with an OD pulley and a car which has a higher than stock idle setting can put out decent volts right at idle.

This is where I bow out - I dont know about 2 alternator set-ups (is that what you were talking about in the first post?). If so, I would imagine that each alternator works easier (having to do 1/2 the work), so perhaps that is normal. I have no experience with it.

If Shane or one of the other gurus sees this thread, he/they will hook ya up with some real good info!

Good luck Derek.

 

[Darek78]

ok thanks for the info
i called a ford delar today and talked with them they told me that in the gauge cluster there is a little amp that keep's the gauge from buging out they told me that that pice may have gone south that's i why i get a bad riding on my gauge cluster
the dail amp will set me back araun $80
today i'm going to chceck all my ground's in the car
that's why i need to know what the alt should put out so now i know that is fine and i have to look else were

thanks again for the respond

Derek.N

 

[mo_dingo]

The regulator will allow 14.4V to get to your battery at first startup. After a few minutes, it will drop down to 13.6 or when battery is charged.

The battery has a max voltage of around 12.6 (2.1V per cell) so anything above that means your alternator is charging.
Scott

 

[LoudToy958]

The regulator will allow 14.4V to get to your battery at first startup. After a few minutes, it will drop down to 13.6 or when battery is charged.

The battery has a max voltage of around 12.6 (2.1V per cell) so anything above that means your alternator is charging.
Scott

He has all the info you need right here. There are a lot of things that can affect charge in these cars. Anything over 13.2 is pretty good. You will only see higher output when the battery and car are demanding tons of power. 14.4 is indeed the regulated level of charge on most alternators. It should never exceed this. I had a discussion with the guys at Pa performance about the same question you are asking. He said as long as you read 13.2+ at the alternator, and the battery and alternator match voltage, you are okay.