voltage drop

[fatboyracing 10+ year member]

Ok I have a 2005 chevy silverado with a 5.3L

A 250 amp alt and a yellow top

At 2000 rpms its 14.5 volts at ideal 700 rpms its 12.6 volts

the belt is not sliping and it is not bad

I went to auto zone and they checked the battery and alt and said they where good

Any ideas

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[93EXT 10+ year member]

like i said in the other thread you made, try a different pulley that gives a little more spin at idle on the alt.

 

[audioatg 10+ year member]

What brand of alt is it. Is internally regulated or externally regulated. What the other guy said too. A smaller pulley will spin faster bring the alts rmps up at idle.

 

[audiobahnuser18 5,000+ posts]

What brand Alt?

 

[fatboyracing 10+ year member]

internal and its a excissive amprage

 

[fatboyracing 10+ year member]

but wouldn't a smaller pully give it to much at higher rpms

 

[lostdaytomorrow 10+ year member]

but wouldn't a smaller pully give it to much at higher rpms

No, the curve levels off.

 

[audioatg 10+ year member]

Adding this too. If its internally regulated. Most likely means that the vehicles computers are controling the voltage of the alternator. next time you test this. At idle with no loads. Its 12,6 volts. Turn the high beams ac blower to high on. Wipers an then read the voltage an see what it says. Its possible this could be normal.

 

[audioarsonal 10+ year member]

actually if its internal its not being controlled by the car ECU.If its unregulated then its controlled by the cars ECU.My jeep is unregulated and controlled by the ECU.A smaller pulley will help with alternator rpm in relation to crank rpm.I would try that and see what happens.What size is your crank pulley?

 

[audioatg 10+ year member]

actually if its internal its not being controlled by the car ECU.If its unregulated then its controlled by the cars ECU.My jeep is unregulated and controlled by the ECU.A smaller pulley will help with alternator rpm in relation to crank rpm.I would try that and see what happens.What size is your crank pulley?

Ummm when we were talking about internal an external. We are saying aftermarket alts. Like external with a big blue box. Like HO excessive alts. Mostly ALL vechiles stock alternator voltage is controled by the Computers.

Also a smaller crank pulley is not going to help him at all. Some one else correct me if Im wrong. But If he goes that way the alt will still be spinning the same rpms. He wants a smaller alt pulley to increase his alt's rpms.

 

[andrewmoore13 10+ year member]

Ummm when we were talking about internal an external. We are saying aftermarket alts. Like external with a big blue box. Like HO excessive alts. Mostly ALL vechiles stock alternator voltage is controled by the Computers.
Also a smaller crank pulley is not going to help him at all. Some one else correct me if Im wrong. But If he goes that way the alt will still be spinning the same rpms. He wants a smaller alt pulley to increase his alt's rpms.

i believe thats what they were saying.

 

[audioatg 10+ year member]

i believe thats what they were saying.

That comment was too "audioarsonal" . Andrewmoore. I think he was thinking that we were all talking about stock alternators not aftermarket ones. And were talking about a smaller pulley for the alternator not the crank. I do belive that putting a smaller crank will do nothin for what he wants to get. He wants to increase the RMPs of the alternator. That will happen with a smalley alternator pulley.

 

[audioarsonal 10+ year member]

I know about the blue box.My question wasn't to get a smaller crank pulley.It was to see what size it is to determine what speed the alt is spinning at with his particullar alt pulley.He may only be at a 2-1 ratio(800 engine rpm and 1600 alt rpm).I'm guessing with a full size truck it's probably an 8in. pulley.But I just wanted to make sure.I wasn't suggesting getting a smaller crank pulley but a smaller alt pulley like 93EXT suggested.You may need a 4-1 ratio depending on this.

 

[audioatg 10+ year member]

I know about the blue box.My question wasn't to get a smaller crank pulley.It was to see what size it is to determine what speed the alt is spinning at with his particullar alt pulley.He may only be at a 2-1 ratio(800 engine rpm and 1600 alt rpm).I'm guessing with a full size truck it's probably an 8in. pulley.But I just wanted to make sure.I wasn't suggesting getting a smaller crank pulley but a smaller alt pulley like 93EXT suggested.You may need a 4-1 ratio depending on this.

I dunno If hes going to know all about that stuff. Some times its better to keep things simple for ppl who dont know much about all of it. Thats why I said just to get a smaller alt pulley.

And On a side note. Is that in your picture there two hk's an with a maxx link. I got the same thing too lol. Going to try that maxx link out too. What ohms are you going to run them. Im a bit nervous to run them link like that at the ohm load i was running them at.