Voltage problems!!!!!!!
Thread Starter
Le Mans Master
Joined: Dec 2002
Posts: 7,981
Likes: 37
From: Piedmont, SC Currently Own: 99 Nassau blue FRC. Previously Owned: 84,95,98 Indy Pace,01 Z06
Voltage problems!!!!!!!
OK, been through two alternators, and my car is still running at 11.9 at idle in drive! I have a 235 amp alternator! If I put the car in park, and let it idle the volts are around 13.5!! Well I also have a digital capacitor, and at idle in park it reads 14.3! In drive stopped it reads around 13.2!! Could I have a connection somewhere loose! With this high output alternator, I should be able to fill the whole back of the car up with speakers, and the volts still be very good!! BTW,If I rev my car up from 650 rpm's to around 800, the volts come up from 11.9 to 13.5!! My battery is good(yellow top optima)! Any ideas? Where are all the grounding points located,so I can make sure connections are tight? My amp also gets really hot , and the bass just quits, until the amp cools back off! It has never done this either!!
Team Owner
Joined: May 2002
Posts: 29,017
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From: Clemson University SC
Cruise-In II Veteran
Cruise-In III Veteran
Your alternator is designed to put out higher amperage, but only at higher rpms(most high amp alternators put out LESS than stock at idle). The only things you can do are to put a smaller pulley on the alternator(so it spins faster at lower engine speeds) or get a different alternator. 
EDIT: Your amps will run hotter because they are pulling more amps than normal to make up for the lower voltage.
EDIT: Your amps will run hotter because they are pulling more amps than normal to make up for the lower voltage.
Thread Starter
Le Mans Master
Joined: Dec 2002
Posts: 7,981
Likes: 37
From: Piedmont, SC Currently Own: 99 Nassau blue FRC. Previously Owned: 84,95,98 Indy Pace,01 Z06
Will this hurt my amp? What do I need to do? I had to upgrade because my stock alternator couldn't keep up with the stereo system!! I think he put the smallest pulley on the alternator, because it did say low voltage and was running in the 10's, and then he said he would try a smaller pulley and that has got me at where I am now! Thanks Jason
Melting Slicks
Joined: Sep 2003
Posts: 3,306
Likes: 2
From: Wesley Chapel Fl
If your cap reads 13.5 and your dash reads 11.5 sounds like something is wrong with your dash gauge. First thing I would do is check your battery post,alternator post and then back at your amps with a VOM to find out if the voltage is consistent through the vechicle. Since upgrading to the new alternator have you upgraded any of the factory leads? Those should be done..power lead from alternator to battery and ground lead from battery to frame. There should also be a ground lead from block to frame..that is usually the ground for the alternator. When you are upping the amperage out of the alternator you also need to upgrade the wires that support that amperage.
Thread Starter
Le Mans Master
Joined: Dec 2002
Posts: 7,981
Likes: 37
From: Piedmont, SC Currently Own: 99 Nassau blue FRC. Previously Owned: 84,95,98 Indy Pace,01 Z06
I did run a extra positive lead from the back of the alternator straight to the battery! Checked my connections at the block for the ground,etc and all was fine there! I did have to use a different wiring harness that plugs into the factory alternators wiring harness, so that it would connect to the Delco cs144 alternator I am using!!
Melting Slicks
Joined: Sep 2003
Posts: 3,306
Likes: 2
From: Wesley Chapel Fl
I would still check your voltages with a VOM. Good deal on the extra power wire but ground has to be done also. Current/voltage is a big circle...has to have the same ability to travel both positive and negative. Also your adaptor you mention could be a your source of problem. I know when we did the alternator in my C5 we had a bit of trouble getting the alternator to communicate with the PCM properly. It took a couple of trys before we got it correct.
Thread Starter
Le Mans Master
Joined: Dec 2002
Posts: 7,981
Likes: 37
From: Piedmont, SC Currently Own: 99 Nassau blue FRC. Previously Owned: 84,95,98 Indy Pace,01 Z06
When you said a couple of trys, what do you mean? I tested at the battery with the car idling, and I got 14.3! The same as what my capacitor reads!! The DIC in the car reads a full 1 volt below that at 13.3 at idle in park! In drive the DIC says around 11.6- 11.9, while the cap says 12.6-12.9! This is with everything on!!
Melting Slicks
Joined: Sep 2003
Posts: 3,306
Likes: 2
From: Wesley Chapel Fl
I can ask the guy that built my alternator for me excatly what was done. But I know we pet the alternator in and took it out 3 times before it was right. I know the car comunicates with the alternator and that was the problem. I can try to find out tomorrow might not be till Monday though. Sounds like your problem is the interface between the computer and alternator.
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Thread Starter
Le Mans Master
Joined: Dec 2002
Posts: 7,981
Likes: 37
From: Piedmont, SC Currently Own: 99 Nassau blue FRC. Previously Owned: 84,95,98 Indy Pace,01 Z06
Yeah!! i'm starting to think it has something to do with the communication to the computer!! Giving me a headache!!!!!! If you can, please see what it was that was done!! Thanks Jason
Melting Slicks
Joined: Sep 2003
Posts: 3,306
Likes: 2
From: Wesley Chapel Fl
Jason...this will be a bit easier for you. Call Art at CAN-AM Motors 813-936-9300 tell him Randy with the black Vette sent you. He is the man with alternators. Custom builds them inhouse. He should be able to tell you what you need to know. Let me know how it turns out for you.
Randy
Randy
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
There isn't anything wrong with your alternator, it is working as designed. Alternators can only deliver rated current at rpm's higher than idle. Also, I hope you have a fuse in the added wire from your alternator output, otherwise you have the potential for a fire!
Your dash voltmeter should not be reading 1 volt low. Typical is 0.3 volts low due to the voltage drop across the ignition switch contacts.
Your dash voltmeter should not be reading 1 volt low. Typical is 0.3 volts low due to the voltage drop across the ignition switch contacts.
