Low voltage at idle
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Joined: Jan 2010
Posts: 61
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Low voltage at idle
Hi guys,
I have an issue with my voltage dropping down to 11.5-12.0 while at idle (2003 Vette). When I give it a little gas or start to move it will jump back to 12.8-13.7.
This voltage drop is causing my auto start alarm to shut down and then restart several times (it senses the low voltage). My dealer says that this is normal in the C5's during summer temps while using the air. I'm not an electrical engineer, but this doesn't sound right to me. I just installed a new Optima red top, but it didn't change anything. Any ideas?
I have an issue with my voltage dropping down to 11.5-12.0 while at idle (2003 Vette). When I give it a little gas or start to move it will jump back to 12.8-13.7.
This voltage drop is causing my auto start alarm to shut down and then restart several times (it senses the low voltage). My dealer says that this is normal in the C5's during summer temps while using the air. I'm not an electrical engineer, but this doesn't sound right to me. I just installed a new Optima red top, but it didn't change anything. Any ideas?
Tech Contributor
Joined: Jan 2007
Posts: 19,401
Likes: 1,143
From: Dyer, IN
Hi guys,
I have an issue with my voltage dropping down to 11.5-12.0 while at idle (2003 Vette). When I give it a little gas or start to move it will jump back to 12.8-13.7.
This voltage drop is causing my auto start alarm to shut down and then restart several times (it senses the low voltage). My dealer says that this is normal in the C5's during summer temps while using the air. I'm not an electrical engineer, but this doesn't sound right to me. I just installed a new Optima red top, but it didn't change anything. Any ideas?
I have an issue with my voltage dropping down to 11.5-12.0 while at idle (2003 Vette). When I give it a little gas or start to move it will jump back to 12.8-13.7.
This voltage drop is causing my auto start alarm to shut down and then restart several times (it senses the low voltage). My dealer says that this is normal in the C5's during summer temps while using the air. I'm not an electrical engineer, but this doesn't sound right to me. I just installed a new Optima red top, but it didn't change anything. Any ideas?
Tech Contributor
Joined: Jan 2007
Posts: 19,401
Likes: 1,143
From: Dyer, IN
The voltage needs to be read at the battery, not the DIC....for troubleshooting. That way you can see if you have an issue with the charging system, the ignition switch, etc. All the common sense stuff applies here, i.e. inspection of battery cables for corrosion/security, starter connections, etc.
Drifting
Joined: Mar 2010
Posts: 1,628
Likes: 15
From: Seattle WA
Hi guys,
I have an issue with my voltage dropping down to 11.5-12.0 while at idle (2003 Vette). When I give it a little gas or start to move it will jump back to 12.8-13.7.
This voltage drop is causing my auto start alarm to shut down and then restart several times (it senses the low voltage). My dealer says that this is normal in the C5's during summer temps while using the air. I'm not an electrical engineer, but this doesn't sound right to me. I just installed a new Optima red top, but it didn't change anything. Any ideas?
I have an issue with my voltage dropping down to 11.5-12.0 while at idle (2003 Vette). When I give it a little gas or start to move it will jump back to 12.8-13.7.
This voltage drop is causing my auto start alarm to shut down and then restart several times (it senses the low voltage). My dealer says that this is normal in the C5's during summer temps while using the air. I'm not an electrical engineer, but this doesn't sound right to me. I just installed a new Optima red top, but it didn't change anything. Any ideas?
I am 100% with lucky on this one. Check wires, grounds, connections, etc.
You said you just replaced the battery; one thing I will say is that I have seen on numerous occasions (not with C5's, but other cars), where a bad battery has worn an alternator to death, trying to charge it all the time and failing. Get a quality multimeter and check the output of your alt at idle; if its under 13 volts, it's bad/going bad/slipping on the belt.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
As lucky mentioned the battery, cable connections and so on, his suggestion with the starter cable is particular important as that is where the battery, starter and alternator all come together. Do not forget that its electrically hot down there unless you first remove the battery's negative cable from the battery itself. If all of those connections are clean, tight and no evidence of burned/overheated wire insulation, then pull the alternator and have it load tested. The normal voltage level is 13.8 to 14.1 for these cars while the engine is running.
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Instructor
Joined: Jan 2009
Posts: 154
Likes: 1
From: Huntley Illinois
Drifting
Joined: May 2006
Posts: 1,616
Likes: 1
From: Minnesota
Basically it involves upgrading three cables in your car. For me I used 4 gauge wire.
- Alternator to Battery
- Chassis to Battery Ground
- Engine to Chassis
Here are a couple links to help. I also recommend YouTube. They have a ton of videos on there.
http://forums.corvetteforum.com/audi...ig-3-pics.html
http://forums.corvetteforum.com/audi...-for-a-c5.html
- Alternator to Battery
- Chassis to Battery Ground
- Engine to Chassis
Here are a couple links to help. I also recommend YouTube. They have a ton of videos on there.
http://forums.corvetteforum.com/audi...ig-3-pics.html
http://forums.corvetteforum.com/audi...-for-a-c5.html
Cruising
Joined: Apr 2010
Posts: 11
Likes: 0
Basically it involves upgrading three cables in your car. For me I used 4 gauge wire.
- Alternator to Battery
- Chassis to Battery Ground
- Engine to Chassis
Here are a couple links to help. I also recommend YouTube. They have a ton of videos on there.
http://forums.corvetteforum.com/audi...ig-3-pics.html
http://forums.corvetteforum.com/audi...-for-a-c5.html
- Alternator to Battery
- Chassis to Battery Ground
- Engine to Chassis
Here are a couple links to help. I also recommend YouTube. They have a ton of videos on there.
http://forums.corvetteforum.com/audi...ig-3-pics.html
http://forums.corvetteforum.com/audi...-for-a-c5.html
Thanks,
Allen
Tech Contributor
Joined: Jan 2007
Posts: 19,401
Likes: 1,143
From: Dyer, IN
Basically it involves upgrading three cables in your car. For me I used 4 gauge wire.
- Alternator to Battery
- Chassis to Battery Ground
- Engine to Chassis
Here are a couple links to help. I also recommend YouTube. They have a ton of videos on there.
http://forums.corvetteforum.com/audi...ig-3-pics.html
http://forums.corvetteforum.com/audi...-for-a-c5.html
- Alternator to Battery
- Chassis to Battery Ground
- Engine to Chassis
Here are a couple links to help. I also recommend YouTube. They have a ton of videos on there.
http://forums.corvetteforum.com/audi...ig-3-pics.html
http://forums.corvetteforum.com/audi...-for-a-c5.html
Guess I'm missing the point. The claim by these audio installers, is the increasing the diameter of the wire (ground and voltage) will precipitate maximum current flow. I really don't see how that applies to the OP's situation. Besides, if there was a current demand on the factory wiring, that the existing wiring was not capable of handling, fuses would blow....and in the absence of fuses, things would melt.
I'm sure having a O gauge power wire looks really cool in a Scion, with a 1000 watt stereo system.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Grounds on our C5's are MINIMUM requirements for proper electrical component / module operation. When you mix in corrosion, loose connections and age, things start to work poorly. Anything that you do to provide a good ground for the car, will help. Do you need O cables. NO. I add a 10 ga wire from my alternatorr to G-101 and it seemed to help with my frequent CHARGING SYSTEM FAULT message at start up..
The alternator BATT connection on the back of the alternator is the OUTPUT, connects to the starter solenoid main terminal and then goes up to the battery. That is prime real estate for poor connections and should be checked for proper connections.
Reading the system operating voltage from the DIC or IPC gage is NOT a very good representation of over all system voltage. Take your reading directly at the battery cables on the battery. Then,,compare that to the DIC / IPC voltage.
If there's are large difference between Battery voltage at the terminal and the DIC/IPC voltage,,,your Ignition switch is most likely at fault and needs to be rebuilt or replaced.
BC
The alternator BATT connection on the back of the alternator is the OUTPUT, connects to the starter solenoid main terminal and then goes up to the battery. That is prime real estate for poor connections and should be checked for proper connections.
Reading the system operating voltage from the DIC or IPC gage is NOT a very good representation of over all system voltage. Take your reading directly at the battery cables on the battery. Then,,compare that to the DIC / IPC voltage.
If there's are large difference between Battery voltage at the terminal and the DIC/IPC voltage,,,your Ignition switch is most likely at fault and needs to be rebuilt or replaced.
BC
Drifting
Joined: May 2006
Posts: 1,616
Likes: 1
From: Minnesota
Guess I'm missing the point. The claim by these audio installers, is the increasing the diameter of the wire (ground and voltage) will precipitate maximum current flow. I really don't see how that applies to the OP's situation. Besides, if there was a current demand on the factory wiring, that the existing wiring was not capable of handling, fuses would blow....and in the absence of fuses, things would melt.....
Not much to add to what Bill said who is real expert in this conversation... but if you need further evidence that the stock system is not as efficient as it could be take a look under your battery and see the puny 10 guage wire that connects your battery to the chassis. Consider the big three upgrade like the HID upgrade. Sure the stock lights work fine but they are MINIMUM requirements... but they could work so much better. Is it worth it? That's for the owner to decide.
Tech Contributor
Joined: Jan 2007
Posts: 19,401
Likes: 1,143
From: Dyer, IN
So you change out the cables, and you get a .5 volt increase. Issue.... probably bad connections. And what exactly do you gain by changing the 4 gauge wire to 0 gauge...let's see.
The O gauge wire has a resistance value of ~ 0.000098 Ohms per foot.
The 4 gauge wire has a resistance value of ~ 0.000292 Ohms per foot.
The 8 gauge wire has a resistance value of ~ 0.000628 Ohms per foot.
I have a hard time believing IASCA would recommend O gauge wire for such a short distance, especially considering the current draw for said length.
....but heck....I'm no expert......
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Wow.... all that extra resistance,,,shucks,,,,,,,changing the wires to O gage,,,is worth at least 20 HP. The looks alone is worth 5 more HP
Oh,,,I forgot,,,
The extra weight of the wire, -25 HP. 
BC
Oh,,,I forgot,,,
The extra weight of the wire, -25 HP. BC
Tech Contributor
Joined: Jan 2007
Posts: 19,401
Likes: 1,143
From: Dyer, IN
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