In dash volt gauge junk?
In dash volt gauge junk? When the car is cold gauge shows 14 or so volts, like normal. Once it is warmed up it will dip to 12 volts just above the orange on occasion, however I get a steady 12.9 volts at the battery even when it is reading this low. Car runs great, starts up fine even after sitting for quite a few days in a row.
Battery, alternator and excitor wire are all brand new and not remaned junk either. Checked all my grounds they are in good shape.
With all that said....thoughts?
Oh and I already did this
Battery, alternator and excitor wire are all brand new and not remaned junk either. Checked all my grounds they are in good shape.
With all that said....thoughts?
Oh and I already did this
Joined: Nov 2001
Posts: 34,629
Likes: 2,551
From: Schiller Park, ILL Member: #317
Are you seeing 12.9v directly at the battery when the engine is running at idle? If so, this would indicate a problem, unless perhaps you have an extremely heavy accessory load running at that moment and you're idling in gear (A4).
Voltage at the battery should be WELL above 12.9v with the engine at idle and a minimal/average accessory load.
The dash gauge should be above 13v at idle under normal or light load. You may see it dip below 13 with a bunch of accessories running at idle. In my experience, the dash gauge always reads lower than voltage observed at the battery.
Voltage at the battery should be WELL above 12.9v with the engine at idle and a minimal/average accessory load.
The dash gauge should be above 13v at idle under normal or light load. You may see it dip below 13 with a bunch of accessories running at idle. In my experience, the dash gauge always reads lower than voltage observed at the battery.
Well I had my stereo cranked, lights on, ac blasting and I had just finished driving all over hell and gone so everything was good and hot. I don't know I am open to suggestions.
TECH Regular
Joined: Oct 2011
Posts: 407
Likes: 2
From: Keller Tx
You have to understand as the wiring heats up due to use it will increase in resistance.
Lets use some basics
R = E/I
R - Resistance of 1.2 ohms for the wiring
E is the voltage of 12V
I is the current of say 10A in this case
1.2 = 12/10
If your resistance goes up say to 1.5 ohms (Heat soak) your current will go down to 8A to keep the same voltage. or in your case the voltage is pulled a little because you still are trying to use that 10Amps at a higher resistance.
1.5 = 12/8
This kind of stuff is used more for car stereo and cable size to run with big amps but also applies to cars with older wiring.
Please correct me if I missed something.
Lets use some basics
R = E/I
R - Resistance of 1.2 ohms for the wiring
E is the voltage of 12V
I is the current of say 10A in this case
1.2 = 12/10
If your resistance goes up say to 1.5 ohms (Heat soak) your current will go down to 8A to keep the same voltage. or in your case the voltage is pulled a little because you still are trying to use that 10Amps at a higher resistance.
1.5 = 12/8
This kind of stuff is used more for car stereo and cable size to run with big amps but also applies to cars with older wiring.
Please correct me if I missed something.
All of this will cause a normal voltage drop in the system. In particular, your A/C and headlights suck a lot of power. (Maybe your stereo, too if its aftermarket.) If you are going to measure your charging system, you'll want to turn all that stuff off before taking your measurement.
