Alternator output voltage is low
10-01-2012, 11:15 PM
#1
Alternator output voltage is low I am finishing up installing a LS2/4l70e out of 2008 TBSS with a new 2005
Corvette accessory drive into a 69 Camaro. When the motor is running the alternator output is 11.6V.
Even though the alternator is new I may have it bench check , but first does anyone have any suggestions?
Corvette accessory drive into a 69 Camaro. When the motor is running the alternator output is 11.6V.
- Exciter wire - I soldered in a 470 ohm resistor inline on the red exciter wire in my harness going to the alt plug.
- Grounds - I have two 2/0 cables going from the engine to the body, the engine harness is grounded directly to the body and the trunk mounted battery has a 2/0 cable grounded to the body.
Even though the alternator is new I may have it bench check , but first does anyone have any suggestions?
10-02-2012, 09:27 PM
#3
After recharging the battery tonight on initial start up the alternator reading was 11.47V and the at the battery 11.76V. After the engine warmed up 10-15 minutes, the alternator output dropped to 10.6V and the battery 11V. I really don't think the alternator is being turned on by the exciter wire, OR the alternator plug wiring has the wires crossed.
Does anyone know where I can get a schematic for the alternator and wiring?
10-03-2012, 02:12 AM
#5
ditch the 470 ohm resistor..go with a light bulb
should help drastically...if it doesnt... potentailly the alternator is bad
the resistor doesnt provide any real voltage drop which is what the field wire is looking for, it see's too much voltage and shuts down.. the light bulb will give it the proper voltage drop and the alternator should output proper voltage at that point.
should help drastically...if it doesnt... potentailly the alternator is bad
the resistor doesnt provide any real voltage drop which is what the field wire is looking for, it see's too much voltage and shuts down.. the light bulb will give it the proper voltage drop and the alternator should output proper voltage at that point.
10-03-2012, 06:02 AM
#6
This thread...Also, see the redirect in post #7.
https://ls1tech.com/forums/generatio...r-problem.html
Hope this helps.
https://ls1tech.com/forums/generatio...r-problem.html
Hope this helps.
Well this is a lesson in humility. I check the resistance on the exciter wire and noticed I had 900 ohm resistance. I removed my 470 ohm resistor and the reading drop to 400 ohm. I reconnected the wire, started the motor and like magic the alternator output jumped to 13.2v and measured 12.7v at the battery.
When I originally got my harness from SSP Wiring, they did not label any of the wires like they said they would and they never replied to my emails about the hooking up the alternator exciter wire. I was so enamored with the fact I read I needed a 470 ohm resistor I did not check to see that they had already done this......
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10-03-2012, 07:09 PM
#9
change to a light bulb like I suggested...
take any 12v ignition on source, and put a light bulb in line, then hit the alternator field wire terminal....
you should see 13.5+ volts....
there is also the option of a one wire(also known as a self exciting) Alternator
then you dont have to worry about the field wire at all.
Last edited by soundengineer; 10-03-2012 at 07:17 PM.
10-03-2012, 08:33 PM
#10
I preferred the durability of a resistor. I removed the light bulb on mine and played around with the resistance.
To arrive at the 'proper' resistance, I wired a pot, in line.
After achieving 14v, I measured the resistance of the pot, then substituted a fixed resistor.
To arrive at the 'proper' resistance, I wired a pot, in line.
After achieving 14v, I measured the resistance of the pot, then substituted a fixed resistor.
