Alternator problems
Thread Starter
Pro
Joined: Nov 1999
Posts: 509
Likes: 0
From: lantana,fl.
Alternator problems
What else would cause low voltage output from alt.
I've had this problem for about 8 months.
I just put in a new 100 amp alt,electric water pump,spal dual fans. I had this problem before any of this was put in, the volt gauge when I first start the car will be at 10 then when I hit the gas it'll jump up to 13. When everything was ok before The gauge would be at 14 plus and never go below 12.
The battery is about a year old top of the line diehard if the battery was the problem wouldn't the gauge be at 14 to try and keep it charged?
The battery will go dead in about a week if I don't run the car.
I know I need to check for a current draw but that wouldn't explain the low output??????????????????
Any help??
I've had this problem for about 8 months.
I just put in a new 100 amp alt,electric water pump,spal dual fans. I had this problem before any of this was put in, the volt gauge when I first start the car will be at 10 then when I hit the gas it'll jump up to 13. When everything was ok before The gauge would be at 14 plus and never go below 12.
The battery is about a year old top of the line diehard if the battery was the problem wouldn't the gauge be at 14 to try and keep it charged?
The battery will go dead in about a week if I don't run the car.
I know I need to check for a current draw but that wouldn't explain the low output??????????????????
Any help??
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
Ugh, can I assume we are discussing a 74? You need to check to see if it is the regulator or the alternator or the wiring. Look at the back of the alternator. You should see a D shaped hole in the housing. There is a little metal tab down there in that hole. Take a small screwdriver and short that tab to the alternator case. Check the voltage while doing this. It should be charging to beat the band. If not you have a bad alternator, if it does you have a bad regulator. If there is no deflection in the guage but the lights brighten and there is a pull on the engine, the guage is bad. Also check the wiring to the alternator. Both terminals on the plug should be 12V.
Drifting
Joined: Nov 2002
Posts: 1,665
Likes: 1
From: Ontario
Battery getting drained with car off sounds like a short. This could also cause a low voltage level from your alternator; as current draw from the alternator increases past its max rated output the alternator will lower the voltage to compensate.
Power = Current * Voltage
The max output power of your alt is fixed.
A low voltage output from your alternator will also not charge your battery effectively, further contributing to your battery being dead in a short time.
Good idea to check the current draw from the batt. I imagine the short would have to be fairly substantial to bring down the voltage of your alternator. If your not blowing fuses there is a good chance the short is before the fuse block (starter wiring for example).
Let us know how it goes, I like to know when I'm right or wrong
Oh and you may find some usefull info here:
http://www.madelectrical.com/electrical-tech.shtml
Power = Current * Voltage
The max output power of your alt is fixed.
A low voltage output from your alternator will also not charge your battery effectively, further contributing to your battery being dead in a short time.
Good idea to check the current draw from the batt. I imagine the short would have to be fairly substantial to bring down the voltage of your alternator. If your not blowing fuses there is a good chance the short is before the fuse block (starter wiring for example).
Let us know how it goes, I like to know when I'm right or wrong
Oh and you may find some usefull info here:
http://www.madelectrical.com/electrical-tech.shtml
Last edited by Boofers; Mar 24, 2005 at 03:19 PM.
