Electrical Problems
Thread Starter
Safety Car
Joined: Jan 2006
Posts: 3,566
Likes: 4
From: Mt Laurel NJ
St. Jude Donor '06-'07
Electrical Problems
Hello everyone.
I am having a problem w/ my car. I have had a problem w/ it not starting at times, I would just get a click. Tapping on the starter or waiting would get it to start. This would happen when it was cold and hot. Today I changed to starter, and it now starts fine, w/ no problem-BUT, I noticed a few days ago the the alternator is not charging as it should. The needle in the dash only goes about half way down, which is less then it was before, so I guess the alternator is dying. Or am I missing some thing? The strange thing is that if I run the car at night w/ the lights and the power amp on, the lights look fine, they do not "fade" or go up and down in any way. I will check the charging system out tomorrow, but I wanted to know if anyone had any ideas as to what would be causing this, expect for the obvious?
Thanks for your help.
Randy
I am having a problem w/ my car. I have had a problem w/ it not starting at times, I would just get a click. Tapping on the starter or waiting would get it to start. This would happen when it was cold and hot. Today I changed to starter, and it now starts fine, w/ no problem-BUT, I noticed a few days ago the the alternator is not charging as it should. The needle in the dash only goes about half way down, which is less then it was before, so I guess the alternator is dying. Or am I missing some thing? The strange thing is that if I run the car at night w/ the lights and the power amp on, the lights look fine, they do not "fade" or go up and down in any way. I will check the charging system out tomorrow, but I wanted to know if anyone had any ideas as to what would be causing this, expect for the obvious?
Thanks for your help.
Randy
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
I don't know if you're against them or not, but if you went to autozone or advance auto parts or something they could check the alternator for you. Their machine has come in useful for me and my family multiple times..
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Hard to advise since you have not made any measurements yet and high and low needles are hard to go by. But generally speaking, you should be charging about 14.5 in the morning. As the battery charges this number will come down to 14 or so.
When battery gets charged up and you have a lot turned on and drawing much current, at an idle tit may drop down to 13 volts. But when you increase RPM it might go up to 13.8 or 14 volts.
Now these numbers are just estimates and the exact value would be dependent on the specific car. But just want to give you a general feeling of what basic voltage swings you might normally expect.
It would be helpful to measure these voltages at the different conditions to see what is going on. If you were getting down in to the 11 volt or low 12 volt range, that might indicate a problem.
Since you had you starter replaced and had the battery cables off probably, make sure you currently have good connections. I understand the car starts fine and all looks good on the surface, but just a suggestion.
When battery gets charged up and you have a lot turned on and drawing much current, at an idle tit may drop down to 13 volts. But when you increase RPM it might go up to 13.8 or 14 volts.
Now these numbers are just estimates and the exact value would be dependent on the specific car. But just want to give you a general feeling of what basic voltage swings you might normally expect.
It would be helpful to measure these voltages at the different conditions to see what is going on. If you were getting down in to the 11 volt or low 12 volt range, that might indicate a problem.
Since you had you starter replaced and had the battery cables off probably, make sure you currently have good connections. I understand the car starts fine and all looks good on the surface, but just a suggestion.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Normal alternator voltage is 14.7 volts engine cold and this drops to 13.7 volts at full temperature. The dash voltmeter will show 0.3 volts less than this due to the 0.3 volts drop across the ignition switch.
Thread Starter
Safety Car
Joined: Jan 2006
Posts: 3,566
Likes: 4
From: Mt Laurel NJ
St. Jude Donor '06-'07
OK, I measured the alternator output this morning, here's what I got: the battery was reading 11.3 before start up. The car cranked slowly, but started. After start up, the charge at the battery was 14.4, and about 5 minutes later it was 13.2. Keep in mind I was using a cheap mutlimeter, so the readings could be off a little. I also had the stereo system on, which includes a power amp for the speakers.
Sound like a bad battery?
Randy
Sound like a bad battery?
Randy
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Sounds like you have a battery that is heading south.
Battery surface voltage(ie ignition off, nothing running) s/b :
12.5V < Bat. < 12.8V
Your low surface voltage will make the alternator work harder.
Battery surface voltage(ie ignition off, nothing running) s/b :
12.5V < Bat. < 12.8V
Your low surface voltage will make the alternator work harder.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You had a discharged battery at the best and a defective battery at the worst. Charge your battery overnight with a battery charger and if your car can sit for at least 6 hours, measure the battery voltage again. 12.0 volts and below, discharged, 12.9 volts and above, fully charged and linear in between. If after charging and sitting you still measure below 12.0 volts, then you have a battery that is defective and needs to be replaced.
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