I don't usually post new topics about my technical problems because I usually search and find it myself, but I have never ran into this type of thing before. I just recently replaced my alternator a couple days ago, and when I took the car for a drive it felt normal but when I took it to 7k my battery light came on and when my rpms go below 7k the light turns off. Just curious if anyone ran into this type of thing before. I am stumped on what it could be. Any help would be very much appreciated. Thanks.

 

hook up a volt meter and see what voltage it reads when the light comes on. My guess is the alternator might be new/reman but the voltage regulator might have been a bad one, it might be putting out too much voltage at that rpm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Crx Jimmy &raquo;</TD></TR><TR><TD CLASS="quote">hook up a volt meter and see what voltage it reads when the light comes on. My guess is the alternator might be new/reman but the voltage regulator might have been a bad one, it might be putting out too much voltage at that rpm</TD></TR></TABLE>

Where do I check the voltage? I'm not a big fan of electrical issues so my knowledge is very little.

 

negative and positive batt. terminals. its not strange at all, in fact i saw this problem fry an ex-grand am cup type r ecu at roebling from too much voltage for too long. be weary until you have this problem rectified.

 

I just took the car for a drive, when I get to 7600rpm the car cuts off and when the rpms drops back down to 6k the car comes back on..I am gonna go test the voltage right now.

 

I checked the voltage and the voltage stayed stable all the way to 8k at 12.5.

 

doesnt sound like alternator is charging the battery.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jonknee &raquo;</TD></TR><TR><TD CLASS="quote">doesnt sound like alternator is charging the battery.</TD></TR></TABLE>
Really? does the voltage change as the rpms go higher?

 

check the tension on your belt. is it tight enough?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wizdom1 &raquo;</TD></TR><TR><TD CLASS="quote">check the tension on your belt. is it tight enough?</TD></TR></TABLE>

Tension is good

 

your alternator is suppose to be charging your batttery at 14.5v or so. not 12v. 12.5v is a static battery

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pandarex &raquo;</TD></TR><TR><TD CLASS="quote">your alternator is suppose to be charging your batttery at 14.5v or so. not 12v. 12.5v is a static battery</TD></TR></TABLE>

I see, since my voltage stays at 12 while my car is revving, then my alternator is not charging the battery....imma double check my connections tomorrow, and do another voltage test.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cheeech &raquo;</TD></TR><TR><TD CLASS="quote">
Really? does the voltage change as the rpms go higher?</TD></TR></TABLE>

No. That's why there is a regulator.

Ok, you need a crach course in how an alternator works.

The alternator is basically a small electric engine, brushed engine. When polarity is reversed and you spin it, it will create electricity. Running a belt on a pully makes it all happen. The electricity that gets created is quite capable. At idle you should be in the mid 12V to low 14V range. When you spin it faster (7000rpm) you should be creating more electricity, but luckily for us honda put on a regulator, that limits it to 14.5V I beleive. When ever you go over that you risk cooking your wire. How do I know? Well my regulator died and the wire for my alternator got so hot it melted the loom right off, it also set fire to the alternator. When I did my testing it prooved a faulty regulator had stopped working and allowed the alternators full potential thru.

Now, if at idle you are making in the 12V range, your alternator is more then likely fine. I would do a check on your wiring/battery to make sure everything is ok. The other test I would do is a load test on the alternator, that requires you to remove it. There is a chance your alternators brushes are working at low potential, and when forced to rev high, produce a low output.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ludesrv &raquo;</TD></TR><TR><TD CLASS="quote">

No. That's why there is a regulator.

Ok, you need a crach course in how an alternator works.

The alternator is basically a small electric engine, brushed engine. When polarity is reversed and you spin it, it will create electricity. Running a belt on a pully makes it all happen. The electricity that gets created is quite capable. At idle you should be in the mid 12V to low 14V range. When you spin it faster (7000rpm) you should be creating more electricity, but luckily for us honda put on a regulator, that limits it to 14.5V I beleive. When ever you go over that you risk cooking your wire. How do I know? Well my regulator died and the wire for my alternator got so hot it melted the loom right off, it also set fire to the alternator. When I did my testing it prooved a faulty regulator had stopped working and allowed the alternators full potential thru.

Now, if at idle you are making in the 12V range, your alternator is more then likely fine. I would do a check on your wiring/battery to make sure everything is ok. The other test I would do is a load test on the alternator, that requires you to remove it. There is a chance your alternators brushes are working at low potential, and when forced to rev high, produce a low output.</TD></TR></TABLE>

Good info, i did not know this I did check my wiring to the battery and all is well, the ground is grounded properly as well as my other grounds..tranny, valve cover etc. How do u do a load test? after the alternator is removed?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ludesrv &raquo;</TD></TR><TR><TD CLASS="quote">

Now, if at idle you are making in the 12V range, your alternator is more then likely fine. </TD></TR></TABLE>

as far as my knowledge extends your alternator is suppose to be holding a constant 14.something volts. get out to your car with a voltmeter and see. good luck with fixing your problem

 

my alternator mitsuba or w/e manual said it was supposed to be from 13-14 volts at idle.