Battery gauge Dive
Thread Starter
Racer
Joined: Jan 2001
Posts: 452
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From: The Dark Side of the Moon
Battery gauge Dive
Sometimes when I am idling at lights or in traffic or just coming off the highway and stopping, the battery gauge jumps from the middle to about 10 or so. The lights dim briefly and the aftermarket radio shuts off for a minute. I went to Auto Zone and got the alternator tested and it is charging fine. The battery is only about 4 months old. I don't have any test kit for codes (any recommendations?). Any idea as to what is causing this or what I can do to diagnose it?
Instructor
Joined: Oct 2000
Posts: 206
Likes: 0
From: Nashville, Tn. 37211 TN.
Re: Battery gauge Dive (Shawn93PoloConv)
Sounds like a voltage regulator which I believe is built into the alternator. Maybe a loose or worn positive wire grounding out. I had a loose conection at my starter once and it gave me fits til I located the problem.
LOL :flag
LOL :flag
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Re: Battery gauge Dive (Shawn93PoloConv)
:cheers:
look for previous posts concerning heat build-up and alternator output.
You're symptoms seem to come when heat is probably high and little air flow under the hood.
Chances are pretty good that alternator is tested with hood open or off car...less heat.
Stuck in traffic I have watched my voltage drop to high 11's on a new alt....opened the hood to cool it down and it came back up to 13.5 pretty quickly.
You are probably seeing the early warning signs of Alt failure
Be prepared, as you have seen and I have experienced, when Alt goes car shuts down...even in the middle of an intersection :(
Hope I am wrong, check all the usual things like loose or dirty connections. Try opening the hood when it is hot and volts are low, see if it makes a difference
:seeya Jack
look for previous posts concerning heat build-up and alternator output.
You're symptoms seem to come when heat is probably high and little air flow under the hood.
Chances are pretty good that alternator is tested with hood open or off car...less heat.
Stuck in traffic I have watched my voltage drop to high 11's on a new alt....opened the hood to cool it down and it came back up to 13.5 pretty quickly.
You are probably seeing the early warning signs of Alt failure
Be prepared, as you have seen and I have experienced, when Alt goes car shuts down...even in the middle of an intersection :(
Hope I am wrong, check all the usual things like loose or dirty connections. Try opening the hood when it is hot and volts are low, see if it makes a difference
:seeya Jack
Burning Brakes
Joined: May 2000
Posts: 1,181
Likes: 0
From: Puyallup Washington
Re: Battery gauge Dive (Shawn93PoloConv)
Spend a little more money with a quality rebuilder. Ask for the welded diodes (stock is soldered, they get hot and the solder melts), upgrade the stator to 130 amp (a little better than the stock 105 on the early C4's), replace the rear end frame with the one that takes the 10mm wide rear bearing (it also has cooling fins on it). It will hold up and charge much, much better! The local guy gets $220.00 exchange. He does not have a lifetime warranty, but you will not spend the rest of your life changing them either.
[Modified by moffitt, 7:28 PM 10/2/2001]
[Modified by moffitt, 7:28 PM 10/2/2001]
Le Mans Master
Joined: Oct 1999
Posts: 6,366
Likes: 34
Re: Battery gauge Dive (Shawn93PoloConv)
My 90 does a votage dive down then comes right back up when my 2nd fan turns on at idle.
Also, at idle, if I turn the turn singnal on, the voltage will dive with the flash.
It was my understanding that the 130 amp alt puts out less juice at idle? anyone know for sure?
Also, at idle, if I turn the turn singnal on, the voltage will dive with the flash.
It was my understanding that the 130 amp alt puts out less juice at idle? anyone know for sure?
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Battery gauge Dive (Shawn93PoloConv)
At idle speed the alternator cannot deliver its rated output . I doubt that you were drawing 105 amps. At any temperature , I have never seen my voltage drop below 13.3 volts. You must have a battery at the end of its life and a very low amphour capacity because it should hold up 12 volts for much longer than a long stoplight. You might also have an alternator with an open diode which can deliver rated current at high rpm, but very little at idle rpm. Most ignition analyzers show the voltage waveform across the battery and this will definetely show if any diodes are not doing their job. If you know someone with an oscilloscope, you can look at the waveform also and it should be continuous half sine pulses with none missing. I suspect both your alternator and your battery.
Le Mans Master
Joined: Oct 1999
Posts: 6,366
Likes: 34
Re: Battery gauge Dive (jfb)
I meant the 130 amp alt put out less juice then the 105 amp at idle. I thought I read that somewhere on the net a year or 2 ago when I was looking into a 130 amp alt, but you never know what is true on the net. :confused:
My voltage gauges has done this dive thing for all 5 years I have owned it. over that time I must of put 10 alts in it and 2 batteries, I have no idea why it does it. I figure with that amount of parts thrown at it, something is not right elsewhere.
My voltage gauges has done this dive thing for all 5 years I have owned it. over that time I must of put 10 alts in it and 2 batteries, I have no idea why it does it. I figure with that amount of parts thrown at it, something is not right elsewhere.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Battery gauge Dive (bill mcdonald)
Bill, I sincerely hope that all 10 batts and alts were really defective. Take a digital voltmeter in the car with you and measure the cigarette lighter voltage when your dash voltmeter dips and see if both voltmeters agree. Be careful not to short the center connector on the lighter socket to ground when you are measuring the voltage. You probably just have a dash voltmeter connection problem. Your car will stop running at 10 volts and since it hasn't , the battery voltage probably isn't really at 10 volts.
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Battery gauge Dive (Shawn93PoloConv)
If the voltage dips and then comes back up, It's probably because your fans are kicking in. Check your fan relays and connections. If you have a DVM, make sure there's no voltage drop on the wires or across the terminals. A quick check (be careful of moving parts!) is to feel the wires at the connectors. If they're really hot, it's probably the connectors.
Drifting
Joined: Jul 2001
Posts: 1,511
Likes: 1
From: Winter Park Fl
Re: Battery gauge Dive (Shawn93PoloConv)
The "old style" 130 amp alt. also has larger bearings and will last forever. The retro is well worth the effort. ( unless you are preserving your car for the next guy 100 years from now.)