voltage problems
Thread Starter
Instructor
Joined: Sep 2015
Posts: 143
Likes: 25
voltage problems
Hello,
92 base model. I start the car, and runs good for a few minutes, then voltage starts going up and down. Turn on headlights. car just about dies. Voltage on battery is 12 volts even, so I put slow charge on it and if time permits. I might pull the alternator and have it tested. The auto parts store said their machine will test everything as a whole unit ? Not sure if that covers the voltage regulator or not ? Anyway on hold until I can get the battery up to full and go from there. Could be a bad battery ? Have had interior lights flicker or dim with door open pressing on brake. Could be a bad ground too ?
92 base model. I start the car, and runs good for a few minutes, then voltage starts going up and down. Turn on headlights. car just about dies. Voltage on battery is 12 volts even, so I put slow charge on it and if time permits. I might pull the alternator and have it tested. The auto parts store said their machine will test everything as a whole unit ? Not sure if that covers the voltage regulator or not ? Anyway on hold until I can get the battery up to full and go from there. Could be a bad battery ? Have had interior lights flicker or dim with door open pressing on brake. Could be a bad ground too ?
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
A quick assessment: measurement of battery voltage with and without the engine running.
If both are the same - charging problems
If running voltage is 1.5 volts higher than stopped voltage, other problems may need looking into.
If both are the same - charging problems
If running voltage is 1.5 volts higher than stopped voltage, other problems may need looking into.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
I would check all battery connections especially on the engine and chassis. See if anything is loose and clean them.
Make a measurement with an external DVM when running OK and when problem is happening. Can also make some resistance readings on the ground wires where possible.
Make a measurement with an external DVM when running OK and when problem is happening. Can also make some resistance readings on the ground wires where possible.
5th Gear
Joined: Dec 2015
Posts: 5
Likes: 0
A battery should show high 12 to low 13 volts if its any good. low 12s and its on its way out. Mine was showing 13.2 down to 12.1 inside. Put my tester on after a fresh alternator and battery. 14.5 dead even. idle or wicking it.
Here's a trick. My little Bro works for Johnson controls building new battery's and this has work a couple times.Completely discharge the battery. hook it up to a dc welder. About 60 amps was as brave as I could get .give a good 60 second blast a couple times.Sometimes this is enough to clean the plates so she'll charge again.
That is a small sample of what they do to them once there assembled.
Here's a trick. My little Bro works for Johnson controls building new battery's and this has work a couple times.Completely discharge the battery. hook it up to a dc welder. About 60 amps was as brave as I could get .give a good 60 second blast a couple times.Sometimes this is enough to clean the plates so she'll charge again.
That is a small sample of what they do to them once there assembled.
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Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
No harm having the battery and the charging system checked out, just to be sure nothing else, perhaps, is lurking there. (I'd also have a load test done by a shop or one of the parts stores equipped to do so...properly (as in having the proper equipment and following correct procedures).
14.7 volts is nominal for a cold engine (battery at room temp). 15.58v...isn't exactly alarming (to me), but would depend on what circumstances were present at the time. But, if everything else checks out, e.g., the battery load test, all connections are cleaned (not merely "looked at"), and that voltage remains high, even after driving for half an hour to an hour or so, w/ or w/o the lights on...I'd be concerned enough to replace the regulator and retest.
(Ya don't want to "cook" the battery dry, or have the alternator crap out (over-heat) either.Bottom line...I wouldn't be comfortable were that reading be my car, except under unusual circumstances. Just me....
Last edited by Paul Workman; Dec 29, 2015 at 09:18 AM.
Team Owner
Joined: Feb 2006
Posts: 23,144
Likes: 117
From: San Antonio Texas
Sometimes even a tight connection isn't an electrically good one. The batt. terminals and cable ends sometimes get some kind of hard glass like coating on them that acts like an insulator. It doesn't look bad like corrosion but it isn't a good metal to metal connection, kind of a dark grey glassy look. A good wire brushing gets that stuff of and suddenly everything comes alive again! Ground straps to frame get rusty too. Crummy grounds cause all kinds of weirdness.
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
Sometimes even a tight connection isn't an electrically good one. The batt. terminals and cable ends sometimes get some kind of hard glass like coating on them that acts like an insulator. It doesn't look bad like corrosion but it isn't a good metal to metal connection, kind of a dark grey glassy look. A good wire brushing gets that stuff of and suddenly everything comes alive again! Ground straps to frame get rusty too. Crummy grounds cause all kinds of weirdness.
Good point.
Once the surfaces are cleaned (sandpaper) and threads chased on both the battery and the side-mount terminal connections, you can buy some terminal spray-on dressing to protect the connector somewhat from futher corrosion. OR, (my preference) is using some dielectric grease: either will retard further corrosion for a long time.
Thread Starter
Instructor
Joined: Sep 2015
Posts: 143
Likes: 25
still guessing
I replaced the alternator with a decent remanufactured one. I felt it was a good idea at the time. The battery appears to be one year old. I will have it tested this weekend ? It's weird , because it starts good and runs for up to 10 minute, then starts with erratic voltage ? I put it in drive and starts missing, running like crap. I put the headlights on and it starts to really flip out. Unless I missed a ground or I have computer issues ? Or even a opti ? I'll give it another go after the holiday. Thank you.
Intermediate
Joined: Jul 2015
Posts: 38
Likes: 0
Just a thought...
I drove my 87 from NJ to Florida this past weekend. My dash lights started the flickering a few hours into the ride. The whistle over the stereo got worse and the V indicator was pretty erratic. It all got worse when it got dark and put on the headlights.
I have anew alternator and battery and post bolts.
After looking thru the forum, I keyed in on the distributor and the all the plugs going into the coil. Saw no change.
Then I wondered if maybe the gauge cluster itself may be the issue so I began pulling fuses related to the gauges, inst lights etc. With the cluster and lights all unplugged, the whistle thru my speakers stopped. One by one I popped the fuses back in. The trouble stopped. I'm thinking I may have had an oxidized fuse w/ a flaky connection. Voltage now steady, no flicker and no stereo whine.
.... Now I just hope she gets me back up to Jersey. Also treated her to a window tint while down here
I drove my 87 from NJ to Florida this past weekend. My dash lights started the flickering a few hours into the ride. The whistle over the stereo got worse and the V indicator was pretty erratic. It all got worse when it got dark and put on the headlights.
I have anew alternator and battery and post bolts.
After looking thru the forum, I keyed in on the distributor and the all the plugs going into the coil. Saw no change.
Then I wondered if maybe the gauge cluster itself may be the issue so I began pulling fuses related to the gauges, inst lights etc. With the cluster and lights all unplugged, the whistle thru my speakers stopped. One by one I popped the fuses back in. The trouble stopped. I'm thinking I may have had an oxidized fuse w/ a flaky connection. Voltage now steady, no flicker and no stereo whine.
.... Now I just hope she gets me back up to Jersey. Also treated her to a window tint while down here
Safety Car
Joined: Aug 2006
Posts: 4,147
Likes: 452
From: Port St. Lucie West Florida
Just a thought...
I drove my 87 from NJ to Florida this past weekend. My dash lights started the flickering a few hours into the ride. The whistle over the stereo got worse and the V indicator was pretty erratic. It all got worse when it got dark and put on the headlights.
I have anew alternator and battery and post bolts.
After looking thru the forum, I keyed in on the distributor and the all the plugs going into the coil. Saw no change.
Then I wondered if maybe the gauge cluster itself may be the issue so I began pulling fuses related to the gauges, inst lights etc. With the cluster and lights all unplugged, the whistle thru my speakers stopped. One by one I popped the fuses back in. The trouble stopped. I'm thinking I may have had an oxidized fuse w/ a flaky connection. Voltage now steady, no flicker and no stereo whine.
.... Now I just hope she gets me back up to Jersey. Also treated her to a window tint while down here
I drove my 87 from NJ to Florida this past weekend. My dash lights started the flickering a few hours into the ride. The whistle over the stereo got worse and the V indicator was pretty erratic. It all got worse when it got dark and put on the headlights.
I have anew alternator and battery and post bolts.
After looking thru the forum, I keyed in on the distributor and the all the plugs going into the coil. Saw no change.
Then I wondered if maybe the gauge cluster itself may be the issue so I began pulling fuses related to the gauges, inst lights etc. With the cluster and lights all unplugged, the whistle thru my speakers stopped. One by one I popped the fuses back in. The trouble stopped. I'm thinking I may have had an oxidized fuse w/ a flaky connection. Voltage now steady, no flicker and no stereo whine.
.... Now I just hope she gets me back up to Jersey. Also treated her to a window tint while down here
Last edited by enventr; Jan 1, 2016 at 11:50 AM.