low voltage worries

jvandyke

jvandyke

True Classic
Starting a new thread on this though it was started in this one.
Symptoms: voltage meter reads very low when headlights are on. At all other times it's slightly above the halfway point. Headlights seem dim, blinkers seem slow. Turn off headlights and meter goes back up to "normal". Red warning light does not come on or glow at anytime (while car is running, it lights up when key is on before start up, as it should).
Have heard slight belt squeal occasionally. Belt is new but I cheated and put on a slightly longer one and now I question that it is tight enough. I will first put on the proper belt (despite installation hassle).
I installed a second voltmeter running straight off the battery and it follows the factory one in behaviour though the readings are generally a bit higher, when "low", under headlight usage, it is still above 12v, though only a bit, when no headlights it reads closer to 14. I'm getting nervous the battery isn't getting recharged sufficiently and I'm on borrowed time. I did put the battery on a charger the other night and the charger said it was charged by morning. I think I'm recharging sufficiently every afternoon on the commute home but obviously that's not "good enough".
Things to look at beyond slight belt slippage? I will also check connections at the alternator. I did read wire connection issues INSIDE the alternator can be problematic. Here's a shot of mine, can't remember if I took this before or after I put the new belt on but you can see there's no room left for tightening and wires are stressed and if there's supposed to be a rear cap, there ain't.
alternator.jpg


PS
headlight are on relays, wired in before the fuse block, BWM done at the fuse block and the ignition switch, ground cable at battery upgraded and engine ground strap "refreshed".
 
!

My car (an 86) does the same thing, even after replacing the alternator. I've never had problems with dead battery, and the red warning light never comes on.

I assume that the alternator output is just low. I wonder if anyone has installed one of the many Bosch alternators out there with a higher output?
 
eflexter said:
My car (an 86) does the same thing, even after replacing the alternator. I've never had problems with dead battery, and the red warning light never comes on.

I assume that the alternator output is just low. I wonder if anyone has installed one of the many Bosch alternators out there with a higher output?
Click to expand...

I read up on different alternator options during my research, GM is common replacement it seems, Bosch was mentioned but pricier and not as robust as I recall. I won't panic then I guess but will put the proper belt on (for better tension) and check/clean connections on the alt. Wondering why it wasn't like this, now it is. Variables recently played with are;
new belt, 1" over size, mild evidence of slipping (but that was put on and working fine weeks back, could have stretched to too loose since I suppose).
Cluster pulled for speedo play and white gauge face install and voltmeter replaced twice, dead the first time, 2nd one pegged full 16 with key on, current one (3rd) in use as described.
Several weeks of winter driving including cold, wet, snow and salt could be taxing the alternator/connections/belt.
 
!

I also believe that I have a bad ground to my instrument cluster area. My window wipers are slow, and I've replaced the motor with a known good one.

Whatever is up with my wipers may be also making the guage read low.

I know there are things not perfect on my car, but it keeps running and I don't want to take it apart all the time! It's possible that the circuit that energizes the alternator and makes it charge harder under load, is the same circuit that make my wipers run slow, and also the guage read low.

Probably something like the ignition switch!

But it keeps working, so I keep driving.
 
Me too

I have the same problem. I changed the voltage regulator to an adjustable one from IAP it helped allot I was able to adjust the voltage up to 14.7 ( if I put the adjustment up all the way it gos over 15v but then its over charging and that's bad )but when the car worms up it gos down to 14.4 and with headlight on its 13.9 .someday I want to go to the GM one wire because a good quality one will regulate the voltage much better.I think most of the problem is our alternators are just old technology newer alternators do the same thing just not as bad I put a digital volt meter on my 95 Dodge Neon it dos drop in voltage when the head lights are turned on but not much so imagine a brand new good quality GM one wire.

hears the link to the IAP Adjustable Voltage Regulator
http://www.international-auto.com/index.cfm?fa=p&pid=2543&posid=907592

38504000w.jpg


you can adjust it on the fly with the car running I used a Digital volt meeter. I cheeked at different places like battery,fuse box ,cigarette litter and at the alternator.
 
One other cheat I have used

Hi Jeff,

On my 78 I had a similar issue with the volt meter dropping off the chart and reading low in general. I added a 10 gauge wire from the alt's output lug to the starter lug with the large green wire that connects back to the battery. This new line is in addition to the exiting wire, but gives a nice clean path between the alt and starter without 30 years of decay.

This new wire did make a difference in the voltmeter and things seemed brighter, however the VM still drops a lot with the headlights on, etc. I will be putting in my BobbyB relays this spring.
 
Well, this is weird.
Left work for home with a stop at parts place to get a 32" belt.
Started, took off, volt meter normal, turned on lights, drops to just above red zone. Turned lights off, volt meter did NOT return, stayed low through town. Now I'm a bit worried, got on highway, a few miles, meter reading very low, secondary volt meter says just over 12. When I got off the highway I was surprised that while at a light the voltmeter slid back up. Drove to parts store, turned lights on and off while idling. NO movement. Left for home. Turned lights on halfway home, meter stayed up. It's not consistent with lights I guess.
Alright, I'll put the correct 32" belt on, clean up connections and monitor.
I've got relays on the lights already.
 
!

The Bosch voltage regulator (similar to the picture up above) is pretty flaky anyway. I've had problems with them on my Volvo, BMW motorcycles, VW's and Porsches. It's like they get "sticky" as they get old. The ones I have would stick in the over-charge position and the headlights get REAL bright. Then they pop back to normal or fail completely.

Your regulator may be getting old, and it's making the diagnosis more complicated.
 
Built in VR on the Bosch

If you were look at the wiring side of the alt as a clock face, it would be about 4 o'clock in the picture you put in the initial post. You can see it directly below the wire bundle. It is oblong with screws at both ends, black in color, plastic and has a circular protrusion.

alternator.jpg
 
Alternator....

I've seen something similar to this on an old Toyota Tercel. (a buddy's car)

He was out of town and called me with this....his lights were really dim, but the Charge Light wasn't on.

He had good lights earlier, and seemed like they dimmed after he drove through some slushy snow.

I had him check all the obvious things, belt, bolts, wires etc.

One last thing I had him do is give it a good tap with a tire iron :mallet:( he didn't have a hammer) while the engine was running.

All of a sudden the lights went much brighter.:headbang:

He got it home and replaced the alternator. We figure the brushes were worn just enough to still have contact on the armature but not enough contact to give a full charge.

Hope this helps,
 
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Okay thanks, I'll play with it tomorrow. Gunna let discretion be the better part of valor and give the poor thing tomorrow off, it's earned it.
 
New 32" belt. Cleaned little spade connection at the alternator, should probably solder a new one on. I could turn the alternator by hand before, could not after new belt and tighter. One quick run, voltage did not vary, stayed right around 13/14. Looks good.
altbelt.jpg
 
Run into work, voltage is steady at 14ish no matter what I have turned on.:headbang: Headlights are back to bright (relatively) and I'm not so worried anymore.
Pretty sure the culprit was a looseish belt allowing slippage and poor charging, I did clean up alternator connections too though. Still should hunt down and reinstall a belt shield.
 
Guess what? Voltage drop out again, worse than ever, light actually came on and I was turning off lights and wipers. It was raining so I'm thinking wet belt slippage BUT it started with in a few feet of leaving work, can't imagine it got wet so fast but maybe. It would periodically jump up for a bit then fall. RPM effected it in that respect, like as the torque changed the belt caught. On highway was fluctuating mostly low then read low and started to turn on idiot light after about 10 miles into it but after getting off, it came back up, was normal at idle, only really get's low at speed. I detected a bit of belt squeal as I rounded the corner for home. I will tighten the belt up some (it was new mid Jan.).
so, should I just go GM,
source a belt splash guard (I don't have one)
I'm thinking GM mod and be done with it. Did it to my Opel, I can do it to the Fiat too.
 
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