Electrical Battery Recharge Issues

Discussion in '1994 - 1995 Specific Tech' started by JordanB21, Jul 4, 2012.


  1. JordanB21

    JordanB21 Active Member

    Joined:
    Feb 7, 2012
    Messages:
    804
    Likes Received:
    26
    Trophy Points:
    29
    My battery doesn't recharge, but it does stay at constant voltages.

    For example I started it and it would stay at a very low 12.51-.53 volts. I turn on the a/c and headlights and it stays on at a constant 12.15-.17 volts. The battery I had tested and charged at a battery shop, the battery is still good. I had the altnerator replaced a few months back with a rebuilt one because the old one went bad. Taking into consideration the battery shop said the battery shouldn't be lower than 13.6 at the lowest and should be as high at 15.3 volts.

    Recently I installed a new headunit and it worked fine till recently (I think the fuse in the back of it might of popped, still have to check) and now it doesn't turn on. The battery issue arised when I kept taking off the negative terminal for precaution and it had a crack down the side causing it to not start. then I replcaed it with some cheap-o terminals and they cracked (really cheap). Bought heavy duty ones and now it starts but this weird low voltage issue is occuring, and only started after I had messed with the terminals. I had also put in an 8'' sub along with the headunit but with or without the fuse in the line for the sub it read low volts.

    My questions are is there a fusal wire between the alternator and battery, is it possible the alternator is bad, or going bad (it's complicated because the car wouldn't die out, just stay at a low constant charge).
  2. revhead347

    revhead347 I have face herpes.

    Joined:
    Jun 14, 2004
    Messages:
    6,456
    Likes Received:
    254
    Trophy Points:
    124
    Yes, there is a fusable link in the line between the alternator and the fuse box. Check the voltage at the battery when the engine is not running, and then again when the engine is running.

    Kurt
  3. HISSIN50

    HISSIN50 "How long does it take to get help in here? SN Certified Technician

    Joined:
    Nov 30, 1999
    Messages:
    31,148
    Likes Received:
    13
    Trophy Points:
    79
    You could do a continuity test on the link if you disconnect both ends of the cable. If you do this, wiggle test the wire as you test it - links can act kinda funky when they burn.

    Is your battery light on (does it prove out when you turn the car on)?

    If your light is functional and the charge cable is ok, test the regulator wiring. The wires are labeled with letters on the side of the regulator. A should show battery voltage. I should show 2-12V (it should be ok if the battery light proves-out). S should float about 1/2 alternator output.

    Be sure the alt cable is clean and tight on the side of the fusebox. That connection can get corroded or loose.
    If your alt or bracket is painted or powdercoated, the alt needs to be grounded.

    Good luck.
  4. JordanB21

    JordanB21 Active Member

    Joined:
    Feb 7, 2012
    Messages:
    804
    Likes Received:
    26
    Trophy Points:
    29
    Kurt, the numbers were 12.62 off, and 12.33 on, the on was constant while idling.

    Hissin, sorry I didn't see your post till today, I'll try and get a chance to do that all today. The cars sitting at a parking lot of an automotive scrap yard right now (I know the owner) since I couldn't get it home and don't want to risk it yet.
  5. revhead347

    revhead347 I have face herpes.

    Joined:
    Jun 14, 2004
    Messages:
    6,456
    Likes Received:
    254
    Trophy Points:
    124
    Ok, the next question is, does the voltage go up if you rev the engine. You shouldn't have to rev it up much at all. Sometimes you get a discharge at idle with a poor alternator. The voltage has to be higher with the car running then with it off. If you want to test that fusable link, just test the voltage between the alternator stud and the case. If it's higher than the voltage at the battery, it's possible you blew a fusable link. Most likely it's a bad alternator though.

    Kurt
  6. JordanB21

    JordanB21 Active Member

    Joined:
    Feb 7, 2012
    Messages:
    804
    Likes Received:
    26
    Trophy Points:
    29
    The voltage doesn't go up at all, I would use the throttle in the engine bay lightly to where it would touch the EGR pipe and it stays constant at whatever voltage it was resting at originally.

    and by case do you mean the casing of the alternator, or the fuse box?
  7. revhead347

    revhead347 I have face herpes.

    Joined:
    Jun 14, 2004
    Messages:
    6,456
    Likes Received:
    254
    Trophy Points:
    124
    I was saying the alternator case. Double test for the fusable like, and a good ground on the alternator case.

    Kurt
  8. JordanB21

    JordanB21 Active Member

    Joined:
    Feb 7, 2012
    Messages:
    804
    Likes Received:
    26
    Trophy Points:
    29
    Alright, I took my multimeter to the top terminal on the alternator where the wire is connected to and grounded it on the case and it read 12.33 or so. Got the same reading from the battery. So I think that means the fusable link is good still and the alternator is bad.

    One thing I don't understand is how is the voltage that the alternator is putting out constant even when I press the throttle? It's constant no matter how fast the belt is spinning.
  9. HISSIN50

    HISSIN50 "How long does it take to get help in here? SN Certified Technician

    Joined:
    Nov 30, 1999
    Messages:
    31,148
    Likes Received:
    13
    Trophy Points:
    79
    You're probably just running off of the battery. If you turn on the lights and HVAC fan, does the voltage drop?
  10. JordanB21

    JordanB21 Active Member

    Joined:
    Feb 7, 2012
    Messages:
    804
    Likes Received:
    26
    Trophy Points:
    29
    yes it does, at the alternator it went as low as 11.84 while the battery was slightly higher, that was with brights on and max a/c. Then going back to lights and a/c off it returned to a low 12.14. Down from the original 12.33. So if it's the current of the battery going through to the alternator it makes sense.
    Im going to try and take it to advance auto(where I got the alternator from) and have it replaced. Lifetime warranty:D
  11. HISSIN50

    HISSIN50 "How long does it take to get help in here? SN Certified Technician

    Joined:
    Nov 30, 1999
    Messages:
    31,148
    Likes Received:
    13
    Trophy Points:
    79
    Sounds good. If it passes for some reason, do those quick wiring tests (takes 3-5 minutes) to see if that's the issue.
  12. JordanB21

    JordanB21 Active Member

    Joined:
    Feb 7, 2012
    Messages:
    804
    Likes Received:
    26
    Trophy Points:
    29
    alright, ill have to take it to them tomorrow, doubt it will pass after the numerous times ive taken the multimeter to it. Thanks Hissin, thanks Kurt!
  13. revhead347

    revhead347 I have face herpes.

    Joined:
    Jun 14, 2004
    Messages:
    6,456
    Likes Received:
    254
    Trophy Points:
    124
    Yeah bad alternator. It won't pass; not if the voltage is consistently nothing.

    Kurt
  14. HISSIN50

    HISSIN50 "How long does it take to get help in here? SN Certified Technician

    Joined:
    Nov 30, 1999
    Messages:
    31,148
    Likes Received:
    13
    Trophy Points:
    79
    I agree that the alt is probably the issue, but bad wiring could keep the alternator from having any output.
  15. revhead347

    revhead347 I have face herpes.

    Joined:
    Jun 14, 2004
    Messages:
    6,456
    Likes Received:
    254
    Trophy Points:
    124
    I tell you one thing. I had a similiar issue that took me months to figure out. The damn printed circuit on the back of the instrument cluster burned out, and that causes the alternator not to function. I tracked it down to the printed circuit and changed it. It worked for 5 minutes, and then printed circuit burned out again. I assumed that it had to be a wiring problem that was causing a high current on the printed circuit forcing it to fail, and I must have traced every wire in the car. Turns out I had 2 bad printed circuits in a row. What are the odds?? The worst part is, they don't sell those anymore. So you have to find a used one. I got lucky and someone here on stangnet mailed me another printed circuit for the cost of shipping.

    Kurt
  16. HISSIN50

    HISSIN50 "How long does it take to get help in here? SN Certified Technician

    Joined:
    Nov 30, 1999
    Messages:
    31,148
    Likes Received:
    13
    Trophy Points:
    79
    I remember that Kurt.
    If it happens again, you could do some bypassing, running crank/run power through the battery light (manually connect wires to the light socket itself) and your own 500 Ohm resistor (in parallel), and run that to the I circuit on the alternator's regulator (disconnect the OEM I circuit at the regulator so it does not interfere with the new I circuit).
  17. revhead347

    revhead347 I have face herpes.

    Joined:
    Jun 14, 2004
    Messages:
    6,456
    Likes Received:
    254
    Trophy Points:
    124
    I was actually planning on rebuilding the stock printed circuit by gluing thicker metal strips down to the old printed cicuit and using a dab of solder at the light connection and the resistor. Wiring it manually would have involved extra plugs to secure back in behind the cluster. In all honesty, what I probably should have done is just put a matching resistor into the wiring harness directly so that power could bypass the printed cicuit altogether. I really don't need a charging fail light since I have a voltage gauge. It just kills my OCD not to have it working the way it should be. I got lucky someone had an extra cluster. Those clusters go for $75-$150 used on ebay, and I wasn't going to buy another one.

    If the test bench at the autoparts store shows the alternator still working, don't get in a fit. Those test benches are damn accurate. The only thing they don't show is if the alternator has a charge problem at low rpm, which isn't the case here because yours isn't working at any voltage. The yellow wire is hot all the time from a fuse in the underhood fuse box. Make sure that has constant 12+V. The white wire just circulates from one part of the alternator to the other. Not sure why that circuit wasn't just put internal to the alternator in the first place. It goes from the 3 wire connection to the single wire connection. Make sure there is good continuity on that wire. The green wire is the ****. That is the one that tells the alternator to turn on. It is wired all through the car. It is tied through the ignition switch through the light in the cluster and then to the alternator.

    Kurt
  18. JordanB21

    JordanB21 Active Member

    Joined:
    Feb 7, 2012
    Messages:
    804
    Likes Received:
    26
    Trophy Points:
    29
    Probably should've let you guys know. Got the alternator for free, warranty restarted and is good for a year and the problem is solved. Im on my second new alternator and second new battery in the past 6 months.

    The new alternator seems to be working better than the last, it constantly compensates for the voltage to keep it at around 14 volts. The last alternator would only compensate for low voltage, when the meter would drop down to around 12 volts and then pick backup. The only thing im worried about now is that at idle my sound system (when turned far up) can actually show the meter jumping up and down a small segment. Maybe in the future as I upgrade the sound system and add other electrical draws ill upgrade the alternator to a higher amperage one.

Share This Page