Alternator Charging Issue

[ledzilla]

So, yes, looks like I have yet another alternator issue. I've had a few issues where I'd come out to my Bronco, but there wasn't enough juice in the battery for it to start. I ended up swapping batteries a couple times in the last month or so from the local junkyard (one battery wouldn't hold a charge at all). I was thinking that I had some sort of weird parasitic draw even though the only pull on the battery when not running was the radio's memory circuit (verified to be 0.3A draw when the battery connects and then reduces to below what my meter could read after several seconds, so less than 0.01A). So that wasn't the case. Then I noticed the last two times this occurred, I had driven some distance from home. I headed out in segmented runs, making stops and getting further. But it was just one straight shot home each time. No issues encountered while out and about, only after getting home and trying to start the Bronco again later on. The return journeys were all more than 30 minutes of driving with highway driving or travel on roads near highway speeds. On one of these drives, getting near home, I noticed the instrument cluster looked relatively dim and I tried fiddling with the dimmer switch, but it didn't help. Makes me think it was all running on reduced alternator output.

So, I'm of the mind that the alternator is the problem, but as with most things I don't think it has more than a one year length on the warranty. But assuming that it's not a quality issue with the alternator itself, could there be something else going on under the hood that could cause such an issue on longer drives like this? Maybe too much heat, something pulling an unexpectedly high draw on the alternator? Just want some things to look at before I try looking into replacing the alternator. I don't want to replace it only to have the same issue come back again.

 

[L\Bronco]

So, yes, looks like I have yet another alternator issue. I've had a few issues where I'd come out to my Bronco, but there wasn't enough juice in the battery for it to start. I ended up swapping batteries a couple times in the last month or so from the local junkyard (one battery wouldn't hold a charge at all). I was thinking that I had some sort of weird parasitic draw even though the only pull on the battery when not running was the radio's memory circuit (verified to be 0.3A draw when the battery connects and then reduces to below what my meter could read after several seconds, so less than 0.01A). So that wasn't the case. Then I noticed the last two times this occurred, I had driven some distance from home. I headed out in segmented runs, making stops and getting further. But it was just one straight shot home each time. No issues encountered while out and about, only after getting home and trying to start the Bronco again later on. The return journeys were all more than 30 minutes of driving with highway driving or travel on roads near highway speeds. On one of these drives, getting near home, I noticed the instrument cluster looked relatively dim and I tried fiddling with the dimmer switch, but it didn't help. Makes me think it was all running on reduced alternator output.

So, I'm of the mind that the alternator is the problem, but as with most things I don't think it has more than a one year length on the warranty. But assuming that it's not a quality issue with the alternator itself, could there be something else going on under the hood that could cause such an issue on longer drives like this? Maybe too much heat, something pulling an unexpectedly high draw on the alternator? Just want some things to look at before I try looking into replacing the alternator. I don't want to replace it only to have the same issue come back again.

Hey Led
do you know the battery voltage engine running?
It should be between 13.4 and 15.2 (depending on temp)
I'd measure DCV across the battery at 2000rpm.Then make the same measurement between the alternator B terminal and the housing. (also at 2000 rpm)
They should be pretty close to 2VDC higher than the battery, (engine off), and within .5V of each other.
If there is no charge, (Batt voltage doesn't rise), touch the rear bearing area of the alt (at idle) with a prybar or other metal tool and see if its magnetic.
No magnet means a brush or voltage regulator issue (Or primary power supply)
Magnet and no charge is a stator winding, diode, or output harness issue.

If it is charging, turn the headlights on, run at 2000rpm and measure A/C voltage between the alt B terminal and the housing. (This will test your diodes and stator windings)
It should be below .5V a/c at 2000rpm medium load (headlights)
Sorry for the blast of info.
Hope it helps.
Cheers

 

[Tiha]

Yep, check for over 13 volts when running, voltage should increase and not decrease if you rev the engine.

That era had a bad wire harness, for the longest time new alternators were coming with new harnesses so check that for burnt wires as well.

 

[ledzilla]

Well, I've already tested it to kick out approximately 14.5V at either fast or regular idle and only 0.10-0.15 volt drop with the lights on, and not running the voltage tested at something like 12.67V when I knew the battery was properly charged. The wiring is good. I upgraded the battery cable from the alternator to something like a 4ga battery cable last year. And that's the thing, that the charging is just fine when it isn't running for very long. I can go to the store, grab some food, or whatever when it seems like the engine won't be running for more than maybe 20 minutes.

I'm thinking maybe I should take one of these USB power ports I have sitting around and hook it up. They have a voltage display in the middle. Get it wired up and sit it on top of the dash, keep an eye on that actual voltage, see if I can identify when it drops or something.

Hey Led
do you know the battery voltage engine running?
It should be between 13.4 and 15.2 (depending on temp)
I'd measure DCV across the battery at 2000rpm.Then make the same measurement between the alternator B terminal and the housing. (also at 2000 rpm)
They should be pretty close to 2VDC higher than the battery, (engine off), and within .5V of each other.
If there is no charge, (Batt voltage doesn't rise), touch the rear bearing area of the alt (at idle) with a prybar or other metal tool and see if its magnetic.
No magnet means a brush or voltage regulator issue (Or primary power supply)
Magnet and no charge is a stator winding, diode, or output harness issue.

If it is charging, turn the headlights on, run at 2000rpm and measure A/C voltage between the alt B terminal and the housing. (This will test your diodes and stator windings)
It should be below .5V a/c at 2000rpm medium load (headlights)
Sorry for the blast of info.
Hope it helps.
Cheers

So, the back of the alternator looks like the attached photo. Would the "B" terminal be the big red terminal?

 

[L\Bronco]

Well, I've already tested it to kick out approximately 14.5V at either fast or regular idle and only 0.10-0.15 volt drop with the lights on, and not running the voltage tested at something like 12.67V when I knew the battery was properly charged. The wiring is good. I upgraded the battery cable from the alternator to something like a 4ga battery cable last year. And that's the thing, that the charging is just fine when it isn't running for very long. I can go to the store, grab some food, or whatever when it seems like the engine won't be running for more than maybe 20 minutes.

I'm thinking maybe I should take one of these USB power ports I have sitting around and hook it up. They have a voltage display in the middle. Get it wired up and sit it on top of the dash, keep an eye on that actual voltage, see if I can identify when it drops or something.



So, the back of the alternator looks like the attached photo. Would the "B" terminal be the big red terminal?

You bet!
Let me know what you find.
Cheers

 

[ledzilla]

OK, so it's actually quite difficult to reach that terminal with the alternator installed, and I started getting a little panicky trying to reach it with the engine running, thinking I was going to mash my hand against the headers. So instead I touched the multimeter probe to the other end of the cable where it connects to a 350A bus bar (as seen on TV-- I mean in the attached photo). It gave me a reading of ~14V. I then tested against the battery terminals and got the same voltage reading.

 

[L\Bronco]

Ok cool, its charging and the cables look ok.
Do the A/C voltange check. Go from your bus bar and the alt housing (in A/C voltage mode) with the headlights on. Bring the rpm up a bit too.
You should see well under .5V a/c
A diode or stator winding could be bad, in which case it will appear to charge normally. The symptom you get sounds a lot like your issue.
Lets knock that one off the list, then move on
Cheers

 

[ledzilla]

Well, I took it for it's first drive around since repairing the exhaust the other day. I actually noticed several times that everything dimmed here and there. These instances weren't long, no more than a few seconds each time, but it's telling. I'm willing to bet that had I connected a multimeter or a voltmeter and watched the readouts each time the lights dimmed, there would have been a voltage drop from charge voltage to battery voltage.

Guess it's time to see whether or not the warranty has expired on that alternator.

 

[ledzilla]

So, yeah, the warranty expired a few months ago. I'm tempted to order a voltage regulator from somewhere like RockAuto and swap it out, just to rule out the alternator itself completely failing, since regulators are much cheaper than entire alternators, but I don't trust the quality of aftermarket regulators. I've had a lot of trouble with them on my '78 LTD.

 

[ledzilla]

I actually contacted Tuff Stuff to see if they have recommendations on replacement voltage regulators, given that for some reason they don't retail any replacements. No response at all. So, I'm not much inspired to give them any continued business should I need to replace the alternator. From what I can see, PA Performance offers replacement regulators, and I might just order one of theirs. They appear to be the same format that I need. Or maybe I'll grab one from RockAuto or Bronco Graveyard. Either way, the options all look pretty cheap to purchase.

 

[johnnyreb]

So, yes, looks like I have yet another alternator issue. I've had a few issues where I'd come out to my Bronco, but there wasn't enough juice in the battery for it to start. I ended up swapping batteries a couple times in the last month or so from the local junkyard (one battery wouldn't hold a charge at all). I was thinking that I had some sort of weird parasitic draw even though the only pull on the battery when not running was the radio's memory circuit (verified to be 0.3A draw when the battery connects and then reduces to below what my meter could read after several seconds, so less than 0.01A). So that wasn't the case. Then I noticed the last two times this occurred, I had driven some distance from home. I headed out in segmented runs, making stops and getting further. But it was just one straight shot home each time. No issues encountered while out and about, only after getting home and trying to start the Bronco again later on. The return journeys were all more than 30 minutes of driving with highway driving or travel on roads near highway speeds. On one of these drives, getting near home, I noticed the instrument cluster looked relatively dim and I tried fiddling with the dimmer switch, but it didn't help. Makes me think it was all running on reduced alternator output.

So, I'm of the mind that the alternator is the problem, but as with most things I don't think it has more than a one year length on the warranty. But assuming that it's not a quality issue with the alternator itself, could there be something else going on under the hood that could cause such an issue on longer drives like this? Maybe too much heat, something pulling an unexpectedly high draw on the alternator? Just want some things to look at before I try looking into replacing the alternator. I don't want to replace it only to have the same issue come back again.

When you get out. Have you c heck the brake lights? Sometimes the pedal will stick and the brake lights will run the batter down. Has anyone been having trouble NOT getting message from Bronco Zone ? I have --seems like they quit sending them to me. I hope they will start sending them to me again. Maybe its why we don,t see as many people on hear like we used to.

 

[goodO1boydws]

This sounds like something that happened to me a long time ago. Have you double checked to see how good your ground cable connection from the battery is? If there's a weak connection on that one, say from rust/oxidation and/or a loose bolt, and its close to a heat source, the contact area may be opening up from heat expansion and breaking contact completely or be intermittent ONLY when it heats up enough. (Like during a long drive.) If that happens, the alternator wouldn't charge the battery-while that contact is open, and you'd be running on only the battery's voltage, like during a long drive. (which could explain the dim instrument lights. If that's what's going on, you might get the same results by letting the Bronc run for a good long while on your driveway. Or using a hair dryer, concentrating on the connection areas.

 

[ledzilla]

When you get out. Have you c heck the brake lights? Sometimes the pedal will stick and the brake lights will run the batter down.

Yeah, I always end up walking around behind it. The lights are always off.

 

[ledzilla]

This sounds like something that happened to me a long time ago. Have you double checked to see how good your ground cable connection from the battery is? If there's a weak connection on that one, say from rust/oxidation and/or a loose bolt, and its close to a heat source, the contact area may be opening up from heat expansion and breaking contact completely or be intermittent ONLY when it heats up enough. (Like during a long drive.) If that happens, the alternator wouldn't charge the battery-while that contact is open, and you'd be running on only the battery's voltage, like during a long drive. (which could explain the dim instrument lights. If that's what's going on, you might get the same results by letting the Bronc run for a good long while on your driveway. Or using a hair dryer, concentrating on the connection areas.

I'm fairly certain the ground is good. It's a new terminal and cable, and I cleaned off the mount point on the block during installation. However, the last time I fired it up at night I noticed the dimming occurring immediately for a couple seconds each time. Things didn't have a chance to fully heat up and expand. But, I figure it can't hurt to double check the connection. With any luck I can do it myself, but I'm not sure with my hand all bound up right now. Might be too difficult to hold myself in place over the fender with a mangled thumb, but it's worth a try.

 

[ledzilla]

Ok, so I haven't yet checked the battery negative cable, but I did get the voltmeter installed. I fired up the Bronco last night, because it's easier to see when things are being weird at night with the exterior lights turned on. It started up a little oddly, and there were a couple sparks from near the solenoid. Checking that out, I didn't see anything out of place, so not sure what happened there. Well, it idled fine, warmed up. I walked back to the house to get my keys so I could lock up and drive around a bit. When I looked back I could see the lights dimming and brightening. I walked back, but it stopped doing that by time I returned to the Bronco, but I did see the voltmeter return to 13.8-13.9 from maybe somewhere around 13.2-13.5, I'm not really sure as I didn't have the best view at that moment. I ended up driving around for well over 30 minutes (wasn't paying enough attention to the time, so not really sure how long I was out), but the issue never returned the entire time while driving. The issue I've had with the turn signal indicators not illuminating but dimming the cluster didn't appear, either (the signals themselves still operated without issue when this happened). Everything worked perfectly the entire time. I took it out again this morning for coffee and donuts, again without incident. The only thing I managed to do was install the voltmeter onto the steering column (strapped on with a heavy duty zip tie with a piece of rubber underneath to prevent sliding).

I'm left thinking that maybe there's an issue with a wire or something under the dash and my voltmeter installation work jostled it back into an appropriate position, but I can't think of anything that would be under the dash that could have this much effect. Is it possible that there is some kind of intermittent short that could cause a lack of charging and the turn indicators to malfunction?

 

[ledzilla]

So, I had some surgery on one hand, which has made things difficult. But using my good hand and my shoulder I was able to install an exhaust repair because the pipe from the passenger side header broke where it connects to the muffler. Happened after a few days of everything working as it should (seems to have happened when accelerating after slowing down for some maintenance vehicles blocking a lane). So, go to take a little cruise around the neighborhood to see how well the exhaust sounded with the repair. Shortly after taking off the voltage dropped like there was no charging at all. It would periodically bounce up into the low 13's, but was mostly in the low to mid 12's. This was just a couple days before the holiday, and I haven't had a chance to poke at it further. I'm not so sure it really is the voltage regulator, because if it was, normally, it simply would not work at all either not limiting the voltage or not providing any charging. The intermittent nature of the issue has me bothered because there really hasn't been anything sufficiently reliable and repeatable about the whole thing. If the fender-mounted regulator was still being used, it would be easy enough to swap it out just to be sure, but it's difficult enough with trying to reinstall this alternator because it requires two people: one to maintain high tension on the belt, one to tighten the bolts. Really want to replace the mount setup with something that raises the alternator a bit higher and uses a turnbuckle for belt tension, but that's not in the cards for quite a while.

 

[L\Bronco]

Hey Led,
Id look really close at the side of the solenoid that the batt cable /alt feed hooks to. If you saw sparks there, that indicates a bad connection. Find the fusible link for the alt. (It will be one of the leads from the batt side of the solenoid) give it a tug, it may be burnt inside and intermittently connecting explaining the arcing. It should be solid when you pull, not rubbery.
Hope that helps
Cheers

 

[ledzilla]

Hey Led,
Id look really close at the side of the solenoid that the batt cable /alt feed hooks to. If you saw sparks there, that indicates a bad connection. Find the fusible link for the alt. (It will be one of the leads from the batt side of the solenoid) give it a tug, it may be burnt inside and intermittently connecting explaining the arcing. It should be solid when you pull, not rubbery.
Hope that helps
Cheers

Well, checking that fusible link will be more difficult than it should be. Everything that is normally connected to the battery side of the solenoid was relocated to the rear driver side of the engine bay. You can see the cable running over to it in the picture I attached in post #6 as it passes by the alternator. I can check my wiring diagrams to see what color wire and all, and just hope that it's still the same color. A previous owner did some odd stuff under the hood with the wiring. It's quite frustrating because I can't find the wire that supposed to connect the ignition switch to the solenoid. I had to put in a push button and wire that to the solenoid. The guy who sold it to me was jumping cables across to the battery. The positive post was partially melted because of that.

As for the sparks, after taking a look at the solenoid I'm thinking it's likely the cable for the starter. I have a replacement that I have yet to install. It was mean to be swapped in last year when I did the rest of the heavy power cables but it got late and I got tired and I never got back to it. It will likely have to wait until next year because it will certainly be too cold to deal with that by time my hand is healed up enough to do it myself.