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Electrical/Alternator issues

Cvcoda

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Sep 22, 2012
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318
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Omaha, NE
Hey guys, looking for some help with what I think is an alternator issue. I've got a brand new red top optima battery installed - charged with a gel cell tender. I go to start it up and everything is fine. But while it's running, my tach and radio will go out after running for several minutes. If I hit the gas pedal, the tach and radio come back on for a while and goes through the same cycle.

My very limited knowledge of charging systems/electrical makes me think that it's the alternator. Does this sound feasible? Any way to test? Any other ideas?






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blubuckaroo

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Jun 11, 2007
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11,795
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Ridgefield WA
You'll need to check the voltage output of your alternator at idle. It should be between 13.8 and 14.2 volts.
If it's not up to that voltage, you can do a "full field test" to determine whether the problem is the alternator or regulator.
To do this you simply unplug the regulator and jumper battery voltage to the "F" terminal of the regulator connector. The output voltage should now be 18+ volts if the alternator is good.

https://www.youtube.com/watch?v=cxNK7N0ZdDs
The full field test example starts at about 1.40 of this video.
 

DirtDonk

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Not sure it would hurt anything, but if your tender is designed for gel-cell batteries only, it might not be doing right by your Optima. Which is not a gel-cell battery.
You may just have been using that term generically regarding your tender though, so if that's the case then there's probably nothing wrong with using it on the AGM (absorbed glass mat) Optima.
Just thought I'd mention that though, since a lot of people, including the guys on the Power Nation shows still refer to Optimas as gel cells.

But yes, your symptoms could be that of a bad alternator. Unfortunately they could also be indicative of a bad battery, a bad voltage regulator, or some bad wiring.
As buckaroo said, you'll need to verify voltage at different points first. Then do some testing to determine exactly where the fault lies.

Good luck.
Oh, and how old is the Optima and how long does it sit unused?
Even with a tender, a battery can still go bad. And at some points in their history, the Red Tops have had some issues. I'm still running one that's about 10 years old, and have had several go longer than that. But it's still possible to get a bad battery no matter what brand.

Paul
 

Steve83

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Jul 16, 2003
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Memphis, TN, USA, Earth, Milky Way
I've got a brand new red top optima...
That's not a very good battery, but since you've already installed it...
But while it's running, my tach and radio will go out after running for several minutes. If I hit the gas pedal, the tach and radio come back on for a while and goes through the same cycle.
This would be easier to understand if you were more precise. How long does it run before they shut down? Does it happen while driving, or only if you leave it idling? How long after revving it do they keep working? Do you have to put the charger back on the battery every time you park it?

Adding ALL the truck's details to your signature (like blu's & Paul's) would also help A LOT... %)
My very limited knowledge of charging systems/electrical makes me think that it's the alternator.
So you're just guessing?
Does this sound feasible?
Yes, but not LIKELY. And it would have to be both the alt AND the battery failing.
Any way to test?
Sure: voltage across the alternator output to its case; voltage across the battery posts; voltage across the radio power & ground wires; voltage across the tach power & ground wires.
 
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Cvcoda

Cvcoda

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Omaha, NE
Not sure it would hurt anything, but if your tender is designed for gel-cell batteries only, it might not be doing right by your Optima. Which is not a gel-cell battery.
You may just have been using that term generically regarding your tender though, so if that's the case then there's probably nothing wrong with using it on the AGM (absorbed glass mat) Optima.
Just thought I'd mention that though, since a lot of people, including the guys on the Power Nation shows still refer to Optimas as gel cells.

But yes, your symptoms could be that of a bad alternator. Unfortunately they could also be indicative of a bad battery, a bad voltage regulator, or some bad wiring.
As buckaroo said, you'll need to verify voltage at different points first. Then do some testing to determine exactly where the fault lies.

Good luck.
Oh, and how old is the Optima and how long does it sit unused?
Even with a tender, a battery can still go bad. And at some points in their history, the Red Tops have had some issues. I'm still running one that's about 10 years old, and have had several go longer than that. But it's still possible to get a bad battery no matter what brand.

Paul



So the Optima's aren't gel cell??? I just ordered one of the Optima chargers so that I can at least the battery fully charged.

The battery is new - bought it about 3 or 4 weeks ago. It's been sitting up until I got it installed last weekend.


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Cvcoda

Cvcoda

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Omaha, NE
That's not a very good battery, but since you've already installed it...This would be easier to understand if you were more precise. How long does it run before they shut down? Does it happen while driving, or only if you leave it idling? How long after revving it do they keep working? Do you have to put the charger back on the battery every time you park it?

Adding ALL the truck's details to your signature (like blu's & Paul's) would also help A LOT... %)So you're just guessing?Yes, but not LIKELY. And it would have to be both the alt AND the battery failing.Sure: voltage across the alternator output to its case; voltage across the battery posts; voltage across the radio power & ground wires; voltage across the tach power & ground wires.



Bought the Optima based on reviews - and they were overwhelmingly positive. Why are they not good?

The tach light going off and on is random. Upon starting, it's lit up but jumping up and down. Then it would go out after maybe 20-30 seconds or so and it sounded like the engine idle would drop at the same time that the light would go off. If i hit the gas, sometimes it would immediately kick the power back on to the tach and stay on for maybe 5 seconds or up to 30 seconds or so. I have not yet driven the truck since installing the new battery.

Appreciate any additional advice. And as I said, I have very limited knowledge of charging/electrical systems.


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jw0747

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San Antonio, TX
This is simple enough to diagnose without a big hassle for a guy who admitted limited knowledge. Take it to almost any auto parts store or the place where you got it and they'll test your charging system and battery free of charge. It's what auto parts stores do probably more than once a day.

I had a red top Optima that went bad after one month. Had a dead cell so I got a replacement free. This was an exception not the rule and for someone to tell you Optimas are bad is dumb. Take it back to where you got it and have them test it. If bad they'll replace it.
 
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Steve83

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So the Optima's aren't gel cell?
No, they work exactly like a common automotive battery. The only difference is that, instead of being flooded with liquid acid sloshing around between lead plates, the acid is held almost stationary within a fiberglass mat (Absorbed Glass Mat = AGM) that's rolled up with 2 coils of lead foil. That's why the body of the battery has the shape of 6 cylinders - those are each of the 6 cells, just like the 6 (rectangular) cells of a conventional 12V flooded battery.
Why are they not good?
Because they don't work any better (and WORSE in several important ways) than a conventional battery that costs 1/2 as much. The only thing they do better is keep the acid in when mounted sideways or upside-down, or when punctured. That's it. Every other specification is the same as, or WORSE than, a decent flooded battery, including deep-discharge recovery, vibration tolerance, longevity, charge time, discharge rate (CA, CCA), warranty... Don't trust me - read them for yourself.

I haven't read it lately because I'd never buy one, but for many years, the red-top warranty specifically EXcluded vehicles with "any modification to the electrical system", which would include adding a radio/amp, off-road lights, a winch, or even a trailer connector. The way it was worded, it would even exclude changing the battery to the red-top.

Many years ago, there was a website that showed EXTENSIVE testing of red-tops, including nearly all of the published specs for the battery. And the results were NOT good. That's probably why the site was taken down.

People who use this BBS & several others report that current Optimas are being made in a different country than the early ones, and that their quality (which was never great) has dropped substantially. I'm sure you can search up those discussions if you're interested.

But as I said initially: you already have it, so just run it. But don't treat it like it's indestructible because it isn't. Treat it like any other battery, and it might last 6~8 years.
 

CA10Cruzer

New Member
Joined
Nov 17, 2016
Messages
15
sounds like you have a bad connection in the power or ground circuit of the two components that stop working, if everything else is still functioning? do the tack and radio pull power or ground from the same points? if they do? that's where i would start
 

DirtDonk

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So have you measured the battery voltage yet?
And measured the alternator's output voltage?
If the battery voltage is low after sitting, then there is either a drain on the battery or the battery itself is bad.
If the alternator is putting out 13.5 to 14.5 volts when the engine is running, then it's doing it's job just fine.

And I'm curious, why is a one month old battery on a tender? Was it in need of a charge? Were you planning on it sitting for extended periods, so just taking precautions?

Not sure where my head was the first time I read through your question, but I can't see how a charging system (alternator) issue would cause only the tach and radio to go out. If it was the charging system (or the battery), then EVERYTHING electrical would suffer.
The alternator is not particular.

...I've got a brand new red top optima battery installed - charged with a gel cell tender.

As has already been mentioned, "new" doesn't mean anything anymore. So even though at this point it does not seem you have a bad battery, you should always keep an open mind when diagnosing trouble.

I go to start it up and everything is fine.

That's a good first sign. The fact that it starts up fine means that the battery was charged the last time it was turned off and there was not sufficient drain to cause trouble.
So far, so good.

But while it's running, my tach and radio will go out after running for several minutes. If I hit the gas pedal, the tach and radio come back on for a while and goes through the same cycle.

While this does seem to be consistent with a discharging battery perhaps, I would think your ignition would be suffering too, so the engine would not run properly. What happens to the headlights and heater and gauges when this happens?
And speaking of gauges... What does your ammeter read when the engine is off, and then again when running? This is just the type of situation that the ammeter is in place for.

My very limited knowledge of charging systems/electrical makes me think that it's the alternator. Does this sound feasible? Any way to test? Any other ideas?

It's seeming less and less feasible to me now. Without knowing what the other electrical accessories are doing, or what your ammeter is telling us, or what your volt-meter checking of the battery tells us, it's going to be hard to say.
As far as testing, do the things outlined previously and we can go from there.

But as CA10 said, it sounds more like you have a poor connection or some other fault with the tach and radio.
And tachometers are notorious less for failing themselves, than they are from having poor connections made by the installer.
Been there, done that.

Paul
 
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Cvcoda

Cvcoda

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Omaha, NE
So have you measured the battery voltage yet?

And measured the alternator's output voltage?

If the battery voltage is low after sitting, then there is either a drain on the battery or the battery itself is bad.

If the alternator is putting out 13.5 to 14.5 volts when the engine is running, then it's doing it's job just fine.



And I'm curious, why is a one month old battery on a tender? Was it in need of a charge? Were you planning on it sitting for extended periods, so just taking precautions?



Not sure where my head was the first time I read through your question, but I can't see how a charging system (alternator) issue would cause only the tach and radio to go out. If it was the charging system (or the battery), then EVERYTHING electrical would suffer.

The alternator is not particular.







As has already been mentioned, "new" doesn't mean anything anymore. So even though at this point it does not seem you have a bad battery, you should always keep an open mind when diagnosing trouble.







That's a good first sign. The fact that it starts up fine means that the battery was charged the last time it was turned off and there was not sufficient drain to cause trouble.

So far, so good.







While this does seem to be consistent with a discharging battery perhaps, I would think your ignition would be suffering too, so the engine would not run properly. What happens to the headlights and heater and gauges when this happens?

And speaking of gauges... What does your ammeter read when the engine is off, and then again when running? This is just the type of situation that the ammeter is in place for.







It's seeming less and less feasible to me now. Without knowing what the other electrical accessories are doing, or what your ammeter is telling us, or what your volt-meter checking of the battery tells us, it's going to be hard to say.

As far as testing, do the things outlined previously and we can go from there.



But as CA10 said, it sounds more like you have a poor connection or some other fault with the tach and radio.

And tachometers are notorious less for failing themselves, than they are from having poor connections made by the installer.

Been there, done that.



Paul



Been away from home all week so haven't had a chance to work on any of this yet. I'm hoping to get to dig in this weekend and I'll report back. Definitely going to need some help on this one. Appreciate everyone's feedback so far.


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Cvcoda

Cvcoda

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Finally started looking into my electrical issues a bit more over the weekend. Just to give some background on the situation, I've owned the bronco for about four and a half years now and haven't had any electrical issues until now. It has mostly all original wiring.

Here's what I've added electrical-wise since owning:

-aftermarket CD player (there was already one in the truck when I got it but it was not working) which was installed by a car audio shop over four years ago. Only issue I've ever experienced with the stereo was a short in one of the speaker wires from being pinched between the door and door straps. Been like that for about three years and haven't fixed it yet.

-I added a tach a few years ago - no issues since install.

-neutral safety switch was replaced due to short in the original.

-brake light switch replaced

-new battery (Optima red top)

I've had the battery on an Optima tender to keep the battery charged. If I disconnect the tender, the battery will be drained in a matter of a couple hours or so.

Something strange that I noticed tonight was that if I step on the brake pedal with the engine off, the tach light comes on and is very dim. And if I turn the key to accessory power only, the tach lights come on at the same intensity as when I step on the brakes. If I connect the tender to the battery and then step on the brake pedal, the tach does not light up. And when I turn the key to accessory power the tach light comes on with full intensity.

Does anyone have any ideas about what might be going on here?


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broncobilly72

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Nov 8, 2010
Messages
349
check the wires under your dash. Sounds like you have a dead short that's draining your battery. If things go on and off when you depress the pedals, then some wire close to the pedals is shorting out. In a normal situation with the key off, the only draw should be your radio.
 

DirtDonk

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...I go to start it up and everything is fine. But while it's running, my tach and radio will go out after running for several minutes. If I hit the gas pedal, the tach and radio come back on for a while and goes through the same cycle...

Ok, after re-reading the first post, I have NO IDEA how we got on to the subject of alternators. In no way whatsoever does this sound like a charging issue. If the engine starts and runs, the battery is good. If the battery is good every time, then the charging system is doing it's job.
If it varies from that norm in any way, then we can look at things differently. But since you're saying it's only the tach and radio acting up, the first suspect is the wiring under the dash.

-aftermarket CD player which was installed by a car audio shop over four years ago.

Does it work when the key is off, or only when on?

-I added a tach a few years ago - no issues since install.

Tachs are notorious for failing and killing the engine and keeping it from restarting, but they don't normally do any other malfeasance. But from reading further, I'd say you DO have an issue.

-neutral safety switch was replaced due to short in the original.

Do you know what was shorted? And what did it do to let you know? Or did it just stop working?
Either way, the NSS does not seem to be an issue here (with tach and radio)

-new battery (Optima red top)

Here again, ANY battery can be defective. Not just Optimas, but they did have an issue a few years ago where they did not last but a couple of years. All of mine are 10 years old or older at this point, so I can't say I've ever had a bad experience.

-I've had the battery on an Optima tender to keep the battery charged. If I disconnect the tender, the battery will be drained in a matter of a couple hours or so.

Ok, so now we're getting somewhere! This by itself could be an alternator issue. But did you mention this before?
Only two things usually can do this. One is the battery is defective. The other is the alternator's diodes sucking power. Or whatever it is diodes do when they die.
Are you talking about with it hooked up to the vehicle, or disconnected? If disconnected then it's only one thing. The battery itself.

-Something strange that I noticed tonight was that if I step on the brake pedal with the engine off, the tach light comes on and is very dim. And if I turn the key to accessory power only, the tach lights come on at the same intensity as when I step on the brakes. If I connect the tender to the battery and then step on the brake pedal, the tach does not light up. And when I turn the key to accessory power the tach light comes on with full intensity.

Ok, as said this is not right. And since the tach is not a stock factory item, nor is the radio, and the brake light switch has been replaced, something is rotten in Denmark under the dash. And you're just going to have to dive under there and dig through the wiring until you find it.
Something is either connected wrong, working lose, corroding, or wearing a hole in the wire's insulation so that it's touching some metal, or another bare wire.

Time to dig out the flashlight, flex your joints, exercise your neck muscles, and turn yourself into a half-pretzel to see what's going on up under there.
Follow the tachometer wires first, then the radio, then the brake switch.
The brake light switch gets it's power from the headlight switch. The tach (if it's lighted) has a wire connected at least indirectly to the headlight switch, and so might the radio.
Does your tach light up? If so, does it light up only with the headlight knob pulled, or as soon as you turn the key?
What about the radio? These days I guess most radios light up with the key, but does yours dim when you turn the headlights on?

Lots going on here. Mostly effecting non-stock items. So get to diggin'!!!

Keep us informed as you go and we might be able to make more suggestions as you find more clues. Even to the point of posting up pics of the wiring under your dash.

Good luck.

Paul
 
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Cvcoda

Cvcoda

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Ok, after re-reading the first post, I have NO IDEA how we got on to the subject of alternators. In no way whatsoever does this sound like a charging issue. If the engine starts and runs, the battery is good. If the battery is good every time, then the charging system is doing it's job.
If it varies from that norm in any way, then we can look at things differently. But since you're saying it's only the tach and radio acting up, the first suspect is the wiring under the dash.

Update: After talking to a local Bronco brother who is a mechanic by trade, with electrical being his specialty, I disconnected the battery on his advice. After disconnecting the battery cables, I connected the Optima tender which has the ability to analyze the battery and found that it's completely drained - reading less than 1.25V - (or there's some other issue that won't allow it to charge). So now I'm wondering if the battery is defective or if it's just been drained too low to be charged? But immediately before I disconnected the tender, it was reading 100% charge and maintaining at 12.9V. So I'm completely confused on this.


Does it work when the key is off, or only when on?



Tachs are notorious for failing and killing the engine and keeping it from restarting, but they don't normally do any other malfeasance. But from reading further, I'd say you DO have an issue.

The tach light would come on dimly without the key being on, all it took was to step on the brake pedal to get it to light up.

Do you know what was shorted? And what did it do to let you know? Or did it just stop working?
Either way, the NSS does not seem to be an issue here (with tach and radio)

The insulation on one of the wires was rubbed off because of poor routing. I knew it was shorted because nothing would happen when I turned the key. My buddy found the issue and told me it was the NSS. Replaced it and it wasn't an issue after.


Ok, so now we're getting somewhere! This by itself could be an alternator issue. But did you mention this before?
Only two things usually can do this. One is the battery is defective. The other is the alternator's diodes sucking power. Or whatever it is diodes do when they die.
Are you talking about with it hooked up to the vehicle, or disconnected? If disconnected then it's only one thing. The battery itself.

The battery drains completely when connected. But as I mentioned above, the Optima tender said the battery is at < 1.25V and that's immediately after disconnecting the tender while it was connected and showing 12.9V.


Ok, as said this is not right. And since the tach is not a stock factory item, nor is the radio, and the brake light switch has been replaced, something is rotten in Denmark under the dash. And you're just going to have to dive under there and dig through the wiring until you find it.
Something is either connected wrong, working lose, corroding, or wearing a hole in the wire's insulation so that it's touching some metal, or another bare wire.

Time to dig out the flashlight, flex your joints, exercise your neck muscles, and turn yourself into a half-pretzel to see what's going on up under there.
Follow the tachometer wires first, then the radio, then the brake switch.
The brake light switch gets it's power from the headlight switch. The tach (if it's lighted) has a wire connected at least indirectly to the headlight switch, and so might the radio.
Does your tach light up? If so, does it light up only with the headlight knob pulled, or as soon as you turn the key?
What about the radio? These days I guess most radios light up with the key, but does yours dim when you turn the headlights on?

Lots going on here. Mostly effecting non-stock items. So get to diggin'!!!

Keep us informed as you go and we might be able to make more suggestions as you find more clues. Even to the point of posting up pics of the wiring under your dash.

Good luck.

Paul


My buddy is willing to take a look for me in a couple weeks, so in the meantime I'm going to get under the dash and see if I can find anything obvious. I'll report back with pics of anything I can find.

Appreciate the suggestions from everyone.



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Steve83

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Only two things usually can do this. One is the battery is defective. The other is the alternator's diodes sucking power. Or whatever it is diodes do when they die.
When an alternator's high-current diode fails, it either becomes an open circuit (like a broken/disconnected wire) and causes low charging voltage with a pulse (detected by charging analyzers as an AC component to the DC output); or it becomes a SHORT circuit (causing a continuous drain on the battery when the alt isn't spinning). But a diode that can handle 1/3 of the alternator's peak output (so, typically 20~100A) can usually overwhelm a battery charger. So while it's certainly possible, it doesn't sound likely from what I've read so far. My impression is that the battery is bad.
...analyze the battery and found that it's completely drained - reading less than 1.25V - (or there's some other issue that won't allow it to charge). So now I'm wondering if the battery is defective or if it's just been drained too low to be charged? But immediately before I disconnected the tender, it was reading 100% charge and maintaining at 12.9V. So I'm completely confused on this.
That still makes me think the battery OR ANALYZER'S terminals are dirty. All of the metal needs to be shiny-clean. But assuming it's accurate... BAD BATTERY.
But as I mentioned above, the Optima tender said the battery is at < 1.25V and that's immediately after disconnecting the tender while it was connected and showing 12.9V.
Now you're confusing me! :eek: How can the tender give you any reading from the battery immediately after you disconnect it? ?:?
 
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Cvcoda

Cvcoda

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Drove it over to my buddy's shop tonight. Good thing too, because when I went to turn it off after pulling it into the garage, I turned the key to the off position but it kept on running. Had to disconnect the ignition control module to get it to shut off.
When he was disconnecting the negative battery cable, there was a pretty significant arc so I'm interested to see what he finds.


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