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Discussion Starter · #1 ·
Request to 2005-2007 owner: how hot does that relay I circled in red get in your car?
When you try to manually spin the radiator fan, does it spin very freely or does it feel draggy?

So, I suddenly got check battery light in my dash. It usually happens while cruising along on the road and almost always turns off when I come to a stop and sit at idle for 30 seconds or so. Under load, the voltage drop as low as 11.8v.

I had the charging system checked with a instant check tool at auto parts store and it reads low system voltage as I observed, and indicates alternator diode failure. However, I am wondering if the diode pack failed due to excessive load. I could replace the alternator, but it will fail again if failed due to excessive load and I'd rather avoid that given that it's not in the easiest place to access.

Under the hood, positive battery terminal is so blistering hot that I can spit on it and it would boil and sizzle.
The short 8" jumper that connects that jumps between the chassis and the negative terminal also gets quite hot on the chassis side crimp terminal. I don't have a clamp meter that can measure DC, so I'm not able to determine if the heat is due to excessive current or excessive resistance caused by degraded connection. I'm inclined to think the former, because the ignition relay in the battery junction box gets too hot touch comfortably as well.

The positive terminal gets above boiling point. The relay on red box gets uncomfortably hot.
311362


Battery cable insulation melted where it meets positive terminal.
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I can't answer your questions, or make any guesses yet. I have a question or two for you.

Your battery terminal lugs look remarkedly clean. Does your car have the original battery and/or the original alternator?

My initial thought is that both Alt and Batt are bad. Defective battery can & will kill an alternator. Car part stores can test battery health, did they do that while you had the car charging system tested?

You are at a point where if you replace only the batt OR only the Alt, you might kill a new Batt or a new Alt. Go slowly and carefully as you troubleshoot further.
 

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Discussion Starter · #3 ·
Battery isn't original. It wasn't replaced due to a failure. It tested as marginal, so I had it replaced as a preventive measure some years aback. Alternator has never been replaced.

When I had the charging system tested yesterday, I was told battery is fine. It was tested on a handheld tested at O'Reilly that load tests the battery and do a few other checks. That thing read bad diodes.

The wire with melted insulation goes directly to alternator's B+ and starter is connected in between. However, it is the hot relay that has me thinking maybe the radiator fan is dragging and causing a high draw. If I had a DC capable clamp meter, all I have to do is amp the accessory connection which is the wire you see attached with a nut on the terminal but I don't know what the normal draw should be..
 

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You have a 2005 and it's around 17 years old now. There's no way you ever would have had the original battery in it and still have it working. Additionally, by averages you should be on battery #3 by now. Even if you got 7 or 8 years out of a battery which is usually on the high side for anything but a Motorcraft then if this is only battery #2 I would say that it's definitely at the end of it's life.
I would have a more thorough test done to the battery than O'reillys quick dinky little handheld tester. A shop or better yet a dealer will have a professional tester that after charging the battery will check the voltage and load test it after some time has passed.
Look on the date of the battery. It'll have a decal or stamp usually on the side or top of the battery with a letter and then a number. The letter is the month and the number is the year. For instance, if it's a D4 that would mean April 2014.
If your fan works as it should and comes on/off with the a/c on and when the a/c is off it also comes on/off then the fan is probably just fine.
A weak alternator will constantly be working to charge a battery. If the battery is also weak then the battery will get hot as a weak alternator is always pushing current into a battery that's resisting taking it. A weak battery will resist taking a charge and it can literally boil the acid inside of it. I've had that happen once myself.
You know the alternator is junk. Replace it. A diode will usually fail for no particular reason whatsoever. Alternators are one of the most commonly replaced parts on a vehicle. Unless you put that battery in only a couple years ago I would also highly suspect that it's also no good.
 

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You have a 2005 and it's around 17 years old now. There's no way you ever would have had the original battery in it and still have it working...
That was an obvious brain-fart of mine. Yes, there is no way the battery is original. Here in Phoenix AZ, you are lucky to get 3 years of use from a car battery.
 

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Discussion Starter · #6 ·
So, surprising failure points. They feel fine and look fine other than the melted insulation on one of them. VD is excessive. I was seeing around 0.3v drop across just one junction.

But wait a second, these are just the most visible connections. These connections are likely failing just as bad where you can not see it. I guess I should just replace the whole damn cable. fault points are marked in red.
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This pig tail on the right carries much of the electrical load. In fact, when you remove this pig tail, the car acts as if you removed the whole negative terminal. I was noticing it was getting rather toasty on the body end. I improvise a new temporary connection and it stopped getting hot. Voltage drop is now 0.06v down from 0.3v

I cut off the positive terminal and replaced with a $3 generic terminal. It stopped getting hot and starter actually turns audibly faster. I feel uncomfortable about the longevity though.
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So, surprising failure points. They feel fine and look fine other than the melted insulation on one of them. VD is excessive. I was seeing around 0.3v drop across just one junction...
Uh, I disagree? The color of the first picture is probably washed-out due to picture compression that happens once you upload it to this or any website. I see the color of your conductor wire strands as "washed-out" and not as vibrant as they should be. They should be bright brass or bright copper colored when healthy. Your wire strands look stressed? blonde? weak?

The primary cable from the Alt to the Starter to the Battery was surely damaged during your high-current & high-heat charging. As you have found, there is evidence of wear or damage at the ends of this cable? This damage should be somewhat apparent at the Alt, Starter and Battery terminals. Your pictures here might not "do it the justice it deserves". Your in-person inspection of the cable and the health of the terminal-lugs are best done by you. Your second picture has no detail. I can not see any detail of those connections.

A bad wire or a bad terminal lug (crimp) DOES BECOME a resistance and a resistor. Hence and therefore your voltage drops + your improvement once a new terminal lug is added. This is one good step, keep stepping. That is a very good helping repair, but it obviously does not make a final fix. I think you are about to replace the entire positive cable from Alt-Starter-Batt and I would agree with that decision ((TBD)). I believe you have a Bad Alt and a bad Battery.... and this is looming over your head.
Good luck.
 

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I think you are about to replace the entire positive cable from Alt-Starter-Batt and I would agree with that decision ((TBD)).
I agree with doing this as well @Shifterguy. Ford still stocks this cable, and would be smart to replace. They are known to fail like you've noticed, and corrosion can creep far down the cable, increasing the resistance. There's no harm in running a nice ground from battery to chassis negative, 4ga would be more than sufficient, to augment the factory ground. I would also recommend one going from the engine to chassis. As these cars get older, corrosion and marginal factory grounds can exacerbate electrical issues.

If you are still seeing the battery light come on or weird charging behavior, look into the alternator pigtail replacement (another common failure and can cause the battery light to come on intermittently), or a new battery and alternator.
 

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The cables are pretty much cooked the entire length now. I would replace them. They got hot enough to melt the insulation off and that's clearly visible in the first pic. Have you replaced the alternator yet?
Also, I would turn the resolution up in your camera settings r use a better camera for uploading pics since they're washed out and a bit blurry.
 

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Discussion Starter · #10 ·
As for the negative terminal all the electrical load that returns to chassis returns to battery through this jumper. I was seeing 300mV before with radiator fan + blower fan running. This makeshift re-wiring dropped the voltage drop to about 50mV. From alternator frame to vehicle frame, I am seeing about 60mV under load.

After I reworked the positive battery terminal and this jumper, The battery is at about 14-14.5v at idle but now the battery light comes on consistently. I now need to do a voltage drop test between the battery terminal and alternator B+ terminal... once I figure out how to attach a probe without having it tangle on things.

I want to save replacing the alternator as the very last thing, because it seems to be quite involved. I'm reading through posts around here with people complaining about their battery light remaining even after changing the alternator, so it seems prudent to make these repairs first and see where it takes me.

That wire used to go to the red circle at the bottom. This is after my temporary repair. I'm going to just buy a new ring-to-ring jumper lead.
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As for the negative terminal all the electrical load that returns to chassis returns to battery through this jumper.
FYI - There is a Batt negative terminal cable that attaches to the engine/transmission. This term lug connection is located very close to the Starter. The negative battery cable you ID'ed and the one I just ID'ed are primary for completing the circuit for the Charging System. There are also other misc. other paths that complete the negative/ground circuit of Batt & Alt but those are not designed to be used as "the primary low resistance" path to ground for the charging system. Let us please not examine this statement further,... it will only go down into a rabbit hole of speculation about "what if"...

I'm going to just buy a new ring-to-ring jumper lead
Yep! I did that too! Most car part stores sell those pre-fab'ed ground cables in various lengths (6 to 36 inch??). Wire gauge is about 4ga? I bought & installed 2 of these cables, to supplement the originals on my Focus. At that time, I did not own a crimp tool capable of crimping a heavy duty lug onto 4ga wire. I now own one that does this, down to 2ga. Wish I also owned a real good one, to crimp heavy wire/lugs at 0 or 00 size = Prep for Zombie Apocalypse or just regular car/truck stuff for battery cable gauge & high power car audio amp installations.

For testing Alt B+ voltage output or to perform a voltage drop test from B+ to Batt+... Here is how I did that:
My Alt B+ is impossible to get at without some parts removal or disassembly. Because of this, I did "get in there" and then attached a small gauge 3 or 4 foot wire under/onto the B+ nut, then ran the test wire up top-side of the engine. This "temporarily installed test wire" connected to B+ stayed on my car for about a year or two. Obviously you gotta keep that un-fused test wire safely stored and capped in order to prevent damage, sparks or a fire!?

This Alt B+ added test wire allows for both (1) direct test of the Alt output voltage (2) testing for a voltage drop between the Alt B+ and through the Starter connection, and then ending at the car battery positive terminal lug. If you find an unusual voltage drop between these two points, the Alt/Batt cable connections located at the Starter should be inspected & cleaned. However, in your case, you should be replacing this entire Alt/Batt cable in the near future. TBD.
 

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Discussion Starter · #12 ·
FYI - There is a Batt negative terminal cable that attaches to the engine/transmission. This term lug connection is located very close to the Starter. The negative battery cable you ID'ed and the one I just ID'ed are primary for completing the circuit for the Charging System.
There's an even larger wire going from the battery neg terminal towards the alternator area of engine block. I didn't look to see where it ends, but the size suggests the purpose is to carry the starter's current. However, the voltage drop across negative terminal to engine block, between alternator frame and engine block, and between engine block and frame don't suggest a troubling level of drop.

That 10 to 8 AWG pigtail is the primary return path for vehicle electrics to battery terminal such as radiator fans and blower fans. Even the dome light shuts off when that pigtail is disconnected from the body. So perhaps with that jumper removed, the engine block is completely isolated from the body through the motor mounts.

The heavy cable on both terminals carry the same current during starting, although the crimp on the negative battery side terminal didn't show abnormal drop or heat build up. Just the crimp on body side ring terminal and big crimp on positive side. Others have complained about cable heating on positive side as well. So I wonder why the positive side is the one prone to failing....
 

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There's an even larger wire going from the battery neg terminal towards the alternator area of engine block. I didn't look to see where it ends, but the size suggests the purpose is to carry the starter's current...
An even larger negative wire? -other than the 2 we have ID'ed previously? And you do not know where it ends? When you have time, please look and find out where that larger wire ends, where does it terminate? It is my guess that this "larger wire" is not a different one, and it is actually the same one I identified??-> it should connect onto the engine/trans area VERY close to the Starter; it does not connect directly onto the Starter.

The Starter & the Alt do not have a stand-alone negative cable connection routed back onto the Batt. The Alt and the Starter share the engine/trans as a common ground point. The engine connects to Batt Neg via the cable I identified. I have an old picture that will help, I just gotta find it and post that pic here. ((Initial searches on my PC was a fail. I can't find that picture atm)).

...That 10 to 8 AWG pigtail is the primary return path for vehicle electrics to battery terminal such as radiator fans and blower fans....
I disagree?? And I do not understand you. What pigtail are you speaking about?

The heavy cable on both terminals carry the same current during starting, although the crimp on the negative battery side terminal didn't show abnormal drop or heat build up. Just the crimp on body side ring terminal and big crimp on positive side. Others have complained about cable heating on positive side as well. So I wonder why the positive side is the one prone to failing....
Your set of questions are a spider web of potential good or bad answers. My reply is only one of other TBD better answers to your set of questions.
Why is Positive hotter than Negative battery terminal? The positive cable is direct from the Batt-Starter-Alt cable connection. This positive cable is fully isolated and it is a relatively short cable length. In contrast, the negative side has the benefit of allowing some heat dissipation to occur within the engine block/transmission (for Alt & Starter) + there is also the cable connection from the eng/trans that ends at the battery negative terminal. The engine/trans acts like a heat isolator and/or it allows for some heat dispersion (for the Alt & Starter current) this happens prior to the battery negative terminal. Anyone here want to add (or delete) into this theory that I just pulled outa my ass?

Lastly, no, I do not believe the engine is FREE of electrical ground WHEN these two (or three) primary ground cables are removed. This goes back to what I said yesterday:

"There are also other misc. other paths that complete the negative/ground circuit of Batt & Alt but those are not designed to be used as "the primary low resistance" path to ground for the charging system. Let us please not examine this statement further,... it will only go down into a rabbit hole of speculation about "what if"..."
 

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Discussion Starter · #14 ·
You have no idea what you're referring to. The positive terminal (at the battery) was scorching hot, because the crimp connection developed a defect. The negative terminal wasn't hot. The pig tail was hot on the body end, because for some reason, crimp defect developed on the ring terminal on the body end. Looking through the forum, multiple people reported the insulation melting on the cable at the terminal.

What I said is that I don't know why the crimp at positive battery terminal seems to have a propensity to fail, an observation based on multiple people reporting same symptoms in various threads.

Your dissipation theory is null about why the battery terminal at negative didn't experience failure.
 

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Discussion Starter · #15 ·
I disagree?? And I do not understand you. What pigtail are you speaking about?
I don't understand how you can disagree about something that you admit to not understanding.

The pig tail I am referencing is the one that is wrapped in the hand drawn red circle. When this pig tail is disconnected, everything behaves as if entire battery is disconnected. Even the interior dome light does not work when this pig tail is unhooked. When it is connected, this pig tail carries a substantial portion of vehicle's electrical load.

The "other" wire I am talking about is the larger of the two wires that is crimped into place in the "hammer head" looking crimp on the "-" battery terminal. I believe that one is the jumper that connects the battery to the engine block at a point near the starter or the alternator. I say I believe, because I haven't chased down where the other end lands.

To be even clearer, I am saying the "hammer head" crimp on the negative is fine, no excessive VD (Voltage Drop) at the crimp. That wasn't the case at the positive terminal. The VD was right at the hammer head crimp.

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The positive terminal (at the battery) was scorching hot, because the crimp connection developed a defect. The negative terminal wasn't hot.
It was scorching hot because the alternator is trying to push current thru a smaller pathway. What happens when you put a high load on too small of a wire? It's the same principle. It's why circuit breakers and fuses exist on most circuits: to prevent overheating and possible fires.
It's no shock to me that the negative side isn't that hot as that's normal in such a situation. The negative is simply for ground.

I don't understand what the debate is supposedly about here. If you disconnect that major body ground(what you are calling a "pigtail") of course it's going to shut down lots of electrical components. What's the surprise? All the ground points are necessary for the car to power all the systems as designed and to effectively charge the battery too.

All your cables have gotten WAY too hot and have melted the insulation and actually turned it into liquid near the terminals. You should be replacing them and your alternator. There's not much mystery here. You have bad cables and a bad alternator.
 
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