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Discussion Starter #1
Today I start up the car, and when I turn on the headlights, the car shut off! Cautiously tried it again, the second I turn on the headlights, car shuts off. Dash lights were still on. Third time was a charm, didn't do it. It did this one time about a month ago, but I thought it was a fluke.

What part is going bad? Do I need this Big 3 mod I have heard a little about?

Thanks,
Al
 

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Sounds to ME like the battery voltage is dropping too low when you turn the headlights on at idle.

I'd look into the Big Three (that's ALWAYS a good thing to do!), but also check battery, both ends of both battery cables, alternator, and regulator (regulator is inside alternator).

RwP
 

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Discussion Starter #3
The battery is a pretty new Motorcraft 850, the battery side ends of the cables are good. When I turned the lights on, it was on high idle, around 1000 RPM.

Al
 

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If you have a voltmeter; here's how to check your overall electrical system:
attach voltmeter to battery - should measure 12.5v
Place the meter somewhere you can see it from the drivers seat
Start the car, the voltage should not drop more than a volt, 1.5v max. - If it does, you've got a bad battery.
Then quickly the voltage should be at 14.4v. - If it does not reach 14.4 at idle give it a little gas ~1K RPM. If it does not reach 14.4v; you're alternator is bad.
If all that checks out, you can start turning on things, like lights, etc. and watch the voltage. If it drops and recovers at this point you would benefit from the Big 3.
 

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Discussion Starter #5
Thanks for the tips Scott.

Al
 

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Discussion Starter #6
Battery voltage is 12.55. When I start the car, I see 10.8-11.0 v for a split second, but it sounds really strong.

With the car running, I am seeing 13.80-13.85v, but that is exactly same as our Crown Vic.

Turning on headlights and A/C only dropped the voltage .01v. However, when I was driving it later, the headlights dimmed for a split-second every time the A/C clutch kicked on. One time, the dash lights flickered at the same instant as if the car lost all power for a split-second. The voltage drop issue seems to be intermittent.

I will get the alternator tested. Has anyone had any luck just replacing the battery cables, in lieu of doing the big 3 mod? I don't have a bunch of audio equipment.

Thanks,
Al
 

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Crawl under it, and measure the big wire at the starter, while an assistant tries to start it.

I'll bet it drops a bunch. :frown2:

Check the big wire to the starter, and the megafuse; I'll bet you have green rot in the cable, and it's going bad.

Lumps in the jacket, or green powder or whatever coming out the ends of the cable is a sure sign.


It sounds like the charging system and battery is ok, but you're losing connection intermittently.
 

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Discussion Starter #8 (Edited)
The battery side of the cables look perfect, at least now they do. When I got the car 2 1/2 yrs ago, it took 2 hrs to clean those terminals with baking soda.

CARQUEST tested the car - both the battery and alternator checked out. I guess the Big 3 is in my future.

Thanks,
Al
 

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Discussion Starter #9 (Edited)
I was looking around at Big 3 info. I found this kit, which looks pretty nice, a little pricey though. I don't mind paying a little extra if the wires are already cut with terminals are already crimped on. https://ceautoelectricsupply.com/product/2-awg-big-3-upgrade-kit-for-top-post-batteries/

Any recommendations on Big 3 kits? Do I need an inline fuse for the + alternator wire? It looks like the 3 ft kit is plenty long enough.

Car has no stereo upgrades other than a new receiver.

Thanks,
Al
 

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Discussion Starter #10
Okay, so I'm in the process of installing a big 3 kit, and there is a 4th wire, a smaller gage ground strap. Should I ground the radiator to the chassis?

The research I have done leaves me even more confused. Some say that grounding the radiator completes the circuit to allow galvanic corrosion in the cooling system. There are so many contradicting theories on this subject. I know some aftermarket radiators come with a ground strap.

Others say the rubber mounts for the radiator are to keep from grounding the radiator to the frame. Personally, I think it is just good engineering - rubber donuts to keep metal to metal contact from rubbing the paint (and metal or plastic) from the joined components. It is mostly the plastic end tanks that touch the mounts anyway.

Opinions?

Al
 

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IMHO, if you ground the radiator, ground the heatercore.

If neither have been an issue, I wouldn't change it.

The groundstrap goes from the pass motormount to the core support, iirc.

Our cars already should have one there; most cars don't.
 

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ground strap is located between the passenger motor mount and the "frame" near the airbox.

Never seen a radiator grounded. Galvanic corrosion is caused by a difference in metals in direct contact with eachother - the radiator isn't exactly connected to the engine by any means that would allow the flow of electrons since its already isolated by the rubber hoses. The rubber mounts are meant for vibrations. You wont see galvanic corrosion through plastic either. Electrolysis is caused by water flowing through the systems - it generates an electrical current, and you will find galvanic corrosion evident on something like a Steel water tube connection threaded into an Aluminum intake manifold, etc … depending on where they are on the galvanic scale. I find a lot of copper to steel connections in plumbing without a dielectric fitting install between ( plastic ) and the steel erodes at the weakest point of direct connection ( threads )
 

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Discussion Starter #13
Here is the money shot of the Big 3. I got a pre-made kit from Auto Electric Supply. https://ceautoelectricsupply.com/car-audio-products/big-3-upgrade-kits/big-3-upgrade-kits-top-post-battery/

The pre-made cables were really robust and flexible. It came with military grade terminals. I also got the military grade covers.

I kept all of the existing wiring, and just piggybacked. I took the new alternator ground from one of the long bolts, and grounded it to a spot on the shock tower. The new battery ground, I ran under the radiator support and put a bolt thru the top of the support. I cleaned the paint off all the spots, including the existing battery ground to radiator support.

The only thing I really noticed is when I was putting the cables on and off the battery, it never "sparked" like you usually get when you put that last cable on the battery.

Al
 

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Discussion Starter #15
Thanks Scott, and thanks for your help!

Al
 
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