Help! Battery Relocation Cable/fuse Size Issues?!?!

jrp27540

Active Member
Sep 9, 2016
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So the PO had relocated the battery to the back. He did an OK job with it, but he left some key points exposed for grounding out ot touching things. I have been having electrical issues with the car since I owed it.

The issue occurs when trying to start the car after it warms up and I drive it for at least 30 minutes...it won't hardly crank. At first I thought it was a charging issue due to a bad ground in the trunk. Ends up that wasn't the issue as all the charging numbers were spot on when the car was running and the battery maintained the correct volts.

After about catching my car on fire last night, I finally believe I found the issue. Either I have an issue with my positive battery cable somewhere between the battery and the starter solenoid.

When getting stranded last night, I tried again and again to crank the car. I started smelling fire shortly after and noticed smoke in the back of the hatch. After quickly pulling the trunk floor cover back, I noticed the battery cable got so hot it caught the floor padding on fire due to exposed bolt posts on the inline fuse box. :(
The battery cables were smoking hot and even ended up melting the inline fuse case and part of the cable housing.

I'm absolutely shocked that the inline fuse didn't pop(fuse has 25 amp stamped on it). At that point I new I had an issue that I can't ignore. I took two sets of battery cables and daisy chained them together and put one end on the positive battery post(long positive cable still attached to the battery) and put the other end of the cables on the starter solenoid post that the battery cable connects to(again, I left the battery cable still attached. I tried starting it again and the car fired right up!!!This tells me that I have an issue with my positive cable having a bad connection somewhere in the mix, corrosion issues inside the cable, or incorrect cable size.

The current battery cable size is 2/0 (good up to 500 current amps 60% duty cycle at a Max of 100 ft). The stock battery cold crank amps is 540 amps. Since that number is higher than what the current 2/0 cable can provide, should I go to 3/0(good up to 600 current amps 60% duty cycle at a Max of 150 ft)?

So my core questions are out of this rant is:
1: Is my current battery cable the correct size?
2: What size/style of inline fuse should I be using?

I know a lot of guys/gals don't run an inline fuse...but I prefer having one.

Thanks!
 
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Well if 1/0 is the recommendation and I'm running 2/0, then size isn't the issue. I must either be dealing with a poor connection due to corrosion somewhere on my connectiors or I have corrosion inside of the cable...
 
Well if 1/0 is the recommendation and I'm running 2/0, then size isn't the issue. I must either be dealing with a poor connection due to corrosion somewhere on my connectiors or I have corrosion inside of the cable...


????? 1/0 is LARGER in diameter the 2/0. You need to run 1/0 or even better 0 welding cable
 
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Rear mounted battery wiring recommendations

For a battery cut off switch, see http://www.moroso.com/catalog/categorydisplay.asp?catcode=42225
is the switch http://www.moroso.com/catalog/images/74102_inst.pdf is the installation instructions.
Use the super duty switch and the following tech note to wire it and you will
be good to go.

Use the Moroso plan for the alternator wiring and you risk a fire. The 10 gauge wire they recommend is even less adequate that the stock Mustang wiring.

There is a solution, but it will require about 40' of 18 gauge green wire.

Wire the battery to the two 1/2" posts as shown in the diagram.

The alternator requires a different approach. On the small alternator plug there is a green wire. It is the sense lead that turns the regulator on when the ignition switch is in the run position. Cut the green wire and solder the 40' of green wire between the two pieces. Use some heat shrink to cover the splices. See http://fordfuelinjection.com/?p=7 for some excellent help on soldering & using heat shrink tubing.

Run the green wire back to the Moroso switch and cut off the excess wire. Try to run the green wire inside the car and protect it from getting cut or chaffed. Crimp a 18 gauge ring terminal (red is 18 gauge color code for the crimp on terminals) on each wire. Bolt one ring terminal to each of the 3/16" studs. Do not add the jumper between the 1/2" stud and the 3/16" stud as shown it the
Moroso diagram.

How it works:
The green wire is the ignition on sense feed to the regulator. It supplies a turn on signal to the regulator when the ignition switch is in the Run position. Turn the Moroso switch to off, and the sense voltage goes away, the voltage regulator shuts off and the alternator quits making power.

The fuse & wiring in the following diagram are for a 3G alternator. The stock alternator uses a dark green fuse link wire that connects to 2 black/orange wires. Always leave them connected to the starter solenoid even if you have a 3G alternator.

attachment.php?attachmentid=49809&d=1175911130.gif



Rear mounted battery ground wiring. Follow this plan and you will have zero ground problems.

One 1 gauge or 1/0 gauge wire from battery negative post to a clean shiny spot on the chassis near the battery. Use a 5/16” bolt and bolt it down to make the rear ground. Use a 1 gauge or 1/0 gauge wire from the rear ground bolt to a clean shiny spot on the block.

One 4 gauge wire from the block where you connected the battery ground wire to the chassis ground where the battery was mounted up front. Use a 5/16” bolt and bolt down the 4 gauge engine to chassis ground, make sure that it the metal around the bolt is clean & shiny. This is the alternator power ground.

attachment.php?attachmentid=48657&d=1169348060.gif



The computer has a dedicated power ground wire with a cylindrical quick connect (about 2 ½”long by 1” diameter. It comes out of the wiring harness near the ignition coil & starter solenoid (or relay). Be sure to bolt it to the chassis ground in the same place as you bolted the alternator power ground. This is an absolute don’t overlook it item for EFI cars
Note: The quick disconnect may have fallen victim to damage or removal by a previous owner. However, it is still of utmost importance that the black/green wires have a high quality ground..

Picture courtesy timewarped1972
ground.jpg


Crimp or even better, solder the lugs on the all the wire. The local auto stereo shop will have them if the auto parts store doesn't. Use some heat shrink tubing to cover the lugs and make things look nice.


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring
http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg
 
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No 2/0 is larger.

/0 work in the positive direction until 4/0 then you move onto kcmil sizes.
8
6
4
2
1
1/0
2/0
3/0
4/0
250kcmil
350kcmil
500kcmil.
Ect.
Why in the hell couldn't the old-time developers of the electrical standards have used some more reasonably-based sensible system of calling out electrical conductor sizes?? :stir:
 
Don't know heck kcmil stands for
K= thousand
C= circular
Mil= one thousanth of an inch

The abbreviation for this was MCM depending on where you are in the country and how old your work partner is these terms are interchangeable.
 
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Don't know heck kcmil stands for
K= thousand
C= circular
Mil= one thousanth of an inch

The abbreviation for this was MCM depending on where you are in the country and how old your work partner is these terms are interchangeable.
For that matter, why is size Zero cable commonly called "ought" or "one-ought"? Ought to what? imp
 
Ought to not ask questions with obvious answers...
If one asks a question, do you presume him to already know the answer? If the answer were obvious to him, why would he ask the question?

Or, coincidentally, perhaps ALL the answers to all questions are mysteriously available to some chosen few.

The Gods of Answerdom must have bypassed me.

imp
 
If one asks a question, do you presume him to already know the answer? If the answer were obvious to him, why would he ask the question?

Or, coincidentally, perhaps ALL the answers to all questions are mysteriously available to some chosen few.

The Gods of Answerdom must have bypassed me.

imp
Alot of things bypass me, I just don't have enough brain cells left to over think anything,
I think?
Probably not. :nonono:
 
OK, I wanted to close the loop on this conversation for others who are searching for a solution to this similar situation.

I replaced all existing wire with 1/0, and ran a ground wire to the engine block. This resolved all of my my issues. The car charges and starts perfectly now.

I did not run the alternator charging wire(green/red wire) to the rear yet. I'm not planning on running the car at a track anytime soon, so I'll add that part when the day comes.

Thanks for all the help/advice!
 
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