Bypassing the Amp gauge - Question about the MAD Electrical method

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MobileCustoms

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I am now working on my firewall and all the wiring, dash, etc.
I have read about the MAD method and that has already partially been done to my car by someone else.
Anyways, after looking at the diagram, it seems to me that I could just eliminate one of the wires (the black one) from returning back through the firewall and it would effectively be the same without any additional load, correct?

I just don't understand why we would need to complete that loop if the amp gauge has been eliminated/bypassed.

I have modified the diagram to show what I am proposing. Feel free to correct me if it will have any negative effect.
I just figure the fewer wires I end up with in the engine bay, the better.

Also, where's the best place to by the good quality fuseable links at?

Thanks!

Doug
 

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Yes you can. It is just a loop of power and that is it. There is also no reason to splice where it says to behind the amp gauge. Just put both on 1 lug at the gauge, if you are keeping the gauge in the dash.
 
Basically, using both the wires as shown by MAD does at least two things:

By running the alternator output direct to starter relay, you have a shorter path to the battery and less connections. You have eliminated TWO connections in the bulkhead, and the ammeter, plus "the trip back" through the long wires through the bulkhead and back

To answer your main question, by using the original black lead as they did, you now have created TWO battery "infeeds" into the car. This effectively makes one great big wire......that is the red and black are now in parallel.

I would either do it the way MAD does, or string a complete new, larger wire for the battery feed into the car.

And, ESPECIALLY if people use a "one wire" replacement alternator, the alternator charge wire needs to be MUCH larger. This is because the "one wire" is now also the voltage sensing wire.

This is one reason I used to get sideways with Dan. He claimed the MAD guys are "Chevy heads." The actual fact is, this is very well thought out using a minimum of intrusion with factory wiring.

Ma KNEW that her wiring was shaky, even back then. Google up "fleet wiring." This was done, either factory, or dealer, on taxi/ police and other cars with heavy duty alternators. The ammeter was still kept inline, but the wiring was made heavier, and was run separately through grommets in the firewall.
 
Thanks for the replies. I should have also mentioned that I purchased the headlight wiring relay kit upgrade from Crackedback so that is another large load I will be removing from the under dash and bulkhead areas. I also have a brand new engine bay wiring harness.

As for the Amp gauge, I have purchased the sunpro mini volt meter and intend to use the guts of that in the amp meter hole with the original amp meter face as my general charging indicator.

Here's a link to some of that info for anyone else who might be interested:
http://www.forabodiesonly.com/mopar/showpost.php?p=1302646&postcount=17
 
just put both on 1 lug at the gauge, if you are keeping the gauge in the dash.

x 2 When the ampmeter fails, I've found that the car will start but will not run. Putting the leads on one lug is a good field fix if the gauge fails enroute.
 
I've been reading up on this subject for a while now. Putting together a 66 dart convertible. Have headlight relays, and top motor relays or it and brand new harness' including engine dash and body. I will run a #10 shunt from the alternator to the hot/battery side of the starter relay. Is there any reason I would want to bypass the ammeter?
If there is, I guess nows the time. BTW, no huge stereo, electric fan or electric fuel pumps, pretty much stock.
What do you all think??
 
You don't have to loop it, it does make for a large in-feed wire as Del mentions if you choose to loop.

Ammeters have been known to spontaneously combust... Cars sitting parked just flame up from the meter melting. It's live all the time.
 
You don't have to loop it, it does make for a large in-feed wire as Del mentions if you choose to loop.

Ammeters have been known to spontaneously combust... Cars sitting parked just flame up from the meter melting. It's live all the time.

Thanks crackedback
 
You don't have to loop it, it does make for a large in-feed wire as Del mentions if you choose to loop.

I understand that but feel that is not so correct in this case, since both wires tie back together and share the same smaller fuseable link.
It's no big deal, just figured why not clean up some more extra wires as long as I am doing the mods.

Thanks again for all the info!
 
.............t feel that is not so correct in this case, since both wires tie back together and share the same smaller fuseable link.

That is not quite correct, either.

Even though the fuse link is smaller, it's a very very short piece of wire. This means that even if it's overloaded, it does not produce the same larger voltage drop as a longer wire. So the two wires together still act together to produce less voltage drop.

That's why I said earlier, I'd either run one larger than original wire, or go ahead and just hook it up as MAD did it.
 
I will most likely end up running just one single, larger wire from a fuseable link at the starter relay through the firewall with no splices in the engine bay. That will be safer and cleaner looking.
 
I did the MADD conversion the exact same 2 wire diagram feed way and made my own fusible links based on their specs and recommendations. I'm a fan of the 2 wire method myself simply because a single wire would have to be more than twice as heavy to carry the same load and I like the redundancy. Current/amps=heat. Call me a better safe/just in case guy. You can still keep it extremely clean and it just feels "done right".
I also bought Robs headlight relay kit and am very happy with everything I've done.
Just my own thoughts....Brian
 
Just thought I'd share a couple of photos of my old harness here, after removing everything last night. Both the main red wire and black wire had done some melting at the bulkhead. Someone had re-routed the red wire through the firewall which was a good idea... BUT, then they merely hand-twisted the wire back together under the dash and used a flimsy piece of electrical tape to hold it together, and left it hanging low and flopping around.
I could hear the wires crackling and sparking last time I went to fire up the car, It sounded like bacon in a frying pan.

I think I got to this one just in time!
 

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but the mad guy is very correct in a lot of things. i talked to him on the phone (he likes to yack so if you call him set aside 1 hour+ !)

anyways a crimped, soldered, splice with heatshrink (Mad's method) to bypass the ammeter guage is superior to using 1 post.

why?

using a post you now have 2 solder joints and two connectors bolted to a post instead of just a single joint. much less chance of the joint degrading with Mad's method.

a degraded joint with current flowing through is what creates heat and lights to go dim and melted stuff etc.

i got a bunch of stuff from Mad to do my car when the time comes. but the guy knows what he's talking about.
 
MobileCustoms,
My 64 Valiant was about the same when I bought it. Someone had run thick yellow wires thru holes in the firewall to replace the factory red and blk ones, but no grommets to protect them and the same shoddy work. I had to use jumpers to drive it home. I am putting a 65 bulkhead in it since those don't have the melted terminals problems. They have large buss-bars to feed the ALT and BATT wires thru, as did 63 cars. Wouldn't work for you since 65 doesn't have the 3rd connector for the wiper in the engine bay.
 
Yea, I am about to do this to. Run a wire from alt. directly to starter relay, then, I don't see the need for 2 wires where the amp guage was. unplug the amp guage, and run a single wire from the side feeding the other stuff....
 
What you propose is the "MAD Bypass" (search). Connect the 2 ammeter wires together, but don't leave them hanging w/ exposed copper. Most people put both wires on a single ammeter terminal stud. You already have the 2 big ALT and BAT wires to feed the cabin. No need for a new wire. They will no longer carry the large alternator current.
 
I leave the OEM wiring as is and bypass the ammeter.
 
I asked because I found this...single wire vs the MADD way....other pic

bypass_zps49bc138d.jpg


AMP-GA27.jpg
 
The red wire DOES NOT touch the welded splice, diagram A is a PIA to perform. Unless you want to peel apart the harness to attach a wire to the splice, waste of time and effort. The welded splice is in the black wire run. The easy way to do a one wire approach is to connect ammeter wires red/blk and run a single wire to the red, terminate black wire before bulkhead to keep from shorting anywhere.

Much easier to leave the OEM stuff alone and run the charge wire from alt stud to starter relay.

Pick which way you want to do it and go.
 
The red wire DOES NOT touch the welded splice, diagram A is a PIA to perform. Unless you want to peel apart the harness to attach a wire to the splice, waste of time and effort. The welded splice is in the black wire run. The easy way to do a one wire approach is to connect ammeter wires red/blk and run a single wire to the red, terminate black wire before bulkhead to keep from shorting anywhere.

Much easier to leave the OEM stuff alone and run the charge wire from alt stud to starter relay.

Pick which way you want to do it and go.

I know this is a really old post and I've been reading about the MAD bypass (and other electrical issues) for days. I would like some direction from the FABO experts! The 67 Barracuda I have had many many splices in the entire wiring system, I said had because I'm attempting to rewire it back to the correct way, close to factory, with new wire feeds, eliminating the bulkhead connector, ect. The question on the MAD bypass I have is the red ammeter wire is gone, not in the car, could a single wire set-up work? Looking at the different diagrams it looks like this would be a solution, they same that Shainsboostin and MobileCustoms were asking about. Like I said there is no red ammeter wire in the car, not going to the starter relay, not on the ammeter post, nowhere (not sure what the heck the PO did to the car but it is a mess). I did locate the welded splice within the harness and there are five wires connected to it, one comes straight from the alternator feed (I'm calling this the main feed, right?) there is a black w/tracer going to the lights switch, a red going to the ignition switch, a red w/tracer feeding power to the fuse box, and finally the black ammeter wire. If we are bypassing the ammeter, and alternator black "main feed" wire is going to the starter relay now via a 14 gauge fused link, why couldn't the black ammeter wire be eliminated or at least capped? I would have, from the starter relay, a 16 gauge fusible link connected to a new red wire (gauge size?) that connects to the welded splice. Yea, I know I'm not going to have parallel wires.

Single Wire Bypass.png
 
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The way the MAD thing works out "in the end" is that the original black and red end up being a parallel feed, and the black no longer carries alternator current. There are several ways to do this. The MAIN thing is that you have some sort of fuse protection so that a massive short won't burn things down

Couple'a versions:

You need a fuse from the battery feeding the rest of the car so that a big short anywhere will pop the fuse or link. The way the original is set up IF YOU ADD a jumper FROM the alternator to the battery, depending on how (model year changes) the fuse link is set up, you can end up with NO fuse protection IF THE ALTERNATOR diodes short. And by the way this DOES happen.
 
The way the MAD thing works out "in the end" is that the original black and red end up being a parallel feed, and the black no longer carries alternator current. There are several ways to do this. The MAIN thing is that you have some sort of fuse protection so that a massive short won't burn things down

Couple'a versions:

You need a fuse from the battery feeding the rest of the car so that a big short anywhere will pop the fuse or link. The way the original is set up IF YOU ADD a jumper FROM the alternator to the battery, depending on how (model year changes) the fuse link is set up, you can end up with NO fuse protection IF THE ALTERNATOR diodes short. And by the way this DOES happen.
I agree about having fuses to protect, that's the last thing I want, to have a electrical fire. I suppose I could run another wire to replace the original red for the ammeter and connect it like the MAD original.
 
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