Amp Meter ByPass

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charger426

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I know this has been asked/coved all over the net but I'm still lost about what I need to do.

I have a 140amp PowerMaster 1-wire alternator that I want to install in my 71 Dart. I had originally thought about doing the "fleet" upgrade and just upgrade the wire gauge to the amp meter. But the more digging and research i've done it sounds like the stock amp meter can't handle 140amps. So my question is what do I have to do to make this work? All of the diagrams I've seen are for stock style alternators not the one wire style. I would also prefer to use an actual fuse rather than a fusible link just for ease of replacement should something go wrong. Thank you all for your help.
 
The major issue is and always has been the fact that the oem design sends the bulk of the charging current through the bulkhead, to the ameter then back out again. You can do the fleet u
 
The issue has always been that the factory design sends the bulk of the charging current through the bulkhead connector and up through the ameter. You can do the fleet upgrade and beef up the components to alleviate the issue especially if you really want to keep the stock ameter functional (ie - restoration etc). But since your gonna run a 140amp alternator I'm assuming your gonna run a volt meter. If that's the case, the easiest way to take the load off the bulkhead is to run a piece of wire with a fusible link directly from the starter relay lug to the alternator post. It's what I've done on all my cars. I just rewired my Duster with an engine harness from Bill Evans and did this while I was at it and wrapped it all together, looks clean, super easy and no more ameter issues.

Lastly begs the question, why are you running that big an alternator?? Unless your running ALot of extra stuff (ie- elec fuel pump, big stereo system, elec water pump, elec cooling fans etc etc) then you really don't need it! I've got a stock replacement Autozone special 65amp alt and it handles everything just fine.

Lastly highly recommend Rob (aka Crackedback) headlight relay conversion! He sells a kit that puts the headlights on relays and really helps brighten up all the lights including dash lights etc and further help take load off the charging circuit!

Just my long winded .02 cents
 
Hi,

I too am puzzled why people put such big alternators on an older car. 140 amps is a lot of current to deal with. The "fleet bypass" modification was never intended to deal with these kinds of currents and the ammeter certainly can't. To install his kind of alternator safely you will want to run a new wire of something like #4 gauge from the alternator output stud directly to the positive post connection on the battery. This new wire should be fuse protected with a fusible link or fuse rated for the alternator output. Next, the original alternator output wire should be clipped off at the bulk head connector and the original ammeter wiring removed except for the black wire from the ammeter to the splice joint connection. This wire should be connected though the original fusible link or better yet a new 50 amp Maxi-Fuse blade type fuse to the battery stud on the starter relay. Any connections to make use of all that current should be connected directly to the positive battery post.
 
I am installing a big stereo in addition to other things like an MSD box and electric fans. Plus I got a deal on this single wire PowerMaster that was new in box. I did a relay kit for the headlights already and while I haven't had a chance to drive it around at night to test it I'm hoping thats the fix the my headlight flickering.

So I looked at the MAD page before I posted this thread and I'm just not 100% sure what wires I need to keep/cut/upgrade. My understand is with the one wire I was under the impression that I just run one wire to the battery positive. I was going to do that with 4ga wire and a 150 amp fuse. Now is there wires coming from the starter relay that are going into the bulk head connector that i'm to replace? If I could I would really like to keep the factory amp gauge but It sounds like even if I up the wires to the gauge its a fire waiting to happen if I throw 140 amps to it.
 
There is no possible way I'd consider "keeping" the amp gauge with a 140A. Even "Ma" knew this was a problem with SIXTY amp alternators, as "she" offered optional "fleet / taxi" wiring which ran the ammeter wires in through separate grommets, IE bypassing part of the bulkhead connector.

Depending on what dash you have, there was a thread on here on modifying the ammeter for mounting a voltmeter, but my understanding is that the original Sunpro gauge is no longer available. However "the project" would be similar for any voltmeter

http://www.forabodiesonly.com/mopar/showthread.php?t=119480

You can CERTAINLY wire a direct wire from the battery to the alternator. Frankly, I don't care for "one wire"

Problems.........

You need a VERY large charge wire. Why? Because the charge wire is now the SENSING wire and any voltage drop on the charge wire would cause system voltage to vary

I'd say with a 140A, that no6 might even be small

Here



NOTE This website no longer allows proper posting of URL to a file

put in http://www.

and then put this in

tuffstuffperformance.com/pdf/1-wire_alternator_instructions.pdf

You are headed for a no4 charging wire

Racing / rear battery / disconnects. A "one wire" can complicate battery disconnects, required for racing with trunk mount battery.

Yeh. they're easy. Hook 'em up.
 
Search my post "Modernized Engine Wiring" or such. I use a diode-pair as a "progressive ammeter bypass", so I keep the ammeter functional but don't over-range it. I also installed a 95-99 Jeep fuse/relay box. But those take 60 A max fuses I recall. I bought a separate ~180 A fuse at Autozone for the BATT+ connection (after starter current). I bolted that to the Battery Brain I use.

Re current output needed, I just measured my 1996 Voyager since I suspected its alternator was not outputting OK (still original at 205K mi). I have a clamp-on DC ammeter that I measured right at the alternator output. I measured ~40 A with AC clutch on, cabin blower high, headlights high-beam, and radio on, which is probably a typical load for an EFI engine (though a 4 cyl). When the 2 radiator fans turned on, it jumped to 60 A. I probably have the base 90 A alternator, so still ample head-room (and works fine). There is a 120 A alternator option, but no need. I don't think the radio draws much unless you are "all about that bass" and put in a ground-thumper (also need stiffer T-bar on R side if bass babe rides shotgun). Don't calculate based on fan nameplate since probably the starting surge current. Steady running is probably ~10A per fan, but more if the Ford 2-spd fan which hot rodders use. Your engine-driven fan should do 90% of the job, w/ electric just to help the AC condenser. BTW, my 1996 alternator is the same "isolated field" type alternator as the squareback in 1970's Darts, though a Nippondenso.
 
I'm out to do this as I installed a VOLT guage. But, how come on the mad instructions, you can't just run a wire from alt. to starter relay, then, unplug the amp meter, and just run 1 wire instead of 2 directly to the starter relay as well?
 
I answered this in the other thread where you asked the same question. Search "MAD Bypass".
 
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