Mad ammeter bypass question

[JG1966]

I am going to upgrade wiring on 1972 RR with Mad ammeter bypass. I am running an 8 gauge wire from 75 amp alternator to a 12 gauge fusible link at starter relay. But
can someone please explain why the two 10 gauge wires coming from the bypassed ammeter and through drilled holes in bulkhead connector would be spliced to a 16 gauge fusible link attached to starter relay? Fusible links are supposed to be four gauge sizes smaller than the wire they are protecting. So how come TWO 10 gauge wires spliced together get a 16 gauge fusible link? I trust the people at Mad but, to me, it doesn't make sense.

 

[Kern Dog]

That site has some great info but I didn't like the way that they rerouted the ammeter wiring.
What I did works but is not the only way to do it. Read on if you care to know.
I ran a 10 ga wire from the alternator to a 14 ga fusible link attached to the starter relay. I then replaced the ammeter wire "loop" entirely. I ran a single 10ga wire through the firewall and inside where it splits off to power up the interior.
The factory had a wire enter the bulkhead and attach to one post on the ammeter. The other post had a wire that split off into several areas. It split to send power to: Headlight switch, Starter switch, fuse panel and finally it came back through the bulkhead, a fusible link on the end, then it was attached to the starter relay. I essentially took the loop out of the harness because I thought the return wire they showed was redundant.

 

[KENTON]

That site has some great info but I didn't like the way that they rerouted the ammeter wiring.
What I did works but is not the only way to do it. Read on if you care to know.
I ran a 10 ga wire from the alternator to a 14 ga fusible link attached to the starter relay. I then replaced the ammeter wire "loop" entirely. I ran a single 10ga wire through the firewall and inside where it splits off to power up the interior.
The factory had a wire enter the bulkhead and attach to one post on the ammeter. The other post had a wire that split off into several areas. It split to send power to: Headlight switch, Starter switch, fuse panel and finally it came back through the bulkhead, a fusible link on the end, then it was attached to the starter relay. I essentially took the loop out of the harness because I thought the return wire they showed was redundant.

Seems like a lot of stuff to feed with one 10 gauge wire. By looping them together you cut the load in 1/2

 

[Darthomas]

Why not eliminate factory gas gauge and temp gauge too?

If it's less information you want then go the whole way.

Don't worry, you'll still know when the car has overheated and when you run out of gasoline.
The gauges just cause trouble, so do away with them.

I don't yet comprehend how so many people would willingly give up knowing charge/discharge information, then show up in a tech forum later asking about low charging effectiveness.

The problem is not having an ammeter, the problem is way the stators are wound now on alternators, with too few turns in each pole section, resulting in low output at idle speed.

Get a stator wound as the factory original was with at least 12 turns per loop, and everything will work as designed.

Why couldn't crappy alternator rebuilding for the last 35 years plague GM or Ford vehicles...why are their stators wound to factory specs and Mopars get stuck with low output @ low rpm....the higher amps they advertise, the only thing they do is wind the stator out of heavier wire, but then they can't fit as many turns in each loop, and the idle output suffers greatly.
But I actually believe this was a conscious decision by rebuilders to handicap Mopar vehicles, made sometime around 1977.

 

[mmissile]

Never had one fail? They can make a nice fire[been there]. I always eliminate my amp-meters.

 

[lukedukem]

I kept mine in my 69 charger. I just ran parallel wires to help with the load. I also upgraded to a new ammeter rated for 60 amps. I had burnt the original one while running wipers, a/c fan and lights all at the same time. I run a 60 amp alt and I've had no issues since then.

Luke

 

[Darthomas]

Never had one fail? They can make a nice fire[been there]. I always eliminate my amp-meters.

No, never.
But I am an electronics engineer, and know to keep terminals tight.
I've shed years in junkyards inside many cars with dashfires at the ammeter.
But this is like saying, no, there's no way we could ever ensure that this one particular pair nuts cannot be kept tight like any other...no, it's under the dash and is forgotten until there's high resistance and someone starts selling people a product instead of old fashioned learning-understanding and/or elbow grease.

More Coffee!

 

[PRND21]

Ammeters carry the full load of the charging system, they weren't designed for 75 amp alternators. A volt meter will tell you if the alternator is charging or not with just a single 16 ga. wire running to it.

 

[texas69bee]

No, never.
But I am an electronics engineer, and know to keep terminals tight.
I've shed years in junkyards inside many cars with dashfires at the ammeter.
But this is like saying, no, there's no way we could ever ensure that this one particular pair nuts cannot be kept tight like any other...no, it's under the dash and is forgotten until there's high resistance and someone starts selling people a product instead of old fashioned learning-understanding and/or elbow grease.

More Coffee!

You have argued this point many times in the past but yet the safest route is to prevent the full load going through the bulkhead.
If the ammeter was that effective and safe, they would still be using it in cars today!!!

 

[Darthomas]

I agree in eliminating the bulkhead connectors, using the police/taxi setup, or even removing the shunt from the meter, and remote mounting it in the engine compartment. Then run two tiny wires over to the meter.
Anything but eliminating the meter.
That's my point... there's many engineering solutions, but also people willing to just sell stuff to those who don't have enough information.
There are so many people here with such vast knowledge of every last drop of mechanical experience in engine building and racing.... electronics is just as understandable.
I hate spraying new parts at just anything that's not yet understood.
Always have been, and that's how I make my living...."That's not broken, it's just not quite right".
And then the giant web press runs.

I remember seeing the MAD website about 2012, and, boy did it ever make me cranky!

 

[JG1966]

Why not eliminate factory gas gauge and temp gauge too?

If it's less information you want then go the whole way.

Don't worry, you'll still know when the car has overheated and when you run out of gasoline.
The gauges just cause trouble, so do away with them.

I don't yet comprehend how so many people would willingly give up knowing charge/discharge information, then show up in a tech forum later asking about low charging effectiveness.

The problem is not having an ammeter, the problem is way the stators are wound now on alternators, with too few turns in each pole section, resulting in low output at idle speed.

Get a stator wound as the factory original was with at least 12 turns per loop, and everything will work as designed.

Why couldn't crappy alternator rebuilding for the last 35 years plague GM or Ford vehicles...why are their stators wound to factory specs and Mopars get stuck with low output @ low rpm....the higher amps they advertise, the only thing they do is wind the stator out of heavier wire, but then they can't fit as many turns in each loop, and the idle output suffers greatly.
But I actually believe this was a conscious decision by rebuilders to handicap Mopar vehicles, made sometime around 1977.

I appreciate the debate of whether to keep a functioning ammeter (I'm putting in a voltmeter), but can someone please address my original question.
Why would two spliced 10 gauge wires get a 16 gauge fusible link? Thanks

 

[Darthomas]

Because the fusible link is supposed to be a certain size...it is a fuse.
But it is always good practice to provide larger gauge wires to reduce voltage drop,
two smaller wires are often easier to deal with and more flexible than one larger wire.

 

[Darthomas]

Ammeters carry the full load of the charging system, they weren't designed for 75 amp alternators. A volt meter will tell you if the alternator is charging or not with just a single 16 ga. wire running to it.

If you knew what the voltage was when the engine was off, and no load on it, then mentally noted it, and the analog gauge has an expanded scale showing only the range between 9 volts and 15 volts, then could see just how much above that level you are when the alternator is charging, you could see what level you are at, but no easy way to tell if you've lost a diode or two. It's far less information, and kind of a "the horse is already out of the barn" information.
When everything is working right, you won't ever need 75 amps of current, unless you are running a 1000 watt electric resistance heater as you drive.
Give me my voltage output at low rpm where it's needed...going down the road there's always been plenty of amps, but that's what they sell 'em and rate them by, instead of volts/rpm @ avg idle speed.

 

[bm02tj]

The only time the currant is flowing through the ammeter is to charge the battery or when the battery if supplying the power
The bulkhead connector has to carry the load so bypassing that connection will help
or relay some of the high draw items

 

[mmissile]

The nuts on the back of the amp meter in my hemi road were tight. The post was loose inside the gauge . Instant bypass for me. I had a good-sized fire inside my Hurst-300, due to an amp-gauge.

 

[Darthomas]

The nuts on the back of the amp meter in my hemi road were tight. The post was loose inside the gauge . Instant bypass for me. I had a good-sized fire inside my Hurst-300, due to an amp-gauge.

Yes, that's why I very much like the idea of putting the shunt in the engine compartment. Then it becomes almost impossible. Sorry that happened.
You point out that it would be wise for all of us with amp gauges to pull them and ensure that internal connections are also tight. Because of heating/cooling, there is a likelihood of loosening.

 

[texas69bee]

That's what we need, more crap on the firewall or be safe and use a volt meter.

 

[khryslerkid]

I bought these awhile back, still in their original box. Luckily they still make them, so I replaced the amp guage with a voltmeter. Apparently the manufacturer doesn't want responsibility for the risk.

 

[Yatzee]

Best to run a single 10 ga wire directly to the interior fuse box from either the battery + terminal, alternator + terminal or where the battery cable connects to the starter. Screw the fuseable link altogether and go with a mega fuse rated the same as the fuseable link you intend to use. Fuse values are the same as the "link's" value and you won't be waiting for a slow burn, rather the fuse is instantaneous. Easy to change, cheap to buy, out of site and some will indicate when their blow with a small pilot light. Take the original alternator wire and run it directly to the battery, again fused for what ever the max output is of the alternator. If you upgrade to higher output alternator, up the fuse's value.

 

[Darthomas]

Yes, you can bypass the ammeter going straight to the fusebox, but then you will never see the ammeter center out when the voltage regulator is "satisfied".
You will see the meter displaying the actual amount of charging current needed to keep things in balance.

Which is also fine, if you mentally adjust for that new condition.
I like seeing the ammeter center out when the battery is full charge.
Then if a tail-light wire shorts out in the trunk if something shifts, I see that rightaway on the gauge, before there is a fire, or the battery is sucked dead.

I like the stuff on the firewall.
But I understand some folks don't.