The main issue here is whether or not the car has an ammeter. With an ammeter, the goal is to avoid having large amp loads flow through the ammeter. Hooking large loads to the stud is one way but, if the ammeter is left in place, a large wire from the stud directly to the battery will bypass the ammeter and carry most of the load...a voltmeter will be needed to monitor the system voltage.

IOW, there is no right/wrong way, it's simply a matter of preference.




Since the stud is hooked directly to the battery (Nacho's first diagram fails to show that), the load is handled by the battery...as long as the wire is sufficient in size, no problem...the load is handled by the battery as a "total loss" system.

I didn't fail on show the alt stud hooked directly to the batt... simply because is not... they are linked sure, but running throught the bulkhead, amm, starter relay stud.

i simply did show how how are actually wired every car with full load ammeters (shunted systems are a diff story, but not so different)... Mopars, Phords... whichever other brand. And ALL cars with ammeters get their devices sourced on alt side of the ammeter... no matter if an intermediate splice, ammeter stud, alts tud or some juntion point... Fuse box is also sourced from this side, being spliced into the amm-alt line. Yes, it says BATT, but just as a reference for a constant power coming from the power sources... alts if cengine is running or batt if engine is off.... or batt-alt combination depending on alt capacity.

JUST the starter motor is not sourced from alt side, of course. Sometimes some accesories which just work at certain points being not a constant power source suckers, like power windows could be also on batt side not on alt side

Thanks John. At least you see it. This nonsense of wiring high amperage devices to an alternator stud without having the rest of the system able to carry all the possible loads is asinine. Its also senseless as there are better ways to CORRECTLY wire an alternator for loads. When using high out put alternators the alternator should be CORRECTLY wire sized and CORRECTLY wired direct to a distribution block with protection on that circuit. The distribution block would be linked direct to the battery. All circuits then would be CORRECTLY fused with relays as needed out of the distribution block.

If keeping ammeter and planning to keeping reading correctly, you SHOULDN’T wire anything into the batt side.

I never said wiring doesn’t need to be upgraded or at least adviced, but there is a just one correct way to make it keeping the ammeter working correctly and is not linking the batt and alt with a jumper wire

BTW, you can install a 500 amps alt, but if the car just sucks 45, the amp will provide just that. Amperage is demanded by the accesories, not simply put out by the alt by its own.

You feed with the same battery the map light with a 18 gauge wire than the starter motor with a 2 or 4 gauge wire. The wiring must be matched with the device to be sourced, not necesarilly with the source capacity

Well that's stupid. It sure wont work as designed that way. Might as well tie the wires together and run a voltmeter.

Some C-bodies of the seventies had such a distribution block in the form of an insulated stud that mounted on the inner fender panel near the battery...when junk yard hunting in the old days I used to snatch these up for use on my rods. Hi-amp loads like power windows/seats and tailgates drew their power from this stud.

Nowadays I use this:

https://www.summitracing.com/parts/rra-fs46540

some late 90's, early 2000's minivans have a nice, compact distribution block with fuses and relays, that measures 3" wide, 8" long, and 3" tall.
these can be easily wired and hidden if necessary, in our early rides.

Just for interest of anyone interested… and just testifying about a satisfied “customer” (if my personal experience I share, made on my own car is still not enough) with some suggestions I made privately for it:

https://www.forbbodiesonly.com/mopa...e-to-a-volt-meter.240840/#post-912248339

There is about half of dozen of ways to make it quite fine… some with more intervention of the wiring (like the one posted), some other with lighter mods (like the one I made on my car). But allways splicing out correctly the power source ON A HIGHER POWER PLANT CAPACITY unit ( aka, alternator ) able to source the new adds at the lower alt speed as posible and still with the stock “tiny” ammeter gauge on line.

On the previous reply to the one I linked (#12), a member is quoting the thread I composed, BUT is still with the attachments missed. As mentioned previously, hoping will be recovered.

Yes, on B bodies with those same options, these accesories were sourced straight from amm stud on batt side (which is the same than using a junction close to the battery like the one you described ) instead the alt side like regularly should be because these are not constant power suckers, just ocassional. Leaving these on batt side, the ammeter will register the small amount of the charge load the battery lost when working althought for more time depending on alt speed, but will be safe from the load peak they suck on the operation moment. Just like the starter motor, which its operational load is not registered on amm, but the load lost after crank up getting back to the batt (charge) slowly and on lower rates than what was used to work once alt is able to do it when spinning.

I think I mentiond this on a previous reply… not extensively detailed like I did now.

Just more jiberish on a hack job.

Wiring an electric fan on a OEM charge path muscle era mopar is an exercise in select the lesser of the evils you wish to confront. There is no perfect spot to pull power in engine running and engine off modes.

The only gibberish in this conversation is coming from you.

Agreed, however also depending on how you wire the setup for the best. If you set it to be turned off with ign key or automatically with a temp sensor switch no matter the ign key.

On the second case the fan should turn off in a minute or so. And if the paths are upgraded you shouldn’t get any problem.

But the ammeter can be still on the line. The fan won’t suck more than the ammeter is able tiohandle, being the only device still sucking once you parked your car.

Assuming also of course, the Charging system has been checked for weak spots before any alt upgrade or accesories added. You can’t expect to get a perfect system on a non checked 40 years car when adding stuff. Call it electrical or mechanical parts, but tipically electric parts use to be underestimated, then failures appear and begin to blame everything but the real cause.

Is like when you select a camshaft going for a power upgrade and CR along with TC being or not considered, so you can fall into an “overcamed” car. The difference is a camshaft won’t get in fire your car, like an underestimated electric system for check and mantenience could be able to.

One crucial point to keep in mind when wiring add-on electric fans..
Since they draw large amounts of current (>30 amps) do NOT use the bulkhead connectors, as it exceeds their handling capabilty..

Just my $0.02....

Yes, but STILL if bulkhead terminals are kept as the main path there is allmost nothing to worry if wired into the CORRECT alt output rate. Just when engine is off, and when this happen as mentioned if you set them up to be on JUST with ign switch on… and if to be automatically off with temo sensor switch, fans will be working for a minute or even less. Still on this stage, bulkhead will hold it nicelly.

Take in mind, RELAYS are made with prongs allmost just like the packard terminals, and they handle the load! But sure, when installing those, they are fresh brass… but bulkhead terminals… not. Check and MANTENIENCE is the key

Over the years, we have rebuilt multiple Mopars and wiring systems which were modified by less experienced guys for electric fans...
Bulkhead connectors and associated OE wires were not designed to handle the high current. Since we have designed & built multiple vehicles for CES and SEMA shows we do know a little bit about this..

Just my $0.02...

The point everybody is trying to make is DON'T RUN HIGH-AMP LOADS THROUGH THE BULKHEAD CONNECTORS AND AMMETER. Whether it's wiring directly to the alternator stud or a parallel wire is a simple matter of preference. No right/wrong here.

small, cheap,
digital readout amp meter
with remote placement hall effect current sensing loop

https://www.amazon.com/bayite-Digital-Current-Voltage-Transformer/dp/B01DDQM6Z4

I would guess there are other designs,
and maybe even past OEM car and truck dashboard gauges to be found in salvage yards?

Yes, there is a wrong way to make it if you don’t understand how it works.

Attaching to the alt stud WITH THE CORRECT alternator, won’t get the bulkhead or ammeter loads going through, except with engine off and if fans are still running.

ONCE AGAIN, WITH THE CORRECT ALTERNATOR OUTPUT RATE.

Anyway, get the bulkhead path bypassed it will get a better charging system STILL with the ammeter in line, as far ammeter is also in good conditions… checked/serviced after all these years of use and abuse.

STILL WITH A 500 AMPS ALTERNATOR.

(Amps are not pushed in by the power source but sucked out by the accesories. Power source just need to be able to provide them anytime)