1963 Imperial - Bulkhead Connection and Alternator Upgrade - Please help me understand?

[72RoadRunnerGTX]

OK, here's my current plan, with the goal of keeping everything 100% reversible:

- The factory circuit has a 40A fuse on both ends, preventing over-current from entering the original harness
- I'm using marine battery terminal mount fuses, which have the advantage of no added wiring, and bolting right over the alternator and starter relay lugs. (picture below) They also have some pretty heavy-duty capacity.

Now, with the 95A alternator installed, I've got two problems:

- I'm still not getting enough charge current at idle
- The alternator sounds like it's working really hard at curb idle

I called Powermaster's tech line (major credit to them for USA-based product and support!) and the specialist I spoke to suggested my problem is that I didn't upgrade the charge circuit wiring. The alternator just can't push current to charge the battery along with everything else through the 12ga wire.

So, I'm proposing adding a #4 charge wire direct from the alternator to the starter relay, per Powermaster's recommendation. I've also ordered a solid state voltage regulator, as the packaging also suggested that would work best with the new alternator.

I'm hoping people here can check my work. This looks suspiciously like the "shunt wire" that @72RoadRunnerGTX debunked with his videos, which I've watched. (Thank you, those were so informative!) However, my understanding with the shunt wire bypass is that the problem is that the fusible link is only at the starter relay, on the "left" side of the circuit, and the shunt allows overloading the "right" side of the circuit without activating the bypass. In this design, both ends of the stock circuit are fused, so that shouldn't be possible? I guess if something shorted, it could pull 40A from each leg, culminating at 80A at the termination - but that should blow a smaller fuse in the interior fuse block first.

I think this might invalidate the ammeter, but I have a modern voltmeter as well so that doesn't concern me.

In this design, the only place high current can travel is between the battery and the alternator (and the starter, but that's irrelevant) right? If this doesn't work, I guess my only options are a full custom harness, or back to the 39A alternator.


View attachment 725556

Suspiciously? that is the “shunt wire” bypass. While the two added 40-amp fuses should protect the stock under-dash wiring from over-current in the event of a short and it will defeat the ammeter’s accuracy, it will no longer be useful as it was originally designed.

You still need fuse/circuit protection on the shunt wire near the battery to limit battery current in the event of a short on the large shunt wire, an internal alternator short or short at the alternator stud.

If the alternator is not keeping up with loads at idle, not seeing how this will correct that.

BTW, I’ve heard of that same Powermaster support response numerous times, they don’t understand this system or are only concerned with not having to deal with a warranty return.

 

[UGW]

Suspiciously? that is the “shunt wire” bypass. While the two added 40-amp fuses should protect the stock under-dash wiring from over-current in the event of a short and it will defeat the ammeter’s accuracy, it will no longer be useful as it was originally designed.

You still need fuse/circuit protection on the shunt wire near the battery to limit battery current in the event of a short on the large shunt wire, an internal alternator short or short at the alternator stud.

If the alternator is not keeping up with loads at idle, not seeing how this will correct that.

BTW, I’ve heard of that same Powermaster support response numerous times, they don’t understand this system or are only concerned with not having to deal with a warranty return.

First of all, thanks for explaining. I've been on internet forums way too long for a flame war - I really want to learn! I watched the videos on your youtube channel, and I feel like I understand so much more.

I'm ok with the ammeter not being accurate. I am NOT ok with fire! I have an aftermarket volt meter that is accurate, so that's good enough for me.

For fuses on the shunt, I could use the second fuse terminal off the alternator with 100A fuse, and add another at the end closest to the battery. That should cover all scenarios you mentioned.

I share your skepticism of the Powermaster response, but I figure it's at least worth a try, if only to strengthen my warranty claim. Shouldn't take more that 10 minutes to install, and immediately obvious if it makes any difference. Given my understanding of electrical current as "volume of water in a pipe" it makes some sense that the stock wires could be a limiting factor.

My goals with this car are maybe a little different than most people. I'm not aiming for a show car; I want a car I can drive and count on whenever I feel like it.

Goals:
- Not on fire
- Better charging
- Ability to run electric fans
- 100% reversible (so far, so good - I haven't snipped a single factory wire or terminal. I could revert the entire system to stock in under 2 hours.)

 

[UGW]

I finally got this working the way I'd like. Thanks to all who helped! Critically, the Powermaster alternator didn't seem like it was working well (or at all) until I added the 4ga charging cable, the solid state regulator, and rechecked the belt tension. It still whistles slightly under high loads at idle, but nothing like the horrible noises it made when I simply hooked it into the stock system. The electronic regulator was key. Even with the charge cable, the 95A alternator did not play nice with my original, mechanical voltage regulator or the brand new Standard Motor VR-101 I tried.

As noted, the ammeter is no longer useful, but I have a voltmeter, so that doesn't concern me. It could work again if I reverted everything, too, so I consider that acceptable.

Leaving an update here for any who may follow:

Goal:
Upgraded charging for a 1963 Imperial without modifying the factory wiring harness

Components:
- Powermaster 95A, single pulley, round-back alternator
- Powermaster 4ga, 8 foot charge wire, 5/16 terminals
- Blue Sea Systems MBRF 2-terminal stud fuse block (x2) (link)
- MBRF 40A fuse (x2, plus spares for the roadside kit)
- MBRF 125A fuse (x2, plus spares)
- Solid state voltage regulator for 1960-69 Mopars (link - turned out to be a Bouchillon unit, which I've heard good things about, but I didn't know that until it arrived)
- "star" washers of various sizes
- 10ga black automotive wire (optional)

Steps:
- Ensure your battery is charged to at least 12.6V before starting!
- Disconnect negative battery terminal!
- Disconnect red, 12ga red factory battery wire from starter relay stud
- Install MBRF terminal fuse block over starter relay stud
- Connect red, 12ga factory battery wire to one of the terminals on the fuse block, with 40A fuse
- Disconnect and remove existing voltage regulator (save as emergency spare)
- Install solid state voltage regulator in stock location with stock connections
- (optional) use "star" washers on the mounting screws and the field terminal to ensure a good connection
- CHECK: Ensure voltage regulator has a good ground by using multimeter to check resistance between mounting screws and a bare metal point on the body. Should be 0 Ohms. (You can also check between mounting screws and the negative battery terminal, but this won't work while the battery is disconnected.)
- Disconnect and remove existing alternator
- Install new alternator (ground second field tab to case), set belt tension
- connect brown ground wire from factory harness to alternator case
- (optional) I added an additional 10ga ground from the alternator case to the engine block. Not strictly necessary, but the factory wire seems so wimpy, and extra grounds won't hurt anything.
- CHECK: Use a multimeter to check resistance between the alternator case and a bare metal point on the body. Should be 0 Ohms. This means the alternator is well-grounded
- Install MBRF terminal fuse block over alternator battery stud
- Connect black, 12ga factory charge wire to one of the fuse block terminals, with 40A fuse (I did need to expand the ring terminal hole from 1/4" to 5/16", so technically I modified the factory harness here, but there's no reason the terminal couldn't still connect to the stock alternator stud in that state.)
- Connect one end of the 4ga charge cable to the other fuse block terminal with 125A fuse
- Route the 4ga cable back to the starter relay in a way that pleases you. I ran mine along the core support.
- Connect the other end of the 4ga charge cable to the free stud on the fuse block terminal you added to the starter relay, using 125A fuse
- CHECK: Use a multimeter to check resistance between the battery stud of the alternator and the stud of the starter relay. 0 Ohms should mean your charging circuit is complete and healthy
- Reconnect negative battery terminal
- With a multimeter measuring voltage across the battery (+) and (-) terminals, or a volt gauge installed the car (I already had one), start the car!
- You should see between 13 and 14.5V at idle.
- Turn on accessories (headlights, radio, ect) one at a time and observe voltage changes. Even with everything running, and the motor at warm idle, I never saw below 13V. I could tell the engine was working to turn the alternator, though.
- Turn off accessories, observe voltage recovering
- Take the car for a drive, ensure voltage stays within range, slowly adding accessories

I took the car for a few drives this weekend, and I swear it feels like it's running better than ever. I can even crank my radio, run my headlights, and my auxiliary fans without voltage drop. When I got home and shut the car off, my battery still showed 12.9V, which is also exciting, because I think my standard system was slowly killing batteries via repeated under-charging.

Voltmeter at idle, with accessories running

With accessories running

Fully warmed up, accessories off

MBRF terminal installed on starter relay

MBRF terminal installed on alternator (4ga charge wire not yet installed)

 

[Torky]

Background

Like the title says, I have a 1963 Imperial Custom that's pretty much stock. It has a dealer-installed Mopar AC from the 1960s, and I have added a CD player, some modern aux gauges, and a 3rd/center mount brake light. The AC is wired into the back of the fuse block, as was standard procedure. The radio and gauges have their own fuses, 15A for the radio, 5A for gauges, and are also tapped into the fuse block. The brake light is tapped into the existing brake circuit, which is already protected.

In the future, I'd like to add an electric radiator fan, because even my 7-blade fan with no clutch can't keep up in traffic on these 95 degree days. My plan is to connect the fan using a relay with integrated fuse straight from the battery or starter relay, so that only the signal wire (low current) runs into the passenger cabin for a manual switch, thus reducing current in the wire harness. (I believe this is how the factory horns work, if I am reading the manual wiring diagram correctly?) Some day, I'd also love to add a small, 30A powered subwoofer, but that is a long way off.

My alternator has a 1963 date stamped on it, so (according to the service manual) it's at most 39 amps if it was upgraded with the AC, or 35 amps if it wasn't. In a way, I suppose this is good because the alternator physically can't produce enough current to cause trouble. However, it also struggles to keep the battery charged on a hot, rainy day, when I'm running my headlights, wipers, and AC together, in town traffic below 30mph. It also doesn't always fully recharge my battery on short trips, which is most of my driving.

The Problem

I'd like to upgrade my alternator. It doesn't need to be crazy - even the 60A units Rockauto specifies for this car would be a major improvement.

Now, I've read the MAD Electrical article, which some people love, and some hate. I've read lots of posts on this forum and others. I've watched @72RoadRunnerGTX 's videos about the dangers of a bypass. The last thing I want is to set my car on fire. (Which is why everything I've added so far has a dedicated fuse.) However, I'm more confused if anything.

1. Does that MAD article even apply to me? 1963 has the screw-type connectors (picture below), which I've read are superior to the packard/delphi 56 terminals most articles reference. Unfortunately, most articles aren't aimed at early 60s Imperials, but later Chargers, trucks, etc, so information is scarce.
2. I'm ok with bypassing my ammeter. One of my aux gauges is a voltmeter, so I would still have eyes on my charging system.
3. The connections on the back of my ammeter also look very good to me. I did the RTE solid-state volt limiter upgrade on my gauge power last summer, and everything looks remarkably clean.

My bulkhead connector, for reference, power terminal circled. I know it looks a bit grungy, someone went crazy with the Ziebart on this car at some point.
View attachment 724633

And here is the inside, so you can see the general condition:
View attachment 724634

Do I need to modify my wiring to upgrade my alternator?

Second question: Instead of a bypass from the alternator to the starter, what if I just made a jumper wire from the red to black terminals, inside the engine bay?
I haven't seen anyone mention this, so maybe it's a bad idea? My thinking is that this would prevent excess current from going into the dash by providing a second pathway to the battery, but it would still be a single pathway, which would preserve the utility of the fusible link at the starter relay? I suppose maybe this does not help if the factory red & black wires aren't up to the task? Or maybe the bulkhead terminals themselves would still overheat?


Here's an example of what I was thinking. (Black terminal is obscured by 6-pin connector above it)
View attachment 724635

Anyway, really would like some advice here. I'm no electrical engineer.

Finally, here's the wiring diagram if it helps anyone:

View attachment 724636

My input, not necessarily in order of importance: First: A question for you and the readers: How might one find and install a bulkhead connector replacement for the one in my '64? It does not have the screw connections, leading to MAD if connections are deteriorated. Necessary to cut a larger hole in the bulkhead? For you: Clean up the connections at the bulkhead connector. I see no benefit to bypassing the Ammeter as it only indicates current draw to and from the battery. The alternator provides current for most everything else with that current passing into the passenger compartment through the bulkhead connector and routed directly to the light switch, ignition switch, radio, blower without going thru the Ammeter. Some current goes back into the engine compartment to power the ignition, horn and starter relays, washer pump & A/C clutch. Blower ballast does not pass through the bulkhead connector. Certainly, adding any additional load under the hood that runs fairly continuously will add in and out current and, perhaps, require an Ammeter upgrade. There are many ways to rewire these cars to reduce load on the bulkhead connections, I recently saw a headlight relay design to assure slightly more Voltage to the headlights. Proceed with caution. These cars can burn to the ground at the drop of a hat. Nothing new in the automotive world. I interviewed Chrysler for an ME job in 1960 and my engineering guide voiced disappointment at design interference by green eyeshade guys. I have noted similar disappointment in my Chrysler products and also in my engineering career. Footnote: Perhaps the bulkhead connectors in Imperials all have the screw connectors while Chryslers do not (''63-'64, anyway?)