85amp alternator ?? - 69 B-body

if no high amp accessories are added to a factory 69 B-body [my charger] wiring harness, will it hurt to have an 85amp alternator in the system ?
the wiring harness is in perfect condition, as well as the bulkhead connectors. i realize the alternator will [should] put out only what the system will require load wise, to replenish the battery needs.
i am planning to tie the amp gauge wires together, and go with an accessory volt gauge, as well as adding an 8 or 6ga wire from the alternator output stud to the starter relay, with a 100[?] amp mega fuse.
i "may" at some point, install an OEM electric fan and shroud system, running off of a relay bank that will use a ground connection as the relay[s] trigger[s].
i'm not sure of the original alternator output, but it may have been a 35 or 45 amp output ?
for whatever it's worth, i'm planning on an all LED bulb conversion, including headlights, although my night time driving will be very limited. [ya know about "old people" going to bead early, right ? ]
is my electrical experience thinking this correctly, or has my foggy noggin' forgotten something important ?
TIA to those that keep this old dumhead on the straight and narrow.

Really? Do I need to talk about this? LOL.


Just and advance… you can fit a 500 amps alt but if the car request just 30 amps, the alt will just put that.

The advantage on a higher amps alt is the guarantee about its output at any speed, so the batt won’t be requested (except for cranking) and the ammeter will NEVER see any load, and will look like a death gauge LOL.

No load throught, no heat.

You can keep the ammeter, and just for safety, run a parallel path between alt and ammeter. 10 gauge is plenty keeping the existant 12 gauge wire

Then run a new path between amm and starter relay. 10 gauge with a 14 fuse link and despite the existant one throught the bulkhead

Sounds like you have it covered pretty good.

The important part not to be overlooked

Actually important just in case on a battery discharge, but keeping an average close to stock car load request, not even that is really important.

The main problem has allways been the constant car load added by a constant battery discharge status due the stock low alt capacity at iddle. Once that is saved, you are maybe saving around. 10-15 amps of constant extra load running throught the charging system to recharge the batt when revving up the engine. If the car tipically demands 25-30 amps of load at night for example, this increases up to 35-45 amps. This is the red line to the bulkhead.

one other thing to mention.
if you are special ordering this alt, consider the m-body alt instead.
every parts store carries it and it is 78amps.
it will be a square back so if original looking is more important disregard.
but if ease of getting it replaced if it fails is, then consider that instead.
I have never mounted one to a BB, but on a SB you need a longer swing arm and the 10 dollar chrome GM one that all parts stores seem to carry works with spacers to bring it out far enough away from the block to match up with the alt.

i forgot about the M-body alternator.
originality doesn't concern me in the least, and i can fabricate any brackets and spacers necessary.

Where do the extra amps come from? Do they use thicker wire in the field and rotor? There's only so much room in there, and I'm thinking this would mean fewer windings, and therefore lower voltage per resolution, leading to the dim headlight issue at idle. Can anyone confirm my assumption?

All 1969 Mopars had wiring problems is what I'm remembering about them from the past, many engine and under dash wiring harness problems melting the amp wires at the bulkhead connections and the charge wires from the alternator to the bulkhead and to and from the amp gauge
I would check the inner nuts that hold the studs from the amp gauge to make sure they are tight, not a 1/4 turn loose
IHTHs

The 100a units had 6 diodes per bridge instead of 3.

That is what I used when I converted my 51 Plymouth from 6v to 12v.

Running and electric fan, a good one, is the only real addition to the electrical system, right now. EFI is coming though.

Wider stator… hence why housing is a revised design and the alt unit itself is also couple of millimeters wider

Do you have relays on your headlights? That alone really increases their brightness, takes a lot of the load off most of the power circuit going through the dash, and reduces or eliminates the discharge at idle. May be a good idea even with LEDs. Separate circuits with relays for any of the larger power draws that eliminate all the power going through the bulkhead connector and dash cures a lot of ills on our old dinosaurs. And may reduce the size of the alternator that you need as well as protect your under dash circuits.

headlights and fan will be powered from a relay bus, with the relays energized by the ground circuit.

Now that all depends on where you source the power feed for those relays. Too many use the battery terminal, which does nothing for the current thru the bulkhead connections and puts all that load thru the ammeter where is does not belong.

If the headlights are noticeable brighter, then the new power source is okay. If they aren't and it is still discharging at idle, then the power source to the relays needs to change. At least in stock form.

The only thing that might be better than that simple test would be for you to provide a schematic.

This is a thread I wrotte up loooong time ago, (in my still crude english… maybe a bit better now LOL) which began maybe the “fight” between ammeter lovers and haters LOL

It’s a sticky thread on dodge Charger board
http://www.dodgecharger.com/forum/index.php/topic,33574.0.html

Several hard discussions about this at FBBO too.

Not my idea, just refloating a Mopar solution used on high load consumption cars (specially fleet cars) which I adopted, adapted and EXPLAINED for those with stock bulkhead connections cars. No need to remove but just adapt.

Please read EVERYTHING. Is a learning procedurement. I have made some “upgrades” on the initial idea along the years.

Mattax (a member here and at FABO too) took this info for his personal website.

http://www.heritech.org/cuda/Charge.html

As far you understand what the ammeter reading really means (I’d say maybe 75% of the ppl doesn’t understand the gauge, hence why the myths floats on) you will be safe.

The deal on this is get the best alt as posible able to feed everything you need at the lower RPMs as posible and get EVERYTHING feeded from the alt side of the game like factory did. This will asure the correct amm reading.

If the alt you get is a 60 amps but is able to feed 45-50 amps at iddle, good (this is tipically unreal). If you get a 100 amps alt but it gets the same rate at iddle, good too. IMHO if you get an alt able to feed 55-60 amps at iddle…GREAT!

Tuffstuff alts are able to feed this, also some powermaster units… on stock look. Tipically rated at ~100 amps.

I’m pointing out someday in the future to a 8509DP Tuff Stuff alt for my car.

The alt just puts out what the car and batt demands to get everything correctly sourced.

The less the battery gets discharged, the less stressed the charging network will be.

The batt just should source the cranking moment and some load peaks quite often, but the constant operation must be sourced by the alt.

Yes: as when people charge a completely dead battery in the car with only the alternator supplying power.
Ant then you wonder why the stock connections are overloaded.
Alternator is meant to replenish the battery capacity after a "normal" cranking start,

Good info