Charging system

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GRNTHNDR
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Charging system

Post by GRNTHNDR »

So I have to replace the alternator on my 66’ w/390. What amp rating to go with? I believe 42 amp is factory.?? What rating are you using? I’ll change my name to electronicallyconfused. Thanks in advance for any advice.
jtschug
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Re: Charging system

Post by jtschug »

I am currently running a 75 amp alternator from and 1974 Lincoln, with a matching solid state voltage regulator.

I chose this because it still uses an external voltage regulator and requires very few modifications to get it to work properly. A little bit of tweaking at the wire harness on the back of the alternator, and some grinding on the spacer between the engine and the alternator to get proper belt alignment.

If you have a 1964 Thunderbird, I would NOT increase the size of the alternator without disconnecting the AMP gauge circuit, it is a fire hazard. '65 and '66 T-birds use a shunt, which is safer.
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
GRNTHNDR
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Re: Charging system

Post by GRNTHNDR »

The alternator I just removed is 75 amp as well as yours. I don’t understand why they used higher than factory. Could using higher amp burn out window and seat motors? Thanks again.
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RedBird64
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Re: Charging system

Post by RedBird64 »

GRNTHNDR wrote: Thu Mar 14, 2019 10:56 am The alternator I just removed is 75 amp as well as yours. I don’t understand why they used higher than factory. Could using higher amp burn out window and seat motors? Thanks again.
Not to worry, it wont hurt motors or any other parts.
The alt doesn't put out current unless it is asked for. All the things that use power in your car pull power from the alt. If anything, the bigger alt is easier on motors since it wont have the voltage drop of the smaller alt when current demand is high.
A higher output alt can come in handy when your sitting at idle with lots of electrical things running. It also charges the battery faster if it's discharged.
The low output alternators they used at the factory (due to the technology at the time) are generally upgraded when replaced. Rebuilders use upgraded parts so every alt they build is higher output - there's no down side to it. (the Vreg. doesn't care what the current rating of the alt is either.)

I used a 65 amp alt in my 64 for several decades without issue. When that died I wen't to a 100A single wire alt, which blows the old ones out of the water in terms of performance and simplicity since it doesn't use the cars orig Vreg.
1964 Coupe Wimbledon white/Rangoon Red w/black int. Owned for 42 years. It was my folks car before that (second owners). VTCI # 12013.
GRNTHNDR
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Re: Charging system

Post by GRNTHNDR »

Ok.. I’m having a much better understanding from you guys. Thanks again, I will stick with using 75amp. Time to start shopping.
WhiteThunder
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Re: Charging system

Post by WhiteThunder »

As RedBird64 said, this is a very common misconception. I have read numerous articles about the "hazard" of putting in a high capacity alternator in an older car. The truth is that, assuming no other changes to the car's electrical system, it will pull the same amount of amps from the alternator regardless of the rated capacity of the alternator. Just don't go adding more electrical loads that would pull additional amps through the ammeter.

I did a 3G upgrade on my 64. I added a few high draw loads, such as an in-tank fuel pump, but I powered these with a completely separate circuit that is in parallel with the rest of the car. I took power from the alternator output to a new standalone fuse box. This way I can take advantage of the extra capacity without putting any additional load on the car's factory electrical system. It is also nice to not have the lights dim at idle!

PA Performance makes a nice looking box that takes the place of the external voltage regulator. This allows you to use the factor wiring with the 3G's on-board voltage regulator. I actually made my own box by gutting an old voltage regulator and using it to house a new relay to provide key-on field voltage to the alternator.
RAVEN
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Re: Charging system

Post by RAVEN »

Moderator I believe this needs to be moved to the MODIFIED SECTION
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redstangbob
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Re: Charging system

Post by redstangbob »

Moderator I believe this needs to be moved to the MODIFIED SECTION
I think the subject is pertinent Wally, we're not talking CHROME alternator :badgrin:
I did a 3G upgrade on my 64. I added a few high draw loads, such as an in-tank fuel pump, but I powered these with a completely separate circuit that is in parallel with the rest of the car. I took power from the alternator output to a new standalone fuse box.
This is the most important sentence in the whole thread. jtschug mentioned the 64 wiring harness, but only the AMP gauge, the bulkhead connector is where the fires start. If an owner needs more output, a bigger alternator is the answer. I would run a new wire from the battery through a mega fuse into the cabin where I would run my high load accessories. If you just add a big alternator and don't change the wiring, all the current still has to pass through the firewall connector, and we know it can't handle that many Amps. JMO Bob C
It's gonna be cool when it's done
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GRNTHNDR
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Re: Charging system

Post by GRNTHNDR »

Ok. I finally installed the new alternator. I went with 65amp. Good to see the gauge on the C+ side,window motors like it too. Except for one, with assistance it’s getting better. Even the clock wants to start working. Next job is to install the new heater core. Thanks again, for all input.
GRNTHNDR
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Re: Charging system - new issues

Post by GRNTHNDR »

New issues. When heater blower on, headlights on, and brake lights on. The turn signal won’t blink as should. Seems to be too much draw. Any thoughts as to why? Thanks again.
jtschug
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Re: Charging system

Post by jtschug »

Which turn signal? Front, Rear, or fender bullet?
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
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RedBird64
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Re: Charging system

Post by RedBird64 »

You say it "Wont blink as it should" - do you mean it doesn't blink at all or somehow acts oddly?

Scott
1964 Coupe Wimbledon white/Rangoon Red w/black int. Owned for 42 years. It was my folks car before that (second owners). VTCI # 12013.
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paulr
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Re: Charging system

Post by paulr »

redstangbob wrote: Mon Mar 25, 2019 8:55 pm the bulkhead connector is where the fires start. If an owner needs more output, a bigger alternator is the answer. I would run a new wire from the battery through a mega fuse into the cabin where I would run my high load accessories. If you just add a big alternator and don't change the wiring, all the current still has to pass through the firewall connector, and we know it can't handle that many Amps. JMO Bob C
Exactly. In 2015 I swapped to the 65A alt without knowing this info regarding wiring. The only increase in modified draw on my car was halogen headlights. Maybe that was enough increase, I'm not sure. I do drive a lot. In 2017, not responding to any kind of electrical issue but, instead, replacing the carpet and r&r-ing the sound deadener, etc. I discovered my passenger side bulkhead connector was compromised. Not melted or burned, exactly, but the bullet connector for the ammeter wire (yellow/black) was corroded and separated, but somehow still conducting. I found it by accident and not a minute too soon, really. As Bob described above, I disabled that wire and ran a fused segregated wire through the firewall to avoid the bullet connector in the bulkhead. Oddly, my ammeter (original) has never looked less than new on this car.

What gnaws at me now is whether there is a next weakest link and where.
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GRNTHNDR
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Re: Charging system

Post by GRNTHNDR »

jtschug wrote: Mon May 13, 2019 1:11 pm Which turn signal? Front, Rear, or fender bullet?
I noticed only looking at fender bullet. Along with a drop on the dash gauge, power windows barely working. After turning off all accessories and speed up the engine a bit, the belt starts squealing for a few seconds. I’m going to try to get it to a shop today. Thanks again, I’ll update later.
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