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Well guys I am needing an alternator that will handle an electric fan a Stereo system and a CB radio I have the serpentine belt 4bt from a P30 van.
 

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There are a number of possible alternators that will fit the ticket. Do you know which alternator you currently have? Some models may require a different bracket which usually isn't terribly expensive. One unit common on those engines is a J180 mount Delco Remy which can be found in all kinds of power ratings. 130-160 amp units are common. Here is a list of parts for option EH9029 that covers that alternator or a Bosch N-1 type. You might check your bracket and it may be the one for the Delco Remy. This bracket covers Delco models 21si, 22si, and 24si with the J180 mount.
129607


Parts list:
1. 3052061 1/2-13 x 1" Hex Head Cap Screw
2. 3900630 M8 x 1.25 x 20 Flange Head Cap Screw
3. 3900631 M8 x 1.25 x 25 Flange Head Cap Screw (3 req)
4. 3903105 M12 x 1.75 x 150 Flange Head Cap Screw
5. 3903210 M12 x 1.75 Flange Nut
6. 3919023 Alternator Support Bracket (Alternates 3284120,3965923,3965924)
7. 3520815 Roll Pin
8. 3910924 Alternator Brace
9. 3918275 Alternator Pulley (Alternates 3920560,3284474)
As you can see there are several parts with alternates. This could be due to pulleys of various diameters or just part number updates. Things to note. The 21si is the oldest model and was replaced by the 22si which was an improvement. Genuine models were made in either the USA or Mexico. There are tons of clones of this model on the market. Genuine models are usually priced in the $170-200 or more range while the clones can be under $100. The 24si is the newest model and improved over the 22si. It has an internal cooling fan vs the external on the older 21si/22si. One common unit is part 8600310 which is 160 AMP. Various models of these may or may not have a W terminal for tach operation if that is important. Just remember that when you go to one of the higher AMP alternators your wiring must change to match it. See photos below.
 

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I’d definitely like to have the w port for the tach I’m fine with a clone. What size wiring as I am rewiring the whole truck
 

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That is a Delco 10si alternator - the visual clue is the stamped steel fan behind the pulley. You will want to upgrade to a Delco 12si alternator - newer technology, produces more amperage and handles heat better.

My GO-TO reference is MAD Electrical Company:


I re-read this every time I have to upgrade an alternator (about once every 5 years...).

Wire size (AWG) will have to be increased from the alternator to the battery. If your vehicle has an ammeter - the new charging current will SMOKE the alternator. Personally, I re-wire directly from the alternator output terminal to starter "+" solenoid lug (the one with the big cable directly to the battery "+" terminal.
 

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Wow a lot of different alternators just gotta find one with high amps and the w terminal for a decent price. I have a 1000 amp Optima red top battery and will have one or two Subwoofers a CB and the electric fan to run. So have to base this off those power needs.
 

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Well I’ve been searching the net and not sure how to tell if the alternator has a W wire for a tachometer and what amp will fit my current brackets. Do I get a one wire setup just a bit confusing?
 

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Well still researching down the alternator rabbit hole would any 22si alternator fit my brackets directly. I am thinking I’ll need 150a to 200a with any route I go prefer a 200a or something HD.
 

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Well still researching down the alternator rabbit hole would any 22si alternator fit my brackets directly. I am thinking I’ll need 150a to 200a with any route I go prefer a 200a or something HD.
Why so many Amps? Do you intend to use the alternator to arc weld?

I'm a 78 year old retired electrical engineer - having trouble with the need for that much power... Maybe you need to add up the amperage requirements for headlights, air conditioning, fans, audio gear, etc

Up front - I am running a stock 94 Amp Delco 12si in a 1962 Volvo - When the air conditioner is running on a hot day, 2 fans on the radiator, an electric water pump and 2 fans on a heat exchanger - And what ever power that the air conditioner requires. I do understand using the "big hammer" - The "Sledge hammer" might cause more problems that it solves...

This alternator was a direct bolt and plug in replacement for the previous Delco 10si (the 1962 Volvo originally had a generator). I bought a brand new Duralast # 7294-3N (1984 Camaro 5.0L 4BL OHV HP 8cyl) from Autozone.

As far as the "W" terminal for a tachometer, find a diesel General Motors car or truck that has a dash tachometer - then look up the alternator for the "full dress" model and verify the alternator "W" terminal and the Amperage output. AND beware, you will have to switch over your original alternator pulley. AND most likely, the signal output will indicate a wrong RPM due to the pulley ratios changing (i.e. the pulley on the gas motor will be a different diameter than the pulley on your diesel motor).

Got a $95 alternative tachometer:


It has a sender that clamps onto an injector line and senses the injector pulse. Gives a digital RPM readout and does NOT require calibration. My Tiny-Tach is now in the second truck, over 70,000 miles, never failed me. After a month or so, you will be driving by ear and will hardly ever look at the tach.

Russ
 

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I was figuring I d have huge amp draws with 2 bass speakers 2 12” or 2 15” and possibly two amplifiers.
12 Volts x 200 Amps is 2,400 Watts.

In audio equipment, you need to understand the difference between peak power and average power. The peak power is provided by the battery (you need big power wires for high power audio). The average power is what you need from the alternator to keep the battery at full charge.

The 120 NAPA alternator (Post #2 by eggman) ought to be more than enough amperage - Plan on a bigger (thicker AWG) wire from the battery to the alternator.

You need to research all the proposed electrical components and add up the amps for each component.

Russ
 

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That is a neat Tachometer man technology always seems to amaze me detects the injection pulse!
The piezoelectric sender technology was commonly used in the 1950's in record players (vinyl records). It was replaced by better technology in the 1960's.

Russ
 

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I initially ran the 75 amp that came from the bread truck with it under worst case scenarios it would struggle to run everything and recharge the battery's.
With the 120 amp unit it will recharge the batteries while powering everything else usually within half an hour, I am considering things fully charged when my voltmeter is reading drops back to the "normal" ~ 13 volts vs 14.5.
I am running 2 875 amp batteries the alternator is wired to a isolator and then to the batteries with #6 wire and the batteries are set up where one runs the starter and origonal fuse block the second runs the grid heater, stereo, fog & driving lights and the fan, air compressor, AC inverter and pac break systems.
I consider the worst case scenario to be a winter pre dawn cold start when I will also be using between 300 and 500 watts worth of auxiliary lighting and the heater on high.
In this scenario the 120 amp will still hold 14.5 volts but it takes about twice as long to recharge both batteries fully....$.02
 
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I'm running a 92' Ford Turus alt. It fits perfect if your current alt measures 8.25" between holes. This is a 130 amp alt. It is a "3 G" alt which is supposed to be better than the new alternators. (6 G) it is known for high output at low rims. You do have to install the 8 groove pulley.

Question for you electrical guys. I have 4 fans that draw 22 amps each. Two are for the radiator and two are for the AC condenser. On a hot day it's possible all of them could be running. The rest of my electrical system shouldn't amount to much, but starting from 88 amps has me nervous. Do you think I'm over reacting?
 

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I have 4 fans that draw 22 amps each. Two are for the radiator and two are for the AC condenser. On a hot day it's possible all of them could be running. The rest of my electrical system shouldn't amount to much, but starting from 88 amps has me nervous. Do you think I'm over reacting?
88 Amps / 130 Amps = 68% of alternator capacity - you should be OK. Watch your voltmeter if you get stuck in traffic for a long time - if it still shows a charging voltage, all is OK.
 

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Thanks for all the information guys I am looking at alternators in that range up to 160amps as from what I looked at online the prices were decent up to that point and based on everyone’s knowledge and experience that should be acceptable. I’ll keep you updated when I get to the point of the installation.
 

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Russ, you mentioned some numbers on the stereo. I worked in car fi many years ago and we built systems that would make your lights go dim with a stock alternator. Even built some with capacitor arrays to handle the power surge. I have several amps sitting in my closet that have 60 amp main fuses that are only 120 watts RMS per channel and we'd use 2 of those bridged mono for subwoofer applications. Typical minimum wire size we used on big systems was 2ga or sometimes bigger. Main circuit breaker was sometimes 200 amps or more. So much depends on what type amp you use. A pure class A amp is a power sucker for not so much output. Only super expensive car or home amps were of this type. The class AB were the most common when I was in the trade and they weren't nearly so hungry. The class D amps were just getting started when I got out of it and those produce the most power for power input but the output signal wasn't as clean. That has been over 20 years ago so I have no idea what system require now. Enough on the car fi ancient history. LOL.

Now on the alternator and its hook up. The Delco si series can be run one wire or 3 wire. Have read a lot of stuff written on both wiring schemes. Generally, most recommend using 3 wire. There you have signal wire, the output wire, and a dash lamp wire. On that one the charge wire is never run to the battery but to the point where the accessories draw their power. Below is a diagram that shows that hook up. One thing to know is if the dash lamp should burn out the alternator will not turn on. That situation happens on my F250 with an Autolite alternator. $3 dollar light bulb and $100 labor to fix it. On the 1 wire hook up it is often just a single wire direct to the battery. It could also be wired to the point of draw as well. In either case there should be a proper gauge fusible link in line to protect the batteries should the alternator fail. That wire will be smaller than the main charge wire. It does not have the same characteristics as a fuse. Charts I've looked at state that an alternator in the 125-150 amp range should use 2ga charge wire. That's pretty darn big. The fusible link to carry that is color coded maroon and won't likely be a wire but a module with bolt terminals like the photo below. Need to do a lot of research when considering lots of alternator power.
 

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