Big ass alternator that looks stock?

[davepl]

I have found that if my electric fans and electric fuel pump run at the same time, esp. with headlight, the alternator cannot keep up, it reads discharge. Even if you rev it up it cannot get all the way to even and will read at most 13V.

It didn't originally HAVE electric fans and pump, so I had added the internally regulated alternator off of a '84 Camaro, I think, a very common retrofit.

But I think that's maybe 80A and it appears I need more like 120, and I need it at idle.

Anyone know of high output 3-wire alternator that can be run with a V-belt and looks anything like a stock unit? That outputs good power at idle?

[demian5]

Get a real amp meter on it and see what the current output is.

[clay68c10]

I've run a V belt on several CS130's and they did fine.
There are lots of other options in the 12SI type

https://www.speedwaymotors.com/Power...mp,229558.html

[NoNeck]

Dave -

We have had the same problem after installing a Vintage Air Sure Fit Kit and larger electric cooling fans. At idle, the truck would just die because there was not enough reserve amperage to the HEI coil. We installed a 105 Amp One-Wire Internally regulated alternator and a larger gauge wire to a Painless Wiring "Master Fuse" terminal. The alternator has 60 Amp output at idle (700 rpm). We haven't driven the truck yet to see if we fixed the problem, but I know it will be much better.


Typical Current Loads for Automotive Systems, Lighting and Accessories:

Engine Idling (no lights or accessories on) - 35 to 50 amps. This will vary depending on the number of cylinders (more cylinders draw more power for the fuel injectors and coils), the type of fuel injectors (some draw higher amp loads than others), the type of ignition system (single coil or multi-coil), the amp draw of the PCM, and the fuel pump (the amp draw will be higher with higher pressure systems).
Ignition Coil (single oil-filled coil older vehicle) - 3 to 4 amps.
Ignition Coil (single DIS coil newer vehicle) - 5 to 6 amps.
Ignition Coil (coil-on-plug) - 6 amps per coil.
Ignition System (primary circuit) - 6 to 20 amps.
Fuel Injectors - 4 to 6 amps peak, 1 amp hold
Electric Fuel Pump (depends on pressure and flow) - 4 to 12 amps
Electric Cooling Fan (depends on size) - 6 to 30 amps
Headlights (halogen low beam) - 8 to 9 amps per pair
Headlights (halogen high beam) - 9 to 10 amps per pair
Headlights (halogen high and low beams combined) - 17 to 19 amps
Headlights (High Energy Discharge) - 12 to 14 amps during initial start, 7 to 8 amps once bulbs are hot
Headlights (LED) - 0.6 to 1 amps per bulb
Small bulbs (incandescent) - 0.3 to 0.4 amps per bulb
Small bulbs (LED) - 0.04 to 0.06 amps per bulb
Starter Motor - 200 to 350 amps
500 Watt Sound System - 42 amps
Windshield wipers - 2 to 10 amps depending on load
Power Windows - 3 amps
Air Conditioner Compressor Clutch - 2.5 to 5 amps
Heater A/C blower motor (depends on load, size and speed setting) - 2 to 30 amps

Basically, you want an alternator that has an IDLE amperage more than the total of all the accessories that are running. You can purchase a under drive alternator pulley that will increase the rotational speed to obtain a higher amperage at idle also.

I hope this helps.

POP

[Andy4639]

Factory alternator is max out at 60 amps.

I use the later model Buick Riviera alternator.
This thread should help.

http://67-72chevytrucks.com/vboard/s...=363034&page=2

[davepl]

This is the one I have on my blue '402 truck. But it barely has any load, it doesn't really need it! Maybe I'll swap alternators, that'd be smart...

https://www.amazon.com/DB-Electrical.../dp/B008R2UAXA

[leddzepp]

Take your existing alternator to a shop and have them wind it to whatever amperage you need. I had a local shop do that for me years ago on my old 72.

[Already Gone]

Does anyone know what the amperage is on a stock alternator on a 1972 C10 with a 350 and factory A/C?

[cleszkie]

I got a custom built GM unit from a small shop in Yucaipa, CA. Bolts right in place of my stock alternator with no modifications. Puts out 180 amps at idle and 320 amps peak. More than enough to power my HEI, fuel pump, fuel injection, dual cooling fans, A/C fan, 3000W inverter, headlights, wipers, etc, while still maintaining my dual batteries. Its a beast. Nice billet aluminum case too. Spendy, but worth the cost.

[57larry]

thanks for the list of loads, NoNeck

[NoNeck]

One way to determine the ampacity of the alternator is to get the casting number or PN number off it and go to a site like Powermaster to confirm it's output.

Load testing is another option..but it's very hard on the alternator.

The alternator is there to support the system, and TOP OFF the surface charge on the battery. NOT to constantly charge a battery from dead to full charge. No alternator was designed to do this.

The Common misconception is because it says 100 Amps on the alternator that is going to be a full time output to the battery every time the pulley turns. This is just not true. The alternator is only going to put out the demands of the system until it reaches saturation point (13.95 to 14.4 volts). Then the regulator shuts it off until a demand needs to be met again. Without it, the battery would fry and explode from overcharge..

If your System is a bone stock system, (no high current audio, Air bags, juice ect.) and it is putting out 13.95 to 14.4 Volts abd your not having problems, I'd say the system is functioning fine. You probably have a 63 / 70 Amp alternator in there and it's supporting the system with no problems.

Unless your planning some major electrical upgrades in the future, I would not waste the time or more important, your money. Why pay $299.00 for something that is working fine now (and probably could be replaced with an over the counter $39.00 part should it ever fail.

To size the LOAD at the battery, you need to get a load test. A Voltage test will show that current is being drawn but not how much. The higher the current, the lower the voltage. You need that reading to be in series with the load and source, (between the Battery and the draw on one cable) and it must be in AMPS. Since most home meters only go as high as 10 amps you'll need the to have a load test performed (high amp draw) which is usually free at most auto parts stores.

Always use a fuse link or MAXI fuse on the Alternator output circuit and buss support wires. Unlike a standard fuse, the link or Maxi, require Time/Heat to open, and is more stable than a fuse. If you put a standard fuse in there, it will open every time the fuse sees a spike (regulator shutting on / off under load) because it doesn't have "The Time Factor". So you usually end up over fusing it..which can lead to a fire.

Fuses are designed to "Protect" the wire they support, not the devices..This is why proper gauge wire is so important when installing harnessing. If one wire melts in a bundle because of a short, it will melt others causing more shorts. Under gauge wire and over fusing is almost always the culprit as is bypassing or NOT installing fuse links..

Under gauge/over-fuse causes the wire to heat (current doing no useful work) and the end user devices suffer in performance. A light bulb will draw as much current as the filament resistance demands (ohms law) the current available to it is predicated by the source (battery) and wire gauge, and resistance of the circuit (bad connections). If the current is lost in delivering it to the load the bulb will burn dim and the wire will heat trying to overcome the total resistance of the circuit. So Wire gauge AND proper ground bonding are equally important.

POP

[NoNeck]

thanks for the list of loads, NoNeck

You are welcome.

POP

[davepl]

I'm going to go with another 140A unit from DBElectrical. That's what I've been running on the Blue truck for 5 years without a problem.

Right now I have the "IROC Camaro" or "Riviera" unit, which I think is likely the biggest 10SI unit the factory made. But at 80A (or even 94A) it seems unable to keep up with the full load of injection, fans, and electric pumps. So I'll try the 140A, but I have doubts about what it can do at idle.

The reality is that the 10SI case and fan were not -designed- for that kind of load, so I don't think it can really cool the alternator properly with the old metal fan at those kinds of output for very long. I guess we shall see!

Meanwhile, for the 2+2 convertible I'm restoring I had to spend close to $1000 to get a date-code correct unit with the right part number, since the original alternator was long gone. And it puts out a grand total of a whopping 37 amps! That's one thing I love about that car - so basic. No vacuum hoses, no electrical accessories.

[davepl]

If you put a standard fuse in there, it will open every time the fuse sees a spike (regulator shutting on / off under load) because it doesn't have "The Time Factor".

Fuses still have a time factor, they can be fast blow or slow blow, they don't pop instantly. So like a breaker, a delay can be built in. Unless a breaker, a reset cannot!

You might be able to get away with a slow-blow fuse in that circuit, though I can't say I've tried. The factory nominally runs fusible links in that type of application.

[Hart_Rod]

Originally Posted by NoNeck

One way to determine the ampacity of the alternator is to get the casting number or PN number off it and go to a site like Powermaster to confirm it's output.

Load testing is another option..but it's very hard on the alternator.

The alternator is there to support the system, and TOP OFF the surface charge on the battery. NOT to constantly charge a battery from dead to full charge. No alternator was designed to do this.

The Common misconception is because it says 100 Amps on the alternator that is going to be a full time output to the battery every time the pulley turns. This is just not true. The alternator is only going to put out the demands of the system until it reaches saturation point (13.95 to 14.4 volts). Then the regulator shuts it off until a demand needs to be met again. Without it, the battery would fry and explode from overcharge..

If your System is a bone stock system, (no high current audio, Air bags, juice ect.) and it is putting out 13.95 to 14.4 Volts abd your not having problems, I'd say the system is functioning fine. You probably have a 63 / 70 Amp alternator in there and it's supporting the system with no problems.

Unless your planning some major electrical upgrades in the future, I would not waste the time or more important, your money. Why pay $299.00 for something that is working fine now (and probably could be replaced with an over the counter $39.00 part should it ever fail.

To size the LOAD at the battery, you need to get a load test. A Voltage test will show that current is being drawn but not how much. The higher the current, the lower the voltage. You need that reading to be in series with the load and source, (between the Battery and the draw on one cable) and it must be in AMPS. Since most home meters only go as high as 10 amps you'll need the to have a load test performed (high amp draw) which is usually free at most auto parts stores.

Always use a fuse link or MAXI fuse on the Alternator output circuit and buss support wires. Unlike a standard fuse, the link or Maxi, require Time/Heat to open, and is more stable than a fuse. If you put a standard fuse in there, it will open every time the fuse sees a spike (regulator shutting on / off under load) because it doesn't have "The Time Factor". So you usually end up over fusing it..which can lead to a fire.

Fuses are designed to "Protect" the wire they support, not the devices..This is why proper gauge wire is so important when installing harnessing. If one wire melts in a bundle because of a short, it will melt others causing more shorts. Under gauge wire and over fusing is almost always the culprit as is bypassing or NOT installing fuse links..

Under gauge/over-fuse causes the wire to heat (current doing no useful work) and the end user devices suffer in performance. A light bulb will draw as much current as the filament resistance demands (ohms law) the current available to it is predicated by the source (battery) and wire gauge, and resistance of the circuit (bad connections). If the current is lost in delivering it to the load the bulb will burn dim and the wire will heat trying to overcome the total resistance of the circuit. So Wire gauge AND proper ground bonding are equally important.

POP

Great info!

[jayoldschool]

The big 140a off a 94-96 Impala SS/Roadmaster/Caprice will be a great choice, and is readily available. Note that the Roadie and Caprice came standard with a smaller one, the 140 was optional. Convert to V pulley, of course.

https://www.youtube.com/watch?v=Z70844woBXo

[Andy4639]

The one on my 71 C10 in the post I posted did fine with my 305 TPI & 700R4 electric fans, AC, electric windows and 2 amps putting out 1000watts each plus upgraded lights to LED. It was the 94amp version.
Never had any problems but I did have relays on most of it.

[BCOWANWHEELS]

Gm 100 amp 1 wire, db auto electric

[davepl]

Originally Posted by NoNeck

The Common misconception is because it says 100 Amps on the alternator that is going to be a full time output to the battery every time the pulley turns. This is just not true. The alternator is only going to put out the demands of the system until it reaches saturation point (13.95 to 14.4 volts). Then the regulator shuts it off until a demand needs to be met again. Without it, the battery would fry and explode from overcharge..

I'm not sure what you're saying. Here's what I'm saying, you tell me if/where you think I'm wrong.

Electric Fan 1 - 25A
Electric Fan 2 - 25 A
Fuel Pump - 10 A
Headlights - 15A
Injectors - 5A

So that's 80A ongoing load. That's not coming from the battery, that's coming from the alternator.

Once the battery has reached a charge point, if the car is demanding 80A then the alternator makes 80A. The battery just maintains the float in the system at that point.

Obviously at no point is the 140A alternator putting out anywhere near 140A except right after startup when it refreshes the battery.

[davepl]

Originally Posted by jayoldschool

The big 140a off a 94-96 Impala SS/Roadmaster/Caprice will be a great choice, and is readily available. Note that the Roadie and Caprice came standard with a smaller one, the 140 was optional. Convert to V pulley, of course.

https://www.youtube.com/watch?v=Z70844woBXo

That's definitely what I'd go with (the 12SI) if I were a little less concerned with appearance. The fan looks too weird for me.

I once swapped that fan with the old mechanical blade fan off a 10SI and so far as I recall it worked, but I wouldn't bet on its longevity with much load. The 12SI fan is a much improved system.

Gm 100 amp 1 wire, db auto electric

I don't trust 1-wires, never have. Never owned one. Plus I want my idiot light to work accurately, since there's no gauge in this one!