Alternater size

[Michael C Henry]

My car was built as a bare bones car in Reno.Four electric fans and two electric fuel pumps and lights. A small Motorcraft alternater was used. The fans can get ahead of the battery.I plan on installing a heater defroster. How much alternater does a guy need?

[Ron61]

Michael,

What size alternator does your car have on it now ? I don't have a heater but am running twin fans and an electric fuel pump and I have a 100 amp alternator and my voltage never dips at all. My battery is also mounted in the back so I have the extra length to run the battery cables. I was going to use a 65 amp alternator but one of the guys here told me I would be pushing it with my setup even though it would most likely stand up to it for a while.

[Bob Putnam]

Boy, are we getting spoiled!

I know it pains you guys to ever see discharge on the ammeter, but the world is not going to end. (I think that's one of the reasons OEMs went to a voltmeter.)

Unless you spend most of your time at idle with the fans running, even a 50A alternator will keep the battery charged enough - if you have the fans thermostatically controlled. Think about this: It takes more than 4 hours at 10A to fully discharge most batteries. 10 minutes of that ain't goin' to hurt much.

[Ron61]

Bob,

I don't have an amp meter. I just have the volt meter and I watch all of my gauges all the time. I just like the idea of having to much more than just enough. So far as being spoiled I guess most of us are in some way or another. Both of my other cars have amp meters and with all the lights on and at idle they just barely go on the low side of the charge mark. So I have to agree with you and I know it takes hours to run a battery down at that little bit of draw

[HighPlainsDrifter]

Michael,
The old alternator was a 40 amp unit,not enough for high output ignition and fans,etc. I run a ford 65 amp unit ,it is the bare minimum, I should have gone bigger to 100 amps.
Msd= 10 amps
fuel pump=6 amps
electric rad fan=18 amps
heater/defrost=15 amps
lights=10 amps
This is the minimum I use about 60 amps. i don't like to run maximum output on anything so to have some safety margin I would like at least an 80 amp unit.
Just my 2 joules worth
Perry.

[Mr.Fixit]

I have repaired cobras after their owners paid somebody else to install 100+ amp alternator. They melted the wiring loom because it was not designed to handle that much current.

[Roscoe]

I have a Powermaster 100amp racing alt with one wire. It is hooked into a Painless wiring harness and MDS digital ignition, dist and coil. Plus elec fuel pump, fan, h4 halogens, etc. Have 13k on the car and it runs fine.

http://www.powermastermotorsports.com/

As Mr Fixit says, you should check with someone who knows before you just install one of these things.

Roscoe

[RACER X #99]

Bob is right, there is a great misconception about alternator output. A 50 amp alternator will generate 50 amps in 1 hr. a 100 amp alternator will generate 100 amps in an hour. If your alternator was putting out 100 amps continous you would need a wire about the same size as your starter wire, about no. 2 gauge. This is just another case where bigger is not better.

Do not listen to the guy at the auto parts counter. He knows where the parts are located. If he knew how they worked he would be installing them.

Cranky

[Michael C Henry]

I had my old small Motorcraft alternater tested .Turns out to be a 30 AMP.See why I fell behind the charge curve?The more I think about it ,Why or how often would the heater be running if the radiator fans were needed?The old alt is small ,single groove pulley. The plan is to incorporate a Flaming River master switch w ?alt and ign kill,Do not want any run on.Do not want to change pulleys or change belt allignment.

[W2zero]

Michael
I run a Ford 55 amp alt with a Transpo #7078 module on the old Fairlane with two electric fans. It puts out 14+ V at idle. Head on down to Ruston and talk to the guys at Sound Starter Rebuild. They'll whip up anything you need.

[Michael C Henry]

I don't buy alternaters very often.I'm open at this point since I'll be rewiring.Which alternater would be better?Ford,or Delco?One wire , or seperate regulater?Space is the consideration and pulley line up.FE mounted high right side single V- belt.

[A Snake]

Stick with the FOMOCO. No fooling around that way. Unless you ask for it specially built, alternators are internally regulated. Called a diode group which is easily replaced if trouble develops.

I had one done for me at 80 amps. Reason being, my 427 fought the starter when it was warm and really drained the battery....even a big one.

After a little tinkering and a new battery, the problem went away, but I still liked the quick recharge on the battery.

BTW Alternator should put out 13.8 volts not 14+ and you won't have much luck finding a single wire alternator. Remember how an alternator works. The big wire is the output to the battery and there has to be a current TO the alternator in order for it to work. that's the "exciter" wire, which excites or creates the magnetic field and makes it generate current when the rotor spins.

The least number of wires is generally going to be 3, but they go to the alternnator as a group, so it's not messy looking. Some people tape them and some use that split wire covering for neatness.

Al

[Mr.Fixit]

The one wire alternators are not bad. I used a conversion kit on a delco alternator that leaves it with only the 10 ga wire to pos. The conversion kit was made by "ENOS components" and has worked great since '92 never needed replacement, but the alternator has been swapped a couple of times.

[W2zero]

Michael
Give me a shout @ fletchw20@attbi.com and I'll drive over and show you the single-wire Ford setup in mine.

Craig

[Roscoe]

On thing: On a Painless Wiring install it turns a one wire into a two wire. No big deal, just the way they set it up.

Roscoe

[Jack21]

Used and ordinary Delco 63 amp. One wire to the battery. Another to the ignition power to energize the alternator. Same wire that powers electric choke.

Delco runs 100,000 miles. Replace brushes, run another 100,000 miles.

[Michael C Henry]

I took the easy way out Sound starter traded me a fresh Ford alt does 74 amps at 15 volts for my old one and $52 plus tax.How far can a guy go wrong for $52 ?

[A Snake]

Done deal I'd say. Michael, I'd be concerned about the unit if it really does charge at 15 volts. That's a bit hot. I mentioned previously that it should be 13.8. There's a reason for it. If you doubt me, ask a trained auto technician what happens.

Al

[Michael C Henry]

It was only tested at 15 Volts. My Voltage regulater determines the voltage.
It's like testing a pump flow rate at a given pressure. Amps x hours =amp hrs ,amps x volts =watts.I was headed towards 100 amp alt .Ford style doesn't cool good enough. It is packed into engine close and one fan and not baffeled internaly to get the air to the right spots.The Ford 100 amp in that package with engine and header heat .If there were a demand and alt went full tilt it would probably burn out diodes.74 amps is over double what I had before.

[Michael C Henry]

I thouight I was on this thread. I clicked on a website. and I was sent to a place where they had a battery cable end or termanl covers. They had a red cover shown .I want it now and cant find it.Figures.Know where I can find those covers?