[torqhead]

Originally Posted by Bill Hanlon

I'm amazed it takes 36 amps to "run the motor".

Electric fans require 28 amps alone...

[george kujanski]

As I've mentioned before, as the alt (and internal regulator) get warm, the regulated voltage gets lower due to temperature compensation in the reg. Even if you are running at 13.0 volts at the battery, it's getting charged. The voltage should be steady, however.

george

[torqhead]

Well of course I would find yet another issue. Been enjoying the car and discovered when I go to play and run my motor up past 5500, shift point is set at 5900, my gen light comes on indicating the alternator isn't charging, when RPM drops light goes out. I didn't pay much attention initially but I discovered the alternator pulley they've installed on this Tuff Stuff unit is quite a bit smaller. Called them up and of course they recommended installing a larger pulley. Didn't know you could over rev an alternator which would cause it to not charge. Anyhow, I'm hoping I still have good charge at idle after I make this change...

[gtofreek]

Sounds to me like one of the wires on the rotor has come un-soldered, and is trying to pull away from centrifugal force, breaking the connection.

[torqhead]

Originally Posted by george kujanski

Looks Fancy..............but back in my day we tested our alts for extended periods in a temperature chamber to guarantee output and reliability. Unless the seller provides some detailed info about the performance and testing of their units, I personally wouldn't buy them.

Delco designs must meet performance and reliability considerations otherwise there would be nasty recalls that cost hundreds of millions of dollars...these aftermarket mfgrs probably don't have those issues.

The billet fan troubles me....Delco must have spent many thousands of dollars to design the best fan possible for their units...it sure looks pretty tho.

George

George, interested in your thoughts about whether an alternator will just stop charging at a certain high end RPM?

BTW, interesting idea of what the problem might be from Paul.

[gtofreek]

I saw that one time before when I did starting and charging systems for a living, and that is what it was. But at any rate, it has to be rotor related since that is the only thing spinning.

[torqhead]

Originally Posted by gtofreek

I saw that one time before when I did starting and charging systems for a living, and that is what it was. But at any rate, it has to be rotor related since that is the only thing spinning.

Makes sense, heck I haven't taken that alternator off enough I guess... Seems like any time you buy something nowadays you have to go through 2 or 3 of them before you get a good one...

["QUICK-SILVER"]

For lack of a better term, I'm gonna say 'brush bounce'.
Figure pulley diameters and get actual alternator rpm's....the rotors not balanced good enough or true enough for the brushes to stay in contact with it.

Clay

[george kujanski]

I've never seen a high RPM issue like the one mentioned. Brush bounce sounds interesting but if it happens, i wouldn't think it would stop charging. I think it would make enuf contact to maintain charge.

Belt slip may be a culprit tho. Broken wire maybe, I would expect it to be defective after the run or be intermittent at normal rpm afterward.

George Kujanski

[gtofreek]

I too wouldn't think brush bounce would cause a light. The brushes would still arc, and try to charge, at least enough to turn the light out.

The belt would have had to be so loose it would fly off to cause the light to come on. I've seen some really loose belts and have never seen a light come on because of it. So I would rule out a loose belt also.

["QUICK-SILVER"]

Originally Posted by george kujanski

I've never seen a high RPM issue like the one mentioned. Brush bounce sounds interesting but if it happens, i wouldn't think it would stop charging. I think it would make enuf contact to maintain charge.

Torqhead didn't say how bright the light was. And we don't know what bulb he's using for the charge indicator light.

A low watt bulb would come on easier in a low charge (unequal voltage) situation.

Don't know which is which with 168's and 194's...but I've seen cars that simply swapping bulbs would stop a glowing indicator light at idle.

You gents thoughts
Clay

[HWYSTR455]

Belt slip.

.

[HWYSTR455]

Post #31:

"Right around 150a is where the v-belt starts being an issue where it doesn't have enough contact surface and starts slipping. So my guess is your belt is slipping, and why it's not keeping up. Try changing the belt first, but another guess is you're going to have issues no matter what with a 200a."

BTDT

.

[gtofreek]

Originally Posted by "QUICK-SILVER"

Torqhead didn't say how bright the light was. And we don't know what bulb he's using for the charge indicator light.

A low watt bulb would come on easier in a low charge (unequal voltage) situation.

Don't know which is which with 168's and 194's...but I've seen cars that simply swapping bulbs would stop a glowing indicator light at idle.

You gents thoughts
Clay

Typically a very dim light is caused by a bad diode in the diode trio[still charges good], or by a bad diode or burned stator, but those two will usually cause the light to be different brightness depending on charge rate.

[gtofreek]

Originally Posted by HWYSTR455

Post #31:

"Right around 150a is where the v-belt starts being an issue where it doesn't have enough contact surface and starts slipping. So my guess is your belt is slipping, and why it's not keeping up. Try changing the belt first, but another guess is you're going to have issues no matter what with a 200a."

BTDT

.

A loose belt will NEVER cause a gen light to come on, unless the belt plain comes off.

[torqhead]

Sorry guys, been a bit busy and just catching up.

It's not a loose belt for sure, I use a belt tensioner and I bought a new belt.

Light comes on bright red, same as ignition on only before you start the car, so it's not charging like flipping a switch on.

The diameters of the pulleys are crank ~7 7/8 in, water pump ~ 6.5 in the alt ~2 1/4 in. Anyone know how to calculate alt RPM?

[Bill Hanlon]

Assuming no belt slip and your pulleys, alternator RPM = engine RPM X 3.5

[torqhead]

Originally Posted by Bill Hanlon

Assuming no belt slip and your pulleys, alternator RPM = engine RPM X 3.5

How did you come up with that? If that's right in turning it over 20k rpm with a shift point at 5900.

[george kujanski]

That's right. On the flip side, at an idle of 600 RPM, the alt is at 2100.

George

[Bill Hanlon]

Originally Posted by torqhead

How did you come up with that? If that's right in turning it over 20k rpm with a shift point at 5900.

Alternator RPM = Crank Pulley RPM times Crank Pulley Diameter divided by Alternator Pulley Diameter.