Hybrid alternator issues

[Yadkin]

I purchased a "Tuff Stuff) type 7078 100 amp alternator to replace the tired one in my '64 390 build. It is a "hybrid" type (Ford in front, GM in back) and I'm having trouble wiring it.

It requires a resistor type regulator instead of a points type that was original to the car. I bought a solid state type (not knowing the difference) and was having problems with it draining the battery. I tried using the alternator's wiring guide together with the Ford diagram to figure it out, and of course that turned out wrong.

So I did some research and wired it up with the alternator #2 or FIELD to the F tab on the regulator. This is continuous with the green/red wire from the ignition switch, and energizes the field. The alternator #1, or "R" is to the regulator S. The large lug on the alternator goes through the dash ammeter to the battery positive. And of course the alternator chassis is grounded directly to the negative terminal on the battery, which is in turn grounded to the car chassis and to the engine.

The yellow wire in the existing harness is 12v always on and I attached that to the A terminal on the regulator. (Yeah I know, this should be on a switched circuit to avoid draining the battery- I'll do that later). The I terminal is unused.

The alternator was not charging, but the regulator was getting hot. I became concerned that I burned out the regulator so I consulted with a friend that knows a lot about custom systems. He suggested I use a GM style resistance regulator instead of a Ford style solid state, since the hybrid alternator was essentially a GM style, electrically.

I wired that in according to his instructions. Alternator F and R as before. Regulator terminals 3 and 4 both attached to 12V. It charged correctly for a while (14.4V at idle) but I noticed the alternator was getting hot. Then it went to over 15V. Using my infrared I found it to be 230 degrees so I shut the system down. The regulator resistors got hot too.

What am I doing wrong? Have I burned out the new regulator, causing it to to let the alternator over charge?

[simplyconnected]

I purchased a "Tuff Stuff) type 7078 100 amp alternator to replace the tired one in my '64 390 build. It is a "hybrid" type (Ford in front, GM in back) and I'm having trouble wiring it.

I'm not familiar with 'hybrid' alternators and I don't know why they exist, since Ford and GM both have great alternators in many millions of cars.

If this pertained to me, I would contact the manufacturer and the place you bought the alternator. Certainly, they have wiring diagrams for your setup. Did this alternator come with a warranty? - Dave

[jopizz]

The original alternator did not use the S terminal. According to the instructions with your new one that wire on the pigtail (yellow) should be taped and not used. The F wire (green) on the new alternator should go to the F on the regulator. The S terminal on the regulator should go to the ignition switch and the Red terminal on the alternator through the ammeter back to the battery. That's the way I'm reading the instructions. My concern is that the wire to the ammeter and back to the battery is not nearly heavy enough to handle the 100 amp load from your new alternator. You should have a minimum 4 gauge fused wire.

John

[Yadkin]

Gosh John, it never occurred to me that the "real" ammeter in the dash and associated wiring wouldn't handle this load. Right now the dash is out of the car and I have the two lugs to the ammeter bolted together and taped, just so I could get the motor running.

I'm going to need to modify that circuit somehow. Maybe Dave the electrical magician can help me here.

Why the hybrid alternator? I'm guessing, but it's probably to reduce parts inventory. Yes it came with a warranty, but I probably bought it over a year ago. And it works, just that the regulator is not doing it's job.

I found the source of the heat: a slipping belt. It was heating up the pulley and that was most of the heat that I was reading. Tightened it up and it runs cooler, but still fairly high. What is the normal operating temperature for an alternator like this?

I tried again today after setting a new ground on the regulator and same deal: just a tad over 15 volts while idling. Connecting or disconnecting the regulator made no change. I'll try John's wiring suggestions on my next attempt.

[Yadkin]

I've done a little research on the ammeter issue, and potential to overload the wires running through the dash panel.

I think I'm nearly there with my modern fuse panel install that I've already completed. I have a 100 amp breaker directly from the battery/ alternator feeding it, and that in turn feeds the high amp circuits in the car (starter, headlights, horn, stereo). What I need to do is to install a second 40 amp breaker in the ammeter circuit and I should be done.

[simplyconnected]

Output, belt drag (heat) and everything else, depends on the electrical load.

If your system demands 100 amps, that equates to (Watts=volts X amps or 1,200-watts) 1 electrical HP = 746 watts. So, 1,200/746 = 1.6 HP (not including losses).

If you run a small diameter 1-groove V belt sheave (with not much belt area), 1.6 hp is a lot of drag for a small diameter pulley. Mine is about 3-1/2" which slows the alt down a bit but offers much more belt area and more mechanical 'leverage' which makes the alt shaft easier to turn. Usually, slipping belts sound like a loud squealing pig. All that goes away with more belt surface area.

Also, we ran into this before... If you use two belts on both crank and water pump pulleys make sure both pulleys are identical diameters or don't run two belts off of both. One belt that covers both is ok. For the other belts, use either the bottom or the top pulley.

Let's talk about your new alt. It is a GM inside. That means you need a GM voltage regulator not a Ford, because they work differently. Wire according to the diagram you have but use a GM regulator.

Our friends at Tuff Stuff use language that is not industry standard. For instance, when they call for a 'resistor type' regulator, they are really asking for a modern solid state GM regulator. They fail to mention that your original regulator must NOT be used.

If you are getting more voltage than 13.5-14 volts, light bulbs tend to get brighter but won't last as long, the battery usually shows electrolyte around the caps from overcharging, and the system components start failing. After charging a good battery, the voltage slowly returns to about 12-12.5 volts.

Make sure your regulator is keeping the charge at ~13.5 volts. The alternator output wire (just this wire) needs to be fused at around 150 amps because if one of the diodes inside goes bad, it will drain your battery to ground as fast as possible. Without a fuse, your wire becomes the fuse.

The ammeter shunt has a very low resistance and is matched to the ammeter. So, there is a direct ratio of current passing through the shunt (resistor) in addition to a small sample current going through the meter. As with any resistor, if overload the shunt it will burn open.

If the shunt burns open with the meter connected, the meter will immediately fail. Yes, you can buy a shunt that will handle more current and you can safely connect your dash gauge to it. You can also use a zener diode across your meter posts to protect the movement. The way a zener works is, it does nothing until it reaches a set voltage, then it starts conducting. This will let the meter go to full scale then send excess voltage safely on its merry way around the meter movement.

There is another method, a better method for picking up current by wrapping a coil of wire around the conductor you are measuring (sensing). Simply send both coil leads to the meter. No shunt resistor is needed.

I see you are adding a nice fuse panel. Smart move and a step in the right direction. Feed the panel from the shunt but keep all ignition and starter circuits far away. The starter motor does not get a fuse because it draws hundreds of amps and it is relay controlled. The relay acts as a disconnect.

Ford purposely left the start circuit unfused because they want you to get off the railroad tracks at all cost, even if the wire becomes the fuse. Oddly enough, this has worked well over many decades.

I hope this helps.

[Yadkin]

OK Dave now let me pick through all that to see if I understand.

I'm not sire what size the pulley is on the new alternator. The car is at the shop and I won't be there again until next week. Since it came pre-installed I have to assume that they sized it right. I did have to try a handful of belts then modify a bracket slightly before I got one that would fit, so I at least know its not the same as OE.

I bought a regulator for a '70 Caprice, a BWD Select 17053. It has two resistors on the outside. Dummy me thought a resistor type meant resistors, not solid state like the Ford one it replaces. Neither works.

Zener diode, ammeter shunt, shunt resistor. Sorry, but all Greek to me. If the old alternator could only make 40 amps, can I just use a 40 amp fuse to the existing ammeter circuit and sense how much that portion of the system draws?

I have a custom mini-starter. Sorry for the confusion earlier. A #4 wire goes directly to the starter from the battery and I use a relay in my new fuse panel triggered by the ignition switch to trigger the relay located on the starter.

[Yadkin]

OK I did a bit more reading and EE 103 Electrical Engineering for Civil Engineers circa 1980 is staring to come back to me.

A shunt resistor is used to measure current based on the voltage drop across it. So you can put one close to the alternator (fat wires) and have a remote read (basically a volt meter calibrated to the circuit) via small wires at the instruments. That wouldn't be easy to do with my existing instruments.

The traditional ammeter, which I understand is in my instrument panel, runs fat wires through the instrument panel itself. What I'm proposing is to run a parallel circuit to carry the high amp devices, and use the existing circuit to run small stuff through the existing ammeter. If this would work it would be the simplest way.

[Yadkin]

I opened up the Chevy regulator and it looks like I fried the wire that goes from the chassis to the top of one coil.

[Yadkin]

The two pictures show whats connected to where. This looks like a points type with resistors on the back, not at all a solid state unit.

[simplyconnected]

I beg your pardon, Steve. Again, I should have checked because I thought you have a stock '66 T-bird (with a shunt). Now, I see you have a '64, where the shunt is inside the ammeter and the meter requires large #10 wires.

Your new alternator puts out 2-1/2 times the 'full load' capacity of your stock ammeter. This is a problem.

How badly do you need to see amps? If it is absolutely imperative you have an ammeter, the one you have can be reworked. As you described, the shunt inside would be removed.

All meters start out being volt meters. Again, as you correctly pointed out, measuring the voltage drop across a shunt resistor will reveal a voltage which mutually correlates to the number of amps flowing through the shunt.

As current demands in modern cars increased above 100 amps, we see fewer ammeters and more volt meters. An accurate volt meter will indicate everything you need to know about your charging system, the wires are small and can be connected anywhere under your dash (like to your radio power terminal).

To convert your meter, we need to know how many volts it takes to make the needle go to full scale without a shunt. I normally do this test using a radio potentiometer, slowly increasing +12 volts until the gauge needle hits full scale. Then I remove the pot without turning it at all, and carefully measure the resistance across the pot. Knowing this value tells me what shunt resistance to use in terms of "ohms per volt". If your gauge dial only has hash marks instead of hard numbers, this is a snap. You would know that full scale is 100 amps (or any value you make it by sellecting a different shunt resistance, for example).

V-belt pulleys (sheaves)... Ford and GM use the same shaft diameter so many pulley diameters are available. The manufacturer wants to use the smallest diameter so the system will charge at idle speeds. Serpentine belts work well because they have a lot of surface area. Most V-belt setups need two belts OR a larger diameter pulley. You will see... when your system requires 100 amps and the engine is running slow, the belt tends to slip until the battery is filled. See how one change affects three others?

Putting a fuse on the old 40 amp meter will not regulate it. The first time you go over 40 amps, the fuse will blow, which is what you don't want. Fuses simply protect against overcurrent by shutting the circuit totally off. In a perfect situation, we want the meter to safely indicate at least the capacity of your alternator. Every circuit should have ample power without any danger of blowing fuses or overheating wires. Your engineering handbook shows each circuit reserves 20% of full load. (In other words, full load amps are never more than 80% of wire capacity when designing circuits. That covers initial inrush currents.)

You can use the meter the way it is, but you cannot run all the circuits through it. The biggest concern is battery charging and discharging, which is way beyond the limits of your OEM ammeter.

I have an Amprobe tong meter that I will loan you if you want to measure current in any circuit. Simply clamp it around a wire and it will show how many amps are flowing through it, AC or DC. I use it to balance load centers (breaker boxes), so each power leg carries equal current.

The Tuff Stuff people should have been much more thorough in their directions and parts needed. You have a GM alternator and it should work just fine with a good GM type regulator. Rockauto.com has solid state units. Connect it according to the diagram John provided. - Dave

[Yadkin]

I appreciate the offer, but I don't want to borrow your tools. My dad used to have one of those, I'll call him and see if he still has it.

I have a call in to Bud at Tuff Stuff. Hopefully he can help me wire the regulator.

I talked with my dad about this, and here's what we came up with. The new power panel from a 2003 Ford Focus is fed from the alternator through a 100 amp breaker and a #6 wire. This feeds the high amp circuits (40a to subwoofer, 30a to horn relay, 15a low beam relay, 15a high beam relay, 40a starter relay, 10a AC clutch relay). This also powers the turn signals in an emergency flasher function through relays, and a console mounted switch. I need to add a 40a fuse to power the old power panel located in the passenger compartment, right side foot well, and I'm now calling that the OE panel. That will also run through the existing ammeter shunt, located as the right-most of the four dash instruments.

Basically the ammeter will tell me how much power is going through the OE panel. This powers the ignition circuit, turn signals, dash lights, running lights, interior lights, and the 240w (20a) stereo. All of the heavy wires going through the dash that used to power head lights, starter circuit, etc. are all used to signal relays in the main power panel.

On the plus side I have a safe system because the old ammeter wires and shunt are fused to 40amps. It's also easy to wire. On the negative side the ammeter is only monitoring the auxiliary circuit panel and related circuits. But, those are the original wires and connectors, most likely to have issues anyway. And I can always add in a voltmeter or convert the existing ammeter to a volt meter later on.

[Yadkin]

After two calls to him Bud never returned my call. So much for customer service from Tuff Stuff.

I repaired the regulator from the '80 Caprice and still no workie. Lots more research and I wired in the solid state Ford regulator and got that to work, but not as expected.

The wiring is per John's diagram, except the A lead goes to a 12v source, switched by ignition. Apparently the regulator switches internally to give 12v to the F lead and that energizes the alternator. The I terminal is unused in this application, but can be used to trigger an indicator lamp.

Here's why it doesn't do as I expected. It cycles on-off. So at idle the system runs at 12.5 volts until the battery runs down a little then it goes up to past 15. I figured these systems would control the voltage at a steady 14.4 or so.

I am using my dependable Greenlee VOM with a sweep hand and maybe it's off a bit- the scale is hard to read at these low numbers. When I have time I'll use a second VOM that I have to see if it jives with the first. But the Greenlee makes sense with 12.5 on the battery alone.

I've researched and have not found anyone who states specifically how these regulators do their thing. Are they on-off let the alternator smoke the battery or do they run at a set voltage? The former doesn't make sense to me at all.

[simplyconnected]

...I've researched and have not found anyone who states specifically how these regulators do their thing. Are they on-off let the alternator smoke the battery or do they run at a set voltage? The former doesn't make sense to me at all.

I'm missing something here, evidently. You have a GM alternator that takes a GM regulator to make it work correctly. Millions of GM cars use this setup with great success and without adverse battery affects.

The net is full of free diagrams showing how the alt and regulator work and how they are connected. I believe you mentioned that your father is an Electrical Engineer. If you have questions concerning the theory, production or regulation of the charging system I'm sure he can help you. Rather than calling Bud, I'd call your dad and ask him. - Dave

[jopizz]

I've driven GM cars my whole life, with both internally and externally regulated alternators and I've never had one that didn't put out a constant 13.4-13.8 volts. There's still something amiss with either your wiring or your regulator/alternator in my opinion.

John