Alternator replacement? Voltage regulator gone bad?

[KevAndAndi]

If I remember correctly I left the bottom bolt in the alternator and removed the alternator and bolt together. It hit the radiator but was disengaged from the mount

When a car is designed and an alternator is chosen for a specific vehicle lots of things are taken into consideration. One major factor is the wire size required for the alternators output amperage. The wires used in the Fiat Spiders are sized for a 65 amp alternator. One interesting point dealing with "Hot Rod" vendors many of them make a point of this in their marketing and even provide larger wires with the alternator kits. Especially the wires between the alternator output and the starter/battery.
Another factor is the alternators rotor speed the pulley system is designed to keep the alternator rotating within performance limits. Arbitrarily installing a different alternator usually does not address the actual speed the alternator is rotating form engine idle to red line. Another point is the direction the alternator rotates. Alternators produce power turning either direction, however the fan behind the pulley is designed to cool the alternator for a specific direction.
Alternators amperage output is usually designed to be operated with a constant load of 80% of the the alternators rated value. So a 65 amp rated alternator would be expected to supply a constant 52 amps. Momentary loads like turn signals would not enter this calculation. Also the high charging current immediately after start-up would not enter and it should quickly drop to a trickle.
With everything turned on at the same time in a Spider the current draw should not exceed 52 amps. An alternator only puts out what the car asks for. So having a 100 amp alternator on a car asking for 40-50 amps serves no purpose.
Many people state the higher amperage alternators put out 14 volts at idle as this is a good thing. It could very well be the rotor is turning too fast at idle and will be too fast at red line.
Our 65 amp alternators are very simple design almost every part is currently available for them and they are extremely reliable. My 35 year old Spider has 177K on it a 65 amp Bosch alternator.

Thanks for the info and perspective. I (probably like many) do not have sufficient electrical knowledge to have a strong opinion one way or another, and so I appreciate hearing all sides in order to weigh the arguments as best I can.

I have a feeling that the upgraded alternator question is similar to the brake compensator bypass question: It's a modification that is controversial, with some folks saying, Hey, it was designed this way for a reason; why change it? Others say, Hey, the original equipment was under-designed or is problematic; I'm going to change it for the better. Each person has to make the decision he is more comfortable with.

Fortunately, in both the cases I mentioned, there is the ability to do a like-for-like exchange - with a completely new 65 amp alternator or a completely new brake compensator, if one wants to keep originality but with fresh parts.

[So Cal Mark]

all that would be ever needed as far as a wiring upgrade with a high amp alternator is to add a 10 gauge wire from the alternator battery post to the starter battery post.
Your 65 amp alternator won't put out 65 amps until it reaches maximum rpm which is usually rated at 6000rpm and electrical demand has to be high. Even then it probably won't reach 65amps. You'll find that most electrical devices draw more than the rated amperage upon start up. The cooling fan and blower fans are two examples, it takes more amperage to get them started then it does to maintain them, so even if you add up all of the amp ratings of items in your car you will find at times the demand is higher.
I could sell the 55 and 65 amp alternators all day, but I've found a huge improvement in the electrical systems with 95 and 120 amp alternators.
The other aspect you must consider is how long your alternator will last attempting to max out constantly. Lots of heat is generated when your alternator is under full or high load and heat causes failures. It makes sense to use an item at 50% capacity rather than 100% most of the time.
If you haven't experienced the improvement from a high output alternator then you shouldn't bad mouth the item. I've yet to see anyone take off their high output alternator and go back to the low output unit

[spider2081]

If you haven't experienced the improvement from a high output alternator then you shouldn't bad mouth the item. I've yet to see anyone take off their high output alternator and go back to the low output unit

If this comment was directed to me.

I am not a Fiat Parts vendor and do not sell replacement parts.

I am a contributor to this forum with over 50 years of aviation and automotive electrical and electronic experience. My first job out of high school was rebuilding generators/alternators and starters for a small company.

Stating my opinion that the Bosch 65 amp alternator is a good and adequate alternator for our Spiders is not bad mouthing other alternators.

Much of the rest of your post is technically lacking. You might google some information on wire size and practices, heat generated by alternators, and alternator output current demands and find it enlightening.

[DieselSpider]

The other consideration is HP loss and fuel economy. The general rule of thumb is that there will be about a 1 hp loss for each 20/25 amps capacity so a 100 amp alternator has the capacity to consume twice as much hp as a 50 amp unit and the 125+ amp obviously more. Since they never really turn off completely there is also the constant extra minimum drag from the larger units that further decreases overall fuel economy more so then those short periods of when its at maximum output.

On a 300 hp engine turning a 125 amp alternator controlled by the engine ECU it is another matter however those systems don't exist in most old comparatively low powered 124 Spiders which must rely upon a more simple voltage regulator that is not tied in with an ECU. It is a balancing act.

On mine even with the heater core disconnected using an electric heat element instead to take the chill off and defrost the windshield the 50/65 amp alternator is really not having problems keeping up and lasts a good many years before needing brush or regulator service. In 5 to 10 years when it needs another servicing I will have it rebuilt again, if I still am able to drive the car, to maintain the currant balance that is giving me 40 mpg city driving. No fussing with brackets, running a heavy wire all the way to the trunk or any other tinkering to make it work as originally intended, just clean up whats there and slide it right back where it came from.

Last time I had one rebuilt by a local auto-electric shop they used an upgraded regulator to giving me some of the perceived benefits of going with a larger unit.

[spider2081]

Last time I had one rebuilt by a local auto-electric shop they used an upgraded regulator to giving me some of the perceived benefits of going with a larger unit.

It is one of the simplest alternators to repair and service. Having followed your posts I am pretty confident you could do it yourself. The bearings/regulator repair kit is in the area of $30. That includes both bearings and a new regulator/brush assembly. I like to give them a through cleaning and painting while I have them apart, check the diodes replace both bearings, clean the slip rings etc. Painting the individual parts is the most time consuming part of the job. At car shows a dressed up alternator gets lots of attention.

[DieselSpider]

Last time I had one rebuilt by a local auto-electric shop they used an upgraded regulator to giving me some of the perceived benefits of going with a larger unit.

It is one of the simplest alternators to repair and service. Having followed your posts I am pretty confident you could do it yourself. The bearings/regulator repair kit is in the area of $30. That includes both bearings and a new regulator/brush assembly. I like to give them a through cleaning and painting while I have them apart, check the diodes replace both bearings, clean the slip rings etc. Painting the individual parts is the most time consuming part of the job. At car shows a dressed up alternator gets lots of attention.

My brother used to run a shop rebuilding starters and alternators so I miss having access to the lathes and tools to do a bang up job on them. The vibrating cleaner with the glass beads in it really came in handy too.

The only reason I had it done was to get someone more familiar with the piggybacked diesel vacuum pump and to limit down time since its my daily driver.

Mine has a Hitachi starter and alternator common to the Isuzu Diesels. Alternator has the 3 wire internal regulator.

Personally I was head of maintenance at a Boston Area Millworks Facility and built, rebuilt along with maintained all the equipment and a number of the vehicles used by three factories. It was more like working in a museum covering from the Civl War to the Modern Age of Wood Products Manufacturing.

[KevAndAndi]

OK, I received the voltage regulator from Midwest-Bayless. Do the brushes on the old one (on the left) look worn enough to be causing my problem?

[spider2081]

the brushes are not worn too much. I would install the new one anyway to see if the electronic regulator in the old one was bad.

[KevAndAndi]

the brushes are not worn too much. I would install the new one anyway to see if the electronic regulator in the old one was bad.

For sure; hope to do so this weekend - it's supposed to be nice and sunny here in the NYC area.

[spider2081]

Looks like you have a decent replacement. Some of the one coming from China have a much narrower brush than the original

[KevAndAndi]

Looks like you have a decent replacement. Some of the one coming from China have a much narrower brush than the original

It's made in Germany, if I recall correctly.

[KevAndAndi]

Well, I installed the new voltage regulator, and at first the results seemed promising. The alternator/battery light went out. We went for a Sunday drive, and the car seemed just fine. After a while, though, the light came back on. Also, I don't know if this is related, but the turn signals started blinking very slowly. I just tested the alternator at the stud with the car idling and got about 12.1v which didn't change at higher RPM.

Time for a new alternator?

[spider2081]

Sometimes the signal lights will not flash at all with just battery voltage but seem fine with the engine running and a good alternator. They can be that voltage sensitive.

Yes I would think you need a new alternator. Its interesting that the light was out for a while. You might recheck that the screws holding the regulator to the alternator are tight. One of them makes the ground for the regulator when it tightens tot he alternator.

[KevAndAndi]

Sometimes the signal lights will not flash at all with just battery voltage but seem fine with the engine running and a good alternator. They can be that voltage sensitive.

Yes I would think you need a new alternator. Its interesting that the light was out for a while. You might recheck that the screws holding the regulator to the alternator are tight. One of them makes the ground for the regulator when it tightens tot he alternator.

Thanks. The screws are good and tight. I was weighing various alternator options and then decided that I should at least look into alternator rebuilders in my area. Come to find out there is one literally just down the street from my house. I called, and the proprietor, Mario, had a thick Italian accent. I could only understand about 35% of what he was saying, picking out words like "Marelli", "Bosch", and "Brava". No, I don't have a Brava. I have a Spider 2000. "Ahh, Spider. I may have-a de Bosch somewhere." He quoted $110 for a rebuild, with same-day service. I think.

[spider2081]

I think that's a fair price. He will probably test it when you drop it off and tell you what is wrong. He might drop the price a little if he sees you have a new working regulator. If he touches up the slip rings and cleans everything and repairs it he will have over an hour labor into it.