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Old 17-01-2020, 17:55   #1
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Alternator (+) output stud

I bought a new, not remanufactured Nippondenso 50/120 amp externally regulated alternator to place in my Vehicle replacing a reman'd 'lifetime warranty' bosch/chrysler 50/120 that recently failed after 4.5 years of being worked pretty hard on a regular basis. I used that warrantly no less than 6 times in 16 years and they magically lost any records of me ever having bought alternator.

It is made in Malaysia.

The Stud is 6mm and some sort of alloy, not as yellow as brass, nowhere near copper colored but certainly not steel. Perhaps silicon bronze?

Anybody know what materials they use for this stud?

I am rather annoyed with the protective collar around the stud, as it wont fit a good sized ring terminal without some time with a dremel, but more annoyed with the steel nuts. One is to hold the keyed collar in place, and the other one is to compress the ring terminals to the first steel nut.

How is a ring terminal supposed to support a potential 120 amp current when passing through the threads and body of a steel nut?

I am assuming real alternators have a much better contact surface area for a ring terminal.

I am in the process of making a 13mm or wider copper hex nut and intend as many copper threads as possible be in touch with as much of the unknown alloy 6mm threaded stud as possible, with 2 or perhaps 3 ring terminals attached to it.

Little luck in finding an m6 copper nut online. I know they cant handle much torque but I intend to use as much of the stud as I can and will use the steel nut on the end for final compression of ring terminals and be sure to not overtighten.

Anybody here also been unimpressed with this electrical interface and come up with good solutions?
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Old 17-01-2020, 19:17   #2
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Re: Alternator (+) output stud

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Originally Posted by Sternwake View Post

I am in the process of making a 13mm or wider copper hex nut and intend as many copper threads as possible be in touch with as much of the unknown alloy 6mm threaded stud as possible, with 2 or perhaps 3 ring terminals attached to it.
Why would you have "2 or 3 ring terminals" on your alternator??? You can not send a regulated output to two or three different places (since it can only match the needs of ONE!) and using your alternator post as a distribution point for battery power is a very bad idea.

There is no good reason for this, and it is worse the alternator design characteristics that you are complaining about.

Far more problematic is the unisolated ground for this alternator. Proper marine alternators have their own negative return wire to the battery bank, not through the engine block which has way more potential resistance problems than a single steel nut that has you all worked up.
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Old 17-01-2020, 20:25   #3
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Re: Alternator (+) output stud

1. My alternator grounded not through mounting hardware but with 2awg cable to my 500 amp deltec Shunt and 0awg to the battery from the shunt.

No bottle neck there.

The original 6 SAE gauge wire and thin ring terminal from alternator stud to engine battery had a 10 awg fusible link on it, a battery which is no longer located there, but is much closer to the alternator, circuit wise, and crowflies.

The second thickwalled ring terminal is another 2awg parallel circuit going directly to the battery taking advantage of this shorter circuit path. I left original alternator feed in place in case I wanted to sell vehicle and transfer my system to new vehicle.

The third ring terminal is just a 10 awg ring terminal to power my external adjustable voltage regulator. Ideally it would have its own wire right to the battery but 2awg is overkill enough, I just attach it to the alternator output stud instead, as it is close and convenient. Whatever voltage drop occurs that the external adjustable regulator then sees, can be negated by spinning a 10 turn poitentiometer on my dashboard a few degrees and I'll watchmy digital two decimal voltmeter whose ground and voltage sense lead are connected directly to battery to gauge the result.

My previous alternator could regularly achieved its 120 amp rating, at 2400+ rpm feeding my loads, as I have more than one ammeter and can see one from the driver's seat not only how much total juice the alternator is making, but how much of that is going into the battery.

I have had three ring terminals on the previous 'lifetime warranty' alternator output stud, and the one before that, and the one before that, covering a period of 10+ years.

But the stud on the previous alternator had a large flat on the bottom of the stud for a nice fat copper washer and plenty of surface area for the biggest ring terminal to reside upon, then the original thinner one then the even thinner one for my 10awg feed to voltage regulator.

This New alternator that has the removable protective bakelite shroud is not so accommodating of the ring terminals. That in itself is no big issue. It is to be held in place with the steel nut, then the ring terminals stacked upon that, then another nut compressing the ring terminals but if that still gets your panties in a bunch pretend it is just one ring terminal.

So even if I eliminate the steel nut holding the bakelite collar in place, then the ring terminal resides on bakelite/plastic/whatever dielectric material it is made from, and a tiny portion of the inner diameter of the ring terminal touches the threads. then the steel nut, which is ~1/50th as conductive as copper, those threads in contact with the stud represent a tiny amount of surface area in which to pass current.

If you cannot see that this is a huge electrical bottleneck and could be substantially improved, then you should not be giving any advice or questioning the processes of others.

I'm trying to minimize resistance. If I put it together as is with that steel nut and crank my regulator upto 14.7v with depleted battery(s), I can see that tiny interface of dissimilar metals achieving ridiculous temperatures.


I was hoping somebody else can see this potential electrical bottleneck and has come up with a better solution than mine, which is a thick enough copper nut to grasp as many output stud threads as possible and present the biggest surface area that can equal that of the bottom ring terminal. Seems there would be a lot less resistance, less heating, and way more reliability.

But now I'm sorry I asked.
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Old 17-01-2020, 20:41   #4
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Re: Alternator (+) output stud

Nuts don’t transfer power. Then hold the lug against the metal that transfer the power....
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Old 17-01-2020, 20:55   #5
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Re: Alternator (+) output stud

Quote:
Originally Posted by Sternwake View Post
1. My alternator grounded not through mounting hardware but with 2awg cable to my 500 amp deltec Shunt and 0awg to the battery from the shunt.

No bottle neck there.

The original 6 SAE gauge wire and thin ring terminal from alternator stud to engine battery had a 10 awg fusible link on it, a battery which is no longer located there, but is much closer to the alternator, circuit wise, and crowflies.

The second thickwalled ring terminal is another 2awg parallel circuit going directly to the battery taking advantage of this shorter circuit path. I left original alternator feed in place in case I wanted to sell vehicle and transfer my system to new vehicle.

The third ring terminal is just a 10 awg ring terminal to power my external adjustable voltage regulator. Ideally it would have its own wire right to the battery but 2awg is overkill enough, I just attach it to the alternator output stud instead, as it is close and convenient. Whatever voltage drop occurs that the external adjustable regulator then sees, can be negated by spinning a 10 turn poitentiometer on my dashboard a few degrees and I'll watchmy digital two decimal voltmeter whose ground and voltage sense lead are connected directly to battery to gauge the result.

My previous alternator could regularly achieved its 120 amp rating, at 2400+ rpm feeding my loads, as I have more than one ammeter and can see one from the driver's seat not only how much total juice the alternator is making, but how much of that is going into the battery.

I have had three ring terminals on the previous 'lifetime warranty' alternator output stud, and the one before that, and the one before that, covering a period of 10+ years.

But the stud on the previous alternator had a large flat on the bottom of the stud for a nice fat copper washer and plenty of surface area for the biggest ring terminal to reside upon, then the original thinner one then the even thinner one for my 10awg feed to voltage regulator.

This New alternator that has the removable protective bakelite shroud is not so accommodating of the ring terminals. That in itself is no big issue. It is to be held in place with the steel nut, then the ring terminals stacked upon that, then another nut compressing the ring terminals but if that still gets your panties in a bunch pretend it is just one ring terminal.

So even if I eliminate the steel nut holding the bakelite collar in place, then the ring terminal resides on bakelite/plastic/whatever dielectric material it is made from, and a tiny portion of the inner diameter of the ring terminal touches the threads. then the steel nut, which is ~1/50th as conductive as copper, those threads in contact with the stud represent a tiny amount of surface area in which to pass current.

If you cannot see that this is a huge electrical bottleneck and could be substantially improved, then you should not be giving any advice or questioning the processes of others.

I'm trying to minimize resistance. If I put it together as is with that steel nut and crank my regulator upto 14.7v with depleted battery(s), I can see that tiny interface of dissimilar metals achieving ridiculous temperatures.


I was hoping somebody else can see this potential electrical bottleneck and has come up with a better solution than mine, which is a thick enough copper nut to grasp as many output stud threads as possible and present the biggest surface area that can equal that of the bottom ring terminal. Seems there would be a lot less resistance, less heating, and way more reliability.

But now I'm sorry I asked.
My only take on this is, how many alternators have you had in the last 10 years? If you have in fact had that many alternators and they all have failed then perhaps there is a problem with either the install or the size of the equipment installed is insufficient for the task in hand.
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Old 17-01-2020, 21:26   #6
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Re: Alternator (+) output stud

Quote:
Originally Posted by smac999 View Post
Nuts don’t transfer power. Then hold the lug against the metal that transfer the power....
THIS!

At least the top nut doesn't, the bottom one does. Technically the top nut is part of the parallel circuit but in real terms it doesn't carry much current.
Plus use a thick washer to ensure sufficient pressure on the ring terminal(s).

IMHO, a steel nut will be superior to a copper one in this application. Copper is too soft and will not hold torque for long periods of vibration.
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Old 18-01-2020, 00:15   #7
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Re: Alternator (+) output stud

All but the initial alternator, have been remanufactured alternators purchased initially, once, long ago from Kragen Autoparts. I used that warranty, many times when they were Kragen and then when Oreillys bought out Kragen, they honored the warranty.

I can swap them out in 15 minutes in the parking lot. They cost me nothing, but the time to replace them, and the inconvenience of having to so so, usually right in the parking lot.

The initial alternator might have been original or not, replaced by previous owner.

I've worked them hard charging depleted batteries. I will continue to do so. I'd like more amperage at hot idle speeds, but 50 amps is almost enough. I had little motivation to seek a better alternator when they were just handed out free. Now they cut me off. Kind of surprised they did not do so earlier.

Some Alternators lasted months, some lasted years. 4 years ago, I bypassed the engine computer voltage regulator with a 10 ohm resistor to simulate an alternator and not illuminate the check engine light. I now run an external adjustable Voltage regulator. I modified the VR's voltage trimpot so I could have a potentiometer on my dash to choose any dang voltage I want between ~13 and 16v though 30 seconds above 14.7v can illuminate the check engine light and cause engine to run crustier and get worse mpg. Need to reset computer when this happens.

I basically make it seek and hold 14.7v any time the battery is accepting more than 0.5% of capacity and dial it down only then, or if the alternator gets too hot.

I have attached a K type thermocouple with arctic silver thermal epoxy to the stator/exterior casing of the most recent failure and insulated that area from direct windflow from radiator fan and vehicle movement.
I've lots of data Data with amperage output vs temperature at different rpm and vehicle speed and ambient temperature. Basically the danger zone is hot idling maxed out, and slow speed low rpm driving maxed out. Maxed out at 65mph it would not exceed 140f, the Stator casing anyway, no Idea on the rectifier. Thereafter I avoid Idling to recharge, and if forced to drive slow with depleted battery, I lower voltage to 13.7 range to keep stator temp below 165f or so and raise it as battery charges, back upto 14.7v.

Parts stores listed the Nippondenso 50/120 as a drop in replacement. I asked an ornery old contact who used to be heavily involved with alternators back inteh 80's about the ND vs the bosch/chrysler style alternator I had been using, Dual internal fans and 2 more diodes, he said it was likely to perform better at low rpm, run cooler.

I figured i'd give it a shot. New was 25$ more than remanufactured. It was delivered to my door in 21 hours, free shipping 166$ total. It has a 'limited lifetime' warranty, whatever that means in this day and age.

The output stud of the ND, comes out of the back of the alternator with about 5mm of room all around it. the Keyed protective collar slides into the receptacle and prevents stud from touching the grounded body should it take a lateral hit.

With this design, The Nut holding the collar in place, is the surface the ring terminal HAS to reside upon. Without a nut the ring terminal would rest on the bakelite protective collar, making minimal contact with the stud's threads. In this case the Nut HAS to pass current to the Ring terminal. Obviously poor design, but this design is obviously intended for a vehicle that rarely would ever seek more than half its rating, and only for short durations.

This Nut is steel. Steel has ~1/50th the conductivity of copper.

Conductivity Of Metals Sorted By Resistivity | Eddy Current Technology

The Stud and the Steel nut therefore have to transmit the electrons to the ring terminal. There is no wide magical flat spot for the ring terminal to rest upon the stud and the nut being merely there to hold in place.

The copper is obviously soft, the threads not strong. Perhaps I'll get a half thickness steel nut to hold bakelite protective collar to the back of the alternator. Then put a copper nut atop that, one which can grab all the studs threads tightly for lots of surface area, then the ring terminal which barely fits over stud, then the steel nut can go atop that and hold them all tight. Perhaps a high temp conductive grease to help conductivity further.

In the case of this alternator the steel nut provided HAS to carry a significant portion of the current. There is NO other option, with this alternator.

Making a copper nut, to grab as many threads of the output stud tightly is my task tomorrow. Hopefully I can find a half thickness steel nut to go below that and take the stress of the ring terminals being compressed on the copper nut/washers/ring terminal(s) above.

Until I am sure the alternator works, I am not considering removing the backside and inspecting how it is attached to the rectifier. All the nuts holding it together have the paint across them to show if it has been opened.

I actually have No experience opening up alternators, other than the plastic back of the chrysler/bosch units I have been employing upto this point.

I'm going to work this alternator hard too. I will collect lots of new Data. The output amperage should be directly comparable to the previous alternator, the stator casing temperature less so, but I'll collect it anyway.

I've not read the fine print of the 'limited lifetime' warranty, and I am not going to be mid atlantic when it fails, and can drive a good 180 miles, at night, if/when it does fail on the battery alone, as I did a week ago. But I'd like more reliability and I think the steel nut is a glowing failure point in the design, especially as hard as I will be working it compared to the average driver.

The previous one, of the different design, was making 26 amps total, 6 of those going into the 82f battery, at 14.62v, and the casing was 119f when it failed.
I've not opened it up yet to inspect it. I will though. I'd like to rebuild it, make it as tank like as possible. Bigger better diodes, more heatsinking, ect.....
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Old 18-01-2020, 01:31   #8
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Re: Alternator (+) output stud

The stem of the ring terminal is probably creating more resistance than either the stud or the nut. A way around this is to wrap the conductor around a stud and then solder the wrap between two copper washers.
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Old 18-01-2020, 09:33   #9
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Re: Alternator (+) output stud

@Sternwake
Suggest you source a 3/16” copper nut and tap it to M6-1.00.
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Old 18-01-2020, 13:17   #10
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Re: Alternator (+) output stud

M61105DIN 9342590690A0477.41Not sure of what your thread is but McMaster has this brass nut:


You have every right to be concerned about the poor design of the denso.
Our 28V 300A alternator believe has a 5/8 stud.
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Old 18-01-2020, 22:33   #11
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Re: Alternator (+) output stud

Thanks, I did source some copper m5 nuts online, apparently they are used as manifold bolts on some BMWs and mini coopers, but I did not order them.

That Brass nut would certainly be better than steel, for the ring terminal to reside upon.

If pure copper scores a 100, and pure silver scores 108, red annealed brass gets a 37, and 304 stainless steel scores 2.5, and other steel alloys score less.

Conductivity Of Metals Sorted By Resistivity | Eddy Current Technology

I Found some pure copper 'Scruglug terminals' in the hardware store and bought a 6mm tap and plan to make my own copper nut from that stock. I also got a Stainless steel washer that fills the diameter of the protective collar's bottom, and an M6 steel 'jam' nut, which is a nut of half the thickness of a regular m6 nut to leave me more room on the stud and perhaps keep less leverage of the wires off of it.

The steel jam nut and washer should properly secure the collar, better than the provided nut ever could, then I will place the homemade copper M6 nut which will be 12 or 13mm hex size atop that, and should be at least 3mm thick. Then the ring terminals perhaps with copper nuts in between the two largest. I got a grade 8 nut and a few grade 5's too, for the final nut and will have a thick copper washer under that.

The copper scrulug has a threaded steel grub screw in the copper threads and the threads seem to be stronger than expected. No doubt I could strip it with a big fat screwdriver and the lug held in a vice, if I wanted, but could not with a small screwdriver and holding it in my hand.

I'll have lots of surface area of pure copper grabbing a lot of the 6mm stud's threads. and lots of surface contact between pure copper and tinned thick walled ring terminal.

I believe the only way to improve on this would be to take alternator apart and modfy it to accept use a larger stud that has a large flat spot on it for a ring terminal.
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