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jjdugen
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PostPosted: 00:45 - 29 Nov 2017    Post subject: Reg / Recs Reply with quote

Simple question. If one reg / rec is insufficient to dissipate the alternator output, why can't I put two of them, back to back to double the rectifying and regulating capacity.
NOT doubling the alternator output (for the numptys) just doubling current handling capacity.
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Teflon-Mike
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PostPosted: 04:48 - 29 Nov 2017    Post subject: Reply with quote

If one reg/rect is insufficient to rectify and regulate the generator output, two probably wont help much. In series, the first in line would do all the rectification and regulation anyway, second one would just get already rectified and regulated volts, and have nothing to do. If coupled in parallel, they would both do half the work, half as efficiently.

When Reg/Rects fail... (Screams HONDA!!! Just to get that out the way!) When reg/rects fail, the cause will tend not to be that the reg-rect lacks the capacity to handle the out-put from the generator, but that the battery lacks the capacity to take that out-put.

The rectifier 'bit' of the box, is basically a fancy one way valve. Volts flowing backwards and forwards on the input, get directed to a par of valves, so that all forward flow goes down one wire, all back-wards another, and the out-put is all one-way.

The regulation 'bit' of the box, then 'smooths' the volts on the output, which are coming in in a wave varying from 0v to maybe 20v, and tries to flatten that to something closer to a constant 12v, with capacitors and chokes. BUT, it will try and 'clip' the peak voltage around 14v, so that voltage spikes don't blow light-bulbs or wot-not.

The regulator then will try and absorb excess energy at the 'peak' of a wave, and use that to fill in the 'troughs' of the wave between peaks... and only if it gets more electric at the 'peak' of each wave, than it can hold until the next trough comes along, will there be any energy that can do damage to the device.....

So in theory! Properly designed, the regulator should have sufficient capacity to handle the power delivered by the generator, and the regulator shouldn't be damaged by it.

In practice! High-Current power transistors/diodes are some of the most expensive electronic components, and the 'proper design' is likely to be compromised a bit to be a bit 'marginal' so as to use fewer or cheaper components, that are more likely to fail under stress...

That stress though, will usually come from a duff battery, aided and abetted by poor wires and connectors. The battery as a charge accumulator, can do a lot of voltage stabilization, accepting electric in 'packets' from the generator, and delivering them as a steady stream....

If the battery lacks the capacity to store so much energy, or take it as quickly, then the reg/rect can be left holding the baby until it can, and its limited charge-holding to 'smooth' the input,over-loaded, as all it can do with that energy is try ad chuck it away, or dissipate it, basically by getting hot! Now the components in the reg/rect can start to have a tough time and start to break down, dissipating more energy than they were designed to.

Oh-Kay.... so the reg/rect shouldn't have to dissipate alternator out-put. It should just be rectifying and regulating the out-put, conditioning it for use by the bikes electrical equipment. It should only be dissipating a very small amount of that energy, its 'efficiency loss'.

If there is more energy being delivered by the alternator than the electrical system can handle.... then the reg/rect is only one link in the chain, ad f there is so much power coming from the alternator, and so little being drawn from it that the reg/rect becomes a three-bar electric fire... then the answer isn't to try and share that power between two electric fires, so they both potentially get burned out, but possibly 1/4 as fast.... answer is to look at the battery, which 'should' be the thing accepting and storing that power before use, and whether wires let it get that power, and if battery can actually take it.

Back to HONDA.... reg/rect black-boxes of mystery are so easily blamed for problems, that actually they don't very often cause, but their failure is a symptom of.

I used to work in electronics factories, making military grade power-supply modules for aircraft, and an ex leccie engineer, who used to sneak down to the lab at lunch-time or after hours and make reg/rects for bikes, with components way above the specs usually found in bike Reg/Rects, for 'fun'.... & I would often find him ranting trying to repair one of his creations, when a mate had blown it up, and told him it was crap... and he'd be yelling "I told him, I TOLD him to fit a bigger battery!!!" (and/or not to use cheap chtty crimpy connections!) It was a bain of his, that folk would have fitted a diddy little battery on a special, ether because of space or weight, or too cheap to buy a new battery, used a tired old stocker, (and/or old wires and/or chtt connectors!) and unable to take the power the genny made, blow up the reg/rect... frequently.... especially on Honda's! Lol.
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jjdugen
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PostPosted: 08:52 - 29 Nov 2017    Post subject: Reply with quote

For once, Teff, you have missed my point. Not in series, but parallel.
Both 3 phase outputs go to each of the rec/rec in puts, the DC feeds are paired and fed into the loom / battery.
Just so we sing from the same hymn sheet.
A 'shunt' type reg/rec dissipates the surplus current load, through its body, to the heat sink. The battery has little or no bearing on this other than it acts as a giant capacitor, smoothing the pulsating DC output of the rec/rec and acting as a reservoir to power starter motors and other ancillaries WHEN the alternator isn't turning. It is the alternator that powers the vehicle, NOT the battery.
On a motorcycle that can operate between 1K rpm and over 11K rpm, the alternators output varies immensely, it still has to provide sufficient output at low rpm to balance ignition, lights, fuel pumps but will obviously put out far more than is needed at high revs. This excess is basically dumped to ground, the energy converted to heat along the way. Too hot and components fail.
My premise is to spread this heat load over two devices, halving the dissipation in each device.
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The Shaggy D.A.
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PostPosted: 10:26 - 29 Nov 2017    Post subject: Reply with quote

It's quicker to add the second reg/rec and try it, than decipher one of Tef's posts.
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BTTD
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PostPosted: 10:33 - 29 Nov 2017    Post subject: Reply with quote

jjdugen wrote:
For once, Teff, you have missed my point. Not in series, but parallel.


He did actually cover that, and even had a charming story about workplace theft thrown in towards the end.


I'm at work, I'm leaving soon, I have time to read.
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stinkwheel
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PostPosted: 10:39 - 29 Nov 2017    Post subject: Reply with quote

In terms of regulation, I'd expect only one of them would work, the one which shunts at the lowest voltage.

If you're worried about the reg/rec, get a switch-mode/mosfet one, fit it, forget about it.
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Matt B
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PostPosted: 10:40 - 29 Nov 2017    Post subject: Re: Reg / Recs Reply with quote

jjdugen wrote:
If one reg / rec is insufficient to dissipate the alternator output, why can't I put two of them, back to back to double the rectifying and regulating capacity.


Why would one be insufficient is the question you should be asking. Seems an odd question to ask.

What is the actual problem you have with your charging circuit?
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Teflon-Mike
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PostPosted: 11:00 - 29 Nov 2017    Post subject: Reply with quote

Second Sentence, first paragraph, if coupled in parallel, both will do half the work, twice as inefficiently.

Point was, that a correctly rated Reg/Rect in a charging circuit that's in good condition, with a good battery to accept its out-put, SHOULDN'T need dissipate very much excess energy as 'heat', if the reg/rect gets hot enough, often enough, then the fault is usually not the reg/rect, that aught have the capacity to handle the output of the genny without doing itself harm, trying to dissipate energy it probably shouldn't have to, if the battery is good, and wiring good, and connectors good, and it has some-where to put the charge it rectifies, and not have much left to regulate.

More common killer of reg/rects then isn't that they are too small, or too fragile, as so often suggested, but, as old Lcuas Leccie who used to make them in his lunch hour suggested; because people so often were too cheap to buy a new battery; or they fitted too small a battery to save weight or find space; OR they fitted a rect/reg from a scrapper, often under-rated for their genny output, cos cost of propper bit.

Either way, the reg/rec had to dissipate whatever extra charge the genny made, the battery wouldn't take, eventually getting fried in the attempt.

Two reg/rects in series, yes is just a redundant component. Two in parallel, would mean that each only has half the 'wasted' energy to dissipate...so they shouldn't get 'as' hot, which would tend to help their longevity, but their getting hot, is symptom, not cause, so whilst you may increase the heat-soak capacity to dissipate more energy, why is the system having to dump that much energy to start with?

Tackle the cause, not the symptom. A mod that masks a symptom, isn't a solution; problem is still there, only better hidden.
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Teflon-Mike
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PostPosted: 11:38 - 29 Nov 2017    Post subject: Reply with quote

jnw010 wrote:
even had a charming story about workplace theft thrown in towards the end

I never implied he 'stole' his transistors!

I recall he'd been promoted to purchasing, where he had a lot of components rejected by quality for suppler return and investigation... but no soldering iron!

He sneaked into the lab, because if he was caught by the prototyping manager, he'd spend the rest of the day studying an oscilloscope and get a rollicking of his own boss who'd be disturbed from his Auto-Express magazine, to field his 'phone calls!

It WAS the tag end of the BL Hey-Day, though, and folk taking home entire cars in kit form, in their boot, over a few months!

Actually, on family farm, when my Grandad retired he let the unused sheds as units. A Tractor factory rented one as a 'field repair center' A decade later, it was raided, as MF had let the lease go after a couple of years, but chap that had worked there, had kept it going for his own private use.. and kept getting 'repair-parts' sent to the address under warranty, until he'd built a whole ruddy tractor! Which stayed there! It didn't fit out the doors! Which was why MF had let the lease lapse, in the first place!!!

Rather makes a few paper-clips or a couple of questionable capacitors seem like pretty small potatoes, that one! LoL.... Thank heavens he didn't work for Boeing, I suppose! "For sale, brand new unused, Jumbo Jet, just needs paint to finish dry stored, sledge hammer wll be supplied for collection. Offers." lol!
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smegballs
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PostPosted: 12:00 - 29 Nov 2017    Post subject: Reply with quote

The problem with semiconductors is that there is always some difference in real life performance between parts with identical part numbers, which is why the datasheet specs min/max values.

As such, devices in parallel are unequal and one will try to handle all the current and blow itself up.

Ie you can't use 2x 5A diodes for a 10A current for example (without additional complexity like load balancing resistors etc).

For motorbike application, fit a mosfet type RR and forget about it
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stinkwheel
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PostPosted: 12:29 - 29 Nov 2017    Post subject: Reply with quote

smegballs wrote:
The problem with semiconductors is that there is always some difference in real life performance between parts with identical part numbers, which is why the datasheet specs min/max values.

As such, devices in parallel are unequal and one will try to handle all the current and blow itself up.

Ie you can't use 2x 5A diodes for a 10A current for example (without additional complexity like load balancing resistors etc).

For motorbike application, fit a mosfet type RR and forget about it


Exactly what I was trying to say but more clearly put.

It's the same issue as if you try to jump start a bike from a car with the engine running. You effectively have two voltage regulators in paralell (the one on the bike and the one on the car). If the bike one happens to dump at a lower voltage than the car one regulates to, you land up with the bikes reg/rec dumping excess output from the car and going pop. Which is why you should only ever do this with the car engine off.
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Teflon-Mike
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PostPosted: 12:48 - 29 Nov 2017    Post subject: Reply with quote

stinkwheel wrote:
Which is why you should only ever do this with the car engine off.

Or take battery off bike, which tends to save lots of swearing at crock-clips, as well as risk of frying a reg/rect, and 'little' niggle of flat, probably cos its duff, bike battery, flattening the car-battery, you then can't start either.... not a lot of fun, especially if its a auto..

Though letting folk who insist they can bump it, and tell you to get in and put it in 2nd, push it up and down the car park a couple of times, before they say "I thought I told you to drop the clutch?" and then watching them scratt around the footwell, perplexed when you say "Yeah, I cant find that" can be amusing....
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WD Forte
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PostPosted: 13:15 - 29 Nov 2017    Post subject: Re: Reg / Recs Reply with quote

jjdugen wrote:
Simple question. If one reg / rec is insufficient to dissipate the alternator output, why can't I put two of them, back to back to double the rectifying and regulating capacity.
NOT doubling the alternator output (for the numptys) just doubling current handling capacity.


How many bikes use or need two RRs?
I'm wondering if there are issues as yet unmentioned
or you just have a poor quality RR

I'm still using a 'Honda' (actually Shindengen, Honda don't make RRs)
from the 70's on a commonly used G8 250W stator and find them
robust and reliable units
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jjdugen
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PostPosted: 13:45 - 29 Nov 2017    Post subject: Reply with quote

If reg/recs worked in a steady state environment, they could be spec'd to work quite reliably. My point is that they are dealing with widely differing supply / loads. The alternator supplies the electrical power which rises with revs. The (shunt type) reg/rec has to rectify, then REGULATE this widely differing supply / demand dumping it to earth, they get hot. Blame the cost accountants if you must, but even MosFets fail (Oh yes they bloody well do!). Given the cost / manufacturing constraints, my point was to merely half the work done by the single, borderline efficient device.
I take the point of an unbalanced output, one device working better than the other, but a hefty diode on the DC outputs will isolate one device from the other. The Ac flow cares not a jot, the devices internal rectifying diodes just accept whatever they are fed.

I'm doing the charging system on my Aprilia, no worse, or better, than any Jap, the same crispy alternator pug/socket, other borderline connectors, all by-passed and hard soldered. I look at the R/R and think to myself that this is now the weakest link...... I have these thoughts...... Maybe I should get out more!
(I'm in the process of doing this, I'll report back, yea or nay).
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stinkwheel
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PostPosted: 14:02 - 29 Nov 2017    Post subject: Reply with quote

Ok. Here's one for you.

My Royal enfield has a 3-phase alternator. It has one rectifier and two voltage regulators.

The largest power draw on it is the lighting circuit.

So, they hit upon the idea of splitting the charging system. Not in the shonky way they do on small bikes by sharing a coil. The battery is charged by two of the alternator phases. The headlight is run by the third phase on regulated 12v AC direct from the alternator.

This actually works very well. The only real downside is that the lights only work when the engine is running (the sidelights kick in if the engine stalls) and get dim at idle. The lighting is super efficient because it's not dumping half the waveform. The alternator is only actually generating anything on that phase when the lights are on. If the lights are off, the AC regulator isn't having to dump excess power because the circuit is open.

You're effectively taking the largest consistant source of power draw (65W. On a modern bike with twin lights, it would be closer to 120W) away from the DC circuit. Yes a modern bike will also have to work the starter but that's only intermittant.

As a result, the DC circuit doesn't have such a high throughput to deal with. Less stress, less likely to fail.

I have binned the Indian made DC reg/rec in favour of a ZX6R one and just ran the two phases into it.

Not suggesting you do it, the switching for the lights gets a bit complex but it does demonstrate another way of thinking about it.
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RhynoCZ
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PostPosted: 16:12 - 29 Nov 2017    Post subject: Re: Reg / Recs Reply with quote

WD Forte wrote:
How many bikes use or need two RRs?

None? A rectifier is a ''plain'' diode that transforms AC (alternator's output) to DC. That's all to it. Thinking
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jjdugen
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PostPosted: 19:38 - 29 Nov 2017    Post subject: Reply with quote

Hi Stinkwheel.
The Enfield has a much simpler electrical circuit, only one coil, no fuel pump, no injectors, no ECU, (unless yours has FI, and even then, its minimal load). But, your point is valid, one of the highest drains is the lighting system, it has definitely given me pause for thought. I'll have to research AC regulation, not something I have had any dealing with. Dunno how the indicator relay would deal with AC up its chuff but thats not insurmountable, just run them on DC, (as I presume the Enfield does?).
In essence, I am trying to make this thing bombproof, I know that reg/recs are an Achilles heel, just trying some ideas to make it a little more rugged.
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stinkwheel
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PostPosted: 20:00 - 29 Nov 2017    Post subject: Reply with quote

jjdugen wrote:
Dunno how the indicator relay would deal with AC up its chuff but thats not insurmountable, just run them on DC, (as I presume the Enfield does?).


Yes, the Enfield just powers the headlights on AC. As I recall lambrettas also use a 12V AC regulator. Electrex stock them I think.

However. Stop worrying. Get a quality mosfet reg/rec. Fit it somewhere sensible where it can both heat sink and radiate with good connectors and forget about it.

If you're concerned. Buy a £2.99 LED voltmeter and fit it to a switched live somewhere you can see it. If you're totally paranoid, carry a spare reg/rec.

Or buy a bike with a field-coil alternator and worry about broken brushes instead.

I solved the reg/rec overheating problems on my early 2nd gen VFR750 by fitting a CBR one with cooling fins and drilling some holes in the side panel to let the air in at it.
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I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.


Last edited by stinkwheel on 20:02 - 29 Nov 2017; edited 1 time in total
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Kawasaki Jimbo
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PostPosted: 20:00 - 29 Nov 2017    Post subject: Reply with quote

jjdugen wrote:
In essence, I am trying to make this thing bombproof, I know that reg/recs are an Achilles heel, just trying some ideas to make it a little more rugged.

I think Tef has already answered that. Think of the charging system as a whole, where each component is reliant on the good health of the others to work properly. Dirty/corroded connections or a tired battery will start the rot, so keep on top of those and you'll have no problems.

The R/R is likely to be the second component to show symptoms (after the battery), but will leave you stranded when it does go. Usually it's at that point you'll remember how the battery did seem to be struggling a bit in the past week.

The one thing I would do is wire the R/R direct to the battery terminals with wire of a thicker gauge than the loom was using.
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jjdugen
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PostPosted: 21:59 - 29 Nov 2017    Post subject: Reply with quote

Hi all.
Aprilia's, Ducati's, any number of Japs are notorious for having insufficient wiring and under spec'd connectors. I've gone through mine from alternator to R/R to battery with heavy gauge wiring. All connectors eliminated. If you refer to my first post on the Falco, I fitted a MosFet and a battery voltage monitor within the first week of ownership, (and a new, high crank battery, I like to start from a known position). Mine charges and starts fine, the R/R is well mounted and ventilated, covered all the bases. Trouble is, I don't have X-ray vision. I have no idea how the internal components of the R/R are fairing, it only takes one diode, one MosFet, one resistor to pop, usually miles from home and you are phoning the recovery people you hope your insurance actually covers. I am the eternal pessimist, if it can go wrong... etc.
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Nobby the Bastard
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PostPosted: 22:12 - 29 Nov 2017    Post subject: Re: Reg / Recs Reply with quote

jjdugen wrote:
Simple question. If one reg / rec is insufficient to dissipate the alternator output, why can't I put two of them, back to back to double the rectifying and regulating capacity.
NOT doubling the alternator output (for the numptys) just doubling current handling capacity.


Why would you need an reg/rec to correct the output of an alternator.

An alternator has a reg/rec built in as it's what a reg/rec + stator as a self-contained unit is called.
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jjdugen
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PostPosted: 08:18 - 30 Nov 2017    Post subject: Reply with quote

Just so you know, Nobby. There are two kinds of alternator, permanent magnet and field coil.
It would be a wall of Tef to explain the differences, Wikipedia should save my fingers a whole lot of typing. Suffice to say, I wish all motorcycle were fitted with field col type alternators, far more efficient and reliable.
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Teflon-Mike
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PostPosted: 11:46 - 30 Nov 2017    Post subject: Re: Reg / Recs Reply with quote

jjdugen wrote:
Just so you know, Nobby. There are two kinds of alternator, permanent magnet and field coil. It would be a wall of Tef to explain the differences,

Err..
When a current passes through a wire it induces a magnetic field... you get an electro-magnet.
When a wire is passed through a magnetic field a current is induced.
Hence a current may be generated passing a wire through a magnetic field created by either a permanent magnet, or an electro-magnet.
A field-coil generator then needs some current to make a magnetic field before it can start generating. A permanent magnet generator doesn't.
Magnets and wires can be arranged so that depending on which moves in relation to which, you can get ether a Direct Current, or an Alternating Current.
Wall o'Tef?

I think this was in a junior school Lady-Bird, book for ten year olds, I had as a kid, that even had instructions for making a dynamo / motor with a horse-shoe magnet, a bit of wire, a sewing needle and a bottle cork! ISTR it also had instructions to make a lemon cell battery, and light a torch bulb with it! It's hardly elevated voodoo semi-conductor electronics! I'm a damn "If it doesn't move, you need a bigga-hamma' mechie for gawdsake!

Nobby the Bastard wrote:
An alternator has a reg/rec built in as it's what a reg/rec + stator as a self-contained unit is called.

I think that that definition is probably one of common usage, as much as anything. A propriety car type alternator, is conventionally an 'self regulating AC generator unit' don't think it 'has' to have built in self rectification and regulation, to be an 'Alternator', just make alternating current at source... A car-type alternator is a bit of a anathema, in so far as as a self contained unit, it's out-put is actually DC current. Term 'alternator' used, as much as anything to differentiate it from earlier permanent magnet generators, usually dynamo's, or called such, that didn't need a start up current before they would generate, and normally did need a separate 'regulator' that may or may not have incorporated a rectification circuit depending whether the generator made AC or DC at source.
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jjdugen
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Joined: 03 Jun 2011
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PostPosted: 12:03 - 30 Nov 2017    Post subject: Reply with quote

Consider myself slapped! It was early in the morning and I'd only had two cuppas and three fags, hardly awake.

As you say, a field coil type works by inducing varying magnet fields into the rotor depending on load demand, it also employs some electronics to monitor this and generate the pulses to energise the electro magnet. All fine and dandy, but it obviously costs more than the accountants will wear and they are bulkier than a permanent magnet unit requiring their own drive and a place to put them in the increasingly tightly packaged engine bay.

Here's one for you Tef. One of my flights of fancy was this. Have the rotor of a PM alternator on a worm screw, as the engine increases in revs, the rotor is moved outwards, away from the coils, reducing the magnetic field, self regulating the output current. (Much the same way as the old bob weights on points advance/retard units). Shall I take out a patent, or was this tried back in Victoria's days. If anyone knows, you will!

Cheers
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ferrisio
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Joined: 03 Jul 2014
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PostPosted: 12:14 - 30 Nov 2017    Post subject: Reply with quote

I would have thought making the heat dissipation at high loads as efficient as possible would be the way to get the maximum reliability from an RR? Some people fit fans etc., others use heatsink compound and move them to get better airflow.
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