checking an alternator?

[PinHead]

I don't know didly squat about diorectieswhatever. Nor about electricity..just a dumb fridgie.

[Spaniard_King]

Is this one of those posts that got out of hand

Somewhere back on the first page the problem was sorted for the original issue.

As for the Honda.. said poster has not come back... bit like pi$$ing in the wind this thread.

[MyWay]

I can not believe .....this is still going on.....

can I be moderator please ....

[finga]

Yep, the thread goes on purely because someone wants to try and bluff people.

First Oldboot said old mate did not have a problem with his alternator. He may have had a problem with his magneto and asked if he's ever had a battery on his motor, and if not, then his rectifier will be, more then likely, 'stuffed' (and I'm thinking it's a 130hp Yammi. It ain't small nor would I like to rope start it all the time)

And this was the beginning......of the waffle
Fed said bollocks and then Oldboot went into his baffle them with bullsh!t routine.
Fed and myself said a magneto's task is to give spark to a spark plug.
Bollocks says Oldboot. A magneto charges.
I said an alternator does the AC bit and a dynamo does the DC bit.
Bullocks says Oldboot.
Oldboot has insisted that that is what people call the the gismo that charges now and terms change over the years. End of story. get over it.

I have asked Oldboot some direct questions to try and understand the DC world (which an electrician has no understanding of) a bit better.
No direct answers to the pretty specific questions.
I have done some research to try and understand where he's coming from and to try and answer the questions I have asked seeing he won't.

Then the argument of hundreds of volts generated by an open circuit charge coil.
Oldboot says there's hundreds of volts generated. BM has measured it at 28V and his mate with over 45 years experience said the same and Fed said this is what he thought the readings should be. Oldboot says bollocks. It's in the magnitude of hundreds.
To be honest I thought it would be a smidge higher then the 28V but not in the magnitude of hundreds of volts.

I like to learn and I am very open to 'suggestions' such as those from BM and Fed as to what's what.
Spaniard King may not know it, but, I have learnt a hell of a lot from him and likewise to Grand Marlin and many others here over the years.

And to answer the question of what is the easiest way to put a load across a charge coil to stop these "hundreds of volts" blowing a rectifier. Bung a light bulb or similar (ie test lamp) across the coil or coils. Instant load.


Yesterday doing a bit of research for another matter (thread in electronics about a 40hp Merc) I came across some Merc service manuals online.
What does Merc call the thingo that Oldboot insists is a magneto (remembering his references to his Merc manual like a bible)?? An alternator. Yep, Merc says the thing that does the charging on their outboards is an alternator. Not a magneto.
Yep. Oldboot has been continually arguing that an alternator is not an alternator even when his own service manual says it's an alternator.

And then reading the manual for the 30/40hp model of Merc I come across a warning about operating an outboard without a battery connected....remembering Oldboot saying all outboards will kill the rectifier due to hundreds of volts generated if you don't disconnect the rectifier when running without a battery...... I read with astonishment. (page 2B-13) of the manual available here)
Operating Outboard without Battery
If desired (or in an emergency), outboards equipped
with an alternator can be started and operated without
a battery (either disconnected or removed) if
“Warning”, below, is followed.
WARNING
Before operating outboards with battery leads
disconnected from battery, the leads MUST BE
taped off (insulated) or positioned in a manner
that prevents a completed circuit between the
leads. Electric wiring harness MUST REMAIN
CONNECTED to electric starting models in order
to “Stop” the outboard with the ignition key.

No mention of disconnecting rectifiers is there? Just tape the battery terminals and jobs done. Easy as if you don't want a battery.

The manual for the 25hp version mentions the warning Oldboot refers to.
It seems to me there is a correlation if there is a regulator present or not in your Merc. outboard and the precautions that should be followed if you want to use your motor without a battery.
But how would I know?? I'm only a sparky and have no right to refer to the marvellous world of DC


Misinformation. I hate it and hate it with a passion.
Hopefully people will read this and realise they may not be up poo creek without a paddle if their battery is disconnected.
They my realise they may not be risking the destruction of their charging system if they run their motor without a battery.
People may realise they should be reading their particular manual and see what's what in regards to their motors and do not take what people say here as gospel.

[oldboot]

WARNING

Before operating engine with battery leads disconnected from battery. Disconnect stator leads (yellow) from the rectifier, insulate (tape) stator lead ring terminals.

If the above is not sufficient for you and you cant grasp the implications your english comprehension, understanging of electricity and diagnostic reasoning are poorer than I expected and you must be thick as 2 short planks.

But by now I have fugured that out anyway.

cheers

[BM]

How bout we agree that it's "Gulliper magic" under the flywheel or like in the etec DVD the pro Fisho Denny says "they've got magic under that hood"??

From my perspective I see both you guys arguing more or less the same thing from different ends and different angles. Pretty humorous actually. Quite a balanced level of insults either way

I don't personally care whether there is a centre tap on the windings or not, nor do I care what peak voltages are produced. That info is good for designers to know but to the layman owner or the repairer but that knowledge is of no benefit.

There's some coils/windings under there that charge the battery via rectified AC and some coils that provide the power pack with it's initial voltage to pass on to the coil/s for amplification and firing duties

There's also some coils under there to control the firing of the power pack (in a diatributorless system).

Finga fire up the outboard of yours and take some voltages from the stator at various rpm. If you kill a reccy in the process I'll post you one....

[oldboot]

The centre tapped coil is a significant issue, significantly when combined with low spec dark age diodes.

In a single coil with a single diode typical of Briggs and stratton motors...the issue does not occur. Because with the battery out of circuit and no accessories turned on the whole thing is open circuit.

in a single coil with a 4 diode full wave bridge (never seen one in a stationary motor or ouitboard, but anyway) the voltage across the rectifier with no load will be half that of a centre tapped configuration.

In the center tapped configuration the voltage across the reverse biased diode in the pair will be twice the voltage some may expect in the unloaded coil even before the open circuit voltage rise is considered..there lies part of the problem.

so if 22 volts DC has been measured on the output of the rectifier with the battery disconnected and the motor at low RPM.
At least 50 volts AC ( average) across the open ends of the centre tapped coil is certainly to be expected under the same circumstances.

We have not yet reved the motor which will significantly increase the voltage, and we have not allowed for an average to peak to peak conversion.
So a end to end voltage of well over 100 volts peak to peak at 5000 RPM is far from unexpected or unreasonable.

Combine that with a dark age spec diode with a PIV of under 100V, and you have a snotted rectifier.

That is the logic for those interested.

It would not be hard to completly illiminate the problem...simply by making rectifiers with something like 400V PIV diodes...perhaps some manufacturers do.... but there are still plenty of dark age spec rectifiers still out there..because for some manufacturers it is the same part made to the same spec since the 60's.


If I was a betting man..and I am not.......that motor that was measured....if it was 22 volts DC that was indicated on the meter at the output of the regulator relative to ground and that was at near idle.....I would not be surprised at all to see 150 to 200 Volts across that open circuit coil measured peak to peak at 5000 RPM.....I would be surprised to see 400V... but not greatly.

Anybody who wants to go and test it...knock yourself out.....I don't need to, because the manufacturers cautions and the enquiries I have made are enough for me.

cheers

cheers

[Bros]

From my perspective I see both you guys arguing more or less the same thing from different ends and different angles. Pretty humorous actually. Quite a balanced level of insults either way

In the Red corner we have nitpicker with prostate problems

In the Blue corner we have someone who doesn't know when he is being baited

and from the audience we have a parrot

The whole thing is hilarious

[mod2]

And this is where it ends. The personal jibes and going over the same ground does no one any good.