generator problem(s)

[NoSpam]

Just started-up a 2.2kW dual-voltage genny after a few years of sitting in the garage and there's no output. It's marked "Allam Generators" and has had very little use, it was perfect when last used. The c/b hasn't tripped and trying the switch in all 3 positions makes no difference. It doesn't seem to have any electronics in it. Any suggestions?

Also, it started/ran with clouds of smoke so I guess it's possible that the rings were rusted and broke when it started. The engine is marked Honda GX160 5.5HP. Where's a good place for Honda spares?

Hugh

[Alan]

You can get Honda spares easily enough on ebay, or I have a good GX160 sitting here if you're interested, located in Luton, Beds. Make me an offer!

As for no output, if it was working OK last time there is not much that is likely to have failed in the alternator. Maybe corroded contacts in the switch(s)?

I have several generators and try and make sure they all get run every few months between "work". I suggest you do the same once yours is in better health.

Alan.

[meow2222]

get yourself a multimeter and do some fault finding. Theres no way we can know which part of the electrical circuit is at fault.

NT

[Mark]

What could have happened are the connections between the exciter wiring and the main field coils have corroded so its not self-energising, they are not usually the most user friendly things to dismantle though. ;(

-

[NoSpam]

The wonderful eBay, I ought to have guessed. Thanks. (Luton is a bit too far and doing the rings should be easy enough - assuming the bore isn't damaged) H

[NoSpam]

Thanks. Presumably it just relies on residual magnetism to get started(?). If there aren't any "well known" failure modes I just need to work through methodically.

H

[Mark]

No it's a bit more complicated then that,

Do a search on Google or Wikipedia for Brushless Alternators to get a better description of how they work.

Without the wiring diagram fault finding can be very difficult unless you fully understand how they work.

-

[NoSpam]

Aha, that's cunning. So a small integral alternator uses residual magnetism to "start-up" and then generate a current that's rectified and fed to the main alternator armature. Load current is taken from the stator and regulation is achieved by varying the current in the stator of the small alternator. I wish I'd thought of that, it's very elegant. I wonder why car alternators don;t work like this.

How does the regulation work, is it just that a proportion of the output voltage is applied across the stator of the small alternator?

With this injection of knowledge it looks like it'll be a connector problem. There's continuity from L-N at the output so presumably the problem is in the control mechanism.

Hugh

[Thomas Prufer]

Some generators may fail with a "no residual magnetism left" mode -- mine has something like that in the manual. The curse, ISTR, is to attach a 12 volt DC source to the output and then start up the generator again.

I've googled a bit and found this:

basically says "read the applicable manual...)

and this bit of magic:

Prufer

[NoSpam]

Fantastic! I'll give it a go over the weekend. The thing is producing so much smoke at the moment that I can't run it in the garage.

Hugh

[Dave Liquorice]

Honda have a very good spares/dealer network in the UK wander off the the Honda website

and click the "dealer search". The one I called, in Dumfries IIRC, about parts for an ancient (and I mean 20+ years old) Honda engine was very helpful and knowledgeable.

What colour is the smoke? Have turned off the choke? These small engines only need choke for about 30s and then only from stone cold.

[NoSpam]

Thanks Dave (and everyone else). It turned-out that the sump was absolutely full (and I mean FULL) of very dilute oil; presumably the fuel tap was left switched on and fuel had found its way into the sump.

Once the sump was drained and refilled it ran sweetly again with no smoke and the speed correctly regulated - BUT there's still no output.

Hugh

[NoSpam]

Fixed the smoke problem and just tried the drill idea, I was right to be sceptical :-( Also tried flashing with a 30V/2A power supply but it didn't do any good

- probably not enough current. In the old days of car dynamos I remember having to flash them to get the correct polarity - ISTR that all we did was briefly connect the car battery directly across the field windings.

Please could you summarise what your manual says?

Hugh

[Thomas Prufer]

I can't get to it now, and it isn't online... I'll watch the thread, and post if it isn't sorted by the time I can get to the manual again.

ISTR just this -- "connect a 12 V DC battery across the output". It's a cheap-and-cheerful asynchronous generator, briggs & Stratton lawnmower engine, rated at 2000 W (by optimists!).

Thomas Prufer

[Mark]

Whoops ! Flashing is normally only necessary on brush type alternators and even then only a 9v-pp3 battery is enough on small domestic types. Self energising brushless alternators have varied methods of energising the exciter field windings, a supply is sometimes taken from the driving motors flywheel gen, or a capacitor is used with a separate pickup coil. As I said fault-finding without the wiring diagram or understanding how that particular generator works is not easy. Of all the DOA small generators I have bought with Zero output, the problem has been corroded connections causing high resistance in the exciter circuit.

-

[Jim Michaels]

It certainly will not work with a variable speed drill

It appears to state that drills have permanent magnets (Ac powered drills don't)

It assumes that a drill will generate some power when spun by hand, this would be a very small amount of power.

Remove SPAMX from email address

[The Natural Philosopher]

Correct.

That is also correct. Most motors with field coils will ultimately spin up and start to generate due to residual magnetism.

[NoSpam]

Thanks, I'll take the advice and have a more thorough check of the connections - visually it looks "as new" inside and it's always been stored in a dry location.

Unfortunately I don't have the manual and the manufacturer (Allam2000) seem to have gone out of business (Allam marine are a different company and the Allam2000 phone number has been reassigned to a firm of accountants).

If the connections all seem OK is there any reason not to start the gen and connect it via a 60W bulb to the mains? (other than the potential nastiness of a male-male cable)

Hugh

[Mark]

Get a large >1000w elec drill plug it in and run it up for a while.

Now Connect a 5v DC meter across the plug L + N, and with it still switched on spin the chuck quickly by hand.

Result ?

Whether this voltage would be large enough to kick the exciter into action is another issue,which would also depend on the design of the alternator.

-

[Mark]

You will have to work out how the exciter circuit works, if for instance it is powered by the motors permanent magnet flywheel gen, you could poke any voltage you like up the output windings without effect.

well maybe a bad aroma and bang

-