Recharging generator field

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  #1  
Old 11-17-04, 07:35 PM
Neil Craig
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Lightbulb Recharging generator field

Have a Honda EM5000S Generator. Has no more than 1 Hr's use. Was getting it ready to use this winter and cranks and runs perfectly, but AC power doesn't work. Took the front panel off, but can't see any burnt wiring or corrosion. It's kept inside of a screen in porch. On this model there isn't a re-set switch on the front panel. Any ideals of what happened? If's like new and was working last year for the short time I used it. Thanks in advance for anyones help?
 
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Old 11-17-04, 11:01 PM
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How old is it? I know you said it was like new, but if the Field has lost it's polarity, it will not generate. Any electric motor shop should be able to re-polarize it if needed for little $$.
 
  #3  
Old 11-18-04, 04:15 AM
Neil Craig
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Honda EM 5000S Generator AC Problem

I Purchased it in 1996.
 
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Old 11-18-04, 05:44 AM
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AC generators depend on a very small residual magnetic field remainng in the metal of the winding frame to build up a stronger field when energized. Sometimes that residual field is lost. You have to "flash the field" when that happens. If you can find the leads labeled F+ and F- connect a D cell battery between those two connections plus to F+ and minus to F- while the engine is running. You only need to be connected for an instant. See if the generator starts working after that. If not, then you may have other internal problems with the regulator. I've done the same operation to large 250 CAT powered diesel generators just fine with a small lantern battery and it works every time. There's a good chance that's all that's wrong with your generator.
 
  #5  
Old 11-18-04, 06:14 AM
Neil Craig
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Honda EM 5000S Generator AC Problem

Jughead, PLEASE FORGIVE, I didn't make myself plain, You stated Electric Generator, This is a Gasoline Generator, If that makes any difference, I'm not familier with generators.The one I have can be located at:
http://www.hondapowerequipment.com/M...elName=em5000S
I would take it to a dealer, but it's extremely heavy and is setting on my back porch, but if you think that would be better I'll do it.
Thanks so much!
 
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Old 11-18-04, 09:40 AM
Azis
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Neil,
Jughead was using "generator" meaning the component in your gasosline engine Driven generator. They all operate under the same principles. Your generator as a unit contains a component which when driven will "generate" electricity, I believe this is what Jughead was making reference to
 
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Old 11-18-04, 12:46 PM
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Correct. The 'generator' part makes the electricity. That part doesn't care how it's turned. It could be done by a diesel or gasoline engine, a gas turbine or steam engine, or even by horses or oxen. In some places the 'generator' is turned by a water wheel. By your post, I presume that the engine starts & runs fine, but you get no electricity being generated. Sorry for the confusion. The place to start is to flash the field to see if that's the fix. A lot of the time that will be all that's necessary. In your situation the field may not be easy for you to recognize because the leads may NOT be marked. If that's the case you just have to go by experience. When experience is limited you just have to call upon more expert help. Since I'm here, and the equipment is there what I'm telling you is only my GUESS as to what may be wrong based upon my experience dealing with many, many sick generators, some very large and some small.
 
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Old 11-18-04, 02:14 PM
Neil Craig
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Thumbs up Honda EM 5000S Generator AC Problem

Thanks for your kind help, I really appreciate it. I'll see if I can locate someone to tell me which is + and - or I will take it to the shop.
P.S. This is a FANTASTIC FORUM
 
  #9  
Old 11-19-04, 06:13 PM
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I try to learn something new every day, and Jughead your it for today. I never knew how to jumpstart a dead field.
 
  #10  
Old 11-19-04, 08:43 PM
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If you try flashing the field yourself, there's one more thing to be aware of. Doing so will produce a momentary pulse of high voltage. Some of the larger generators that I've flashed have quite of bit of inductance in the field winding and when you break the connection with the battery there's usually a good size arc generated when the magnetic field collapses. I know that I've been jolted a couple of time messing around with smaller solenoids & a battery when I was younger, and a generator field is a simular situation. I've never been injured, but I've seen some impressive sparks. It impresses who ever is watching as well and scares them out of trying the same thing. I suppose you should be thankful for the steady work. It's always impressive when a large 500 KW diesel generator comes to life by using a small 6 volt lantern battery. I've even seen some generators with a built in swith for that very function, but the CAT service manuals have a proceedure using a small battery & resistor. So far I've never bothered with the resistor.
 
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Old 11-20-04, 02:57 PM
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Boy, that puts my little 13k generator to shame.
 
  #12  
Old 11-27-04, 07:34 PM
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jughead? HELP!

hi jughead... i am having the same trouble with a small coleman powermate 1500 generator.... does the f+ & f- with a d cell battery apply to a very small generator as well? any idea where i would find the f+ & f- wires on this unit? in the area of the main windings or front switch panel? sorry about all the questions, i have never (YET) tinkered with a generator lol.... also, do these little buggers have brushes that may be needed & are they difficult to install?
thanks in advance
 
  #13  
Old 11-28-04, 07:38 AM
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You may not be able to find separate F+ or F- leads coming out of small generators. Working on generators much smaller than 200 KW isn't something I generally do. However, I happen to own a 2000 watt generator made by Dayton and sold in the Graingers catalog. It was used for a project I built years ago and don't use much anymore. I checked that generator and here is what I found. The field part rotates and is energized by a set of brushes and slip rings. Power for the field comes from the stationary coils as does the output power. Since the field requires DC there's a diode bridge that rectifies the AC before it's sent to the brushes. In my generator the brushes can be gotten to, but I would have to dismount the diode bridge to determine which brush is plus and which is minus. I would then have to solder or carefully use clip leads to connect to the field. If you aren't sure just what you are doing, and aren't familiar with diode bridge rectifiers then the project most likely isn't something you would want to 'do it yourself.' Many 'do it yourself' projects require some level of knowledge and/or experience with simular technology to be successful. Many of the generators that I've worked on in the past used rotating rectifiers and are truely 'brushless'. The field leads coming out of the generator are, in fact, field leads for the generator's exciter, not the generator itself. I would assume that most small generators don't go to that extreme and just use a slip ring/brush setup. I would make that assumption unless your generator says 'brushless' somewhere on it. The big ones do.

It's always best to understand the basics of just how a generator makes AC power in the first place. When you understand how something works you have a real good chance at fixing it when it's broke. If there's no understanding, you are just 'shooting in the dark' and trusting to luck to resolve your problem.
 
  #14  
Old 12-04-04, 07:49 PM
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Talking

Hi jughead!
Sorry so long to reply. I appreciate the time you took to look at your generator & explain (GREAT DETAILS) what you saw & what I might look for as well. I did see what looks to be two diode bridges. I also found an 800# for tech. support on the unit when I was taking it apart. So, I thought I'd wait untill Monday to call the support # rather than TRYING to remove diode bridges, maybe make a mess, & probably waste a lot of time & $$$ too! LOL

Soooo, Monday comes & I call... The tech. guy (Jim) @ Coleman was very helpful too. To flash the field on a small home use generator, I was told to get an ext. cord & cut off the female end of it & strip the wires & connect the wires to a 12 volt car or lawn tractor battery, & plug the male end of the cord, into the 120 A.C. side of the generator.

I was told to make SURE that the black wire which is POS/HOT on an A.C. cord, gets connected to the RED/POS. side of the auto battery, & the white wire on A.C. cord gets connected to the BLK./NEG. side of the battery. If the ext. cord wires are not black & white, then the smaller prong of the plug is the POS./HOT

Plug the other end of the ext. cord into the generators 120 volt side & remove spark plug wire, & pull the starter cord 4-5 times, then remove the ext. cord, reconnect the spark plug wire, start the unit & plug something of 120 A.C. volts in to see if it works & IT DID!!!!!! I then let it run for about a half hour with 2 300 watt lights to help re-generate the unit.

Thanks again so much for your help
 
  #15  
Old 12-04-04, 09:29 PM
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Great. Thanks for the reply. I'll pass that proceedure along, when necessary, when others have problems with small generators. I can see why it should work. It was a lot easier doing it that way than the one I had in mind. Mostly I was familiar with the proceedure outlined in the CAT manuals for their large, mostly brushless, generators and have sucessfully followed it many times will good results. It would probably work for large generators as well if you could be sure the engine wouldn't start when you cranked it over with the starter. The main idea is to artificially produce a residual magnetic field so the generator can bootstrap itself up to produce electricity. No magnetic field no output...no output no magnetic field. If there's no residual magnetism you have to produce just a little with a battery for the cycle, which feeds on itself, to get the generator to work again. I frequently learn something new on here and today was no exception. It works as well to excite the armature as it does to excite the field when the residual magnetism is lost.
 
  #16  
Old 12-05-04, 06:06 AM
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Thumbs up What a great thread!

I've edited the title of Niel's first post to make it easier to find in the future.
 
  #17  
Old 12-05-04, 11:36 AM
cando
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Thumbs up Generator revival

Jughead and Nascar,
Kudos to both of you. This thread is a perfect example of why I browse this site whether I have a problem or not. The solution that Nascar found and shared is so beautiful, and requires no disassembly to implement. I have learned another useful process that I would never have learned otherwise. I am old enough to remember having to "Flash" the field on old generator equiped cars but never thought about it on current portable generators. Thanks again for filling another void in my grey matter. It is great fun to learn things about equipment I didn't know before.
 
  #18  
Old 08-28-05, 12:29 PM
garypm49
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Generator problems

You my have a problem with the voltage regulator. If it quits you won't have any AC power
 
  #19  
Old 01-15-06, 08:16 AM
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Field Flash

By using a drop cord and hooking it to a battery. Plugging it into the AC outlet. Does this work for generators that have brushes or without brushes?
 
  #20  
Old 03-24-07, 03:09 PM
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Flash Charge the Field from the Stator

Hey, I just tried that Flash Charge the Field trick on a friends 4KW Coleman Generator and it worked like a charm.

We had checked all the windings, brushes, diodes, and connectors and everything had checked good but it still did not work. Took out the spark plug, plugged in a power cord, hooked it to a 12V car booster battery, gave it a few pulls, put everything back together and she fired right up and lit up a light bulb like it should. Many many thanks to Jughead and Nascar for the most excelent and useful suggestions.

From what I understand, with or without brushes the trick should still work just fine with just about any generator. It is mostly just random chance that will leave a field without enough residual magnetism to get things running. They should insert a permanent magnet in the rotor at the factory to prevent that from happening, but I guess it's just another one of those planned obsolecence feature things.

Steve
 
  #21  
Old 03-24-07, 10:19 PM
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The manual on my generator clearly states that the unit should be run _under load_ at least once every 60 days or the generator may loose it's field charge.

Simple solution, I run it on the first weekend of every month for about 20 minutes.
 
  #22  
Old 01-01-10, 02:09 PM
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Talking Small Generator Flashing



Great info from all that contributed. The method provided by Nascar 24f fan is great and removes a lot of uncertainty. I will be trying it out tomorrow when I get to my office. Hopefully that solves the output issue of this generator cause it only has a couple of hours of run time and we have already replaced the voltage regulator.

If it works it will make my New Year happier.
 
  #23  
Old 02-10-10, 02:26 PM
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Falshing field

Well I tried the idea of flashing the field on my Honda EG5000x which had stopped putting out power and it worked like a charm. I hooked my multi meter up to my outlets and went through the block on the generator to access the field for + and -.

Excellent idea since I was at my wits end and since I had checked the brushes output and a continuity check throughout the gen as well. Thank you all for the advice.

Nascar24Fan thank you for your suggestions and ultimately the resolution of the problem. You know it is always so great to stumble into those knowledge banks of people.

I hope that someday I may have that bit that others may benfit from as well.

rangercap
 
  #24  
Old 02-10-10, 05:37 PM
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Fixed Winco 3000

I don't normally post in forums once I find a fix but this one is note worthy. I bought a Winco 3000 at an auction, got it home, fired it up and it worked. A week or 2 later the power went out and I fired up the generator but it didnt have any output. I opened up the front panel and found the 2 copper wires going to the diode had been knocked off the diode and cut about 3 inches back. After solering them back I fired it up and still nothing. I finally got to work on it again tonight, took it apart and re soldered everything. Still nothing. While troubleshooting I noticed one lil tidbit on the Winco site at the end of the diode test info talking about flashing the field. Googled it and ended up here. So, I tried flashing it with the generator off and nothing but then I tried with the generator on and walla, it worked like a dream. Scared the hell outta me cause of the blue flash and generator bogging down, but it worked. Here's the link to where I found the info originally.
Winco Generators - All Generators FAQ
 
  #25  
Old 08-09-10, 08:18 AM
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Brushless generator

Further to "flashing", can the same be done with brushless armatures ?. Are the 2 coils supposed to have the same resistance(diades isolated) ?. Is this armature doesn't appear to have a (small)permanent magnet ... others that I have seen, do. There are 6 stator wires, 2 connect to a capacitor. With cap' disconnected, I see 3VAC on those wires, but nothing elsewhere. Please advise.

Thanks
Shane
 
  #26  
Old 08-09-10, 10:38 PM
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Yep, it works on brushless generators too. I use a drill. Plug it in, crank the generator up, pull the trigger on the drill and then give the drill a really fast spin. If it doesn't work, try the drill in reverse and give it a good spin. The small electric drill motor turns into a tiny generator when you spin it, and it generates enough voltage to polarize the field. Doing it this way also eliminates bare wires, the risk of shock, and the large arc when the generator figures out what to do.
 
  #27  
Old 08-10-10, 04:37 AM
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Interesting. I have never heard or thought of using a drill. It's almost too simple.
 
  #28  
Old 08-22-10, 09:15 AM
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Smile 12 kw generator

I bought a low hour, good shape 12 kw generator yesterday from a guy who thought he was just selling a 20 hp running engine as it only had an output of one volt . I just re excited the generator and now have a good gen. with 100 amp output for $300.00 . How cool is that . He was sneaky . He brought it to me with no battery and said it was a good gen . I said bring it back with a battery so I can see if it makes electricity and I will pay you . 24 hours later he came back with it running and told me it would only make 1 volt . I bought it anyway (pig in a poke) and got lucky . Thanks for all the tips, Paul
 
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