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Post by deejais on Mar 2, 2021 22:07:45 GMT -5
2002 Honda Metropolitan winter tinker project and it's almost finished. My only problem left is this: no charging juice is reaching the battery. Battery dies. Multimeter reads 12-ish volts on the battery running at idle and does not increase at all when revving up the engine.
I disconnected the stator leads and metered them on the stator side while bike was running. Zero volts AC. I pulled the stator and flywheel and both were very rusty and inside (magnet side) of flywheel was CAKED with some kind of hard powder or corrosion. AHA!, I thought. Today I replaced stator, stator plate, and flywheel. Problem remains. Zero AC when metering the stator side of the wire connector while running. Same test results on the battery when running/revving. No increase from 12v DC.
With engine off, I tested the three stator wires against each other for continuity. I did get continuity on all wires, which if I read the service manual correctly, that is BAD! My next thought is the voltage regulator/rectifier, which on this bike is built in to the very complicated (and expensive) ECM. I didn't test that today because I ran out of time and was freezing. I really thought the replacement stator/flywheel was the answer. Damn.
I have another scooter, a no-name Chinese GY6 50cc that runs great. When I conduct the exact same tests on that bike, with the same multimeter, I get charging voltage to the battery of more than 14v, and upwards of 40V AC when I test the stator wires (engine running).
I'm stumped. What can I do next with this Honda? I can only throw so many parts at it.
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Post by crackmastick on Mar 3, 2021 1:15:03 GMT -5
I dunno about honda. But I was working on a peace sports 50cc and had a similar issue with power at the battery. It turned out to be a bad rectifier. Replace and problem solved. It was only a 10$ part in my situation however. I heard they are hard to test, or at least my electrical understanding is minimal and just swapping parts was an easy solution.
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Post by deejais on Mar 3, 2021 8:32:01 GMT -5
bad rectifier. Replace and problem solved. It was only a 10$ part in my situation however. I do wish it was that simple here, but like I said, the rectifier is built into the ECM on this bike. I’m actually thinking about how I could wire a traditional voltage regulator/rectifier into this thing.
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Post by jbjhillbilly on Mar 3, 2021 14:39:49 GMT -5
Happypancake! might have some insight. If the stator system was that jacked up, it wouldn’t surprise me if there’s an issue with the wiring as well (not the stuff you replaced). I don’t think adding a rectifier to the ECU is going to work.
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Post by GrumpyUnk on Mar 4, 2021 10:28:37 GMT -5
The rotor(flywheel) and stator work together without anything else required to produce AC voltage. If you get zero volts, you have several possibilities. Poor ground of the stator to the chassis. Bad wires from the stator(new, right?). Bad magnets.(new, right?) If the Honda system is anything like the china bikes, it should be a block simple two piece thingamajiggy. Rotor and stator. Nothing else involved. If the engine was not grounded, or the stator not grounded to the engine block, you would get no measurable voltage from the stator. Make sure you have a good ground for your VOM, and check the ohms between that ground and the 'face'/ground of the bare metal where the stator winding wires come together to get grounded. It should be minimal, approaching zero ohms, but likely a few ohms. If you get Ol on the meter, you have a ground problem. You should be able to check continuity in your old stator windings(and new) by measuring from the W & Y leads(china) and the ground(bare metal) of the stator. Should get a few ohms each. Spec may be available on site. If you get large numbers, or Ol, windings may be open. Check the new stator the same way. You may be able to get a schematic that actually approaches reality for your machine, unlike all the China bikes where a schematic that matches partially is the norm. They must make them up as they go, or hide them from each other so they don't poach on 'better' designs... Who knows. tom
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Post by deejais on Mar 5, 2021 11:21:14 GMT -5
If the engine was not grounded, or the stator not grounded to the engine block, you would get no measurable voltage from the stator. Tom -- thank you for the great reply. Yes, all those parts are new. Your tip to test the stator's ground jumps out to me. I will do that today. Also, there are two wire looms coming out of this stator. One has the three heavy-gauge red leads (red/yellow, red/white, and red/blue) and the other is six wires, one of which is green that the wiring diagram shows me is ground. Would it be valuable to extend that green wire on the stator side to a known good ground when I test the stator voltage? I think that would point to a bad harness if suddenly I get voltage from the stator. Would not surprise me if some wiring is no good. This bike was a junker that sat in the weather for years. I will hopefully get the time to tinker with it today.
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Post by snaker on Mar 5, 2021 16:34:45 GMT -5
Assuming this rig is covered by the service manual shown (left side menu) that is not a simple GY6 style stator. Its a Starterator starter/alternator. That manual has a lot of good info.
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Post by deejais on Mar 5, 2021 21:38:15 GMT -5
Assuming this rig is covered by the service manual shown (left side menu) that is not a simple GY6 style stator. Its a Starterator starter/alternator. That manual has a lot of good info. Yes, it's been quite an education.
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Post by deejais on Mar 6, 2021 8:34:27 GMT -5
I just realized something else, while turning over this problem: in the early days of this restore, I found the starter relay was bad. Now going over the wiring diagram, I see there's another relay, a "main relay" hidden from sight under the ECM. I realize that it's not a central part of the charging system, but "IF" that relay is bad, could it possibly cause my charging voltage failure?
I tested the entire charging system yesterday following the service manual. Stator, harness, ECM, regulator/rectifier, battery, all check out good. Now I'm wondering about that relay....
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Post by GrumpyUnk on Mar 6, 2021 10:35:29 GMT -5
I don't see a manual ... in the menu that I also don't see...
If it is indeed a combo, it may have controls for the field winding. The control would apply / remove power to the winding to make the output variable so as to not overcharge the battery. It is apparently NOT the same as your generic China scooter... so my commentary likely is not germane. tom
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Post by deejais on Mar 6, 2021 11:25:06 GMT -5
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Post by snaker on Mar 6, 2021 12:31:43 GMT -5
I don't see a manual ... in the menu that I also don't see... If it is indeed a combo, it may have controls for the field winding. The control would apply / remove power to the winding to make the output variable so as to not overcharge the battery. It is apparently NOT the same as your generic China scooter... so my commentary likely is not germane. tom GrumpyUnk Its on the left side of the screen, I'm on a desktop so don't know about other platforms. Click on Manuals Go to Honda and select
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Post by snaker on Mar 6, 2021 12:33:59 GMT -5
I just realized something else, while turning over this problem: in the early days of this restore, I found the starter relay was bad. Now going over the wiring diagram, I see there's another relay, a "main relay" hidden from sight under the ECM. I realize that it's not a central part of the charging system, but "IF" that relay is bad, could it possibly cause my charging voltage failure? I tested the entire charging system yesterday following the service manual. Stator, harness, ECM, regulator/rectifier, battery, all check out good. Now I'm wondering about that relay.... There's stuff scattered around on several chapters: 15,17,20. Why not read it all? 15-11 covers main relay
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Post by GrumpyUnk on Mar 7, 2021 8:36:53 GMT -5
Oh... You mean that tab thingy hanging partway down the screen. I just ignored it, never even paid attention as most of the time they are just irritating and meant to get your attention. I had no idea there was a Metro manual there... Did not even look. tom
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Post by GrumpyUnk on Mar 7, 2021 9:07:02 GMT -5
Looked at the manual and schematic. The 'testing' section is rather specific about some things, but ever so vague about others. Inspecting the ECM and charging rectifier diodes, there is no real test noted to verify the condition of the diodes. Replacing the main relay, or fully testing it should eliminate all but the ECM. Given the diodes are inside, and the alternator becomes a starter motor .. at times... replacing with an external regulator/rectifier could be a nightmare. Were it mine, having checked every single item in the system per the manual, digging the diodes out of the ECM and either replacing them or wiring in some external diodes would be my likely course of action. If not that, then replacing the ECM. If the manual is all that Honda techs have to go with, it is kind of disappointing as I don't see how or where the diodes are tested for shorting or high resistance to reverse voltage flow. Maybe they are not expected to ever fail. The China bikes will produce voltage without external power to energize the field windings. The Metro schematic does not show any wiring to field windings, so permanent magnets are likely used in the flywheel. There should be voltage developed on R/W R/Bu R/Y to ground when the flywheel is rotated. The windings are cutting through a magnetic field, and would generate electric current. Them's the rules. Of course, you cannot use the starter to detect that voltage... as the windings are in use otherwise... at least I think they would be. You may be able to remove the spark plug and use an electric drill, 1/4 or 3/8 socket adapter and a socket onto the hub of the cooling fan or the flywheel bolt to rotate at a fast enough rpm to generate volts. Crank over with said stuff and measure the three legs of the stator to ground. Should get volts from each. If not, I'm lost. The 'stuff' you scraped out previously could have been powdered flywheel magnet material that was scraped off due to road debris, etc that got into the stator/flywheel area.
tom
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