melted stator wires

Discussion in 'Mechanics Garage' started by mdange2011, Feb 23, 2012.

  1. Allyance

    Allyance Insider

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    I went with the SH775 because I am running LED headlights and tail lights. Just got back from dinner, unit is cool.
     
  2. CandyRedRC46

    CandyRedRC46 Member

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    The problem with that idea is there would be so much extra current coming out of the Vfr stator that the sh775 probably wouldn't be able to keep up at high revs and either go open circuit or burn up. That's the problem I had with my last series rr, the compufire rr, would let go at 10,000 RPMs and the voltage would spike to 17 volts.


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  3. Allyance

    Allyance Insider

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    The amount of current the stator puts out is determined by the load (resistance) of the bikes entire system. The lower the load, the less current. The stator generates voltage (potential), the higher the RPM, the more voltage is generated. The R/R job is to regulate the voltage and produce DC as required by the load. The series R/R only pass the current required, whereas the OEM R/R's shunt the current to ground, as the RPM and voltage increases, so does the amount of current. E=IR. the bikes load remains constant, therefore, as 'E' (voltage) increases, so does 'I' (current). This is why the stator wires and connectors get so hot. Don't know why your series unit failed, maybe load was to great for the unit. I went with the series to reduce the amount of current being shunted due to decreased load from the stock design as recommended by Jack @ roadstercycle. He is totally aware of the situation when racers disconnect all their lights and unbalance the system.
     
  4. H3nry

    H3nry New Member

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    Rather than current, there is another limit, how quickly the FET or SCR or whatever the switching device is can be turned off. It has to respond in a fraction of a revolution of the engine. The Compufire is designed for a Harley with a redline of under 6,000 RPM and has some margin extra, but not enough margin for 10,000 RPM. Above the maximum switching speed, the regulator can't turn off fast enough to keep the voltage down. Shindengen builds for all the Japanese bikes and presumably designs for faster spinning engines. I hope the SH775 is the first of a series of series R/Rs, and there will be a heavier duty one soon. There is no reason a series regulator is more complex or expensive than a shunt regulator.
     
  5. Allyance

    Allyance Insider

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    Both are the same price on roadstercycle.com
     
  6. CandyRedRC46

    CandyRedRC46 Member

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    Whelp we spun the zx6r ninja up past 12,000 a few times and the voltage never spiked, but I just didn't like all the heat.


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  7. H3nry

    H3nry New Member

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    OK, today I installed the MOSFET R/R. It is not a Shindengen part. Mfr unknown, but "Made in China". That's why it's under $30. It's claimed to be an improved circuit which turns off when too hot and restarts after cooling down. Claims to handle 30 amps continuous, 50 amp surges. I copied CandyRed's mounting on the passenger peg bracket. Tres cool.
    http://www.ebay.com/itm/Mosfet-Volt...Parts_Accessories&vxp=mtr&hash=item4d206f52cc

    It works. It runs much cooler than the Honda OEM part, and it holds a stable 13.9 V at 2,000 to 12,000 RPM. About 12.4 V at idle. Considering that it's 100 F ambient today, and the battery is close to 200 F when riding, 14 V (2.33 V per cell) is about as high as you can charge a battery without boiling the acid.
    http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

    I installed it with new gold plated crimped and soldered connectors so it can be replaced with the original part in case of trouble. The regulator runs warm to touch, but not scorching hot like the OEM part. The yellow wires are warm, but no warmer than they were before. The connectors are no warmer than the wires attached to them. So everything looks OK - the remaining question is reliability / longevity. I am pretty sure this is a shunt type rather than series. I'll keep an eye on it and report how it goes.
     

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    Last edited: Jul 12, 2014
  8. carlgustav

    carlgustav New Member

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    So I'm looking at doing this R/R upgrade before I loose my stock unit (~26K miles on bike). I'd really like to get an FH019 instead of the FH020 ... 50A max vs 35A and same size, but can't find a supplier that provides 1 unit vs 10 ... anyone know of a source?

    ACE
     
  9. fcc

    fcc New Member

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    if the wires are the problem of being too thin, maybe cutting the wiring from the r/r and stator would be a good idea and replace them with a thicker wire?
     
  10. skimad4x4

    skimad4x4 "Official" VFRWorld Greeter

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    Hmm indeed that was essentially what the original VFRNess loom was designed to do BUT sadly it did not really deal with the problem - just moved it elsewhere. In reality the loom is adequate for normal current flows - the problem arises when components (mostly the RR) fail resulting in abnormal current flows, melted wires and connectors.

    Inherently all 4 elements of the charging system (RR, Stator, battery and loom) need to be in good order and a fault in one can damage some or all of the others. Sadly the electrics are pretty much the only significant part of your motorbike not made by Honda - they are bought in from an outside supplier and I suspect that for a while Mr H was not really unhappy to see the endless charging system issues which affected so many makes and models of motorbikes of similar vintage.

    Think of it this way. If the system fails within warranty their dealers will happily repair/replace stuff and behind the scenes the costs will be claimed back from the original supplier. If it fails after the manufacturers warranty is expired the bill falls to the owner, meanwhile the dealership will enjoy a continuing demand for replacement charging system parts and repairs. After endless complaints Honda finally realised this was actually damaging their reputation and loosing them sales, so they upped the budget to secure better quality bought in charging system components and importantly installed more reliable Shindengen RRs on 7th and 8th Gen models, which thus far seem to have largely avoided the gremlins affecting earlier models.

    Indeed a while back, there were a few posts on here reporting that an 8th Gen RR had been successfully retrofitted into an earlier VFRs so that would be where I would be spending my money. The OEM stator is reasonably resilient provided it is not being fried alive by a faulty RR.

    More often than not damage to the stator, battery and loom are simply collateral damage caused by a failing RR, however they may not be spotted at the same time.

    Sadly people tend to stop looking once they identify a faulty charging system component not realising that depending on which diodes fail within an RR, it could short out the stator, or could feed 60+ volts into a system designed to handle a nominal 12 volts blowing bulbs etc, or worse still fry critical electrics if the rectifier fails and starts to feed AC into the bike main loom. All these are bad things.

    That is why it is so important to do the charging system checks(the drill) twice once with the bike cold and once with it hot - because a stator may test out fine whilst cold, but the very fine insulation on the windings can degrade with heat and potentially fail over time especially when hot and allow winding phases to short out and instead of charging the battery that can quickly kill your battery.

    These problems are not unique to Honda, I had very similar issues on my Triumph Street Triple (also built using bought in components) but after they replaced the RR under warranty, I had the good sense to immediately run the drill tests which tested fine while the bike was cold, but when hot revealed that the RR failure had also damaged the stator, so I took it straight back to the dealer to replace that under warranty too.

    Hmm - that is way too long a post so I think The Macallans is calling - I am not sure that helps.

    SkiMad
     
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  11. skimad4x4

    skimad4x4 "Official" VFRWorld Greeter

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    So what's going on Reggie - I am now in Italy ??? I am in Aylesbury UK - an hour north of London.

    SkiMad
     
  12. Grum

    Grum New Member

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    Hi SkiMad. Is there any chance you could provide a link to this. I've never heard of fitting an 8gen R/R to any earlier VFR. That would be quite a tricky modification.
     
  13. Thumbs

    Thumbs Member

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    My exact thoughts on the 8th, but the 7th is a 50amp 5pin, so I bought one to try it on my 2nd, looks like a straight swap with allowance for extra space
     
  14. kennybobby

    kennybobby New Member

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    A sliding electrical contact will eventually fail and should be avoided if possible.

    The stator produces a 3-phase alternating voltage and current that travels to the rectifier in the 3 yellow wires. If one of the legs of the 3-phase AC circuit is opened up for some reason, the current will arc thru whatever path it can create to find a return path back to the stator. The crimp terminals are tin-coated copper which lose their spring temper when heated. The loss of spring tension allows the contact sliding surface to progressively open due to vibration and arc-erosion. Once the arcing starts then it feeds on itself--heats up and loosens the contact, which creates more arcing, more heating, higher resistance in the contact, etc.

    here's one that i caught and if you zoom in on the contacts you can see the erosion traces in the blade due to the arcing at the terminal. The heat damage is greatest at the terminals and progresses up the wiring harness. If the heat gets high enough it will melt the yellow wires and the green wire that is bundled with it in the harness. The loss of the green wire opens up the ground side of the main 12 volt battery bus, and there is no telling where the arcing will occur as the bus currents are trying to find a path to ground.

    And that rectumfier was still good and working properly--the sliding contacts were the root cause and culprit.
     

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    Last edited: Nov 18, 2022
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