My rectifier fried...

Discussion in 'Mechanics Garage' started by rc24ste, Aug 27, 2017.

  1. rc24ste

    rc24ste New Member

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    ...nothing new there, I know. It is a VFR after all and the rectifier did last 31 years on my VFR 750FG.

    I was chugging along when my bike just died. Lights, ignition, every thing gone. The main 30A fuse had blown and there was an awful smell from the rectifier. The back of the unit had started to burn!!

    So, I obtained an Electrex World replacement rectifier and fitted it without any problems. Feeling chuffed I checked the wiring generally. Every thing seemed okay apart from the battery earth which was a bit frayed so I replaced that. I checked the generator's resistance as per the manual and all was in spec. With a new 30A fuse in the bike fired first time. Nice.

    But, I am not sure about this:

    a) Battery volts - 12.5
    b) Battery volts - 16.9 (engine running)
    c) Battery volts - 15.8 (engine running, lights on)

    Looking at the battery (nearly new Yuasa) with the engine ticking over you can see it vigorously bubbling away inside. Is this and 16.9 volts (b) above) normal? The manual says the voltage for b) above should be around 15 volts. I still don't know what took out my rectifier either. If I ride the bike will it trash another rectifier? Do batteries normally bubble away when the bike is ticking over? Why is so much voltage being measured at the battery?

    Please help!! Getting a shipper to take my bike home cost a fortune and what little money I have left went on the rectifier. As if that wasn't bad enough, my mechanical skills are not the best...

    Thanks in advance.

    Steve
     
  2. thtanner

    thtanner New Member

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    That is way too high! You never want to see it hit 15v+. New rectifier is trash. Return it for a refund, or throw in the trash before it causes your battery to fail catastrophically... which could leave your bike as a smoldering pile of metal and plastic ash.

    Note, "Electrex World" stuff is pretty shoddy, at best. This result doesn't surprise me. Have you considered upgrading to a MOSFET instead? www.roadstercycle.com (I know he can sort shipping to UK/EU at a fair price.)

    Also, perform the stator (generator) voltage tests. You want to see ~20-30VAC between each leg @ idle, and 50-60VAC @ 5000RPMs.
     
    Last edited: Aug 27, 2017
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  3. rc24ste

    rc24ste New Member

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    Thanks for the reply!

    Oh blimey, so it looks like the new rectifier is the problem.

    I have sent an email to Electrex World to see what they make of my problem. I will keep you posted.

    Thanks again.

    Steve
     
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  4. derstuka

    derstuka Lord of the Wankers Staff Member

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    Holy jebus! That thing generates any more juice and your will be able to go back in time!
     
  5. Terry Smith

    Terry Smith Member

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    But only if you can hit exactly 88 miles per hour!
     
  6. duccmann

    duccmann Member

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    Just drove by the picture car 5 minutes ago--


    Sent from my iPhone using Tapatalk
     
  7. mello dude

    mello dude Administrator

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    Ask for your money back and don't put that crap on your bike! Goto w www.roadstercycle.com. ... get a. .. FHO20AA

    Gl
     
  8. rc24ste

    rc24ste New Member

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    I've just checked the diodes on the Electrex World rectifier and they are all spot on which means it must not be faulty after all. Or, are there things about it which may still be bust which can't be tested without taking it apart?
    I've rechecked the alternator's resistance and continuity too - all spot on.
    Put it all back together and got 17 volts at the battery when the engine is ticking over - way too high!!
    So, does this all suggest a wiring problem somewhere on the bike or is it still worth sending the rectifier back to Electrex?
     
  9. thtanner

    thtanner New Member

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    As stated, regulator is bad and you should probably avoid that brand in future.
     
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  10. rc24ste

    rc24ste New Member

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    Ok. I'll send it back. Thanks for your help!
     
  11. mello dude

    mello dude Administrator

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    Agree with tanner - Regulator is not regulating! Junk! Send it back, dont get another one.
     
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  12. skimad4x4

    skimad4x4 "Official" VFRWorld Greeter

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    Junk - send it back - or better still get a refund and buy a quality RR from Jack at roadstercycle.com .

    Your RR is meant to do two tasks - rectify the AC stator output into DC and then REGULATE that DC to voltage levels which your bikes systems can safely handle.

    You seem to have tested the rectifier bridge - the bit which converts AC into DC - but your report of 17 volts output shows the REGULATOR bit is defective.

    The system on your bike is a nominal balanced 12 volt set-up. Ideally it needs the volts to stay between 12.5 and 15 volts at higher revs. If the output is too low you drain the battery and then end up stranded, but if your RR is sticking close to 17 volts into the bike for any extended period, that excess voltage will have to go somewhere - the most likely result being it will heat up the loom, begin to boil the battery and blow lightbulbs and fuses and possibly fry the stator and even catch fire. None of this is good and why you should get shot of that piece of carp.

    One last thought - once you fit a decent RR, you might also want to fit a simple LED volt-meter to your bike. The sort which displays volts as digital numbers - there are loads selling for buttons on eBay. They are rarely very accurate but once fitted to an "ignition on" circuit, it will at least allow you to monitor your charging system as you ride. You will soon get a feel for normal numbers and if later you see the volts fall through the floor or shoot through the roof it will at least give you a chance to head for a safe place before the energy left in the battery is drained and you end up stranded.

    SkiMad
     
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  13. rc24ste

    rc24ste New Member

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    Thanks for the helpful post!

    The Electrex World reg/rec has been returned and I have asked for a refund.

    I've just tested my generator. I got 60 volts at 3500 rpm and 25 volts at tickover which I think is about right.

    So, there is absolutely nothing wrong with my bike. It's so frustrating that Electrex sent out a product that was not working properly. You would have thought (hoped) that they test all their products before they left the factory to guarantee that they work.

    My bike has been off the road for a week+ now due to the Electrex faulty reg/rec.
     
  14. skimad4x4

    skimad4x4 "Official" VFRWorld Greeter

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    If fairness to Electrex - I doubt they intentionally sent you a defective item. Unfortunately even reputable outlets sometimes get duped into buying parts with dubious quality and origin.

    The web is increasingly plagued with fake products - resulting in reputational damage to many big name brands whose packaging is often copied. Sadly if you focus too much on the price, then quality/reliability almost always suffers. Fitting a decent RR (is not cheap) but it will help ensure the current flows through your loom remain within safe limits.

    As for melted connectors they usually indicate far too much current was passing through them at some stage. In turn this suggests the Regulator element of the RR is not regulating the current flows properly or that your battery has failed internally and the RR and stator are desperately trying to offset the impact of a shorted battery plate by delivering unusually high current flows into a dead battery. That is why it's important to be alert if your starter turns over slowly - as it may mean its time for a new battery.

    OK even the best connectors will usually increase resistance a little bit - but when a connection starts to heat up like a toaster, it rather suggests the current flow was well above what that connector was designed to handle. Hence if you want a belt and braces solution in addition to fitting a decent RR cut out the stator-RR connector and replace with quality soldered joints.
     
    Last edited: Sep 1, 2017
  15. mello dude

    mello dude Administrator

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    There is 3 legs to the stator - AB - BC - CA - you need to test all 3.
    - Skip any kind of inclination to buy a VFRness.... Snake oil. - If your R/R or stator is going out, the VFRness is not going to help.
     
  16. reg71

    reg71 Poser Staff Member

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  17. reg71

    reg71 Poser Staff Member

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  18. JamesHambleton

    JamesHambleton New Member

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    I too had encountered the exact same issue. I got 16volts from a mosfet reg/rec and was also using a maintenance battery. I tried the system with another 2 mofet reg/recs (so 3 different ones in total) one was a FH012AB and the other was a FH020AA and the output voltage measured across the terminals were the same 16v so I'm guessing the battery is the issue. I've noticed that the wires coming from the stator are getting rather warm too.

    I'm going to get a CTX12-BS / YTX12-BS maintenance free battery as this is apparently a direct fit and see if this resolves the issue.
     
  19. rc24ste

    rc24ste New Member

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    That's weird! What do you get from the battery with the engine off? I get 12.5 volts.
     
  20. JamesHambleton

    JamesHambleton New Member

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    I got something stupid like 14.2V, I know the battery isn't in the best of condition though as it was left to discharge and left outside for almost a year and it's not done it any good as well as having the fluid under the lower level. The battery at one point would also activy rise from the sitting voltage and would climb about 0.1volt every few seconds and would rise to 16v with just the headlight and ignition on and that's without the engine running.
     
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