Question about 2002 Honda VFR 800

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I have the 02 vfr800 and it keep killing batteries. i think the alternator is dying but others tell me it might be the rectifier regulator. does anyone have a way of testing either or both devices so i dont spend money on a part i dont need

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  • elvis_ahuh Feb 07, 2010

    i checked the volts on the battery while running and its mot getting any where near even the late 13.6 volts and to me appears to have not enough power gettint to batteryu to keep it charged. is this the regulator too or is it all down to the alternator?

    i think it seems like the alternator but after reading a few other blogs im starting to have doubts and am now leaning towards tthe regulator rectifier.

    would these low reading be the reg not functioning properly and if not is there a shore fire way to check stator readings to make sure it isnt the prob.

    any help would be appreciated greatly.


  • Joe Stanton Apr 23, 2013

    Jamie The Alternator Is A Perminent Magnet(ROTOR) And A Wound (STATOR) This Produces (AC) Current. There Is A Danger Of Electric Shock When Checking With Engine Running. Unplug The Harness From The Stator At The Regulator .Put The Kill Switch On The Handle Bar In The Off Position. Run The Starter to Spin The Engine. You Should Have Between 40 To 20 Volts(AC) At Cranking Speed. This Is Checked With Volt-Ohm Meter Set At (AC) Volts Between Any 2 Pins At The Connecter(PLUG). If Voltage Is Present Its A Safe Bet Your Regulator Is Bad. See My Postings Elsewhere At This Website For Charging And Battery Issues.

  • Joe Stanton Apr 23, 2013

    Also Do Not Use Aftermarket Rectifier- Regulators.See The Your Dealer Or Call Service Honda In Hammond,In.At (219)-932-3588. They Have The Best Price On Any Brand.

  • Joe Stanton Apr 23, 2013

    Be Sure To Use Dielectric Grease At All Connections(PLUGS) And Grounds.Make Sure Battery Is Fully Charged Using A 2 Amp Trickle Charger Before Running Engine. Check That Water Level In Battery Is Correct Before Charging. Use Dielectric Grease At Battery Terminals Also.


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Hi this might help,normally if the alternator/generater fails you will get no charge voltage at all,if your bike is fitted with an alternator(most later honda models are)then you will have a rectifier and regulator,the rectifier converts the ac voltage from the alternator to dc voltage which is then fed through the regulator and then onto the battery,if the bike is fitted with a generator then you will still have a regulator but no rectifier,a generator develops dc voltage at its source so a rectifier is not needed,a simple way to test the system is with a simple digital volt meter,these are very cheap and reliable and can be got for around 20 bucks,with the engine running at about 1500 -2000rpm test the voltage across the battery with the meter normall voltage at charge should be between 13.8 and 14.8 volts,if you are getting more that this then the regulator is faulty,another way to test the regulator is to slowly lift the engine rpm from idle through to about 3 or 4000rpm the voltage across the battery should not rise any higher than about 14.2-14.8 and it should reach its peak at about 2-2500rpm and not fluctuate more than about 1 volt across the rev range,if the voltage exceeds about 14.8 or fluctuates excessively with engine revs then the regulator needs to be replaced.hope this helps...cheers ian

Posted on Feb 07, 2010

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  • iain kelly Feb 20, 2010

    regulater would be my first step

  • Joe Stanton Apr 23, 2013

    Rectifiers Are Internal In Solid-State Regulators. Do Not Flash (SHORT) Battery Terminals As A Test For Voltage. Use A Meter Or Test Light.

  • Joe Stanton Apr 23, 2013

    This System Is Most Likely A 40 To 35 Amp Full Feild System. Thats Why Battery Maint. Is Criticle. A Bad Cell In The Battery Will Damage The Regulator And The Armature In The Starter.


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See My Postings On Battery Related Problems Elsewhere At This Website. All Charging Systems Use The Same Principle. Magnetic(Permanent) Rotor And Wound Stator Produces (AC) Current To Rectifier. Rectifier Changes This Current To (DC) Current And Regulates It At 14 To 13.5 Volts To The Battery. Regulators Also Provide Signal For Electric Tachometers (R.P.M.). Do No Jump Starting Or Rapid Charging. Very Expensive Damage Will Occur.

Posted on Apr 23, 2013

  • Joe Stanton Apr 23, 2013

    Also Do Not Flash Battery Terminals. Use A Meter Or Test Light

  • Joe Stanton Apr 23, 2013

    Check All Connections For Corrosion,Especially If You Wash Alot. Use Dielectric Grease At All Connections Ground Connections Also.


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