SV650 Charging System Help

Discussion in 'Road Warriors' started by opmike, Dec 1, 2012.

  1. opmike

    opmike Choosing to be here.

    Joined:
    Sep 11, 2011
    Oddometer:
    349
    Location:
    Southeast, US
    The bike in question is a 2004 SV650S with ~22,000 miles.

    I apologize for the length, but I'm trying to be thorough. Try not to fall asleep. Basically, I've been trying to diagnose what may be an issue with my charging system. What lead me to look at it was a stalling issue about a week back that had me limping home. The issue is VERY intermittent (I can go months without an issue, and it will randomly rear its ugly head again) so I finally decided to try to figure it out. Reading around, my intermittent stalling may be a flaky TPS so these two issues may be unrelated. However, figuring that out and probing around revealed a potential issue with my charging system.

    For reference, here is what the service manual says I'm supposed to expect with regard to voltage:

    Voltage at battery terminals @ Idle: Not specified (users report the low 13's with stock R/R)
    Voltage at battery terminals @ 5K RPM: 14.0-15.5 Vdc (15 and above is rare)
    Voltage at stator leads @ 5K RPM (cold engine): greater than 60 Vac
    Resistance at stator leads: 0.2-0.7 Ω

    There is also a table for performing a diode test of the R/R, but you guys will have to just trust that I performed those tests correctly, the unit passed. Stator voltage and resistance tests were all within spec:61 Vac/60 Vac/61 Vac and 0.3 Ω/0.3 Ω/0.4 Ω respectively. It also showed no continuity to ground.

    On a freshly started bike, all of my measurements fell within the spec. Here they are:

    Voltage ignition off: 12.9 Vdc
    Voltage at Idle: 13.1 Vdc
    Voltage at 5K RPM: 14.4 Vdc

    However, the problem arises once the bike has come up to operating temperature, and has been there for some time. This was with the stock R/R:

    Voltage at idle: 12.6 Vdc
    Voltage at 5K RPM: 13.0-13.2 Vdc

    I originally figured there might be something funky going on with stator output as things heated up, but I tested it, and I was still getting around 58-60 Vac. There was a slight drop, but from what I understand, it's to be expected as it warms up.

    Since I had a known good battery (brand new Yuasa), and stator output was good, I looked to the R/R. Even though it passed the couple of tests I could do on it, I figured there may still be something funky going on internally with the regulating protion, and these shunt-type R/Rs in SV's aren't known for being robust.

    So, I wired in a MOSFET-type FH008 from a 2006 CBR600RR. This unit is probably one of the most popular replacement models for our bikes. However, my results were still the same. Good output on a cold start, but once the bike has been warming up for a while, I'm rarely getting much over 13.2 Vdc or so at 5K RPM. Results were about the same as my above test with stock R/R.

    Any idea what's going on here? What drop, if any, should I show at the battery terminals with regard to voltage as things start to heat up?

    I thank you all in advance for your time; I could really use the help as I'm stumped.
    #1
  2. D.T.

    D.T. Difficult but useful

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    I'm not even sure you have a problem. :huh

    Sometimes shorter is better. So stalling is the problem. Like once every year or so? :confused

    Any FI codes displayed when it stalls?
    #2
  3. opmike

    opmike Choosing to be here.

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    Location:
    Southeast, US
    I think there's two problems, but diagnosing one lead me to the other. I originally had a stalling problem just off idle that would happen sporadically every few months. A week's worth of research points towards that being a TPS issue. No codes are thrown, but with the rudimentary FI system in this bike, they don't tend to throw codes unless a sensor outright fails. In figuring that out, I had taken a look at the charging system when I noticed these anomalies. Since I don't do regular tests of any of this, I have no idea of this electrical issue recently started, or if low/weak charging has always been an issue with my bike.

    I'm supposed to be getting greater than 14 Vdc at higher RPM, but I'm barely getting over the voltage of a charged battery, even once the engine speed comes up. Mine is lower than every other SV I've seen measurements posted for, and I can't figure out the source of the problem. Most users report 12.9-13.1 volts at idle and 14.3-14.5 volts as the RPM's come up.
    #3
  4. agent of orange

    agent of orange Adventurer

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    you wired in a mosfet did you do the 12 gauge wire mod?
    #4
  5. Ohio_Danimal

    Ohio_Danimal Midlife Crisis Man

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    Location:
    Cuyahoga Falls, Ohio (The Crooked River)
    My guess is your stator is starting to go. Usually displays reduced voltage once the winding's insulation heats up enough.

    Electrosport makes a stator with a claimed 20% Watt increase over stock (340W output compared to stock 280W) for less than $120 I believe.

    Even though my SV is charging well, I am farkled to near my output limit, and will be installing the higher output stator this Winter as well as going to HIS projectores (to save another 40W over the Halogens)
    #5
  6. Jeff B

    Jeff B Socially Awkward

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    Has the bike been dropped on the stator side? I ask because the rotor magnets are sensitive to jarring and might of lost some of their strength if they did take a hit.
    #6
  7. D.T.

    D.T. Difficult but useful

    Joined:
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    Oddometer:
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    That is a good suggestion right up there...:deal

    The big SV has had issues with the magnets coming loose from the rotor. Fairly common. Never seen it in the 650's though.
    #7