Got Myself A New Stator, New Regulator/rectifier And Some New Cables... Why Is My Voltage Dropping With Hi-Beams On?

So... my VFR died on a trip a few weeks ago and it had to be towed.

Turns out that my stator was toasted, so I had it rewound.

I also replaced my regulator/rectifier. It was an SH689FA and I replaced it with a Shindengen FH020.

Next, I tried to fire it up. It shows around 13 V at idle and climbs up to 14.1 V at 5000 rpm.

However, when I turn hi-beams on, voltage drops at 13 volts and then continues to drop. I have seen it drop as low as 12.5 V and I'm sure that if I had let the engine running any more, voltage would drop even further. Same thing happens when my radiator fan comes on. It also drops and fluctates around 13-13.5 V with turn signals on.

I tried using a different battery and a different regulator/rectifier (the latter taken from a Suzuki TL) and I got exact same results.

I wired the FH020 regulator directly to the battery using 10 gauge wires.

I also tested the stator using a multimeter. Resistance between all three terminals is within standard, there is no continuity between terminals and ground and AC voltage from the stator is around 30-40 V at idle and around 120 V at 5000 rpm, again between all three terminals.

Before my VFR dies, I used to get 14.8-14.9 V while travelling, regardless of using Hi-beams, charging cell phones or anything else.

All cables from stator to regulator and from regulator to the battery seem OK, and I haven't touched anything else.

So, what could cause that drop in voltage?

Any help would be greatly appreciated. Thanks a lot in advance! :smile:

Kaló apóyevma!!!

Have you also tested the new RR with a multimeter?  :unsure:  

It should be good, trust is good, control is better!!!

Your "rewound" stator is the one weak spot in the procedure you employed.

Replacement of the R/R twice and battery with the addition of 10 gauge wires sort of rules problems there out.

I don't know where in the system you took the voltage readings at, so another possibility that I can think of is a poor ground from the battery at the bolt in the rear of the engine that the main battery ground wire attaches to.

But  -------------

My best armchair troubleshooting guess is that the rewound stator is faulty and although it reads ok on a multimeter and shows no ground path, it may not be able to stand up under load conditions.  As an electronic technician, I have seen this happen to transformers before and in all reality, the stator is just a glorified transformer.

Or  a  weak  rotor,  not  likely,  but.

Or  a  weak  rotor,  not  likely,  but.

Could the heat from the stator have cooked the magnets??

Heat  does  do  that  BUT  have  you  check  the  the stator output  with   out  the  R\R  connected ?

Most likely the rewound stator is not as good on output, assuming you have no resistance in your connections, dropping voltage.

<engage broken record mode>

Start with the inexpensive stuff. Check all connections including grounds. Check the starter relay connections (adjacent to the battery).

</engage broken record mode>

<engage broken record mode>

Start with the inexpensive stuff. Check all connections including grounds. Check the starter relay connections (adjacent to the battery).

</engage broken record mode>

?  the  bike  is running  just  not  outputting  the  right  voltage .

To belay worries about the output voltage, it could be to spec. For example some are saying their Honda replacement stator+ R/R is not as high a voltage as the original setup but it is supplying enough power. AKA the voltage out of the R/R is in the 14 V range, but they have no problems, even though the original setup was in the 15 V range. That would probably mean the parts are producing more current at the same voltage.  A thicker winding wire, more efficient R/R, or both.

The winding wire - What is the gauge compared to the original? Got a caliper to measure it? The number of windings determine the voltage and the diameter of the wire determines the current induced. So one possibility is that the wire is smaller and less current is being produced in it than the original winding.

What is the voltage out of the stator from the original setup? Was it the same as what you are posting? (30-120V).  If yes, the stator is producing less current, or the R/R is less efficient, aka power is being lost in the R/R.  

You used a Suzuki R/R? Is this aftermarket, or the same part as the OEM Honda? I am guessing it is the aftermarket one. Someone winding the stator would pretty much know what they are doing (well, bad assumption but winding transformers is pretty specialized.) And aftermarket parts are very hit and miss in terms of complying with OEM specifications and quality. Only your empirical testing has the right answer but I am guessing the R/R is the problem.

This is pretty important... the connectors are often the weak spots on the charging system. Make sure to clean all the connectors with contact cleaner and consider applying Ox-Gard or similar to them. You can pick up some additional voltage this way.

<engage broken record mode>

Start with the inexpensive stuff. Check all connections including grounds. Check the starter relay connections (adjacent to the battery).

</engage broken record mode>

Nice... lots of new posts I have missed! :goofy:

Anyway, here's how it worked out.

Turns out the problem was the rewound stator. I sent it back to the person who wound the stator. This time, he did the job properly.

Now I am getting almost steadily 14.1 V, with only minor drops when I turn on Hi-beams or turn signals. In any case, it never falls below 13.7 V ... and I'm back on the road!! :woohoo: :woohoo: :woohoo:

Thanks a lot guys for your help! :beer:

By the way, I have already mentioned that the stator would produce 120 V  AC at 5000 rpm. It seemed too much to me and I've been told that this was probably because my stator was at first rewound in a Star arrangement, rather than a Delta.

What do you guys think?

It would seem like your just making the RR work harder, having to deal with 120VAC instead of 60ish.

Off my stock stator I get 60VAC, and 14.5VDC off the RR pretty religiously.  

Hmmm  .

Nick, glad its resolved!  Yes, star is high V low I, delta is high I low V (at the same RPM.)

Some theory: 

http://www.reuk.co.u...Alternators.htm

I ordered a New oem stator a week ago for my 2006, to have on hand when mine goes, Ive seen the first sign its not able to produce the voltages it once did, rather than typically running 14.7 to 14.9. its been hovering in that 14.4 to 14.6 area, buts its well over 50,000 miles.

Im alittle surprised its taken a full 8 or 9 days to receive  , for them to ship it to me. I had a large order and the stator was holding everything up, I called this morning, and the stator was just released out of Georgia, Did it come from Japan?

Anyway, that time delay is definitely strange, cause normally its a 4 day event to get it from handa. But I also noted there is a Stator part number change in 2008( I ordered the 2006 number). Having ordered other items previously unique to 2008 and 2009 models, some times found the connector type was changed. So just an fyi with bikes after 2007.