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I connected a phone charger to my bike one day and I've been having intermittent charging problems ever since. After a good ride the battery will be dead & I have to bump start it. It always starts right up too.

I load tested the battery, that's OK

I went by the shop manual & the alternator, regulator rectifier (aftermarket unit) & stator seem OK, but I'm no mechanic. I just had it checked by a local shop too & they said everything was OK. I went for a short 20 minute ride & the battery was dead again!

I plan on riding to the MotoGP at Indy next month. HELP!!

Bobbyn

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Read this thread: http://www.vfrdiscussion.com/forum/index.php/topic/78599-troubleshooting-1995/#entry957308

pay particular attention to post #2 -- "The Drill"

Also check the connectors between the stator & regulator/rectifier & between the R/R & wiring harness. If they show any signs of melting/burning, you'll need to replace or bypass by directly soldering the wiring. If the connectors/wiring are ok, at least tighten the female ends by pinching LIGHTLY with a pair of needle nose pliers. Good, solid contacts go a long way toward alleviating future electrical issues.

I wouldn't ride the bike until you've done all these tests & confirmed where your issue is (could be multiple issues).

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I checked the wiring, all looks good.

I checked the voltage across the battery while at 5K RPM with the headlight on, just after starting the bike: 14.57 V DC.

I checked the voltage across the battery while at 5K RPM with the headlight on after a 10 minute Idle to get the R/R hot: 14.57 VDC

I checked the voltage across the battery while at 5K RPM with the headlight on after a twenty minute ride: 13.35 V DC

I checked the AC voltage on the alternator connector, engine at 5K RPM, A-B, B-C, A-C: all were 65 V AC

I'm thinking its the regulator rectifier.

Any opinions/comments?

PS. I love this web site!

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Those numbers all look good except I'm concerned about your 1 volt drop after 20 mins....that's an indicator something is on the way out. What were the stator & r/r outputs at idle? Were those stator outputs after hot?

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  • Member Contributer

Call me crazy, I think it's a connection somewhere. At 13.5 volts after 20 minutes, your bike should start back up no problem. The fact that it doesn't tell me something else may be happening.

I'd start with a VFRness, and start checking grounds and circuits

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  • 2 weeks later...
  • Member Contributer

First of all remove the phone charger you installed and put it back like it was.

If you have 13.5v across the battery, at 5000 rpm, after a 20 minute ride there should be no problem starting right back up.

Hook up your voltmeter to the battery and ride around some.

Be careful while riding but try monitor the voltage.

If it ranges from 12.6 to 14.6 don't have a charging problem ( a 12v system is really a 12.6v system so less than 12.6v is technically a discharge state).

If you disconnect the battery from the bike and trickle charge it over night and then try to start the bike, does it start?

But the it can't start it again, after riding a short distance?

That's the battery not holding a charge or something is really dragging it down while you ride.

The slightest bit of corrosion, worn or loose connections can cause resistance problems and it will snowball from there.

And the 1 volt drop, across the battery, could just be from the system sensing that the battery is now charged back up after being dragged down a little from the initial start and then charged back up after riding a little while.

A good, fully charged battery should be able to start the bike several times in a row. And definitely after riding around for any length of time with more than 13 volts running to it all the time but not more than 16v.

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  • 1 year later...

After going through many batteries (including a borrowed Li battery, $$$ ouch), and a few regular rectifiers, I've come to the conclusion that stator might be bad. A buddy who is a wiz on electrics confirmed this today, so I need to replace my 1997 VFR750 stator. I'm catching up on this topic and learned the OEM part is history. So its either an aftermarket or a rebuilt unit.

The forums are not really clear on either/or, so I'm asking: for a cheap S.O.B. like me what should I look into?

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I purchased one off eBay. Even with an unknown history/mileage it worked out ok for me.

Study the pictures to look for any signs of burning. I think that's the best you can do.

Also check all the wiring from the stator to the R/R, to the battery, to the starter relay, and all grounds.

Paul in SoCal

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  • Member Contributer

.

The forums are not really clear on either/or, so I'm asking: for a cheap S.O.B. like me what should I look into?

Don't go out for dinner a few times and buy a good stator from Joshua (www.wiremybike.com)

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ok, YOU tested AC voltage output from the stator at idle aND AT 5000 rpm ?

Between any 2 yellow wires at the unpluged connection to the r/r you need to have between about 8 AC volts at idle up to about 60 AC volts at 5k rpm. All combinations of pairs of tested wires should be the same AC voltage or very nearly.

With any VFR charging problem, it's important to unplug the connection atop the starter relay and inspect that plug's bottom and the spade terminals on the relay for signs of melting, burning, or discoloration !!!!!!!! Any bad connections on or under that (usually red, might be green on yours) plug will reduce or eliminate battery charging.

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  • 3 months later...

Holy starter relay, squirrelman! You were right! Its been intermittent charging/starting for weeks.

 

I bought the Chinese knockoff and will install it today and let you know.

 

Thanks, Bobby

IMAG3343.jpg

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Looks like one of mine a long time ago.

I took the opportunity to do a general make-over of the charging system. 

Replaced the R/R with one from a late model GSXR, replaced the wiring with slightly smaller gauge (larger wire), the three wires to the connector behind the right fairing (from the stator), the power wire to the starter relay, and the ground to the battery (or frame, I can't remember which). 

I also found a replacement starter relay off ebay.  Its been many, many, MANY miles, with no problem on this set up.  

I get about 6-7 years out of a battery, but I keep them on a Tender all the time, whenever I'm not riding.  Hopefully you are also installing a new battery at this time too.

I just switched to a Li battery that doesn't require a Tender, we'll see how that goes.

Paul in SoCal

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