Battery takes a charge, but doesn't seem to charge while riding

Hello,

I have a '91 VFR. After every ride, the charge on the battery seems weaker and weaker. Today, when I came to a stop on the way home, the bike shut off and wouldn't crank.

Fortunately, I was about a mile from my house. I brought the battery home and put it on a charger. It read 12.4V but the charger said it was mostly discharged.

I think my R/R has been dying for some time. My battery doesn't charge at idle (voltage is typically < 12 while idling), but it goes up above 14 when I turn the throttle.

Does this sound like an R/R problem? If not, what should I look for? If so, can you recommend a good R/R to replace this one?

 

Your battery needs to be replaced. A fully charged battery will read 12.8 or more at rest, 12.4 indicates that your battery is only at about 40-50% state of charge. Once a battery is worn down it can no longer be re-charged. The fact that the voltage goes to 14 with revs indicates the stator and RR are both working okay.

 

Battery charged to full; reads 12.8V after sitting for an hour. Load test checks out.

Voltage to battery at idle = 18.2V, @5K RPM = 18.7V => bad?

1. Resistance (engine off) 0.5 ohm on each => OK?
2. Continuity from pins to ground = open (infinity) => no short?
3. AC at idle = 21.5V, 5K RPM = 75V => stator OK?

 

I was thinking running the bike was probably a bad idea at this point.

I'll grab the R/R from roadstercycle.com for $150... I'm a ham-fisted mechanic.

When you say hot, you mean with the bike running? The R/R is disconnected at this point, so I imagine not much is gonna fry that hasn't already fried.

 

Looks like you found the culprit

Battery seems to be okay and fully charged.

RR is not regulating--should not go over 14.4 or the battery will boil out.

1. Good reading--no open phase circuit
2. Good reading--no short circuit to ground
3. Good reading--stator is working as it should.

 

I believe it was Tink who said something about you have to experience a fucked up R/R and burnt wires to be part of the VFR club.

So welcome to the club.

 

It has 23K miles. I just warmed up the bike and checked the voltage and it was the same as cold... shut it off and the resistance was the same with no short.

I've seen some traces of chemicals around my battery seals. I guess that should come as no surprise. The battery was also hot to touch when I took it out on Friday, but not hot enough to burn me. It was over 100 degrees here, so I can't say I'm terribly surprised. The battery seems to work OK.

Thanks :smile: Do the 6th gen electrical systems still have these problems? I was thinking I'd get a 2006 or newer next time... with the VTEC after they tuned it to be a little less aggressive. Ever ridden a VFR w/ VTEC? It sounds like it'd be fun.

 

I'm glad I bought the kit pre-done for $150... saved me some headaches. I'm not good with soldering.

Volts at idle and 5K are around 14.2-14.3. Does the R/R have to be flush-mounted, or near-flush? I tried to put it where the old one is. I realize it's got cooling fins on top, but does the bottom need to be making direct contact w/ metal? There's not enough room to get it perfectly flush there... not without drilling.

 

It's no big deal. I have a friend who can help me with the aluminum... I don't have any here and he's better with fabbing brackets. There seems to be ample room underneath the right rear fairing.

Thank you. I feel fortunate there aren't other things that are wrong. The guy selling these couldn't praise the product enough. They must be a quality product since so many people on here are using them. It seems to work well and it's cheaper than a new OEM POS.

Is it typical for the OEM R/R to last this long? It's 21-22 years old at this point. It must've died recently if nothing is roasted, right?

I used both a Bic and a heat gun to get a good seal around the wires... the Bic for the finishing touches. I was lazy and used the butt-end connectors. My soldering is enough to get by with plumbing, but I usually don't do a good job with electrical stuff.

The plastics on this bike are very shitty. I'm currently saving up for other expenditures, but I imagine in a couple years I'll be able to fix the way the bike looks. I'll post a picture when it's all together and it's not so hot out.

 

You think they'd fix a problem like that. It's not a hard repair, but... yeah... are they trying to make money by selling OEM R/R's? I know GM used to do that with their brakes. The new GM seems to have turned a lot of things around -- I can't knock them -- but the old GM lost brake reliability when they got away from asbestos brakes. We used to have to slap a new set on every year.

I'd like to make this bike look good again. Are the plastics from Airtech any good? How would I go about that? Purchase, get 'em painted, drill them, fasten them up? It's only $1K or so to go the Airtech route for the parts... or is it worth the nuisance to get some 3rd gen plastics on Ebay?

If I did go the Airtech route, is it worth it to screw with decals? Is the bike meant to be red, or are there other colors that would look good?

 

Sounds good. Thanks for your help with diagnosing the R/R; my bike's up and running again. I'll post about it when I'm ready to start messing with it, I guess.

 

Glad your up and running again. I think its pretty amazing you got that many years out of the original R/R! My bike had its 3rd installed earlier this year, but this time I ain't messing around. (This is the first one I've installed - other was from PO).

Most guys on this forum have heard me say I have the mechanical ability of a monkey. But after many suggestions - even though I went with a brand new MOSFET R/R and VFRness - I decided to solder the wires. Mind you, I've never soldered before.

Anyway, I watched a few videos on Google, did a couple of practice runs on wire just laying around, and then went to town on the bike. It did take me quite a while to replace the R/R and solder all my connections, but I wanted to be as thorough as possible. Probably 4 hours total, including the VFRness.

Its likely your new R/R will last a while, but if you're sitting around on a rainy day, I'd suggest soldering those connections. Its really not as difficult as you may think.