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I have my bike back now after my accident. I noticed while riding, the headlight brightness is fluctuating.

I had this issue before the accident too. The main ground wire had broken (pre-accident) and I just assumed that was causing the issue.

I fired it up in the garage and measured the battery voltage. I saw 13.5 at the lowest and 16.0 at the highest. I didn't notice any pattern to it. By the time it got hot enough to kick on the fan, it no longer fluctuated and remained steady at 14.

I pulled and jiggled wires but couldn't make it happen. I measured the stator leads AC (while connected) at 8.9 V.

I haven't had any low battery issues. If anything, it seems to be too high of voltage.

Thoughts?
 

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16v is pretty hot, that will over charge the battery. Make sure the battery connections are clean and tight. 14v with the fan on isn't normal.

Probably need to test the r/r.
 

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My headlight did that too. Replacing the stator and R/R fixed it.

and yeah, 16v shouldn't be happening. If the regulator is putting out 16v, I'd have to guess that it's busted
 

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So, you weren't riding the bike, it was parked and idling? You didn't mention what rpms you were getting these readings from.

If your bike is sittimg and running long enough for the fan to kick on, your R/R is likely getting pretty hot too.
Voltages do vary while running, and by this I mean when the bike is moving. I'd see mine occasionally spike at 15 volts or so, but it never sat there for any length of time (perhaps a full second) and would drop to 13.8~14.5 range.

16 does seem high. I think replacing the R/R be a good move. What did it measure before you started the bike?
 

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Discussion Starter #5
I didn't test battery voltage before starting. Most readings were at idle, and staying below 15. Revving it up, it would usually stay around 14-14.5, but sometimes spike to 16v. It wasn't tied to any particular rpm. Above 2k-7k it was the same.
 

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I honestly wouldn't worry about it. I would however mount a digital voltmeter you can use while riding.

The brightness of the headlight varying I'd be more concerned with. The reason I asked what your voltage was before starting the bike was trying to determine how accurate your meter is.
 

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The brightness of the headlight varying I'd be more concerned with.
I’ve been noticing this on my bike lately when riding in darkness. I went out early this morning, before sunrise, and definitely noticed some fluctuation.

I really need to get going on those full electrical tests. But the bike has been running really well lately (knock on wood), so my main point of procrastination has been replacing this front tire.

It’s less about the tire and more a matter of just not wanting to deal with taking the wheel off and putting it back on. So it’s easy to put it off by one more day. And I do that every day 🙂

I’m currently telling myself that I’m waiting for a rainy day. But we’ve had very few of those.
 

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Charging rate is effected by rpms. If you let them drop below 3000 the light may dim compared to running at 5000. Not sure if the mosfit R/R's are better for this.

Having nice clean connections helps. ;) The stock headlight is pretty crappy anyway. Had I kept my Vulcan I would have replaced it with a unit from another bike. It's not just the bulb, it's the reflector too. (I did add driving lights which helped a lot)
https://www.flickr.com/photos/knifemaker1954/albums/72157602271287644

Nowadays I pretty much don't ride at night, so headlight brightness isn't that important.
 

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Always thought the headlight on mine was pretty good, enough to dodge deer at night. Definitely room for more though.
 

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Nowadays I pretty much don't ride at night, so headlight brightness isn't that important.
Oh, I thought the concern was something bigger than the brightness of the light itself, and more about an overall electrical problem. So you're saying if I see this headlight brightness issue, then it's nothing more than a headlight brightness issue? Because it's pretty subtle. I'm just concerned that it might be indicative of some larger problem.

I do plan to replace this headlight in the long term. I like the stock look of it, and the primary purpose of motorcycle lights is to BE SEEN, which I don't think has been a big problem for me. However, when I drive either at night or in the early morning before the sun comes up, I do want to be able to SEE better.

So that's something I want to do relatively soon (meaning... this season... maybe).
 
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I remember the headlight getting brighter/dimmer with rpms on my old ride(s), I put the Silver Star bulb in and then it pretty much stayed the same brightness or wasn't as noticeable.
 

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I put the Silver Star bulb in and then it pretty much stayed the same brightness or wasn't as noticeable.
Oh, that's interesting. I hadn't considered replacing the bulb. Mostly because I put SilverStar bulbs into my pickup truck and they didn't help my situation there.

I found that Amazon sells the 9003 SilverStar, even in a single-bulb package. So I bought it immediately and it will be here on Friday. Thanks.

They have the standard version for $17.99 - http://a.co/d/dTdStqX
And the "ultra" version for $22.99 - http://a.co/d/ggKHJTN
 
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