Author Topic: Electrical: lights dimming under load  (Read 1208 times)

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Rich Mintz

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on: June 23, 2013, 11:29:12 pm
During my long ride last night (with the slipping chain), I was very attentive to the bike, and eventually I figured out that when I applied either the front or rear brake (causing current to flow to the brake lights), the headlight and speedometer backlight dimmed slightly.

(This took a long time to figure out, because squeezing a lever and pressing a pedal feel like very different actions, and I didn't correlate them until I applied an overlay of "engineer's mind.")

What does this mean -- that my battery isn't putting out enough voltage? And what in turn does that mean -- that my battery terminals are dirty?
Rich Mintz - New York City
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Rich Mintz

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Reply #1 on: June 23, 2013, 11:34:17 pm
During my long ride last night (with the slipping chain), I was very attentive to the bike, and eventually I figured out that when I applied either the front or rear brake (causing current to flow to the brake lights), the headlight and speedometer backlight dimmed slightly.

(This took a long time to figure out, because squeezing a lever and pressing a pedal feel like very different actions, and I didn't correlate them until I applied an overlay of "engineer's mind.")

What does this mean -- that my battery isn't putting out enough voltage? That the voltage is available but being "lost" at the battery terminals? And what in turn does that mean -- that my battery terminals are dirty?

FWIW, no charging problems as far as I know. (Remember, I fixed those. :-)

Rich Mintz - New York City
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Arizoni

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Reply #2 on: June 24, 2013, 12:52:40 am
I'm betting you were riding very easy and the engine was running slowly when you applied the brakes?

At low speeds the RE's alternator doesn't put out a lot of power, barely enough to keep the system at 12 volts so with the addition of the brake light the voltage drops even lower.
That is the cause of the dimming you noted.
Turning on your turn signals will do the same thing.

Just to be on the safe side, if you have a multi-meter (volt/ohm) you might want to check the state of charge in your battery.  Especially if you don't have a kick starter on your bike.
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GSS

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Reply #3 on: June 24, 2013, 04:25:54 am
+1.  Seems pretty normal with the UCEs especially if you throw in a 55/60W headlight bulb. You can see the voltmeter flicker each time your turn signal (sorry trafficactor) blinks when you are at a stoplight with a foot on the brake.  No adverse effects so far during almost 3 years of riding the C5.

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hortoncode3

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Reply #4 on: June 24, 2013, 01:47:01 pm
I agree with the above assessments. And get a gel battery for that extra insurance. And replace bulbs with LED's. Well, maybe not the headlight,  Kuryakyn Phase Seven 7 in. L.E.D. Headlights are $227!


Rich Mintz

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Reply #5 on: June 24, 2013, 04:06:23 pm
I have the LEDs for the two pilots already, I just have been putting off installing them because they'll require me to pull apart the wiring spaghetti I taped and ziptied up securely when I fixed my rectifier problem a couple months ago. :-)
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JVS

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Reply #6 on: June 24, 2013, 04:14:20 pm
The two pilot lights are the easiest to change. Just plug and play type.
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Rich Mintz

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Reply #7 on: June 24, 2013, 04:27:15 pm
Yeah, I know -- but the things they "plug" into are currently ziptied in a not very convenient location behind the headlight!
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JVS

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Reply #8 on: June 24, 2013, 04:40:59 pm
Well then you can aim to install those LEDs by this weekend  ;)  :D
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barenekd

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Reply #9 on: June 24, 2013, 06:58:51 pm
You can plug and play the taillight/brakelight, too. About $13.00. Don't bother screwing with the turn signals. More work than they are worth.
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