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06-01-09, 02:51 PM | #21 |
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Re: Why do my lights get brighter when I rev the engine?
Well after reading all of the above I had a similar thing with my Varadero , it would get brighter when on the throttle . It turned out I had a dodgy Rectifier , and to add insult to injury it was knackering the battery . I managed to remove the Rectifier (had a Ducati logo on it as well despite being a Honda bike) and replaced it with another one sourced from CJ Balls at the right price . Battery went on a maximiser for a day and it sorted the problem out for me . My old Rectifier started to smell like fish as well for some reason . Not saying this is your problem but could also be a nod in the right direction .
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06-01-09, 03:11 PM | #22 |
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Re: Why do my lights get brighter when I rev the engine?
Alternator output is highly non-linear with speed. These curves are for car type machines but the curves will be a similar shape for a bike one.
Typically you'll get little appreciable output power at low rpm. Power is the product of volts and amps. You can draw off power for lights etc but if it exceeds what the alternator can produce at that speed then the voltage will start to drop to the point where you are relying on the battery to supply the balance of the current draw, typically down at basic battery volts of around 12V. When you rev the engine the alternator output picks up quickly to the point where it can deliver enough current for the load (lights etc) and also start to recharge the battery, at which the regulator will control the voltage in the right region for charging, somewhere around 14V. lamp resistance increases with temperature so they are not linear either (power vs voltage) but basically as the voltage picks up the current increases and they get brighter. You don't notice this effect so much on cars because a) the battery has a lot more capability to provide current to supplement alternator output, b) the alternator output is generally just about sufficient at idle to cope with basic demand (pulley ratio etc), c) usually the idle speed is increased slightly by the engine management when electrical demand is applied to avoid flat batteries in traffic. Bikes are a lot more basic.
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06-01-09, 04:15 PM | #23 | |
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Re: Why do my lights get brighter when I rev the engine?
Quote:
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06-01-09, 04:20 PM | #24 | |
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Re: Why do my lights get brighter when I rev the engine?
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Badger, PMSL @ your finding the Ducati component on your Honda. I know other companies often provide electrics, but buying a Honda and finding it had Ducati electronics on it? |
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06-01-09, 04:50 PM | #25 | |
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Re: Why do my lights get brighter when I rev the engine?
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The alternator is on the end of the crankshaft, so when you rev the engine it turns faster, this induces a higher voltage in the windings, (a test of the alternator is to see how much voltage it produces; at 5000 rpm each phase should give about 70VAC), the current is regulated, to a nominal 12V, (actually up to 14.7 is acceptable), and rectified from AC to DC, by the regulator-rectifier, (you guessed that bit didn't you?). At tickover the charging voltage may not rise the the level of the regulator limit, as such the electrical system will be powered by the battery - and importantly the voltage that it can supply, if that's less than the regulator limit revving the engine will cause the charge voltage to rise and the lights to get a bit brighter. This very common, particualrly so if the battery is a bit low or not in the first flush of youth, unless you have a specific electrical problem, flat battery, overcharging, blowing bulbs etc, it's unlikely there is anything wrong.
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06-01-09, 05:05 PM | #26 |
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Re: Why do my lights get brighter when I rev the engine?
I agree totaly, my statement was perhaps a bit sweeping. I did say later I'd test it on the meter. the figures you quote are spot on as well
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06-01-09, 05:08 PM | #27 | |
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Re: Why do my lights get brighter when I rev the engine?
are going to try and explain why?
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06-01-09, 05:19 PM | #28 | |
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Re: Why do my lights get brighter when I rev the engine?
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"Some say motorbike mechanics worldwide listen to the wind in the hope that some of his words will reach them, and that he can circumnavigate the world on a single tank of petrol, all I know, is he's called The Squid."
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06-01-09, 05:25 PM | #29 |
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Re: Why do my lights get brighter when I rev the engine?
I'd tend to go with sid's story.
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06-01-09, 05:32 PM | #30 | ||||
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Re: Why do my lights get brighter when I rev the engine?
Thor already did, pretty much.
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voltage (in volts) = current (in amps) * resistance (in ohms) To elaborate, unless R changes wildly (which it doesn't), V is proportional to I, in any part of the circuit. So: Quote:
Quote:
Quote:
Can we have another torque vs power thread now?
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