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It's the amount of charging done that results in a resistance in your dynamo.
But isn't the voltage and current drawn by a charger always going to be the same?
Ie, an iphone charges at like 5v and 1 amp right?
So if you plug it in when the battery is flat and charge it until it's full and then unplug it'll have drawn 5v at 1 amp for say an hour or so.
If you leave it plugged in all the time and the charger maintains the battery at 100% it'll draw 5v/1amp all the time.
No?
I have kind of wondered whether I make things harder for myself by leaving my lights on all the time. I thought that in setups like mine where the on/off switch is on the light, the hub always provided power and therefor had the same resistance. You had to have a switch on the hub (is this even a thing?) that turned power generation on and off to get a difference in the resistance.
M_V-
On all my dynamos, I find it hard to feel the resistant when riding (on or off) however I can feel the vibration when I turn on the light/e-werk/etc.
The switch is usually on the light/device rather than on the hubs itself.
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If you've the lights on, it's drawing current.
If you've the lights off, it's not drawing current.If there is no current draw, the hub is not experiencing resistance.
Hold front wheel in air, spin with light on; then repeat with light off. You'll see the resistance your exposing the hub to by having light on all the time.
Turn the light off when not needed. It's stealing 4Watts, or around 3% of your power input.
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A battery can't be charged more than 100%, so it will draw 1amp for short time, then stop. Most devices these days have some kind of trickle charging too I believe so that the amount of current they draw as they approach 100% lowers.
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If you leave it plugged in all the time and the charger maintains the battery at 100% it'll draw 5v/1amp all the time.
No?
No. If the battery is fully charged, it would stop drawing power as there would be nowhere for it to go. The electricity needs somewhere to flow to, it can't just flow into the ether.
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No, an iPhone charger is 0,5 amp if I remember correctly. It's the iPad charger that's 1 amp, but that's not relevant to your question.
In reality this means if you plug a battery in that's completely flat it's gonna charge at 5 volt and 1 amp for the first second of charging. It charges at 5 volt 0 amp when the battery is full (cause you can't charge a full battery). And in between your amperage (current) slowly drops, that's why your phone charges pretty quickly to 30%, but the closer you get to 100%, the slower it goes.
When you leave on your lights you are making it harder for yourself, when there is no connection between the 2 leads on your hub there is no current being drawn from your hub, there's only a voltage of 6 volt. Current*voltage=power so when your current is zero the power you need to put into your hub is zero.
When you put a 0,5 amp light on your hub and turn it on, your current is 0,5A and voltage 6V resulting in 3Watt (0,5*6=3) of power it uses, so you'll have to put out 3Watt of extra power through your legs.
Back to the iPhone (or di2) charger, when the battery is fully charged the power going to the battery is zero since there is no current, so leaving it plugged in doesn't result in extra Watts needed from your legs.
edscoble
skinny
chiroshi
Turkish
Jaap
I've never ridden a dynamo hub, but I have a physics degree and know quite a bit about electrical engineering and resulting forces..
And no! Whether it's on all the time or not. It's the amount of charging done that results in a resistance in your dynamo. So when you plug it in occasionally, you get a higher resistance for a shorter time. Resulting in the same total resistance..