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Do you know how hard it is to peddle 20 amps!?!?!?!?!!?

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Do you know how hard it is to peddle 20 amps!?!?!?!?!!?

Old 12-28-09, 03:39 PM
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Grim
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Do you know how hard it is to peddle 20 amps!?!?!?!?!!?

Between weather, buring vacation days, commitments requiring me to drive etc I have not been able to do much commuting since Thanksgiving.

Couple years ago the business behind the one I work for moved. They are a fitness supply place.. They had a parted out StairMaster Momentum exercise bike they tossed. The electronic were gone as was all the covers. All the was left was the drivetrain with the alternator they use for resistance by running it against a massive resistor.

When I saw it I immediately thought of my kids that cant seem to turn lights or TV's off when they leave a room so I thought I would make them peddle to watch the TV. Never got around to building it.

Got around to messing with it today. Needed power to to kick it into charging. I think in it stock configuration they were using a variable resistor on the field circuit to control the output voltage and the resistance at the peddles as a result. I need to drive a 12v-110 inverter so I diced to run it straight 12v to the field with a MASSIVE 150ah house battery from my camper that is need of a charge. Well as I peddle faster the voltage comes up making it harder to peddle as it increases the amperage to the battery.

Holy crap! It is all I can do to peddle this bugger for more then a few minutes at a time trying to get the battery up to charge.

I need to get a 12.6v regulator on the field to make this easier and prevent blowing out the inverter.
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Old 12-28-09, 04:52 PM
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Hard to get more than 50w to 100w out of human work on a bike for any length of time, particularly w/o a cooling breeze blowing on the rider. One reason why you sweat so much when riding a bike on a resistance trainer or riding an exercise bike. Racers can do better but they have a cooling breeze on them when racing. I suspect for TV watching power you would want the output required from the rider to be under 25 watts.

For that you will need to choose a low power requirements TV if you actually get the project working.

IIRC you can get light switches with a sensor that turns off the lights when no one is in a room. You could also wire the TV power outlet to such a switch. Everything turns off after a short time if no one is in the room.
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Old 12-28-09, 05:26 PM
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750Watts equals 1HP. At 12V and 10A you're at 125W, but you need to factor in efficiency, say it's ~50% overall, that's 250W input power which is 1/3HP. It takes a pretty fit cyclist to do that for any length of time.
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Old 12-28-09, 05:29 PM
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Originally Posted by Grim
I thought I would make them peddle to watch the TV.
I try not to be a grammar Nazi but this is actually pretty funny. If you don't know what I'm talking about look up peddle and pedal in a dictionary.
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Old 12-28-09, 06:32 PM
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Originally Posted by cooleric1234
I try not to be a grammar Nazi but this is actually pretty funny. If you don't know what I'm talking about look up peddle and pedal in a dictionary.
Ooooh hell! hahaha!

I think the spell check got me on that. Seriously I have some brain damage from lack of O2 a few years ago. My already poor spelling has been worse since that happened. My train of thought is fine just comes out of the fingers jumbled up. I probably misspelled it peddal and it recommended "Peddle" first and it didn't click I was picking the wrong one.
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Old 12-28-09, 08:52 PM
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At some science museums they have a hand cranked generator. I can get one up to about 500 watts - for about 10 seconds. If I had to maintain it, I probably couldn't do more than 50, and that probably only for a few minutes. Using legs, most of us could probably maintain 150 watts for a fair amount of time.
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Old 12-28-09, 09:44 PM
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Originally Posted by ItsJustMe
At some science museums they have a hand cranked generator. I can get one up to about 500 watts - for about 10 seconds. If I had to maintain it, I probably couldn't do more than 50, and that probably only for a few minutes. Using legs, most of us could probably maintain 150 watts for a fair amount of time.
I gave up for the night. My legs are buring after about 5 minutes and I don't want to blow out my knees. That battery is down a lot. Hope it isn't hosed. Thats a $300 battery. Going to top that battery off tomorrow with the charger. Mostly I just need the resistance that battery is giving me for the work out not to actually power anything. If it is too easy once charged I'll throw the inverter on it and plug in a light or two or try the TV or the blower on the fireplace insert till I find a good amount of resistance that I can maintain.

It is pretty quite thankfully. Have to scream over the Advent trainer my wife has her bike on. This thing makes about a 10th the noise.
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