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Old 07-24-2008, 10:36 AM
Y2KMASTER Y2KMASTER is offline
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Default Battery charging system

Hey guys, I'm new to these forums. I've been working on an ev project for a while now and what I basically want to do now is make an external charging system so I don't need to charge my batteries through an electric outlet. I'm a little stumped here. This is what I want to do. Have 2 or 3 low rpm high voltage generators geared to a bike to charge 10 deep cycle batteries in about an hour. I'm assuming I'll need a voltage and current regulator as the rpm's will very depending on how fast you pedal. Any help would be appreciated.
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Old 07-24-2008, 10:41 AM
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Default Re: Battery charging system

Whoa... who will pedal the bike? Arnold Schwarzenegger? If you want to charge your car via bicycle figure on pedaling for about a week and a half. Remember, the energy you put in must be greater than the energy you want to get out. You're basically talking about generating all the energy necessary to push an automobile for an hour... with your bicycle. I don't know about you, but I don't want to tow a car for an hour with my bicycle, and there's no way I could do it at 40+ mph even if I wanted to. Maybe if you built a ten-man bicycle and connected that to a generator... that would give you about 5hp.

If you really want a clean charging method, consider purchasing some solar cells and installing them on your roof or in your back yard. Depending on your location, you could also consider a small wind turbine. I hear solar is easier to live with though.
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Old 07-24-2008, 11:30 AM
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Default Re: Battery charging system

the average person cycles with an output of around 200W. given a 65A 12V battery, thats about 4 hours to charge it up.
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Old 07-24-2008, 12:42 PM
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Default Re: Battery charging system

Considering that typical EV battery has twice the capacity and there are 10-12 of them, it'd take about a week of non stop pedaling to charge up a pack to drive for 30 miles.... I would love to see that pedaling , might as well just take the bike where you were going with that EV
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Old 07-24-2008, 09:13 PM
Y2KMASTER Y2KMASTER is offline
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Default Re: Battery charging system

So in other words I should be looking for generators that output high current? I just know the basic physics, I'm a biochem guy haha.
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Old 07-24-2008, 09:27 PM
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Default Re: Battery charging system

Why do you need a generator? Do you not have access to grid electricity? Grid electricity (particularly off peak) is the most efficient readily available energy source for your charging needs. All you really need is a battery charger.
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Old 07-24-2008, 09:50 PM
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Cool Re: Battery charging system

Quote:
Originally Posted by Y2KMASTER View Post
Hey guys, I'm new to these forums. I've been working on an ev project for a while now and what I basically want to do now is make an external charging system so I don't need to charge my batteries through an electric outlet. I'm a little stumped here. This is what I want to do. Have 2 or 3 low rpm high voltage generators geared to a bike to charge 10 deep cycle batteries in about an hour. I'm assuming I'll need a voltage and current regulator as the rpm's will very depending on how fast you pedal. Any help would be appreciated.
Work being done can be measured "watts" or "horse power" (and others?) . I have a "5" horse power generator that is capable of running my 10 chargers for my 10-12 volt batteries . I'm sure it would take a few hours to charge them . I just read that a man is about 1/10th horsepower . One horsepower is also 746 watts . Now you have more information on what it takes to charge batteries for an EV J.W.
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Old 07-24-2008, 10:58 PM
Y2KMASTER Y2KMASTER is offline
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Default Re: Battery charging system

In university physics we did an experiment to calculate how many horsepower each individual producd. I ended up around 2.3 hp or somewhere around that. i was planning on gearing the generators so they spin faster than I pedal. What I hope to do is create an interchangable system that I can tack on wind generators too for windy days. This is more of just for fun, not to actually beat the system.
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Old 07-25-2008, 12:53 AM
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Default Re: Battery charging system

Human pedal output power is way, way, below 2.3hp. During the Tour de France hill climb a couple of days ago they showed the power output of the top riders. The very best cyclists in the world were averaging about 340 watts (a bit less than 1/2hp) during the hill climb sections. Most non-athletes struggle to sustain more than about 150 to 200 watts when pedalling.

A pedal powered generator will have some losses too, so if you could sustain 200 watts of pedal input power then you'd only get around 160 watts of electrical power out. My best guess is that most people would struggle to deliver even this power output.

Jeremy
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Old 07-25-2008, 02:06 AM
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Default Re: Battery charging system

Quote:
Most non-athletes struggle to sustain more than about 150 to 200 watts when pedalling.
And that is just to pedal the bike. I does not include the energy output to run the generators on your bike under load.
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