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Old 03-10-10, 05:03 AM   #1
f0x
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Recharge

do electric bikes recharge when your going down hill or pedal? I live in the mountains and I'm thinking about getting 2 motors to solve the up hill issue. and it would be perfect to have the 2nd motor recharge the battery 70% of the time?
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Old 03-10-10, 05:21 AM   #2
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Electric bikes have a tough time with hills. That would be the only part where I would say gasoline is superior to electric bikes. Well, it would depend on big of a hill or mountain that we are talking about. If the hill only lasts about 1 or 2 miles, I think it's doable.

I think the Ezee kit might be something that you should look at. Also, consider the fact that if the hill is very long like 4 or 5 miles, you need to think about whether or not the motor can handle the heat generated.

Actually, they can recharge going downhill if you use the brake. There are bikes with regen that replenish some of the battery when you use the brake. I've heard that it doesn't replenish all that much, though.

If the hills are steep and long, I would recommend a gasoline powered scooter.
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Old 03-12-10, 04:16 AM   #3
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Do you think it would be worth dedicating a 2nd motor to recharge?
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Old 03-12-10, 05:18 AM   #4
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Originally Posted by f0x View Post
Do you think it would be worth dedicating a 2nd motor to recharge?
No, I think that would be even less efficient than a bike with one motor. If that was a more efficient option, you'd see more commercial e-bikes with that kind of setup. The most efficient e-bike is one with a lithium battery and is as lightweight as possible. The reason why I think gasoline is better on hills than e-bikes is because of how energy dense gasoline is. You can store all this energy in several gallons of gasoline. It's only been since the invention of lithium that electric bikes can now compete cost-wise with gasoline powered scooters. That's why you weren't seeing a lot of electric bikes before. It was because lead acid powered e-bikes, over the long run, were more expensive to get you around than just running a gas powered scooter. Now that we have batteries that last 3000 cycles or more and potentially 7 yrs or more, e-bikes are competing with gas scooters.
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Old 03-12-10, 05:36 AM   #5
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I can't think of anything you can do with a second motor that can't be done with a single motor with regard to regeneration. And adding in the extra weight and complication it really doesn't make sense.
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Old 03-12-10, 08:55 AM   #6
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Actually having a second motor to recharge the battery would be very counterproductive. If you think about it, what is powering the 2nd motor to charge the battery? the same battery that it's draining? and even if you can manage to setup the 2nd motor to activate on downhills only your bike would probably slow down considerably with all that friction 2 motors would have. The 2nd motor would be highly detrimental for your uphill and flat land riding also with the extra weight = more battery power needed to get it going.

If you really want "some" form of charge on your battery then the best bet would be to attach 1 or 2 of those 12v car solar panels on your rear rack and wire it to your battery. At least this would minimize the friction (panels are lighter than a motor anyday and are not on your drive train)

Last edited by Azreal911; 03-12-10 at 09:00 AM.
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Old 03-12-10, 11:01 AM   #7
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Professor Harold Hill: Have you ever heard of perpetual motion?
Tommy: Yeah, I almost had it figgered out a couple of times.

Sounds like you're trying to chase free energy.
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Old 03-12-10, 12:33 PM   #8
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Are the brushless motors heavy and add friction? I live in the mountains its down hill all the way back from work and I thought 2 motors would solve the over heating issue going up hill?

The solar panel idea sounds cool how big do you think it needs to be?

lol I'm not trying to invent perpetual motion just trying to find a mountain solution.

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Old 03-12-10, 01:06 PM   #9
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how far up into the moutains is your house? Also, how steep of an incline is it?
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Old 03-13-10, 10:12 AM   #10
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The solar panel has to be about as big as a car. Those solar panels for cars, actually RVs, are only to compensate for the very slight slow self-discharge of a lead acid battery.
Do you use a regular bike on these routes? In my experience, an electric bike only helps do what you can already do. It allows you to go up hills easier for instance.
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