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Gene'sG

Gene’s Green Machine
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1Instructables3,205Views5CommentsJoined November 16th, 2017
Interested in green energy with a keen interest in human power.

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• Gene'sG commented on Gene'sG's instructable Best DIY Bike Trainer Generator5 months ago

Yes, you certainly could, depending on your fitness level. That balance charger should work perfectly, with the added benefit that it accepts a pretty wide range of input voltage. The great thing with these balance chargers is you can always adjust the amperage down if you physically can’t maintain the max wattage needed to charge a battery.

I see your quandary - let me try to clarify. To your last statement - the current (amps) will be defined by the load, so when I’m charging my 5500mAh 11.1v Lipo battery, the proper settings to charge it are 5.5 Amps and the volts are managed by the balance charger, starting out at whatever the battery is at, usually around 11.2v. Watts = volts * amps, so we get 61.6 watts of resistance while pedaling. Not exactly - the charger isn’t 100% efficient, so that load is more like 70 watts. The wattage will actually increase as the battery charges until the battery gets to 12.6v, at which time it will taper off as each cell reaches a fully charged state (which makes for a good cool down). To your question about which motor to choose, what you really need to determine is what R...

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I see your quandary - let me try to clarify. To your last statement - the current (amps) will be defined by the load, so when I’m charging my 5500mAh 11.1v Lipo battery, the proper settings to charge it are 5.5 Amps and the volts are managed by the balance charger, starting out at whatever the battery is at, usually around 11.2v. Watts = volts * amps, so we get 61.6 watts of resistance while pedaling. Not exactly - the charger isn’t 100% efficient, so that load is more like 70 watts. The wattage will actually increase as the battery charges until the battery gets to 12.6v, at which time it will taper off as each cell reaches a fully charged state (which makes for a good cool down). To your question about which motor to choose, what you really need to determine is what RPM range you will be in, from low to high. If you’re using a bike with multiple gears, you can always adjust the RPM by shifting up or down. The load will remain relatively constant, and as long as you are in the voltage range of the charger (10v-28v), the charger will be happy. I think your calculations to go with a 63kv motor are off a bit as this would put your voltage at about 68 volts @ 15MPH (using a mountain bike tire as I have in my calculations). Don’t overthink the motor, I’d go with a 320kv for a mountain bike tire and a 350kv for a road bike tire.

• Gene'sG followed bennelson6 months ago
• Gene'sG made the instructable Best DIY Bike Trainer Generator6 months ago

I took the suggestion from simplewriter and hooked the bike generator up to a 5500 maH LIPO battery and using a balance charger, put over 60 watts into the battery - in 25 minutes of pedaling, I’d added 30Wh to the battery. I think this will be a great setup as I can get lots of watts into this battery bank in a short time, then use the battery to charge all the “slow charge” stuff - things like my iPad Pro, Kindle and other things take hours to charge. Now I can just blast a bunch of power into the battery, then hook it to these devices after and let them take their slow sweet time to charge. Thanks for the suggestion, simplewriter!

• Gene'sG's instructable Best DIY Bike Trainer Generator's weekly stats: 7 months ago
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• Gene'sG commented on Gene'sG's instructable Best DIY Bike Trainer Generator7 months ago

Thank you! Glad you like it. No reason why you couldn't use this to charge an RC LiPo battery, although I haven't tried it. The input voltage for a typical B6 IMax or similar Lipo battery charger is 11-18v, right in the sweet spot of this design. The nice thing with using a Lipo battery is you can put a lot of watts (50, max) into the battery in a short time. Typical USB battery packs will only accept 5 watts charging, and quick charge 3.0 battery packs top out at 18 watts. I like your idea! I'll have to get a Lipo battery and one of these chargers ( http://amzn.to/2jzAoKf ) and try it out! As long as the volts out of the Lipo are between 9 and 24, then any good USB car charger will charge your devices with the battery. Great thought!

• Gene'sG commented on Gene'sG's instructable Best DIY Bike Trainer Generator7 months ago
• Gene'sG entered Best DIY Bike Trainer Generator in the Wheels Contest 2017 contest 7 months ago