# EV Bike



## TheSGC (Nov 15, 2007)

With the realization that my dad will be losing his cheap transportation in the coming weeks (because I am almost ready to rip the Civic apart and he is still driving it) we have started to look at a bike conversion, such as his mountain bike or road bike. He always wanted to ride his bike to work, so this should be sweet. This is what I have come up with:

24 volt 350 Watt DC motor (found a good deal)
24 volt 200 AMP controller (One of the prototypes for my Civic EV)
Custom throttle, misc stuff etc.

So my question is what size should the batteries be for a 20 miles range? It will probably have some pedal assist, but the commute is 12 miles each way with recharging at the destinations.


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## VDubber (Jun 2, 2008)

350W motor?

At 24V this is only about 15A. So 15MPH gives you a 48 minute nominal commute for 12 miles. Worst case is that it is uphill both ways and you have to run the motor at close to max the whole time. This would give us a very conservative:

15A * 0.8 hours = 12AH / 80% DOD = 15AH.

So two 12V sealed batteries 12-15AH each should be more then enough.

http://www.batterymart.com/p-12v-12ah-sealed-lead-acid-battery-2pk.html (20lb pack)
http://www.batterymart.com/p-12v-18ah-sealed-lead-acid-battery-2pk.htmll (30lb pack)

The more he is willing to pedal, the smaller you can go on the bats. The first one is easy to wire and would give you a 6" x 8" x 4" or a 12" X 4" x 4" pack. Stick them in a plastic toolbox with a handle and bungy them to the rear luggage thingy. Now you can just unplug it and carry it inside where the charger is. You might be able to fit a smaller 24V charger to the underside of the toolbox lid. Then it is a self-contained power pack you can just open (to avoid heat buildup) and plug into the wall.


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## TheSGC (Nov 15, 2007)

Those 18 Ah look nice. I think I will also look at UPS sites and see what replacement batts cost at those sizes. 

I believe the commute is rather flat because it is a bike trail that is being built over old train tracks and it has reached a point where it goes from our town to my dad's work.


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## VDubber (Jun 2, 2008)

Just make sure you can easily take the bats with you if you lock up the bike outside. People are getting all grabby with batteries lately...

On another note, check out this suicide EV bike:

http://www.electricrider.com/custom/index.htm



> Top Speed: Faster than I want to go. I have reached 51 MPH.
> Climbing: Gains speed quickly and easily on the steepest hills.
> 0-30 MPH in under 4 seconds*
> 0-40 MPH in under 6 seconds*
> ...


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## TheSGC (Nov 15, 2007)

That is one serious bike! 

The current plan is to have the throttle and motor mounted securely to the bike and the controller, battery and charger built into a custom rear cargo bag/box so it can be brought into the building, thrown under the desk and left to charge for the day.


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## xrotaryguy (Jul 26, 2007)

Haha, that bike is way too fast.  I love the movie of it passing a minivan.

Big props to you building an electric bike. It is just so darn easy to build an electric bicycle and way more economical to build and operate than a car. E-bikes are just so darn convenient.

Here are a few pics of the bike that I built. Mine is not as sophisticated as yours will be, but it worked very well... until I burned up the 20 year old motor. Oh well, I got about 2,000 miles out of it, so I'm happy. New motor on the way.


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## VDubber (Jun 2, 2008)

Nice setup, *xrotaryguy*. Props for being so resourcefull.

How did that homemade friction-drive work for you? I noticed the clever use of a handtruck wheel.


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## xrotaryguy (Jul 26, 2007)

Actually, I think that the wheel was an E-bike part right from the get go. The setup worked well... better than I had any right to expect actually. This was my first attempt at building such a contraption and it really did work flawlessly. 

The only condition in which the setup failed was on wet pavement. Not a bid deal in AZ, and I really don't want to ride in the rain these days anyhow. 

However, I did accidentally get caught out in a nasty downpour. I was about 8 miles from home and the motor was totally useless. I tried to ride the canal banks hoping that the aggregate on the top of the bank would provide some traction. It did... for the mile or so that it existed. After that it was all mud and sliding around on slick tires. Kinda fun, but I really wasn't looking for that kind of fun... especially not on a 100 lb bike (I had an extra battery pack with me that day  )

Ok, enough story telling. e-bikes rock. Hurry and build yours. You'll love it!


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