Idea for an electric push trailer... let me know what ya think...

bigkat650

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My idea to make an electric push trailer was to make something economical and functional. The idea is to use it as a peddle assist more then a motorized bike. My girlfriend lives on a massive hill out of town, and I'm a big guy (over 300lbs)... So simply peddling up the hills would be extremely difficult. With the assist of the silent electrical motor, I think I would use my bike alot more, which will help me get back into shape. Anyways, The idea is to use either a 500 or 600 watt electrical motor, and 4 12v 12ah batteries wired to create a 24volt 24ah reserve. Unlike most electrical bikes, I had planned on using an external electrical motor as apposed to the hub style motor. The main reason I chose to do this is cost, and keeping the back wheel around 12inches.

All in all, I think I could build this for less then $300... The batteries are $93 shipped... the motor will be around $60 shipped... Then I would need a thumb throttle, and control unit... which is about $75. Plus scrap metal I can get for free to create the frame.

Below I created some 3D pictures on a basic autocad program which shows basically what it would look like. The 4 batteries are in grey, the motor is in gold, and there is a simple chain that would attaching the motor to the black gear which is attached to the rear wheel. Ideally, above the batteries and motor your could tie down anything such as camping equipment, a basket, or a cooler.

Lastly, if you click HERE you can see what gave me the idea, I wanted something a little smaller, that I can make myself, without being a hub style motor, that would be less then $300... Let me know your thoughts folks... Thanks!
 

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I guess I do have a couple questions...

Is it better to mount to the back axle, or under the seat?

Would a 500 watt motor be sufficient? Or would something like a 300, or a 600 ok? I don't mind peddling, but I want to know I have a decent amount of thrust in case I wanna just cruise for a bit (i don't need to go more then 20mph) The best deal on batteries I found was 4- 12volt 12Ah batteries for about $93 shipped... SO figure either 24v & 24ah, or 48v & 12ah... Either way it calculates to just over 500 watts continuous for an hour. If a 400 watt would be sufficient assist, that may be better... I do have about 25 miles up and down hilly roads to go between my residence and my girlfriends house, and it would be nice to to able to get there on one complete charge.

Lastly, what gear ratio should I use? The 500 watt motor I am looking at is 2500rpm's with an 11 tooth sprocket. Again, i'm a big guy, and I can peddle, I am looking for some assist going uphills and perhaps a decent cruising speed of around 20mph on flat ground (a can peddle to reach that speed if need be)... Lastly I would like to be able to use it for about 25-30 miles while assisting.
 
Found THIS: 24 Volt 450 Watt Direct Drive Electric Motor & Rear Wheel Assembly Which I think would work very well with this design... 450 watts should be a good combination of power and Ah usage. All the scooters run on about 10ah and are rated around 15 miles on a single charge. With peddle assist, and a 24ah battery, I think 30mile range is a practical thought.

Again, I am very new to this, and I have never done a motorized bike... so if you think my calculations are off, please let me know. Thanks
 
I'd just buy it, build it, then run it.

However, I think there might already be some push trailers around... it's a very common idea actually.
 

???

Its a cool bike, but it doesn't fit my needs at all. I live in NY, and motorized bikes are illegal... Which is why I need an electric one, which is silent, and I can hide fairly well within a trailer.

Do we think 24v and 24ah is sufficient for a 450watt motor to assist me for about 30 miles, some of which is over hills? If need be I can purchase 2 more batteries so its 24v and 36ah to be sure I would have enough power.
 
What part of NY? I run a gas bike here and don't get much flack in Buffalo. The burbs are where you get your problems!

I've got lights hooked up to run off of the motor. If I get pulled over, I'll tell 'em the only reason you heard the motor run was because it powers the lights!
 
What part of NY? I run a gas bike here and don't get much flack in Buffalo. The burbs are where you get your problems!

I've got lights hooked up to run off of the motor. If I get pulled over, I'll tell 'em the only reason you heard the motor run was because it powers the lights!

hahahaha thats a good one! If a cop believed it though, maaan they are dense! I think I would let you off just for thinking up the clever response!

But to answer your question, I am in upstate NY as well, Ithaca actually... (cant wait to watch the Bills beat up on the Packers tonight!). But back to the topic... I researched it last summer, and any bicycle that has a motor attached to is, has to be registered as a motorcycle--regardless of the size of the motor. Its a state law, so I'm sure it is technically in effect everywhere. But weather or not the cops know about the law, or would even bother to enforce it... is another story. I just assume not draw the extra attention. I wanna be ultra sleek, so that no one suspects a thing! bwahahahaha.

If I am wrong about that law, let me know... But I believe its one of the top 2 toughest states on motorized bikes.:eek:
 
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