Instructables

how to make a 24 volt electric bike?

I want to make an electric bike but i would really only want to buy one 24 volt battery(to keep weight down and for money issues) but i was wondering how fast i could go with that and i would only be using it to get around my neighborhood cause i don't have a drivers license(only 13) and i still want it to go fast and i was wondering if i could put a transformer on it so i could use a 48 volt motor. i want to keep the cost really low because i don't get that much money not having a job and stuff like that. i have and old bike that i was going to use. i actually have 2 old bikes but one is a geared one and one is not. i was also wondering if i would use the geared one and use the gears instead of a throttle controller and just switch gears to change speeds? i really want to keep the cost down and any suggestions is welcomed. if i get enough feedback and make one i will post and 'ible.


thanks for your help!! 

Liam.great9812 months ago
I'm 15 so I'm in the same situation as you and italia.hill77. 24 volts will give you just as much speed as a higher voltage one, it's the motor that determines the speed. I'm planning a 24 volt bike. A transformer won't work, they only operate on an alternating current. I agree about saving up for a good system though, don't get something cheap.
tusiji2 years ago
buddy,may be you can check the electric bike kit on http://www.electric-bikekit.com ,maybe you can get some tips for the conversion kit and battery.
gas weedeater bikes are soooo much cheaper i went trash picking on fathers day found a working weedeater and a bike peg (spindle). i am done basicly and only spent about $30 gas bikes have more power too
I'm in the middle of building a 1.2kw moped, a little more powerful, but I think some things will carry over.
There are 3 main components to an electric bike: the motor, the battery and the controller.
The motor: You have two options with the motor. 1. You can connect a regular electric motor to the bike wheel using a chain or belt. A great website for 24 volt motors is: www.electricscooterparts.com/ 2. You can use and in-wheel motor or hub wheel motor. This motor comes inside a standard sized bike wheel and requires no chains, no welding, and no brush replacement. In a sense it's plug and play. A really good site for this is www.goldenmotor.com/ There is also probably a lot of good inspiration on there too.
The controller: This is the surprisingly the most important part of the system because, without a bad controller you can toast your batteries and your motor, which is a very expensive mistake. www.electricscooterparts.com/ and www.goldenmotor.com/ provide controller that match up with motors on their sites. This is probably the safest option since these companies have already tested that the motor and controller can be coupled. For a more DIY, but dangerous approach, try www.newkellycontroller.com/
Battery: Your battery is by far the most expensive component, but also determines your power, range and torque. You can have a super powerful motor, but it is only going to spin as fast as your battery can power it. www.goldenmotor.com/ has a great kit for 24 volt bikes which includes a battery, motor and controller for a pretty good price. www.batteryspace.com/ is a much more advanced option that I would not recommend going with unless you knew a thing or two about electric propulsion.
I think the best option for you would be a 24v kit from www.goldenmotor.com/ because it offers a challenge of assembling it, but also has most of the major bugs worked out of the system. The hub motors also provide quite a fun ride, (look up golden hub motors on youtube.)
Sorry if I've gone on for a little bit. I get excited whenever anyone mentions electric bikes. I also am in the same position financially where I am only 15 and there for don't have a lot of money to spend. I think however that it is better to save up the money and get a good system rather than waste it on something that is just going to break. Ask if you have any questions. Have fun.

zipzapper859 (author)  italia.hill774 years ago
ok thanks that really helped. i will look at www.goldenmotor.com/ and see if there is any thing in my price range. you really helped me
jeff-o4 years ago
My problem, when it comes to electric bikes, is that I'm strong enough to outpace and outdistance all but the most expensive systems out there.  There just isn't any reason for me to build an electric bike, aside from laziness. 

I suggest you ride your bike every day, cruising the city for junk that people have put to the side of the road, that you can use to build an electric bike with.  Look for stuff with an electric motor in it already, like battery powered yard equipment and the like.  Eventually, you'll have tree trunk legs AND a good stash of stuff to build your electric bike with.
zipzapper859 (author)  jeff-o4 years ago
thanks that really helped. i am going to try to ride my bike a lot more and once i get my other bike fixed witch is a mountain bike i will try to ride my bike even more. i have been trying to look for stuff like that and anything useful but i live in a city where people don't usually throw away that sort of stuff......also would a washing machine motor work and how about a drying machine motor?
Both of those are AC motors, they need 120V AC to run.  What you're after is a DC motor, in the 18-36V range.  Most modern battery-powered tools (drills, saws, etc) as well as battery-powered lawn equipment (weed whackers, lawn mowers) will fall in this range.  Basically, if it has a motor and runs on a battery, it'll have a motor that *might* work.

As for using the bike gears, yes, it can be done to a certain extent.  You'd basically connect the motor to the front chain ring (assuming there's more than one, that is), and have it "assist" your pedaling.  You can then change gears on the rear cassette at will.  The catch is that the motor must spin relatively slowly (around 500rpm), which most of them will not.

It's more likely that you'll need to connect the motor to a tiny wheel the size of an inline skate wheel, which will rub on the rear wheel or drive a huge pulley connected to the rear wheel.  You would then need to use a traditional throttle with the motor.
zipzapper859 (author)  jeff-o4 years ago
what if i put a dc 36 volt to ac 120 volt transformer? it was just a thought. how big of a drill would i need to power it? and for the last paragraph in you reply that is the one right above this one is that for when i wanted to have both my leg and the motor power?
Well, then you'd get into needing an inverter and a transformer and all that nonsense.  It adds weight ans expense.  No, you need a DC motor.

The biggest drill you can find.  But, it still won't get you up to 20mph.  Not on its own, anyway.

Yes, the motor directly driving the wheel would allow both leg and electric power, but no control through the bike's gears (at least not the electric part, your legs would still get that benefit).
zipzapper859 (author)  jeff-o4 years ago
ok thanks and when i petal would the motor act as a generator and recharge the batterys?
lemonie4 years ago
If you're short on cash, you're probably best using your legs instead.
For fast and light, it's not sounding cheap to me.
Have you looked at any of these?
instructables - electric bikes

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zipzapper859 (author)  lemonie4 years ago
i have looked at some of those but i will look at more and fully read them

it doesn't have to be that fast but like up to 20 mph would be fine with me. i would also like a way that you can flip a switch on it and it would turn off the motor to save battery and i could peddle.
The dual-power option is interesting. I'd weigh up what you can afford and think practical, and base your design on something that seems to add up. Technical problems can be addressed later, but a starting point is going to be from what you reckon is possible.

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zipzapper859 (author)  lemonie4 years ago
ok thanks i will look at my bikes soon and see witch one will work. also do u think useing the bikes gears would work?
You have to have a throttle controller of some sort.
zipzapper859 (author)  steveastrouk4 years ago
ok thanks i will try to find a cheap one