# How to make a 24v source power a 96v motor.

Discussion in 'Electric Bicycles' started by FuglyHippo, Apr 24, 2011.

1. ### FuglyHippoNew Member

I made a thread in the Introduction section but was told to come here for better info! Here's a copy/paste of the thread:

I just bought a new car and am moving to Norfolk Virginia in a few months to attend Old Dominion University. I don't want to drive my car too much around this terrible place due to me terrified of people dinging, scratching, etc. my car. Also don't want to skateboard or anything that requires me to sweat. So I want to make an electric bike, also kinda want to do it just for fun.

I will be picking up a mountain bike from my uncle in about a week, so no bike as of yet, but I do have some other things.

I have 2 x 12v 145ah batteries and a treadmill electric motor - peak 2.25hp, 1.3hp continuous @ 95V 18amps.

Now clearly you see the issue haha, I'm having trouble finding a GOOD way to convert the 24v to 95/96v for the motor.

Any suggestions? Also, will this treadmill motor work?

If I'm not relaying enough info for a solution etc, please tell me, I'm very new to electronics of this kind.

Thanks in advance! :grin5:

2. ### bluegoatwoodsWell-Known Member

Well, let's see. I'm no authority on this, but I have a thought or two.

That treadmill motor is probably designed to work with alternating current. I think it's not likely to work on direct current. (by the way, I wonder why it's not rated at 110 volts?)
But this is just guesswork and might be nonsense.

A 145 amp-hour battery would have to be about as big as a small beer cooler and weigh 50 lbs or so. Maybe you meant 14 1/2 amp-hr? that would make sense.

All you'd need is 8 of those, wired in series, and you'd have 96 volts. But that would be a lot of weight.

You might be better off clicking on some of the vendors here and finding a 24 volt hub motor. If you didn't buy batteries (since you have your own), then you'd get it pretty inexpensive.

good luck.

3. ### FuglyHippoNew Member

I used my camera phone, which is the worst camera ever haha.

But I'm pretty sure my info is right :/

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4. ### DouglasNew Member

Pictures are too fuzzy to make out. Take the stuff outside and take a pics in the daylight.

5. ### bluegoatwoodsWell-Known Member

Still, on the motor I think I read "DC motor" on the label.

But you'd still need an awful lot of batteries. And you'll likely need some sort of gear reduction.

That's not to say that it can't be done. But I have a feeling that it won't be done quick or cheap.

6. ### FuglyHippoNew Member

I'm not worried about gearing, I just need the batteries to juice the motor enough to make me go haha. I dunno how to make a converter to quadruple voltage.

7. ### bluegoatwoodsWell-Known Member

No, I don't think there's any "converter" that'll do that for you.

I'm pretty sure that your only choice on that is to hook up 8 12v batteries in series.

You already have two. So you need six more. Figure on about \$250.00 for those.

Then you gotta figure out how to mount them on your bike.

And I might as well not even go on with that. This just isn't a very workable option.

I wonder if merely applying your 24 volts to the 95 volt motor would work for you. It might not be the most efficient use of that particular motor. But if it moved your bike, then that wouldn't matter. It might be worth a try.

8. ### DouglasNew Member

I say sell the motor and use the proceeds to buy (like bluegoatwoods said) a 24v hub motor. Even if you could get a dc-dc converter, it would just add weight and complexity.

9. ### NeonMember

Could use a step-up transformer, Might be difficult to find the exact input and output voltage though. Plus transformers are kinda huge battery drainers. Unless you know of someone who is able to make them. Of course this will add more complexity and weight as mentioned before. Then there's the problem of some sort of controller. I don't know of any 96v controllers out there. The last i checked 48v was the highest i saw. Could be more available but i don't know for sure. Anyway it is a much better option to purchase an electric kit. Hub motor seems to be the best way to go(as bluegoatwoods said). Put it on, hook up some wires and battery, turn on the power, twist the throttle, and go.

Last edited: Apr 28, 2011
10. ### FuglyHippoNew Member

Well shucks. I just got the bike I'll be using today, it's a typical mongoose mountain bike, but it does have some nifty places to hook up a rack behind the seat, which makes things a tad easier

I also plan on relocating the rear brakes to where the kick-stand is.

I also am not really interesting buying a kit, I want to make this, hence the whole reason for doing it.

I'm thinking with your inputs I'm gonna start searching for a 1500watt+ 24v motor.

11. ### FuglyHippoNew Member

Here's the bike. Got it for free from a relative. Woot-woot.

Also, how do you get the pulley off a typical eletric motor??? haha It seems to be just wedged on there!

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12. ### NeonMember

Nice bike. Some pulleys have a very small set screw or are just pressed on. A puller of some sort may work if it's pressed on. Be careful of the DIY route You may end up with an ugly mess like mine

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14. ### NeonMember

Wouldn't mind having one myself. But it seems a little too good to be true. That much HP for a mere \$169.04. Of course the bidding is not finished yet. Doesn't seem right to me.

15. ### FuglyHippoNew Member

Can you guys link me to some 24v motors that are known to perform well? I want ATLEAST 1000watts.

Thanks!

16. ### NeonMember

You can head over to http://www.goldenmotor.com The motors they have usually get pretty good ratings over at endless sphere. Thinking of getting a magic pie rear hub motor myself once the income tax return comes in. The site is in china but they list distributors all over the world. Cyclone Taiwan may also have what your looking for as well. The motors are good i guess, but the rest of the components seem to be substandard. Sorry there are 72v controllers, possibly 96v as well. You may want to consider different batteries as well. SLA(Sealed Lead Acid) are not recommended for that much wattage. Plus they are much heavier than newer lithium batteries(pick your flavor). But of course they are much more expensive. Just a suggestion you don't have to take it as gospel.

Last edited: Apr 28, 2011
17. ### etardNew Member

Since you are such a noob to all this electronics jazz, I would definately suggest getting a hub motor kit. You want to spend more time riding than fixing right? There are many issues with chain drives:

How to mount the motor so it is solid
Where to mount the motor so it is not in my pedal stroke
How to mount the motor so the chainline clears the seatstay and chainstay
How to fit a sprocket to the motor shaft
How to make sure the motor freewheels while it is off
How to attach a rear sprocket to the rear wheel
How to tension the chain
Which size sprockets to use
Why is my motor getting so hot
Why didn't I just get a Hub motor!!!:rolleyes7:

The treadmill motor wouldn't be too bad an option to start with since it is free. Your voltage is the determining factor in motor speed, so at so 48 volts it is going to be turning at half it's normal speed, which might not necessarily be too bad. If the motor spins too fast you will have problems with gear down to the rear wheel. You can also buy brushed controllers for relatively cheap since they are fairly simple devices. Your batteries are a concern to me, you should look into getting some Ebay PING batteries, the chemistry is LiFePo4. You can also use tool batteries like the 28 volt Milwaukee, or Bosch, or even Dewalt.

Good luck, sick bike parts has lots of good adapters for ebike conversions using an external motor.

18. ### NeonMember

I didn't think sick bike parts had anything to do with electric at all.

19. ### IbedaYankMember

Nominal Voltage 12V
Capacity (25ÂșC) 134 Ah
Length 13.5
Width 6.8
Height 11.2
Weight 94.8 lbs.

thats 758.4 # in batteries i dont see a bike carring that much weight
to get the 96 volts
oh yeah price

Price: \$382.64
it can be done but not cheap and won't be light using that size battery

best bet hub motor and small sla battery pack

Last edited by a moderator: Dec 18, 2015