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diy elec bike assist Answered

I guess I need to explain that I'm an old guy with a bad ticker. I also have some big time balance issues. I needed to get a little more active and work on my balance, so I bought a bike. The bike is about a million year old cruiser, so I had some work to do before I even took off on it. I cleaned and repacked everything. Then I switched out some parts to make it more comfortable. I replaced the sprocket drive set on the 26 inch bike with one from a 20 inch to make the peddles easier for me to reach. I also used the smaller drive sprocket. That might not have been such a good idea as I have to peddle more to get the same distance. I had intended from the start to install a helper motor so the pedal thing isnt really a big deal. I designed it this way. Motor: 24volt 250 watts from a kids scooter toy. drive: friction with a wheel that sits on the rear tire. Now the motor and mount I have worked out just fine. I'm waiting for everything to arrive so I can begin work. My question is about the power source. I really do not want the power source to ever run the bike. I simply want it to assist me climbing hills. I dont want to run out of oxygen (fuel) as is happening now. So this is my planned power set up, please tell me any flaws you see in it. One twelve volt battery 12ah complete with momentary on off switch. Push the button when I need a little assist climbing a slight grade. A completely secondary battery probably 7ah with its own momentary switch just to kick in on top of the first battery. When both are on, It should make a 24volt system for steeper inclines for just a few minutes at a time. What problems do you foresee. Any advice would be helpful. Did I mention I like to tinker with stuff. I found over the years when you buy something you learn to write a check. When you build something you learn lessons that are transferable to all problem solving. And my wife made sure I knew how to write a check early on.

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CameronSS

11 years ago

We currently have two electric bikes. The one pictured is my dad's, a BikeE recumbent with a hub motor in the front wheel, 36V system. The other one is mine, though I don't have a picture. It uses an 18aH 12V battery and a friction drive motor on the front wheel. I well tell you this: There's a reason that friction drive is oftentimes called "scuff drive." It eats tires. At least make sure you have smooth road tires on first, as knobs aren't particularly good with scuff drive.

Bike on Courier.jpg
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retrophotoCameronSS

Reply 11 years ago

I might have posted this already but thanks for the information. How does your assist scrubber work does it help you with the hill climbing

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kld435retrophoto

Reply 10 years ago

i see a problem with normal riding, because of the drag caused by the motor, so if you could find a way to disengage it it would be a good idear.

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CameronSSkld435

Reply 10 years ago

The motor does not cause drag unless it's connected to something that will make it work as a generator. when you take out the throttle, the controller essentially disconnects the motor, and there is very little additional resistance.

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NachoMahma

11 years ago

. Sounds like it ought to work. Just make sure your switch can handle the current. . Instead of running large wires to the switch, it might look better if you used interposing relays and smaller wire to the switch. . Since you like to tinker, why not an electronic controller with some kind of continuous adjustment near your thumb?

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retrophotoNachoMahma

Reply 11 years ago

To be honest I wanted to start with the simplest construction and switching possible. Something that was so simple it would not intimidate anyone. Also something to save the battery charge. I wanted to work off one 12 volt battery full throttle and pulse it. Then a second battery that could be brought onto line to kick the power up for steeper inclines otherwise to save as an equal backup when the first battery dies. I have a lot of experimenting to do first I'm sure. I have some push button switches on order ,if they are too small there is a plan b... I just checked with advance auto while I was picking up some small bungee cords. They have the old push button horn switch for a direct circuit from the auto battery current directly to the horn. That cuts out the horn relay so it should work fine, if the hong kong ones dont that is. I wanted to build something anyone can do in their shop with no special tools. I would like to make a set of simple plans available to anyone who is interested. Plans using inexpensive parts easily available. It's what I did with the polaroid conversion to film plans. Of course I may have to go with the throttle controller type mechanism yet. I hope not.

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lemonie

11 years ago

What about a nice 2-stroke engine instead? I've seen old bikes power-assisted in this way, and you get a better power to weight ratio.

L

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CameronSSlemonie

Reply 11 years ago

It also requires mixing two-stroke fuel (pain in the neck), it stinks (pollution! pollution!), and it makes an obnoxious, rattly whine that I would NOT want to have sitting on my bike. Electric motor requires plugging it in when you get home, has zero emissions, and is whisper-quiet. SO much more pleasant.

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GoodhartCameronSS

Reply 11 years ago

Zero emissions at the point of use. But if the power to charge it comes from a power plant burning coal, weeeeeell ;-)

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CameronSSGoodhart

Reply 11 years ago

Ohhhhhhh dear, you don't want to get me started on THAT subject. Actually, I don't want you to get me started on that subject, because than I might be inclined to crunch numbers, since I've forgotten the exact figures. For a given watt-hour of electricity produced by a coal-fired plant, the emissions are negligible compared to not only the direct emissions from an amount of gasoline with equal energy content, but also the indirect emissions produced by the refinery (which is one of the chief consumers if coal-generated electricity), the emissions released in transport from the Middle East by assorted supertankers, and the emissions released by all the bullets that we're firing to keep it going.

Shall I continue, and track down the numbers?

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GoodhartCameronSS

Reply 11 years ago

Depends on who crunches thenumbers I suppose. I have seen the figures from others that claim it is worse, nobody seems to agree, so I just throw it out there for consideration, not for argument's sake ;-)

Same with "alcohol as a fuel"; some feel it is worse, some better, for the environment. One thing we can agree on, the non-renewables are running out and we have to do something, and very soon.

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CameronSSGoodhart

Reply 11 years ago

Alcohol being burned as fuel is better for the environment, but we don't have enough sources (i.e., corn) to produce enough alcohol to run the country. Also, ethanol has a lower energy content than gasoline. Crunching the numbers--It always makes me wonder...If two people are doing the same experiments over the same problem, they should either get the same answer, or tel us who screwed up.

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GoodhartCameronSS

Reply 11 years ago

>>>
If two people are doing the same experiments over the same problem, they should either get the same answer, or tel us who screwed up.
>>>

The problem comes in the form of many things: are we all working with the same "parameters", the same quantities, the same starting point, and the same methodology (the same set of assumptions)? Change one, and the may be a mismatch of results.

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GoodhartCameronSS

Reply 11 years ago

Alcohol and gasoline, despite the fact that they are from different chemical classes, are remarkably similar. Gasoline is mostly a mixture of "hydrocarbons". Hydrocarbons are a group of chemical substances composed exclusively of carbon and hydrogen atoms. This is a very large chemical class containing many thousands of substances. Most of the fuels we use such as coal, gasoline, kerosene, fuel oil, butane, propane, etc. are chiefly hydrocarbons. The simplest member of this group is methane which consists of a single carbon atom and four hydrogen atoms. Next comes ethane with two carbons and six hydrogens. Propane has three carbons and butane has four. The substances just named are gases under ordinary conditions. As we add more carbons to the hydrocarbon molecule, the chemicals formed become liquids: pentane, hexane, heptane, octane and so on. As we continue with even more complex molecules, the substances get progressively oilier, waxier and finally solid. Alcohols can be thought of as hydrocarbons in which one of the hydrogen atoms has been replaced by a "hydroxyl group" which consists of a hydrogen atom bonded to an oxygen atom. Thus methane becomes the simplest alcohol, methanol. Ethane becomes ethanol, propane becomes propanol and so on. Like hydrocarbons, there are many alcohols of ever increasing complexity. One of the most important properties of a fuel is the amount of energy obtained from it when it is burned. Note that the hydrocarbon octane, which represents an "ideal" gasoline, contains no oxygen. In comparison, all of the alcohols contain an oxygen atom bonded to a hydrogen atom in the hydroxyl radical. When the alcohol is burned, the hydroxyl combines with a hydrogen atom to form a molecule of water. Thus, the oxygen contained in the alcohol contributes nothing to the fuel value. The relative atomic weights of the atoms involved are: hydrogen, 1 ; carbon, 12; and oxygen, 16. Since methyl alcohol has an atomic weight of 32, half the molecule cannot be "burned" and does not contribute any fuel value. As expected, methanol has less than half the heat value (expressed in Btu/lb) of gasoline. Ethanol, with 35% oxygen, is slightly better with 60% of the heat value of gasoline. The production of alcohol consumes energy. Exactly how much depends on the feedstock (raw material) and the efficiency of the distillation process. In a small operation, it would not be uncommon to expend 30-40,000 Btu per gallon of ethanol. On top of all this, I am not convinced that the sudden increase in CO[sub]2[/sub] produced by burning alcohol as a motor fuel would not be as harmful as our present day addition of C particulates. CO[sub]2[/sub], combined with water gives us Carbonic Acid (H2CO3) in our atmosphere.

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NachoMahmaCameronSS

Reply 11 years ago

> Shall I continue, and track down the numbers? . Please don't. heehee . . I have to admit that you did a remarkable job of summing it up. . Just 'cuz an energy source looks clean, don't mean it is. What does it take to get that "clean" energy to you?

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CameronSSNachoMahma

Reply 11 years ago

Ummm...high-tension aluminum power cables... A lot less than it takes to get crude to gas to you... More than it should, but less than it could... Very little... The dirtiness of electricity production is entirely due to unwillingness to use better sources. For example, wind power. People keep complaining that putting wind turbines up across western Kansas will de-beautify the landscape, but no one ever sees more than the 5-mile wide swath visible from I-70. And yet no one cares about the high-tension power lines strung everywhere.

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lemonieCameronSS

Reply 11 years ago

Westar Energy claim to have some amount of wind capacity (bugger-all as compared to coal, oil & gas I guess..?) But you make a good observation with regard to turbines spoiling the view: a lot of people would rather have a coal, oil or nuclear plant that they can't see and easily ignore.

L

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lemonieCameronSS

Reply 11 years ago

If your electricity comes from e.g. Westar Energy, there are emissions, from burning coal, oil & gas.

L

(I know the advantages of electric, I just prefer engines...)

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Goodhartlemonie

Reply 11 years ago

many cities might require a license to drive it on the streets.

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retrophoto

11 years ago

Well my thinking was a gas engine would have me going too fast, just because i could. Probably get me killed with my balance problems. Also it is going to be dead easy to build and install the electric scrubber. I paid less than twenty bucks for the engine. Less than fifteen for the drive wheel clutch included. The push button switches (6 to the pack) were less than then bucks. I could never rig a gasoline conversion for that. I would love to say its about the principle of the thing, but it's really about the money. And the things that I could do myself easily. I wrote one of the pamphlets on how to convert a polaroid camera to shoot film but it was with epoxy and spit. I like to mess around with things making something workable out of things that really aren't designed for the purpose I use them. The idea of buying a complete kit was just foreign to me. Now I may yet have some additional expenses mating the drive wheel to the motor ect. but nothing much. Those chinese gasoline kits are indeed noisy but they say with the new synthetic oil mix they don't smoke too much. I just liked the idea of a bike no one can really be sure is motorized. The lack of noise and the slower speeds appeal to me. I already have a bike trailer made from a rubber made storage container i can carry extra batteries in should I decide to take the rig camping. Not that I likely to do that.