gas -alternator powered 250watt

How do I become an active member if I cannot post?

lol post 3 times and then you'll be "active" - which ofc you just did

It's to help with the evil spam...


|.o

you can post like you just did... for a while you can't hot link that is prevent people from joining just to post a link to their website.. and then never participating again The people here don't want to run a cataloge business.

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OK- update.
I tested a Ford alternator ('86 which has a remote style regulator), NOT using a regulator, on the bench, hooked up to my drill motor (up to 2200 rpm. Energized the field windings with a 12 volt source. Connected the alternator DIRECTLY to the 24v 250w scooter motor.
The volts would go up to around 25 and the motor followed right along. I was surprised at how slow the alt. could turn and still the motor would turn too.
Unfortunately, the little direct drive weed wacker motor's tiny shaft output diameter would not take the strain of inertia ( or my attempt at a coupling) twisting a mild steel square piece or shearing a hardned square. When it did run the vibration was awsome- then all of a suden it ran great- minus the alternator.
I am thinking about waiting for the 2.5 hp HF four stroke engine to go on a bigger sale than right now. The thing needs a belt drive. The "Gen set" would be on the back.

I almost bought a I-zip until I saw a vid on youtube and the poster mentioned how loud it is. Really seems to scream to me - It would drive me nuts.
New York made electric assist bikes legal recently (It's nice to see them do something right) so I looked into electric, BUT the batterys are the big bugaboo. Why not displace them with a gen-set?
From my experiment, you have 2 controls:
The amount of current you give the field and engine rpm. NO controler needed. One small battery needed
I would like to tap off the alt. output with a diode (so current can only go TO the battery and a regulator to send some current to the battery when the alternator is outputing.
I want to power the pedal crank, so as to keep the motor in an efficlent range and still have full gears. I pedal at around 50 rpm. It would spin the pedals by itself along with the back wheel, but that is not a biggie to me.

What do you mean displace the batteries with a gen-set? I'm glad you're experimenting but there's just no way around having to use batteries, usually SLAs. You can spend upwards of $800 for the li-ions but that's insane and they can poop out on you at anytime and most likely, there will be no warranty to protect your investment. Until one of the many promised miracle batteries that are "just around the corner" materialize, we're stuck in the stone ages. Yes, the Currie motors scream like a siren. Some MBers would love the attention that such a noise attracts, but I find it embarrassing. Other than that little problem, the ezip is a great, durable bike.

Hi Professor – Your experiment sounds interesting. You know you need a battery to energize the alternator field but it could be a small one. If you’re not storing a lot of electricity (batteries) then you will be running the engine the entire time – probably just as noisy as the Izip. The laws of physics tell us that the energy required to power the e-motor (250 watts) will show up as “drag” on the alternator. Put a load on your motor and see if it doesn’t slow the drill. There are lots of videos on YouTube showing experiments with a bicyclist pedaling a stationary bike hooked to a generator or alternator. It looks like they’re not working at all. As soon as they put a load on the generator (lightbulbs, a resistor, etc) the bicyclist bogs right down like they’re riding in mud. That’s how those exercise bikes hooked to generators work – higher resistance makes harder pedaling = more exercise. Another thing to think about is: 250 watts is about 1/3 hp. You’re talking about using a 2.5 hp engine to generate 1/3 hp. Seems like a waste to me. Probably much more efficient to hook the g-engine directly to the crank.

Finally – please rethink the idea of powering your unmodified cranks. If your foot slips off and gets caught between the crank and the ground or you are leaning into a corner and a crank hits the ground, the results will not be pretty. There are several places that sell freewheels that fit between the crank sprocket and the crank so you can use a motor (e or gas) to power your chain without forcing the crank to turn. SickBikeParts sells a kit as well as individual parts, or you could look into crank freewheels designed for tandems - jd

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Jdc- I hadn't thought of that. Good call. I will be looking at a way to separate the pedal power from electric.
Geek- The deal is, here in New York, it is now legal to motorize a bike with a 250 watt limit electric motor (no gas jobs).
I fully considered a gas powered super- covert (meaning quiet and hidden) but then I thought, I could still use gas power, only, it would supply juice to the electric drive motor. Most little weedwacker motors make about a hp, so even with the losses involved, there should be enough power to easily drive 250 (or more) watts.

I am NOT looking for speed. I ride around 10 mph on my bike, often using the sidewalk. It would be nice to go a tiny bit faster, or take hills easier, or go to work ( weather permitting) without being a sweat-ball when I arrive.

nice the electric drives it so your within the guidlines but it's gas so just fill it up no waiting to charge batts prolly last longer than batts too

You got it Motor.
Update- After many hours adapting the weed wacker to drive the alternator- the wacker has not enough torque to run the alt. I could not even start the thing with the belt connected.
I have a rain check for the 2.5 hp engine from HF and should be able to pick it up this friday. Only issue is the 23# it weighs! But it will have torque. I am looking at a full up weight of over 70 pounds for the Mongoose with all the drive stuff. Heavy, but no heavier than some electric bikes.
Yes, the engine will be running at all times with varying rpm. The engine and alternator will go on a rack. As for noise level, I will make a muffler and sound attenuate the deal later. It WILL be quiet.

I just ordered a sprocket and attachment to the back wheel. Real unsure about drive ratio, I have 5.2 from the electric scooter to the jackshaft (which is a rear hub from a single speed 20 inch bike with the freewheel side having the scooter sprocket and the other side as small sprocket as I can weld on), the wheel sprocket I ordered is a 44 and the sprocket I welded to the "Jackshaft" is about 2.5 " - maybe 2.5 to one. Can go bigger on the rear sprocket if needed.

I have had a bunch of stuff to do lately (winter preparation-snow tires, rustproofing wife's car with oil/cosmoline........) and will be able to do some more on the bike, especially since rain is forecast fo the next several days.
What is unique to me, is that as far as I know, no one has done this kind of set-up.
If it wasn't for the NY law making 250 watts legal- I would not have attempted it.
If the thing works out, it could be repeated in places like Austrellia (spell?).

I was reading that a weedwhacker engine goes anywhere from 7.5k-12k RPM wide open. That's a pretty high frequency electrical output!