PD: Primary Drive Make your own Generator

Garth Robinson

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In the 70 s, I did a quick Bodge, Cut a Dynamo body in half, Fitted 2 drive ends and put a V pulley on the end.
This Jack Shaft has a V belt to run an Alternator from an old British Mini car, Built in regulator, More Power than I will ever need !, Does not over charge a 4 amp cheap battery, 12 v.
IT'S STILL ON THERE :) .
For my new Bike, I have a Walkernator, Ready to fit, Very well made, Much neater than my effort, Better belt type. Cheers Bill.
Bill,I did the same thing too back in the early 70's too. The alternator I used was off a Mini Cooper that had been wrecked. Mine has been on my B since then too.I went through 2 regulators before I found a poor connection between the alternator and the ampmeter.Instant death! I think the benefit of using this type of automotive gear is that it is well proven unsophisticated and readily available.I didn't have any flash tools at the time so most was done in the fitters room at work. I always carry a spare belt in the headlight so I don't get stuck.
 

Bill Thomas

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Good one Garth, Simple is best.
I had mine driven by the back wheel, For a time, Ron welded a pulley that bolted on to the centre of the rear Disc, With a great long belt !.
But to get the warning light out, I had to get up to speed, So it was drag starts all the time. I went on holiday to the I.O.M., And it worked fine.
But the stress of watching the light all the time, Got to me, So made a better job of it.
Cheers Bill.
 

JustPlainBill0

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Considering my need (and maybe Vic's need too) to increase the speed I'm driving my China motor to produce whatever power it's capable of, it occurred to me that an air tool (die grinder or cut off tool) with a collet/chuck that fit the motor shaft might be a good option. The unloaded speed of a cheap air die grinder using 3 CFM @ 90 psi is 24000 rpm. They do slow down under a load and I have no way to measure rpm on one, but learning the voltage and watts output is all that's needed for the purpose of judging the fitness of my motor as a generator. Any suggestions or other options please?
 

timetraveller

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If your die grinder is the same as mine then there will not be enough torque to keep the revs up once the system starts to take significant power. What would work, and would not cost too much, is to buy two aluminium pulleys designed to take a toothed belt and a suitable toothed belt. The larger of the two could be mounted on a shaft held in a powerful cordless drill and the smaller of the two would go onto the input shaft of the electric motor. I would be looking for a speed ratio of about 3:1 so that 2,000 rpm on the drill would rotate the motor at 6,000 rpm. Suitable pulleys and belts are available quite cheaply from engineering supply companies. The electric motor could be held in a vice and the drill by hand as the belt will allow some misalignment or the whole lot could be made more secure with wood and some clamps. Depends upon what you have available.
Note that I have mentioned a figure of 6,000 rpm for the electric motor. With the Walkernators the alternator runs at about double the engine speed, on a twin, and if you look at most cars there is a large ratio increase in speed between the engine and the alternator. I believe that this is to ensure that there is adequate charge at low speeds. My fear is that the present experiments with relatively small motors and no significant gearing up of the speed will fail to produce what is wanted but good luck to those who are trying. I might be wrong.
 

Gary Gittleson

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If you want to measure the RPM of your test setup, you can use something like this:

I'm sure these are available in many countries; from China, of course. The only problem you might encounter is that the reflective tape they provide could spin off at 24,000 RPM.

I used one recently to set up an electronic tach on a diesel tractor. It worked very well indeed. My calibration speed was in the 2,000 RPM range.
 

JustPlainBill0

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For short term closure: I ran the China motor with an air die grinder @ 60 psi with a sealed beam headlight (55 watts) and measured 18 volts. The light was brightly illuminated. Based on the motor specs ( 1 VDC per 250 rpm) it was turning 4500 rpm (on a Vincent, 3680 engine rpm/ 80 mph. At that speed, the air die grinder had no difficulty spinning the motor. (Note, the motor is configured to run clockwise as is the air grinder. Which means the motor is being turned backward - counter clockwise by the die grinder. Not a problem, just use the red wire as ground and the black as hot.)

At 125 psi the voltmeter showed 29 volts and the die grinder ran out of "steam" in about 30 seconds. Motor speed would have been 7250 rpm. Vincent engine speed would be 5800, miles per hour 126. All perfectly doable...at Bonneville.

Timetraveller is pretty much right about the need to run my particular China motor substantially faster than engine speed to get acceptable power at ordinary road speeds. The brushless motors Vic is working with make full power (up to 400 watts) at 3000-4000 rpm. That's 2400 to 3200 engine rpm (~50 to 70 mph in 4th gear).

When the Watt Meter I ordered arrives, I'll test again and collect volts, watts and amp output to get a better idea as to whether the China motor will suffice or that I should be looking for a brushless motor. Which I already am.
 

Dave61

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Non-VOC Member
In the 70 s, I did a quick Bodge, Cut a Dynamo body in half, Fitted 2 drive ends and put a V pulley on the end.
This Jack Shaft has a V belt to run an Alternator from an old British Mini car, Built in regulator, More Power than I will ever need !, Does not over charge a 4 amp cheap battery, 12 v.
IT'S STILL ON THERE :) .
For my new Bike, I have a Walkernator, Ready to fit, Very well made, Much neater than my effort, Better belt type. Cheers Bill.

Where did you put your battery Bill ?
Cheers
Dave
 

Bill Thomas

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VOC Member
Can't remember Dave, I was always changing things !, Still am !.
I use rear set foot rests, So I weld up a small box thing, And hang it on the side of a front foot rest plate,
Later and now, It's in the Hump of the Rickman race seat.
I should say I fitted the wheel driven job, With Alternator under the seat, On top of the lower rear spring fitting.
This is how the battery is on my L/ning, With a Mcdougleator, Cheers Bill.
 

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JustPlainBill0

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My electrical knowledge is limited too. Voltage generated definitely needs to be limited to prevent recent unfortunate experience with halogen bulbs being blown to dust when the regulator malfunctions!:(
I think there may be some self-limiting effect with generators due to saturation. We need someone with in depth technical electrical know how to confirm this.

I'm with you Ed on the need for someone with in depth technical electrical knowledge to chime in here. Case in point, my China made permanent magnet but with brushes, motor turns easily by hand and will spin up to 6K rpm with an air powered die grinder. I dug up a very old (1980's) brushless 2.8 VDC stepping motor in my shop and the first thing I noticed is that it really resisted being turned by hand (and it had a 1" dia. toothed pulley). The resistance seemed magnetic, not mechanical. Turning the stepping motor in the drill press was possible but required over-tightening the chuck or it would loosen in a 10 or 20 seconds and spin without turning the motor.

If there's a motor expert around, I'd like to know if that's typical of brushless stepper motors, and if it is typical, wouldn't using one as a generator increase wear on the generator bearings and perhaps on the triplex chain -- as well as increase the load (reduce horse power) on the engine in general?
 
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