HT Motor + Shift Kit + 6V/12V generator

AussieSteve

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I'm thinking about putting together a generator/dynamo charge system for 6V/12V 5-7Ah batteries to run from a shift-kit jackshaft via belt-drive.
The generator is only about 1 1/4" diameter and 2 1/2" long - not too intrusive if they work OK.

If the generator that I have in mind does the job properly, there should be about 30-50 Watts of continuous power available, or more for intermittent use, at 6-12V.

I will also build a regulator to suit.

I'm wondering if there'd be enough interest to make more than one, just for myself.
If practical, I'll make them for sale, but wanted to do this little bit of 'market research' first.

I've been thinking about this for quite a while but have been busy on the main parts of the build. That's almost done.

... Steve
 
No replies, so I'm only making a 1-off for myself, it looks like.
I just posted all of this in another related thread instead of here, so I copied it and pasted here where it should be.

I got as far as working out how to mount the motor, (hereafter called a generator), probably just above the jackshaft, it fits like a glove and the approximate gearing to start with, about 8:1 or 10:1. That's just doable in the space. (At 10:1, the generator will be spinning at 1.4 times the speed of the motor. Might be too fast yet. At 7000 engine rpm, the genny will be spinning at 9800RPM. Trial and error will get things right.)
Incidentally, this method has one drawback - it will only generate when the bike is moving. ie The clutch must be engaged to turn the jackshaft, so the battery must carry the lights while the bike is stationary.
Not much of a problem. This type of system needs a battery to function well, otherwise everything stops working when the engine stalls or the lights dim when the idle is low and there'd be something wrong if the battery couldn't run the lights for a short time without generator input.
ie A 12V 7Ah battery could run a 60W headlight for an hour or more. (Not that we need 60W of light.)

The generator is small but gutsy, as a motor it uses about 120W under load, (10A @ 12V). It came from a 12V portable compressor for pumping up car tyres.
It's 57mm x 36mm, with a 3mm shaft that has a flat spot for a grub-screw.
Should go close to doing the job.
For now, at least, I'm setting up with plastic pulleys and a belt, but I'll have to get metal pulleys if it works OK. I'll probably mount the drive pulley on the side of the 17T sprocket, or hard up against it.

I haven't thought about the regulator yet, but that bit will be easy. I want to ensure that I can get usable power first.

Pic of the motor below.

... Steve

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im thinking of doing something similar. My buddy and i are designing a regulator and battery charger, with the logic for a full lighting setup, all LED using a total of 2 amps of power @ 6v, 12v would work too. The generator attached to the jackshaft is a great idea. If you can get it working and geared right i would be a poenetial customer.
 
Hi HseLoMein.
There's no reason why it wouldn't work, once the right generator and gearing are found. Hopefully, the current motor will do the job. They're cheap, readily available and fairly high power for their size.

Now, to my specialty, electronic design. Sounds like you might know what you're doing there, too.
The first bit is mechanics and 'trial and error' to get enough usable power. The voltage is irrelevant, that can easily be converted with a buck/boost style switching regulator.
I've still got tons of spare parts left from my old business, (I no longer work), that would be perfect for the regulator. ie Very low Rds [on] MOSFETS, of the order of 5-10milliohms 'on', several types of DC-DC converter IC, heaps of cores, winding wire and a coil-winding machine. No trouble making a regulator/charger to suit the system.
I've also got Circuit Simulation software, PCB design software, blank pre-sensitized S.S PCB material, etc etc. My specialty was really microcontrollers, and I still have heaps of those, (PIC 12C508, 16C711, 16F84A, 16F876), along with a compiler and programmer, so I could make it a 'smart' system if necessary.

I'll keep everyone posted on how this develops.

... Steve
 
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I need to hop in the first flight the AUS, you sound like you have the perfect workshop. my next project will be trying to wind a more powerful coil. I think i can get more than 10 watts out of the extra coil i have installed. I just dont feel like winding and counting by hand. and i dont have a real good understadning on winding a coil. know of any resources?
 
Resources? I've got lots of books here. When do you arrive?

Best I can say regarding resources is to do a good web search. It's pretty complicated.
I mostly work with high-frequency coils, using (powdered iron or ferrite) cores that I have all of the specs on, especially relative inductance and core saturation figures etc.
First, it's not too hard to work out the number of turns and wire gauge to be used, along with any fancy winding such as double-spacing etc, depending on voltage and current, then the core is chosen to suit.

You're sort of working the other way here - make a core, see how many turns you can fit on it, then cross your fingers as you measure the output.

I had a go at an extra coil under the magneto cover, opposite the original coil, but it didn't show enough promise to be worth continuing, hence the latest effort.
I know that this will work.

The problem with the extra coil is that only the windings are near the magnet, rather than a section of closely-spaced core. That reduce's the coils efficiency dramatically.
If you can make a core the right shape and size, there's not enough room left for a decent number of turns on the coil without going down to too thin a wire for the job.
I had a final attempt with 0.2mm enamelled copper wire, as many turns as I could possibly fit. The voltage came up nicely, but the series resistance was too high under even a moderate load.

The coil I mentioned will be an integral part of the regulator, switched at 20kHz+, for step-up/down to 12V. (Actually, a miniature high-frequency transformer, about 1" x 1", but I'm lazy and call them all coils.)

... Steve
 
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A couple of issues: It will only charge when moving and you will have to gear it way up since it is running off a reduced output speed from the gears. It might work but you would be better off adding a pulley to the crank or driving it directly off the crank.
 
Of course it will work.
I covered both of the issues you mentioned, earlier, in post #2.
(The crankshaft to jackshaft ratio is only 6.97:1, not hard to overcome.)
And where exactly do I fit the generator if I run it off the crankshaft? Of course it would be better, but it's not practicable.

... Steve
 
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Of course it will work.
I covered both of the issues you mentioned, earlier, in post #2.
(The crankshaft to jackshaft ratio is only 6.97:1, not hard to overcome.)
And where exactly do I fit the generator if I run it off the crankshaft? Of course it would be better, but it's not practicable.

... Steve

You are right. I did not read your second post. You were already aware of those problems.
 
No worries, Scotchmo.
As I said, of course it will work, that's a given.
What I don't know is just how well it will work and how long the motor/brushes will last at those rpm. I might have to gear it a little lower, but then it might not provide much current at lower revs.
All trial and error. And fun.

... Steve
 
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