PD: Primary Drive Make your own Generator

Bill Thomas

Well Known and Active Forum User
VOC Member
Is that what many of us refer to as an engine shaft shock absorber? If so that is not doing the same job as a slip clutch and one of our German contributors, Oexing, does not like the ESA. When people started playing about with alternators in the 60s some people use a toothed belt to drive the alternator. It did not take long before primary chain wear become obvious and it was soon realised that some form of slippage was required. That is why the Walkernators use a multi vee belt.
Like the time I was talking to a Bloke with a toothed belt, Mine was a V, He said I might try that !.
I said I was thinking of trying your way, Mine slips a bit !, He said , Well mine breaks the teeth off the belt !!.
So I left mine as it was. Cheers Bill.
 

oexing

Well Known and Active Forum User
VOC Member
Sooo, here are my latest findings from the test set with 48 V three phase brushless motors. Actually I got a lot more power from the mid size motor than I will ever need, starting from low speeds and with no temperature problems in my workshop and no cooling.
My previous tests were tried with same motor but typical brushless permanent magnet alternator motorcycle voltage regulator. That was NOT a great set up just as timetraveller had suspected: The technology with one - or most of - these is simply to earth one or more phases to keep voltage within limits. I observed some groaning in the motor once speed exceeded the specified voltage and in that state the regulator plus the motor started to heat up quickly to unacceptable temps so I had to stop when some Lucas wire smoke appeared from the motor. By doing some Google reading I learned that this type of regulator is widespread in motorbikes when excessive heat gets cooled down in oil bath generators - so no choice for a Vincent.
New idea was to get a standard voltage converter 48 V to 13.8 V to go with the three pase rectifier. I blew up two 55 W quartz bulbs before when I exceeded the voltage limit with a 24 V to 13.8 V converter when I did a quick high speed test to 5000 rpm and the converter blew up two capacitors and the bulbs in a second. The 300 W motor in the photos does 55 Volts AC at 5000 rpm so no surprise really.
When I got the 48 V converter recently I hooked up all components , rectifier for single phase DC and converter to 14 V and got these numbers after half an hour test run, no cooling :

cold motor 55 W bulb sees 14 V at 2450 rpm - 1960 rpm at crank
100 W bulb 14 V at 2520 rpm - 2020 rpm at crank
155 W (100 + 55 W bulbs ) 14 V at 2670 rpm - 2140 crank speed

I then hooked up three quartz bulbs to have 210 W on the motor and did half an hour run, with little reduction of performance at higher temperature:

210 W 14 V from 2820 rpm - 2260 at crank
after a 10 minutes run at 3200 rpm and 210 W load the motor temps came up to 47 degrees C , after half an hour at 210 W load and 3200 rpm at the motor I got 55 degrees on the motor, NO cooling.
The rectifier and voltage converter had practically no temperature rise , so no worry on a bike at all. So my conclusion from that is the mid size 300 W motor is more power than I´d ever need . You can get four sizes from Aliexpress, all same size but different legth, from 100 W to 400 W 48 V , 14mm shaft.
When playing with the generator I fabricated some type of friction clutch for the dynamo so as to post some idea for owners who may run a geared Alton on the triplex chain and old ESA. I do not believe to really need it with my own design ESA but it does not hurt. The mass of the permanent magnet rotor is a lot lower than say a miller dynamo armature so even less critical anyway.
I placed some friction material at both sides of the sprocket and loaded the unit with wave type spring washers. Only road tests will show if I need to add another washer due to too much slip at higher loads from the alternator, no problem.
An Alton is certainly the easiest way to replace the Miller dilemma. But for those who love lathe jobs the cost of all the China hardware is around € 100.- depending on size of motor. So for the difference to the Alton version you may want to mess around in your workshop instead and be creative . . . .

Vic

48 V brushless
48 V converter

P1070256.JPG


P1070265.JPG


P1070266.JPG


P1070271.JPG


P1070272.JPG


P1070097.JPG
 

bmetcalf

Well Known and Active Forum User
VOC Member
It looks like there are two devices on the output of the "motor".

I can't remember all of this thread, but it looks like you have to turn the diameter of the motor to a minimum and make a slip type hub. What mods to the crankcase? Is a special spacer needed between the dynamo cradle and the motor body to center the shaft in the opening to the primary case? Maybe a short summary?
 

oexing

Well Known and Active Forum User
VOC Member
Two devices ? Basically it is a servo motor with a hall sensor at its rear end, not needed here and removed. My last version has a friction clutch on the shaft, optionally, if that is needed is another question. I did it for exercise.
My engines are B-Rapides, no extra cradle, so some minor machining central to the factory dynamo axis was required. 68mm motor o.d. is minimum for this brushless, else you´d cut into the 3mm bolts. 70 mm might be easier, but then you get less of engine contact with smaller machined faces on the motor. So I cannot say much about C series matters when fitting these motors on separate cradles, even more choice I guess.
I made a 40 mm extension cap on the front end for getting another ball bearing next to the sprocket plus an o-ring to seal in the bore of the primary cover. You will get the idea when looking closely on the photos in this thread, first page mainly.

Vic
 

oexing

Well Known and Active Forum User
VOC Member
Well, for me the case is closed: I am completely satisfied with my test findings, way more power than I ever need. In #93 you find all details about this. I´d recommend the 48 V three phase motor with its 14mm shaft, mid size 300 W or less . The longer types just as good but too much wattage for most but space no problem, same fixing sizes , only longer. This is an idea for those who like to mess around a bit at the lathe, hardware costs below € 100.- including three phase rectifier and 48 to 13.8 V converter, see link for 4 sizes of motors. Total length will be shorter as you don´t need the encoder at the rear end. Alternative is an Alton, provided it is ungeared, otherwise it will wreck its gears due to the non-effective standard ESA. My guess, the Alton should be easier on the Triplex chain as the rotor has lower mass than the one in Miller dynamo, same goes for the 48 V motors, masses shown above in photo comparison.
I will need another year or two to finish two B-Rapides for real road tests but am very confident about performances thinking of my tests in my workshop, no air flow, no cooling in half an hour test at 200 W load.

Vic
48 V motors
 
Top