PD: Primary Drive Make your own Generator

oexing

Well Known and Active Forum User
VOC Member
Great discussions again, so I came to some more ideas : Using the dynamo for venting the primary case cannot be a serious proposition, so instead I chose to drill from there into the gearbox dip stick adapter, not a long way to do. So I expect to get any air out the gearbox dip stick cap and no oil leaks from there. Also no risk for washing or rain water to get into there. Some caps are vented some not so, at least in my old stock. So I did some Dremel grooving the thread for easier air venting, no hole on top.
As to dynamos, I do not like the Alton gearbox solution for offsetting the rotor drive. You have to care for lubrication in there . Instead I found some permanent magnet dc and three phase ac motors at small size so they can be fitted in this place after some minor milling the engine case for concentric motors with 68 mm o.d. . I will have a big magneto for ignition so all generated current will go into lighting only.
The dynamos - ahh, dc/ac motors got new longer front plates for twin sealed ball bearings on 8mm shafts for reinforcing this place. Sealing will be an o-ring machined in the motor front plate, no silicone or some such.
I did some power tests today with an electric hand drill and got these readings, revs corrected to crankshaft speeds, 1.25 lower than the dynamo sprocket:

The round dc perm mag. motor 68 mm o.d. performance was :
bulb 6 V 35 W : 6V at 1260 rpm
" 12 V 45 W 13.5 V at 2040 rpm
" quartz 12 V 60 W 12.6 V at 2020 rpm
" quartz 12 V 100 W 10.6 V at 1950 rpm
I could not get higher revs and voltage with the 100 W quartz because the hand drill did not pull it . So I guess at 2300 rpm I will get min. 12 100 W , but don´t really need that.

The square three phase ac motor and its three phase rectifier had these numbers:
6 V 35 W bulb 6V at 1160 rpm
12 V 35 W bulb 14 V at 2070 rpm
12 V 45 W bulb 13 V at 2030 rpm
12 V 60 W quartz 12.4 V at 2030 rpm
12 V 100 W quartz 11,4 V at 1950 rpm
again, slowed down by the drill at 100 Watt load.
So both motors are quite close in performance and show a very smooth pull with 8 or 9 poles. I do not have numbers to compare with the Alton but I believe they will satisfy me completely, no more night driving for me anyway. I got the motors from Aliexpress at € 40.- to 60.- each.

Vic
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Bill Cannon

Well Known and Active Forum User
VOC Member
Great discussions again, so I came to some more ideas : Using the dynamo for venting the primary case cannot be a serious proposition, so instead I chose to drill from there into the gearbox dip stick adapter, not a long way to do. So I expect to get any air out the gearbox dip stick cap and no oil leaks from there. Also no risk for washing or rain water to get into there. Some caps are vented some not so, at least in my old stock. So I did some Dremel grooving the thread for easier air venting, no hole on top.
As to dynamos, I do not like the Alton gearbox solution for offsetting the rotor drive. You have to care for lubrication in there . Instead I found some permanent magnet dc and three phase ac motors at small size so they can be fitted in this place after some minor milling the engine case for concentric motors with 68 mm o.d. . I will have a big magneto for ignition so all generated current will go into lighting only.
The dynamos - ahh, dc/ac motors got new longer front plates for twin sealed ball bearings on 8mm shafts for reinforcing this place. Sealing will be an o-ring machined in the motor front plate, no silicone or some such.
I did some power tests today with an electric hand drill and got these readings, revs corrected to crankshaft speeds, 1.25 lower than the dynamo sprocket:

The round dc perm mag. motor 68 mm o.d. performance was :
bulb 6 V 35 W : 6V at 1260 rpm
" 12 V 45 W 13.5 V at 2040 rpm
" quartz 12 V 60 W 12.6 V at 2020 rpm
" quartz 12 V 100 W 10.6 V at 1950 rpm
I could not get higher revs and voltage with the 100 W quartz because the hand drill did not pull it . So I guess at 2300 rpm I will get min. 12 100 W , but don´t really need that.

The square three phase ac motor and its three phase rectifier had these numbers:
6 V 35 W bulb 6V at 1160 rpm
12 V 35 W bulb 14 V at 2070 rpm
12 V 45 W bulb 13 V at 2030 rpm
12 V 60 W quartz 12.4 V at 2030 rpm
12 V 100 W quartz 11,4 V at 1950 rpm
again, slowed down by the drill at 100 Watt load.
So both motors are quite close in performance and show a very smooth pull with 8 or 9 poles. I do not have numbers to compare with the Alton but I believe they will satisfy me completely, no more night driving for me anyway. I got the motors from Aliexpress at € 40.- to 60.- each.

Vic
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Hi Vic,

Do you have reference numbers for these motors or links to them please?

Cheers Bill
 

JustPlainBill0

Forum User
Non-VOC Member
After seeing Oexing's brilliant post and photos, but not being a machinist, I searched eBay for a suitable substitute motor/generator and found a good variety of "spindle motors" with various DC voltage and watt ratings. I picked this one: which is 52 mm diameter, rated at 200 watts @ 12000 RPM (less at lower RPM), comes with a ER16 collet chuck and a nifty bracket (my Rapide engine case has the removable generator mount). According to tracking info, the motor is on it's way; passing through Greenwood Indiana today.

To convert the power to 12 VDC (actually,13.8 for charging the battery) I plan to use a step up/step down power converter such as this one:
 

oexing

Well Known and Active Forum User
VOC Member
Hi Bill,
there are a number of suitable DC motors, the MY / ZY 6812 are brush types, nicely made, all 68mm diameter. So you´d have to do a bit of milling the engine case like in my photo above. But then you can get replacements any time. I liked the brushless system so the square types could do, after a bit of a turning action in the lathe you could shroud them with a tubular sleeve for a more traditional look.
Aliexpress has a wide selection of motors but honestly I don´t always believe descriptions so first study all features for getting an idea. At least I did my tests and maybe get some more motors for testing. The spindle motors might be suitable , better test them for performance at engine speeds. I ´d think they will not feed much current at our speeds. The more powerful and more expensive motors may have bigger shafts and bearings, cannot tell yet, so I fabricated new end caps for two ball bearings for ease of mind.
So the Altons no longer have gears for upping the revs of the motor ? In this case I´d believe their power dropped a bit to what sort of wattage ? I still could not find numbers about this matter - but then they fit without any mods to the engine.
Anyway, there are a few links below for browsing Aliexpress - or Ebay if you like.

Vic
P.S. the last type is the one in my photo I think.



MY 6812 DC Motor
Brushless 200 W
Brushless 150 W
Brushless 210 W
Brushless 188 W
 

JustPlainBill0

Forum User
Non-VOC Member
What I noticed in my search, is that when they provided info on RPM and voltage for DC motors, the values were like this: "Speed :3000-12000RPM (12v-3000rpm,24V-6000rpm,36V-9000rpm .48V-12000rpm)" which suggests that when using such a motor as a generator, it would produce about 1 VDC per 250 RPM. And, since the generator is being over-driven by the engine (+25%), it looks like at 60 mph (2750 engine RPM/3450 generator RPM) in 4th gear, the generator should be putting out 14 volts. Luckily, in Nevada, it isn't difficult to average 60 mile per hour on a ride (lots of open space here).
 

Bill Cannon

Well Known and Active Forum User
VOC Member
These generators seem interesting and amazingly powerful fot there size.
In my application I am driving it by a vee belt and I wonder if they will stand up to the side loading.
Also many of the AC generators seem to have maximum rating at 3 to 4000rpm. Mine is overdriven by about 2:1 so could spin at up to 12000rpm, so I wonder if that would destroy them.
With the DC motors and the step up/down converter, i wonder if the voltage regulation would be good enough especially for a Lithium battery which I am using.
Good luck, it will be interesting to see both of your progress.
Cheers
Bill
 

vibrac

Well Known and Active Forum User
VOC Member
So do any of these devices provide a possibility of a through drive to magnetic pickups? and would one be found where half engine speed would produce enough current? If so the ultimate goal of nothing in the dynamo position to stuff primary chains would be achievable and we could run both electrical power and electronic ignition from the mag position.
And perhaps? make a path for improved electric start from the dynamo position....
 

JustPlainBill0

Forum User
Non-VOC Member
So do any of these devices provide a possibility of a through drive to magnetic pickups? and would one be found where half engine speed would produce enough current? If so the ultimate goal of nothing in the dynamo position to stuff primary chains would be achievable and we could run both electrical power and electronic ignition from the mag position.
And perhaps? make a path for improved electric start from the dynamo position....

Another interesting possibility would be to use the generator as a starter motor in its' present location. Not a new concept and it has been done in non-motorcycle applications (some hybrid cars). Seems to be a complicated procedure...well above my pay-grade.

As for running the ignition off the back of a generator in the magneto location, this example doesn't appear to make enough power to charge a battery, but is a small 3 phase brushless motor/generator with shafts at both ends and a no load speed (12 VDC) of 2800 RPM: https://tinyurl.com/y3jzhcpb The specs say it's no load current is 0.5 Amps (6 watts). Do a search for "double shaft" motors and you'll find better examples -

Bill
 

bmetcalf

Well Known and Active Forum User
VOC Member
Didn’t Laverda Twins and MV 600s have starter/dynamos? Maybe also ‘70’s MV 750s and larger?
 
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