what to do during a blackout?

HeadSmess

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its cold. its wet. its nasty outside.

so i pulled apart yet another magneto today :)

and rewound with 800 odd turns of .25 wire, ending up with a coil that delivers approx 30 volts at idle. thats AC, with no load, mind you. dare say it drops a bit with load.

then snuck on the main winding, but fell a bit short at 2800, reading back on the last time i did this, appears im about 700 short...oh well! yeah, well, it still only took an hour by hand. would have taken me longer to find my winding machine!

it still started first kick, with a stock cdi and reading about 30 volts there, too. possibly a bit retarded now i guess...

all for what?

well, the 800 turns of heavy wire is for my freaking headlight! 18w 12v led monster of a thing, turns the night to day! and my sla battery died due to the vibration, rather awkward as it gets dark at night... ever tried navigating by the white line when there ISNT a white line to navigate by? and if someone pulls out in front of me...ouch. they always do, too!

theres only about 250 turns normally, so i tripled and added some :)

the verdict?

wired up a reggy reccy from the local "dead pitbike pile", ie my shed, found my multimeter is now grumpy and wont give me a good reading BUT... (3v regardless on DC? maybe i should heed that battery indicator and replace it?)

the headlight and the taillights are now motor powered :) bit of strobing at idle, but that quickly settles down with a touch of throttle.

next...wire it up permanently and fit some capacitors instead of this 3 kg SLA paperweight :)

time will tell how reliable it is i guess. 18w is a fair bit of current draw, and thats not factoring in the tails, at least another 5watts there... so im guessing 2 amps. meh. as long as my headlights blindingly bright, doesnt fry out, and well...im happy :)



pics? what pics? whattya need pics for? maybe in a few days when reliability is thoroughly tested... for now, im keeping that lead counterweight in place, just in case... and carrying a spare magneto :giggle:

was unusual, unwinding this one. appears it was wound "sensibly" with that nasty solder join being what its assumed to be, a centre tap! must have been the one that would run lights previously before it fried out. cus none of the other ones with "white" wires have been able to!
 
so you have a single winding that runs both the CDI and lights?
or two windings?
I know from having mine rewound at a local shop that you can only go slightly thicker in wire (because of space limitations) and still remain close in the resistance reading. But anyway that only reflects on the combination of number of turns and wire gauge. If you can get away with using a thicker wire while keeping the stock number of windings then that is the way to go.
 
two windings.

replaced the heavy winding with 800 turns of 0.2mm rather than the standard 250 of 0.4mm. as far as i can trust my multimeter, it was 30 volts@idle with no load. stick it on the dyno later on if it doesnt fry out, and get some definite voltage/load readings.

as far as i can work out from here, 0.4 should take 2 amps. 0.2 is a quarter that! nothings fried yet though? so many other factors to consider, like duty cycle, etc. remember, its not drawing current constantly, unlike DC would. or even 0.717 of the time, with plain AC.

http://www.powerstream.com/Wire_Size.htm

still had plenty of space for the other 700 odd turns of 0.1 for the ignition, i just didnt check my notes first! im not about to unwind it again. or game to try a join. and as long as its running... doesnt seem to be too critical.

its not delivering the full 18 watts required, plus some, (lights not getting to full brightness but definitely bright enough for night riding) but hey... yeah i need a new multimeter, why the %^^% is the 10 amp socket unfused? been bugging me since i got the thing(first thing i did, fry its amp socket!)... does everything but amps and frequency count. grrr.

anyway, i can safely say that its next to impossible to pull 20 watts or so from a HT magneto without totally re-engineering the setup. multiple poles and new stator plates and all that silly stuff. maybe another couple of hundred turns before i say that 100% confidently? iunno. need to set a four jaw up on the winder so i can hold these nasty things anyway. seems like too much effort! hard enough winding on just a bobbin, chuck in the core and its plain frustrating...


yeah, resistance is meaningless in this case, its the total number of turns that counts. resistance is just the ratio between thickness and length of wire.


maybe if i used silver wire?

:giggle:
 
This is a productive and useful conversation.
What could be achieved if the standard magnet were replaced with a short throw ultra high power neodymium magnet setup?
 
i dare say an increase in voltage...more lines of flux being cut by conductors. and currently (oooh, a pun!:p) i need more voltage for my load to get enough current(2 amps)





mmm, i could make an alloy magnet with a neo or two stuffed into it. problem being they need to be a certain shape so they dont get flung out, but....hmmms. ill think about that one... nothing stopping me from, say...pockets in the alloy, with some steel pole pieces poking through.

then the timing changes but i dare say its not too hard to find exactly where to cut the (new) keyway.


making me want to pull the CRO outta the box. in time, in time. too much on my plate currently. an idea for the backburner, let it stew a bit longer.
 
need to start tinkering with the magneto on a pitbike... they can generate 12v at about 50 watts with just a single coil... couple of magnets in there is about the only difference. is see no real reason other than "thats the way theyre made" to have the magnet inside the stator... definitely a lot easier if its the magnets on the outside ;)
 
this is peculiar.

today, my cdi failed...well, it still was producing a spark, but it wasnt starting. very weak and insipid, that spark was... ripped one off the other bike and well, fired straight up. so, therefore, the cdi has failed. the handwound magneto was fine :)

but while i was fiddling, i decided to add the other 1000 turns to the magneto coil.

still started just as easily, and the run to the PO to get the latest parcel was fine, but heres where it gets weird.

got home and wired up the lights again. they didnt work! at first, i suspected the regulator/rectifier, as 15+ voltsAC was going in... but less than 5 was coming out.

its taken some digging, but i finally found just a standard bridge rectifier.

so. the engine starts, the lights come on almost instantly...and then the engine splutters, coughs, dies. something peculiar is going on here.

cut the wire to the rectifier. engine runs perfectly again.

only thing i can think of...there is a limited amount of flux travelling through that magneto. well DUH! :rolleyes: so, while i had less turns on the ignition side, there was enough surplus to maintain power through the lighting side. exactly how the white wire works as a killswitch. just overloads the poor lil thing. :(

i also suspect the lowered voltage had something to do with the CDI failing. cant be sure of that one. just a sneaking suspicion. its a pretty old box though. i knew something was going to die today. i had that feeling in my guts, and that lil voice that i always ignore telling me to put the coil and homemade unit off the motor in the dyno on instead, for the last day or two. but ive had that feeling since i wound this thing, and ive really been using it hard the last week just to find out :) been through 20 litres of fuel this week :)

so there really is only a few options left.

the neo "rare earth" magnets in the magnet. increase the magnetic strength tenfold!

a separate coil with its own core, but where to put it? there is space in there, but not much :( if i could get something mounted inside the cover, with the poles at right angles to the existing magnetos poles, so im not trying to "steal" power from the ignition part... that was actually one of the first ideas i had before i stuffed around winding a new magneto!

it currently seems the most logical too. grrr. i dont wanna do any machining yet! also means i can use any old magneto again.

make a new magneto system entirely, as mentioned previously. two separate coils, four magnets in the rotor, and then...then one has to change to the same CDI used in just about every other engine...one with a trigger coil! theres that custom work again. not good.

go back to the unreliable battery setup. i hate batteries. they go flat, leaving you in the middle of nowhere, unable to see or be seen... the whole reason ive been doing this! (though i do need a battery anyway, cus if i snap a chain or finally blow this thing up, but can ride home still...its dark!)

hmmms. 3 watts is easy. 18+ is another matter entirely :( i refuse to downgrade these lights!

ive even contemplated sticking a brushless motor in instead of the standard tensioner. but i have the feeling that it just wont spin fast enough to be worth it down there.


oh well. time to start actually measuring and drawing something. cus i reckon i can get this to work still. i know i have about 10mm of depth between cover and magneto. plenty :)


really was hoping i could ride to woolies tonight. i need some dinner... thats a 30km round trip that ive been doing nightly this last week :) tacked on top of what i normally have to do... lots :)


i tend to get complacent... :giggle:

meh. have another coffee and off to bed :)
 
i shall have to order some neo magnets in the near future and try it out.

and a brushless motor with a low KV rating...

this doesnt work...

IMG0006A.jpgIMG0005A.jpg

made a nice core piece, managed to squeeze 600 turns onto it, and all i get is about 7 volts. grrrr. cant get much better coupling than this had, and definitely cant get any more turns in there! i am not in the mood to make another one!

may just be that i have a short, having used no insulation, but as it stands... no go.

(edit...it WAS a shorted turn! back to the winding i guess...)

oh well :)

brushless motor as a generator...

http://www.ebay.com/itm/BGM5208-200T-30KV-Brushless-Gimbal-Motor-for-DSLR-Camera-Gimbal-gi-/360790421619?pt=LH_DefaultDomain_0&hash=item5400c8f073

30kv...hmmms. rough maths... 4000 rpm, sprocket will be just under 1000rpm.

stick a 10 tooth sprocket on brushless, it will spin at 1000 rpm.

1000/30 = lots :) lets say 30 volts for 900 rpm.

thats with no load. could actually work. i always liked the idea of the tensioner being a generator as well...
 
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