White wire succses story!!!!

[duivendyk]

MSP read my previous posts, the WW output is a SHORT ac (going both pos&neg ) pulse.The positive amplitude is about 1/3 of the negative going one,apparently due to the loading by the CDI, so charging battery with the neg going part of the cycle provides more output and also is less likely to mess up the ignition system.A peak to peak rectifier consisting of a large cap (470 microFarad with positive side to WW and with neg. side to anode of clamping diode which has it's cathode (band) to ground.Then another diode from junction of cap& clamping diode ,cathode (band) to junction and anode to neg.terminal of battery (6or 12V) with pos terminal to ground.This circuit provides the largest output(4-5 watt)and does not affect starting since cap takes little current at starting rpm.Diodes need 5 Amp rating since instantaneous currents are quite high because of low duty factor of ac pulses (less than 10%.Plse read my previous posts explaining how ptp rectifier works.

 

[impression]

So would i be better off going the Black ( ground ) instead of the White wire to trickle charge the battery to power the lights ?

it's after 1am here so i'm not too awake at the moment.

Duivendyk a quick picture of your thoguhts would be appreciated

 

[MurraySabrePlus]

Ok, due to further info, here is the FINAL revision of charge circuit.
I hope the mods can delete my earlier schematics to avoid confusion.

 

[duivendyk]

That schematic is basically correct except for the resistor on the way to the battery.It is not really needed and would greatly reduce the charge current,in fact something like 25!times or even more.The reason is that the current is delivered in SHORT pulses,the duty factor ( pulse durtion/cycle time) is probably less than 10%.So of you have an average current of 0.2 A for instance, the pulse current could be 2 amp (without the resistor) and your 100 Ohm resistor would reduce the pulse current to something like a 50 mA and the average to 5 or so.So get rid of that resistor.This is the simplest circuit.The peak to peak rectifier has more output but has more potential (theoretically) of screwing up the CDI.One more thing,I would stick a 1 Amp fuse in the output from the battery.

 

[MurraySabrePlus]

I merely added a resistor to do some limiting, as would be the case of using small, penlight-type cells that some readers might do.

Those types of cells cannot handle high-current charging, and would fail eventually. You want things to last, right?

Now if a heavy battery such as a larger lead-acid cell was used, sure, the resistance could be lowered, or even eliminated, as long as the charge rate is not exceeded.

But I canot stress enough the use of a fast-recovery high-speed 3-6 amp diode with this application.
use of a 60hz style diode will lead to failure soon and cause the diode to short out, most likely shutting down the engine and possibly causing an accident.

 

[duivendyk]

I don't think these dinky cells will be of much use,but that of course depends on your energy needs.I agree about the power rating of the diodes.But the frequencies are so low (less than 100 hz) that to require fast-recovery diodes are to be used, makes simply no sense.These are used in high freq switching supplies at 100 kHz or so. Schottky diodes which are inherently fast recovery types,could produce somewhat higher output because of their lower voltage drop, but are more expensive.

 

[skyl4rk]

The pulses are equivalent to rpm. At 8000rpm, 133 hertz (cycles per second). Thats pretty slow in electronic terms.

 

[BoltsMissing]

MurraySabrePlus can you please repost the shemantics , we tried to delete as requested and pressed the wrong buttons.
I think the forum's programer is working on this editing issue so we don't have to keep answering to requests

Thanks

 

[MurraySabrePlus]

The pulses are equivalent to rpm. At 8000rpm, 133 hertz (cycles per second). Thats pretty slow in electronic terms.

Just HOW do you come up with 133 hz from say, 8000 rpm?
Since the sparkplug fires with each revolution/compression stroke and that correlates with the pulses from the magneto, one would think 8000 rpm would equal 8000hz.
Enlighten me.

 

[MurraySabrePlus]

MurraySabrePlus can you please repost the shemantics , we tried to delete as requested and pressed the wrong buttons.
I think the forum's programer is working on this editing issue so we don't have to keep answering to requests

Thanks

Sure thing Bolts.
Here it is again.