nuckolls.bob(at)aeroelect Guest
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Posted: Tue Aug 16, 2022 9:13 am Post subject: Reverse Engineering an Ultralight Charging System |
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At 09:22 PM 8/15/2022, you wrote:
Quote: | I'm puzzled by a very simple and basic charging system and I suspect that the great minds on the list might be able to help figure out how it works. The manufacturer hasn't been forthcoming about the circuitry.
Here is the extent of the technical documentation that I have found so far:
http://vittorazi.com/manuali/Quick_wiring_Vittorazi_Moster185_electric_starter_eng.pdf
This is a small single-cylinder 2-stroke engine. The flywheel has a permanent magnet, and there is a coil at the top for generating the spark. There is a similar coil at the bottom that is intended to charge the battery. The coils are grounded to the engine case, and on the charging coil, there is a single wire that exits the coil and goes to a small potted device that is presumably a regulator and rectifier. It has three conductors: one for the coil output, one for the battery charge, and a ground. I would guess that the coil is creating an AC current with a frequency related to the engine RPM.Â
It seems like most of the lawn mower regulator/rectifiers have two wires for the incoming AC, then one wire for the outgoing DC, plus a grounded case. What stumps me about this one is that since the gadget in the circuit only has three wires and an insulated case, it must mean the AC voltage happens between the engine ground and the single coil output wire. I haven't yet put a multimeter on the leads while the engine is running but I suppose that would be good data.
I'm tempted to try a bridge rectifier and some type of voltage regulating circuit. Any ideas |
Some of the very earliest battery charging systems
on small bikes were as you've described. A single
coil of wire that gets 'excited' by the flywheel
magneto magnet once per revolution. These coils don't
produce 'AC' output in the classic sense . . . but
a single, high every pulse for each pass of the
magnet.
Rectifier regulators were simple, half-wave rectifiers
combined with an SCR/Zener configured to shunt
excess energy by dead-shorting the coil output at
voltage potentials greater than desired bus voltage.
A relatively low energy system intended to do no more than
support a battery intended to run a small headlamp.
Per Joe's suggestion, I would try a contemporary
law mower r/r or even a full wave r/r of which
there are many to choose and cheap experiments.
If you try a full-wave r/r, just leave the extra
AC input lead disconnected. I suspect the internals
will operate in a 'half-wave' mode.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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