Christ, what a mess.
The next time I create a four component circuit board I'm using an autorouter.
When it comes to free software, you get what you pay for.
Anyway, the boards go out for manufacturing in a few days. I went with a
no-connector design. Solder it up and save 20 milliohms per contact. The caps
are 1 milliohm each, the relays are rated 100 milliohms @ 1 A @ 12 VDC.
That might be a contact potential of about 1 VDC plus a resistance of still
around 90 milliohms, which is unavoidable. At only 2.5 VDC across the contacts,
contact potential can become a problem. Hm.
A serious problem.
What is the self-contact potential of silver-nickel 90/10 alloy?
Anybody?
My own post:
http://www.lns.cornell.edu/spr/2003-09/msg0053747.html
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Also, that contact potential is tricky. I know it's 0.64 volts,
because I figured it out for the rated terminal resistance and
armature resistance myself from the test current of 4 amps.
-------------------------------------------------
That was for graphite brushes and a copper rotor. I have a lower figure for
those brushes with their silver rotor. I have the silver rotor on my desk, and
a motor with pinion failed to get even one bid on ebay. I really must relist
that with a low-price listing. I put too many whistles on it the first time
around.
Is the self-contact potential _zero_?
Six caps hold 15 V. My inverter runs on up to 15 V.
And I have two inverters, for a total voltage of 30 VDC, for maximum
performance from the motor to its design stall of some five seconds at 12 amps,
at which point it gets hot. But nobody will stall the motor. At least I dont'
think anybody will. At stall, contact potential will isolate the cap bank,
acting like back-to-back dioes. I think...
Anything more than 30 VDC requires a controller. 12.5 amps will demagnetize the
ferrite magnets by I'd guess a few percent, leading to poor generator
performance.
The parallel bus and series bus on the board are separate, end to end. So when
you stop pedaling, the inverter goes offline. And when you start, it comes
online with a surge. I have some inrush current limiters to deal with this.
With a normal cycle of operation established through on road testing, a jumper
will join those two busses, providing a 6:1 series/parallel capattery directly
linked to the motor. That's the design goal for now.
Changing the voltage by 6:1 is like a 100 pound skater holding two grand pianos
in close and whirling around, then letting them out to her full reach of some
six feet. It's a real whack, but the generator has series resistance to keep
from throwing you out of the seat. That resistance is just about unavoidable.
I spoke with a product specialist and these relays will work well with the VAC
from the pedal mounted generator. Just a matter of gearing to the rider. If the
rider sprints, some MOVs can clamp the output to keep from overloading the
relays. The coils are in series, and tend to fail open, safely.
Eventually, the tail lights will be wired as stop / turn / tail
lights.
I have moved the tail lights to a newly mounted rack, greatly improving the
manufacturability of the final product. The brackets had been modified and
assembled along a threaded rod. Now, they're stock.
Yours,
Doug Goncz ( ftp://users.aol.com/DGoncz/ )
Read about my physics project at NVCC:
http://groups.google.com/groups?q=dgoncz&scoring=d plus
"bicycle", "fluorescent", "inverter", "flywheel", "ultracapacitor", etc.
in the search box
