About a week ago I wrote a post titled Cycler Current Cystems where I outlined a plan to build an auxillary power system for my bike, allowing me to power an Arduino and LED light strip, an LG phone, a WiFi device, and an Acer 0751h netbook.
I've made some headway. At first, I was pretty frustrated with disjunct and lacking information I came upon, so I wrote a list of the courses I would take at a free school (Hello Star City Shadow School) if courses like these existed:
I've made some headway. At first, I was pretty frustrated with disjunct and lacking information I came upon, so I wrote a list of the courses I would take at a free school (Hello Star City Shadow School) if courses like these existed:
Rock and Roll and the
Military-Industrial Complex
AC/DC 101
DIY/DIWO, Pedagogy, and the State
Academics, Knowledge and [Anti-]Copyright
Technology, Manufacturing and Stateless
Socialism
A Survey of Capitalist Sciences
Electronic Manufacture In Detail
Technology and the 19th Century
Romantics
Ethics in BioHacking
After some time I was able to find some
resources which allowed me to ground myself and break down the
circuits I was trying to build into smaller sections for better
understanding. Most of the resources were found through Instructables
(Thanks Gonzalo), the DuckDuckGo search engine, and occasionally
Google search.
So what you'll find below is:
A schematic of my planned system
The various circuits which make up the
system
Details on the batteries used in the
circuit
Battery Concerns
Ideas for a battery jumper system
Unknowns in the Arduino/LED Light Strip
setup
Websites where I've sourced all of the
parts I'd need to purchase
Websites that I've used as resources
for everything you see
Throughout what you will read below, I
still have several questions and concerns. If you feel you have the
knowledge and time, please educate me by leaving comments below. As
always, I'm in a time crunch to build this, so the sooner I can
resolve these questions, the better.
A schematic of my planned system
The basic charging circuit I'm working
with was taken from Michael Schmidt's website Pilom.de:
Here is a schematic I drew of my
proposed set of circuits. It could be better organized, but I hope it
makes sense to you.
There is a battery charging circuit,
and a battery use circuit. A DPDT switch delegates which circuit the
batteries belong to.
Charge Circuit:
As I stated above, the charge circuit
is based on the Low Power generation schematic on the Pilom website.
A 12V 6W dynamo would provide varying AC power into a Bridge
Rectifier made from four 1N5408 diodes which would output DC power.
The Ampers and Voltage would be measured by an analog ammeter wired
in a series and an analog voltmeter wired in parallel to it (analog
is cheaper). Finally then, the power would go into a series of
batteries. Based on Pilom's design, there would be 10 1.2V 2500mAh
NiMH batteries in a series to charge. A SPST switch would be put in
between the dynamo and rectifier so that I could “turn off” the
circuit when not in use.
Batteries:
1.2V x 10 gives me 12V that could
either be stepped up to 19V or down to 5V. Over 2Ah is needed since
the Arduino + LED Strip can potentially draw up to 2.08mAh according
to the Arduino/LED strip tutorial on the Adafruit website (see below).
Charging & Current: The idea is to “trickle charge” the
batteries with a relatively constant current from the dynamo. I won't
know what kind of output the dynamo will give me until I attach it to
my bike and measure output at different speeds with a multimeter.
Whoever contributed to this section of the Wiki article on trickle
charging NiMH batteries cites a Duracell document on NiMH batteries
that: “Most manufacturers claim that overcharging is safe at very
low currents, below 0.1 C (where C is the current
equivalent to the capacity of the battery divided by one hour).”
0.1C for these batteries would be 250mA. If it is true that the
dynamo produces .5mA at a fairly consistently at some average speed,
spread across 10 batteries, I would be pushing 50mA into them, well
below 0.1C for a relatively “safe” charge and over-charge.
Charging & Voltage: Somewhere, but
I can't find the webpage at this time, I read that if the battery
pack is rated a 12V, the power source must produce slightly more
voltage (~13V-14V) in order to charge them. If this is true, the 12V
6W dynamo may not produce enough voltage to charge the batteries. I
only need 12V from the batteries in order to be able to step up to
voltage to 19V to charge my netbook battery. I could avoid this
problem by removing this capability from the Use Circuit (see Use
Circuit below). At that point, I would only need 5 batteries at 6V to
step-down to 5V for the Arduino and USB port. This would also mean
that if the dynamo produces .5mA, 100mA would be spread across 5
batteries during charging, still below the “safe” C0.1 rate for over-charging
NiMH.
I won't know how much voltage the
dynamo produces until I can test it. But if someone is more
experienced with this issue I'm exploring under “Charging &
Voltage,” please educate me.
Jumper System: I will have 10 single AA
battery holders for the 10 batteries I plan to use. They each have
two tabs on them and I will wire them in a series. The Pilom website
mentions that a jumper could be created so that less batteries may be
used in the same circuit without having to decrease the number of
battery holders, etc. How could this be done?
Concerns:
One drawback here is that I have no
idea when the batteries are depleted or when they are fully charged.
I need to do more research on this, but some pages that I have
scanned stated there is no simple way of doing this. If anyone has
more info in regard to a relatively easy way to measure this, please
let me know.
Measuring charge/depletion seems to be
important because of something that wppltd.demon.co.uk calls “Cell
Reversal” where the cell is depleted prior to the other cells and
the way the current flows is reversed. Some other website (again, I
can't find it at the moment) called this “deep discharge” and
stated that this could damage the rest of the circuits and/or
batteries. Can someone clarify this as well?
Use Circuit:
The use circuit is divided into three
sections using two DPDT switches. Once the Use Circuit is selected,
the first DPDT switch decides whether the 12V from the battery pack
will be stepped up to 19V for charging my Acer 0751h netbook or if it
will be stepped down to 5V. The stepped down voltage (5V) can power
either a female-USB port or the Arduino/LED Strip (LPD8806) selected
via another DPDT switch. The LM2577 circuit found on ebay or Amazon
from Hong Kong would do the stepping up/down. I was originally
thinking of using a 7805 linear voltage regulator to step the voltage
down to 5V for the USB/Arduino-LED setup, but realized that its max
Amperage would be 1.5 at most. This would be insufficient for the
potential 2A+ draw that the Arduino/LED strip would create.
Yet unplanned:
Powering the Arduino & LED Strip.
There is a bit of confusion here which
I need clarified. I want to power both the Arduino and the LED strip
from the same 5V source. The Adafruit tutorial says this is possible,
but the way they word their instruction is unclear. “For a
standalone application (not USB connected to a computer), you can
power the Arduino from the same regulated 5V supply as the LEDs —
connect to the 5V pin on the Arduino, not Vin, and
don’t use the DC jack on the Arduino.” Is this stating I should
connect the regulated 5V into the 5V pin? If so, where do I plug in
the power connector that goes to the LED strip? It states that I
shouldn't power the Arduino/LED strip by plugging into the Vin plug.
Is this because the Vin plug requires 7-12V?
Arduino / Light Strip tutorial –
Power section: [ http://learn.adafruit.com/digital-led-strip/powering
]
Arduino Specs: [
http://arduino.cc/en/Main/ArduinoBoardUno
]
“5V.This pin outputs
a regulated 5V from the regulator on the board. The board can be
supplied with power either from the DC power jack (7 - 12V), the USB
connector (5V), or the VIN pin of the board (7-12V). Supplying
voltage via the 5V or 3.3V pins bypasses the regulator, and can
damage your board. We don't advise it. “
Sourced Parts
Dynamo:
6V 3W
A China-made 6V 3W:
12V 6W
Rectifier:
four 1N5408 diodes
Voltmeter/Ammeter:
Digital V/A meter: [
http://www.electronics-diy.com/store.php?sel=kits&sub=pic_voltmeters
]
Analog 3A Meter: [
http://www.allelectronics.com/make-a-store/item/PMD-3A/3A-DC-PANEL-METER/1.html
]
Analog 30VDC Meter: [
http://www.allelectronics.com/make-a-store/item/PMD-30V/30V-DC-PANEL-METER/1.html
]
Batteries:
10 AA cells NiMH: (2600mAh) [
http://www.batteryspace.com/nimhrechargeablecellaasize12v2600mah-buttontop1pc.aspx
]
or
Single AA Battery Holders: [
http://www.allelectronics.com/make-a-store/item/BH-31/BATTERY-HOLDER-FOR-1-AA-CELL/1.html
]
Perf Board:
Jumper system: ?
Things I may already have:
3 DPDT toggle switches
1 SPST toggle switch
female-USB end & cable
2.1mm barrel adapter & cable
Batteries in a Series or Parallel:
Working Circuit which Charges 4 NiMH
batteries. (Must contact this person.):
Myra Simon's tests of various 6V 3W
dynamos and their power output:
Pilom's Dynamo tests but using a
voltage doubler, which I didn't want to look into at the time:
USB 1 & 2 Voltage specifications:
[
http://www.wilderssecurity.com/showpost.php?s=d96e5c55cbb9987a24e1d045e42260db&p=2014178&postcount=5
]
More discussion on USB Voltage specs:
Watts:
On Linear Voltage Regulators:
Common Schematic Symbols:
NiMH – NiCd Charging Methods:
More on NiMH charging:
More on NiMH charging:
Duracell's Document on charging their
NiMH batteries:
[
http://www6.zetatalk.com/docs/Batteries/Chemistry/Duracell_Ni-MH_Rechargeable_Batteries_2007.pdf
]
Similar Dynamo Bike Light &
USB/Battery Charger Circuit:
Resources related to Academia,
Knowledge, & Copyright:
University of Colorado Interactive
Simulations:
C.R. Nave's informative but
inaccessable “HyperPhysics” Learning Tool at George State
University:
Pilom – M.S. Contact & Disclaimer
Info:
