The Battery Clinic - 2010/05

May 2010 89
Red Scholefield | redscho@The Battery Clinic bellsouth.net
Subhead
FMA Direct has released the
PowerLab 8: a 1,000-watt
battery-maintenance system.
The PowerGenix NiZn batteries and
charger are currently being tested.
Right: A comparison of discharge curves
between Ni-Cd, NiMH, and NiZn batteries.
Below: The Jigs Up soldering fixture makes
it easier to get a good solder joint.
MA HAS BEEN taking some hits on modeling forums for not being
proactive in covering emerging technology, particularly in the field
of energy devices. “You’d think MA would have been on the ball and
getting this out,” read one such post. “I guess they don’t have
anybody there with enough get up and go to keep up to date on stuff
like this.”
That opinion was in reference to an article about paper-thin
batteries made from algae that some of the popular science media
made public. Almost any institution with a chemistry department and
a half-dozen test tubes is working on such projects, looking for the
Holy Grail in energy—but, more realistically, for fat government or
industrial grants to support more research.
Following are comments in one such battery-breakthrough article
from the December 21, 2009, MIT Technology Review.
“A ‘digital quantum battery’ concept proposed by Alfred Hubler,
a physicist at the University of Illinois at Urbana-Champaign, could
provide a dramatic boost in energy storage capacity—if it meets its
theoretical potential once built.
Also included in this column:
• Are PowerGenix NiZn batteries
good for our use?
• FMA Direct takes charging to a
new level
• Central Florida Fun Flyers get
charged up
05sig3.QXD_00MSTRPG.QXD 3/24/10 2:43 PM Page 89
90 MODEL AVIATION
“Today digital quantum batteries are
merely a patent-pending research concept.
Hubler has applied for Defense Advanced
Research Projects Agency funding to develop
such a prototype, but the concept presents
significant challenges.”
If you are interested in developments that
have little chance of becoming usable in our
hobby during your lifetime, all you have to do
is Google “Flexible Energy Storage Devices.”
You will find at least 60 pages (I gave up at
that number) on the subject.
Another technology not to get too excited
about is Lithium-Sulfur batteries. Following
is from the article “Revisiting Lithium-Sulfur
Batteries,” from the May 22, 2009, MIT
Technology Review.
“Lithium-sulfur batteries, which can
potentially store several times more energy
than lithium-ion batteries, have historically
been too costly, unsafe, and unreliable to
make commercially. But they’re getting a
fresh look now, due to some recent advances.
Improvements to the design of these batteries
have led the chemical giant BASF of
Ludwigshafen, Germany, to team up with
Sion Power, a company in Tucson, AZ, that
has already developed prototype lithiumsulfur
battery cells.
“‘Compared to existing technologies used
in electric vehicles, the plan is to increase
driving distance at least 5 to 10 times,” for a
given-size battery,’ says Thomas Weber,
CEO of a subsidiary of BASF called BASF
Future Business. Other experts say that a
threefold improvement is a more reasonable
estimate.”
Lithium Sulfur Dioxide batteries used in
aircraft emergency-locator transmitters at one
time had the disconcerting habit of
spontaneous ignition. Add to that other
“exciting” breakthroughs, such as micro fuel
cells applicable to modeling applications, and
you can dream on.
Cold fusion anyone? How about running
your car on water? What about carburetors
that will get you 100 miles per gallon?
Remember those personal aircraft in every
garage that we were promised in the late
1940s?
So at the risk of not keeping you up to
date on the latest vaporware, I purposely
report only on those “breakthroughs” I can
touch and get samples to test.
Nickel-Zinc Rechargeable Batteries: This
antique electrochemical couple has been
around for a century or longer. Thomas
Edison originally conceived of Nickel-Zinc
(NiZn) batteries for use in high-power, highenergy
applications.
However, a severe flaw limited these
batteries’ use: dendrite formation during
recharging. Dendrites reduce the overall
performance of the battery and could even
lead to shorts, rendering the entire cell
useless.
Atlanta, Georgia-based Air Energy
Research spent more than 10 years
researching and developing zinc-air batteries
(hearing aid technology). They convert
Left: The Central Florida Sport Flyers has
an impressive charging station.
Below: Central Florida Sport Flyers
President Brad Paul’s electric-powered
Balsa USA Nieuport 11.
oxygen to electricity to power cellular phones,
pagers, handheld video recorders, and other
small electronics.
Unable to bring the product into
production, the company folded. Now
PowerGenix, another player in the battery
market, brings us rechargeable NiZn that
might show some promise.
I received a dozen 1.6-volt NiZn AA
rechargeable cells (1500 mAh) to evaluate,
along with the consumer charger. PowerGenix
also offers a Sub-C NiZn in 2000 mAh.
Before PowerGenix, in partnership with
Hunan Corun Hi-Tech Co., Ltd. (a Chinabased
battery manufacturer), could make
NiZn battery chemistry available, it needed to
solve the technical problems associated with
the instability of the zinc electrode in a
rechargeable cell. The company claims that
the cornerstone of this solution is in
electrolyte formulation that reduces zinc
solubility and prevents dendrite shorting
problems.
The PowerGenix NiZn batteries cost
roughly the same as other rechargeables. They
are listed on Amazon.com for $2.50 per cell.
This battery, with its higher cell voltage, has
close to 50% more energy density (Wh/kg)
than Ni-Cd or NiMH batteries. Cycle life is
05sig3.QXD_00MSTRPG.QXD 3/24/10 2:45 PM Page 90
reduced, while long shelf life (charge
retention) is touted.
Charging NiZn batteries requires a
constant potential current limited charger,
much the same as Li-Poly cells does—just
with different voltages and current limits. The
limit is 1.9 volts with 1C current limit; charge
should terminate when the current drops
below 75 mA.
The charger accommodates one to four
cells, charging individually and taking one
hour for one to two cells and two hours for
three to four cells. Because they are a constant
potential system, cell balancing should be
employed, as with Li-Poly packs.
I have been unable to determine the
impact of deep discharge on NiZn cells. Until
that is known, it is suggested that you don’t
take them lower than 0.9 volt. As with Ni-Cd
and NiMH cells, reversal should be avoided.
In receiver packs, using four NiZn cells
gives you a nominal voltage of 6.4 with a
high just-off charge of 7.2, which would
dictate a regulator for most receivers in which
7.2 volts could be exceeding the limit. A
transmitter normally powered with eight cells
would require only seven NiZn cells.
The catch in both of these situations is
charging. There are currently no units I know
of that will accommodate charging and
balancing NiZn packs. I see no reason why
chargers such as the Cellpro Multi-4, with its
open programming architecture, could not be
upgraded to charge and balance four-cell
packs.
On the other hand, a seven-cell charge/
balance unit has yet to be offered for NiZn. I
guess if one used an eight-cell holder in which
the cells could be individually removed and
charged with a dummy cell (made from a 1/2-
inch-diameter wood dowel with jumper wire),
using the consumer four-position charger that
PowerGenix sells, one could manage.
If you have trouble soldering battery
connectors, “The Jigs Up” soldering tool might
relieve your pain. Michael Howell submitted
the following information.
Gregg Paxton developed this tool for his
friends to use while soldering connectors on
their speed controls and for other RC electrical
needs. They were using the “old” methods of
needle-nose pliers, tweezers, etc. to hold the
hot wires while trying to make good solder
joints.
The Jigs Up ends all of those problems. It is
machined from bar-stock aluminum, with
spaces that hold a variety of connectors such
as, but not limited to, Deans T-plugs, Deans
two-pin plugs, and 2mm and 3mm bullet plugs.
The face of the tool has recesses and holes
for holding various electrical connectors. A
thumbscrew through a 1/2 x 1/8-inch strip of
aluminum is used to facilitate the clamping
action to hold the plug part to be soldered. The
machining and finish are excellent.
A hot soldering iron is needed to
accomplish a good, strong solder joint. The
paste flux is my favorite way to solder, even
though I also use flux-core solder.
(Editor’s note: RadioShack 60/40 Rosin
Core Solder, item 64-008, serves our electrical
soldering purposes well.)
Make sure that the soldering iron you use
has enough mass at the tip to assure good heat
transfer. A 1/4-inch-diameter chisel tip with a
40-watt iron is recommended.
The wires must be tinned first, and you
must also tin the plug parts. This keeps from
overheating the metal portion of the plug and
melting the plastic portion.
With The Jigs Up, soldering to your
connector is greatly simplified. Not only does
this tool act as a clamp, but it’s also a heat sink.
If you need to solder any plug to a battery,
my preference is to slip on a piece of heatshrink
tubing that is longer than the plug. This
acts as an insulator against accidental shorting
across the plug’s terminals, to be on the safe
side.
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for just 4 Screws?
We have the hardware you need
at a fraction of retail!
Order today at:
www.rtlfasteners.com
or call 800-239-6010
800 Battlefield Blvd. South, Suite 109
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Why Pay a Dollar
for just 4 Screws?
We have the hardware you need
at a fraction of retail!
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800 Battlefield Blvd. South, Suite 109
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Soldering the vertical post on the connector
is easy and quick if you turn The Jigs Up on its
side. I have found this tool to be a worthwhile
investment of time and money when I am
performing these important and necessary
tasks.
FMA Direct has released another
breakthrough charger: the PowerLab 8.
Pushing 1,000 watts of power, the company
addresses the needs of the electric flier who
wants to take things to the limit.
This unit has all the features one could
want in battery maintenance. Priced at
approximately $250, this charger should be
shipping by the time you read this.
PowerLab 8 is the most advanced battery
maintenance system I have seen. Open
architecture presets allow for customization of
any user preset, including show/hide presets
on unit, preset name, editing, and as many as
100 parameters can control how presets are
displayed.
This unit also has charging/discharging/
cycling parameters associated with particular
batteries and/or charging strategies. It includes
25 user preset banks preloaded for most major
battery types/chemistries and 50 library
presets.
This only scratches the surface of the
capabilities and features this charger offers.
Space prohibits my including a full list, but
you can see all of the details at the FMA
Direct Web site, which is included in the
“Sources” section.
I had the privilege of being a guest of the
Central Florida Sport Flyers during the
Christmas holiday. This club is heavy on
electric power, with a first-class charging
facility. It is fortunate to have AC power at the
site to operate a heavy-duty 12-volt system.
I have included a photo of the club’s
president, Brad Paul, flying a 1/4-scale Balsa
USA Nieuport 11. It is powered with a
Scorpion 2516 outrunner motor and has a
Phoenix Ice HV 60 ESC on 8S2P A123 M1
cells.
The AMA forum on its Web site is up and
growing. Stop by for discussions and to join
the fun! MA
Sources:
PowerGenix
(858) 547-7300
www.powergenix.com
The Jigs-Up
www.thejigsup.net
FMA Direct
(800) 343-2934
www.fmadirect.com
AMA forum
www.modelaircraft.org/forums
The Battery Clinic
12219 NW 9th Ln.
Newberry FL 32669
www.hangtimes.com/redsbatteryclinic.html