FL 33618; Tel.: [813] 765-0124; Web site:
www.rcaccessory.com/) imports the Bantam
line of chargers.
The BC-5 has the individual voltage
balancer that can charge and balance Li-Poly
batteries. It monitors the voltages of each
Lithium cell during the charge process to
equalize the peak voltage. No external
balancer is needed.
Up to 5S packs can be charged and
balanced at the same time. Other features
include backlit display, temperature
probe/sensor (optional), and safety timer.
This charger has gone against convention,
placing the negative
cell at the top rather
than at the bottom.
This necessitates that
one of the balance
adapter leads be
twisted to put the
negative in the right
place.
The BC-5’s
specifications are as
follows.
Operating voltage:
DC 10-15 volts
Ni-Cd/NiMH: One to
14 cells
Li-Ion/Li-Poly: One
to five cells
Charge current: 0.1-
5.0 amps
Lead acid: 2-12
volts
A close look at some new Li-Poly balancing chargers
November 2006 109
Also included in this column:
• Which switch?
• The battery we’ve been
waiting for?
• Pin schemes
The Battery Clinic Red Scholefield | [email protected]
The Bantam BC-5 multichemistry charger/balancer with adapters.
The balancing Li-Poly charger from DNPower.
IT SEEMS THAT battery and charger items
are landing at “The Battery Clinic” nearly
every time the brown UPS truck passes. This
month brings two more offerings with
balancing capability and an exciting new
battery that may tip the scales in electric vs.
glow power.
Bantam Chargers has introduced a Li-Poly
balancing charger—the BC-5—but there is
more. This charger will balance your Li-Poly
packs while it takes care of your conventional
Ni-Cd, NiMH, and lead-acid batteries. RC
Accessory, Inc. (3304 Foxridge Cir., Tampa
Cell balancer: Up to 5S Li-Poly
Weight: 12.4 ounces (350 grams)
Dimensions: 5.2 x 3.5 x 1.1 inches (130 x 90
x 28mm)
Battery temperature cutoff: 20-80 degrees
Celsius or off (temperature probe optional)
Maximum charge input limit: 10 to 9990
mAh or off
Key beep and buzzer: On or off
LCD backlight brilliance: 0%-100%
Warranty: Twelve months from date of
purchase
Price: $129.95
I put this unit through the usual tests and
found that it operates as advertised. Voltage
and current readings were within 1.5%-2.0%
when checked with a Fluke 87 digital
multimeter. Balancing is accomplished by
looking at the individual cells and discharging
each one a bit to bring them all together.
Programming is almost as simple as it
gets, with four buttons that follow
essentially the same protocol as other fourbutton
chargers. The instruction book
(which consists of 10 6 x 8-inch pages)
can be found at www.bantamtek.com/
Manual/BC5%20English.pdf. It appears to
have been written by someone who has
actually used the charger.
Ignore any reference to discharge
function; this was a glitch in the publishing.
In addition to explaining all the functions,
displays, error messages, etc., the manual
features a flow chart to act as a road map
when programming.
This is the first charger I have encountered
that addresses all the different batteries we
use and provides for Lithium balancing. For
charging there are the conventional banana
jacks.
If balancing is required, there is another
eight-pin socket to which various available
adapters may be connected for balancing
Poly-Quest, Hyperion, E-Tec, Thunder
Power, and Kokam (not FMA Direct Cellpro)
Li-Polys. Bantam Chargers can also supply
you with a pigtail with which you can make
your own adapter for other packs.
The BC-5 unit has one shortcoming: it
does not have cycling capability that you find
in the popular Triton or Multiplex LN 5014
11sig4.QXD 9/26/06 8:47 AM Page 109110 MODEL AVIATION
A discharge curve comparing Li-Poly 2100 with A123Systems’ M1 cells.
A safety switch setup schematic that was presented on the WattFlyer Web site.
chargers. If you feel that you need a charger
that is dedicated to a specific battery
chemistry, and there are a number of pros
and cons in this discussion, XUS Hobby
has an alternative.
XUS Hobby (www.xushobby.com/servlet/
StoreFront) sent me one of its new Li-Poly
balancing chargers by DNPower. The price
is $85.95. You will find the same charger
under at least two other labels: Common
Sense R/C and Tenergy.
I was immediately impressed by the
instrument’s quality metal case and the
large display. This charger is almost as
simple to use as you can get. This is
fortunate because the instructions confused
even me.
This unit is essentially four individual
chargers with currents adjustable from 200
mA to 2 A in 200 mA steps. Connect to
your 12-volt source, set the charge rate, and
hit the start button.
There are charge ports for one-, two-,
three-, or four-cell packs, plus a screw
terminal five-pin connector block you can
connect to your own adapter. Adapter
cables are supplied for Thunder Power and
Electric Power packs.
The display gives you individual charge
voltages and the status of the individual
cells. The display shown is the only one
there is. You get cell-voltage readings, the
charge current, and an “okay” indication
when that cell is charged. Testing verified
the current readings for each cell in a pack
in which cells were deliberately unbalanced.
Input and output have reversal protection.
Considering the number of different balance
connector pin outs, this is essential. I let the
smoke out of one balancing charger I was
testing where the balance connector was
physically compatible but wired in reverse.
A123Systems M1 4S2P batteries installed
in the author’s Telemaster Electro.
I’m sure I’m going to get a number of
questions, such as “How does this charger
compare with the FMA Cellpro reviewed in
the September column?”
I found the cosmetics of the Cellpro’s
packaging, with overall clear heat shrink
rather than a case, a bit on the cheesy side. It
has many features including charge input with
1% accuracy, state of charge (fuel gauge)
accurate to 5%, charge time, 10 mV voltage
display accuracy, and PC viewer software, all
at a slightly lower price. On a strictly
technical basis I would give the nod to the
Cellpro.
Which Switch? As more venture into electric
power and learn that propellers on electrics
are as dangerous as those on wet-powered
models, manufacturers have come to the
conclusion that there should be some safe way
to prevent random start-ups.
Those little switches that come on some
ESCs only switch the signal lead to the
receiver. The battery is still connected. I like
to put a switch in the red lead of the battery
circuit that completely disconnects the battery.
Battery
Pack
ESC
Astro
Zero Loss connector
Astro
Flange for mounting on three-pin Zero Loss connector
fuselage wall
Charger or
Voltmeter
External battery for
bench testing
Ammeter
To left and center socket
To center and right socket
Jumper Plug
modified Zero Loss pins on
a copper-clad board
11sig4.QXD 9/26/06 9:03 AM Page 110Contrary to what you might think about
the switch rating, you don’t need a switch to
handle switching of 30 amps that your motor
might draw. One with 6 amps will be okay
since you are not actually switching that
much unless the motor happens to be on,
which it shouldn’t be.
Switches can carry much more current
than they can switch and are rated at their
switching capability—not how much current
they can carry after the switch action. I have
been using miniature toggle switches with 6-
amp ratings with no problem on models that
draw as many as 35 amps.
There are some other even more foolproof
methods that employ a shorting plug that is
accessible from outside the model to connect
the battery. A photo shows an elegant setup
that was presented on WattFlyer (www.watt
flyer.com/forums).
Is This the Battery We’ve Been Waiting
For? A thousand charge/discharge cycles,
30C continuous discharge capability, 15-
minute charge, and safe! That is quite an
order, but it is what A123Systems
(www.a123
systems.com/html/home.html) is claiming.
The company is interested in the hobby
market and sent me a couple four-cell, 2300
mAh packs for testing. The voltage delivery
is lower than with Li-Polys and they require a
different charge regime (constant current to
3.6 volts vs. the normal 4.2 volts).
112 MODEL AVIATION
With the lower voltage I used the fourcell
packs, running in parallel to replace the
3S2P 3200 Li-Polys I had been using in a
Telemaster Electro. A bench run of 29
amps (13C), the limit of my CBA II, gives
you a comparison with regular Li-Polys.
Although the voltage is approximately
.5 volt lower, the discharge is flatter than
either of the Li-Poly cells.
A123Systems has established
A123Racing (www.a123racing.com),
which focuses primarily on the car
market—at least for now. Batteries and
chargers are available from the company if
2S and 3S is all you require. I hope highercell-
count packages will be added. These
packs’ size and weight do not lend them
well to the lower-capacity flight
applications.
I am using a Vencon
(www.vencon.com) UBA4 programmable
system, checking for balance on a Cellpro
and then charging individual cells as
necessary for 3.6 volts constant voltage
with 50 mA current cutoff. So far the pack
seems to stay well balanced. If you have
access to a power supply that has voltageand
current-limit settings, that should work
also.
Sid Kauffman of SLK Electronics (the
ElectriCalc guy) is offering a modified
LiPoDapter that enables you to charge up to
6S M1 cells (this seems to be the designation
given to these cells) with your Ni-Cd charger.
I have tried the modified version, and it does
the job on the 3S and 4S packs I’m testing.
Visit Sid’s Web site at www.slk
electronics.com; some excellent Li-Poly
information is presented there—particularly
in the section on LiPoDapters.
I look forward to any input from others
who are using these cells. Accumulating
1,000 cycles is going to take me a very long
time.
Regarding the proliferation of connection
schemes, contradictory pin-out
arrangements with the same physical
connectors reversed from one vendor to the
next, and every conceivable connector ever
listed in Digi-Key and some that are not,
heaven help the poor guy (such as myself)
who has packs from more than one source
until the industry gets its act together and
standardizes balancing connectors and pinout
conventions.
Although it is obvious that battery
vendors are copying each other’s marketing
hype, they cannot be accused of copying
anyone else’s balancing-connector protocol.
We are just going to have to adapt to
sorting out pin outs, connections, pin
spacing, and all the other variables thrown
at us to make our own adapters to adapt the
other adapters.
Last month I mentioned a tour of The
Battery Clinic lab. I have not forgotten that,
but with all the important stuff hitting us
I’ll save it for when I run out of important
things to bring you.
If E-mail doesn’t do it for you, the mail
to Newberry is slower, but you can write to
me at 12219 NW 9th Ln., Newberry FL
32669. Please enclose an SASE if you want
a personalized, autographed reply. MA
Edition: Model Aviation - 2006/11
Page Numbers: 109,110,112
Edition: Model Aviation - 2006/11
Page Numbers: 109,110,112
FL 33618; Tel.: [813] 765-0124; Web site:
www.rcaccessory.com/) imports the Bantam
line of chargers.
The BC-5 has the individual voltage
balancer that can charge and balance Li-Poly
batteries. It monitors the voltages of each
Lithium cell during the charge process to
equalize the peak voltage. No external
balancer is needed.
Up to 5S packs can be charged and
balanced at the same time. Other features
include backlit display, temperature
probe/sensor (optional), and safety timer.
This charger has gone against convention,
placing the negative
cell at the top rather
than at the bottom.
This necessitates that
one of the balance
adapter leads be
twisted to put the
negative in the right
place.
The BC-5’s
specifications are as
follows.
Operating voltage:
DC 10-15 volts
Ni-Cd/NiMH: One to
14 cells
Li-Ion/Li-Poly: One
to five cells
Charge current: 0.1-
5.0 amps
Lead acid: 2-12
volts
A close look at some new Li-Poly balancing chargers
November 2006 109
Also included in this column:
• Which switch?
• The battery we’ve been
waiting for?
• Pin schemes
The Battery Clinic Red Scholefield | [email protected]
The Bantam BC-5 multichemistry charger/balancer with adapters.
The balancing Li-Poly charger from DNPower.
IT SEEMS THAT battery and charger items
are landing at “The Battery Clinic” nearly
every time the brown UPS truck passes. This
month brings two more offerings with
balancing capability and an exciting new
battery that may tip the scales in electric vs.
glow power.
Bantam Chargers has introduced a Li-Poly
balancing charger—the BC-5—but there is
more. This charger will balance your Li-Poly
packs while it takes care of your conventional
Ni-Cd, NiMH, and lead-acid batteries. RC
Accessory, Inc. (3304 Foxridge Cir., Tampa
Cell balancer: Up to 5S Li-Poly
Weight: 12.4 ounces (350 grams)
Dimensions: 5.2 x 3.5 x 1.1 inches (130 x 90
x 28mm)
Battery temperature cutoff: 20-80 degrees
Celsius or off (temperature probe optional)
Maximum charge input limit: 10 to 9990
mAh or off
Key beep and buzzer: On or off
LCD backlight brilliance: 0%-100%
Warranty: Twelve months from date of
purchase
Price: $129.95
I put this unit through the usual tests and
found that it operates as advertised. Voltage
and current readings were within 1.5%-2.0%
when checked with a Fluke 87 digital
multimeter. Balancing is accomplished by
looking at the individual cells and discharging
each one a bit to bring them all together.
Programming is almost as simple as it
gets, with four buttons that follow
essentially the same protocol as other fourbutton
chargers. The instruction book
(which consists of 10 6 x 8-inch pages)
can be found at www.bantamtek.com/
Manual/BC5%20English.pdf. It appears to
have been written by someone who has
actually used the charger.
Ignore any reference to discharge
function; this was a glitch in the publishing.
In addition to explaining all the functions,
displays, error messages, etc., the manual
features a flow chart to act as a road map
when programming.
This is the first charger I have encountered
that addresses all the different batteries we
use and provides for Lithium balancing. For
charging there are the conventional banana
jacks.
If balancing is required, there is another
eight-pin socket to which various available
adapters may be connected for balancing
Poly-Quest, Hyperion, E-Tec, Thunder
Power, and Kokam (not FMA Direct Cellpro)
Li-Polys. Bantam Chargers can also supply
you with a pigtail with which you can make
your own adapter for other packs.
The BC-5 unit has one shortcoming: it
does not have cycling capability that you find
in the popular Triton or Multiplex LN 5014
11sig4.QXD 9/26/06 8:47 AM Page 109110 MODEL AVIATION
A discharge curve comparing Li-Poly 2100 with A123Systems’ M1 cells.
A safety switch setup schematic that was presented on the WattFlyer Web site.
chargers. If you feel that you need a charger
that is dedicated to a specific battery
chemistry, and there are a number of pros
and cons in this discussion, XUS Hobby
has an alternative.
XUS Hobby (www.xushobby.com/servlet/
StoreFront) sent me one of its new Li-Poly
balancing chargers by DNPower. The price
is $85.95. You will find the same charger
under at least two other labels: Common
Sense R/C and Tenergy.
I was immediately impressed by the
instrument’s quality metal case and the
large display. This charger is almost as
simple to use as you can get. This is
fortunate because the instructions confused
even me.
This unit is essentially four individual
chargers with currents adjustable from 200
mA to 2 A in 200 mA steps. Connect to
your 12-volt source, set the charge rate, and
hit the start button.
There are charge ports for one-, two-,
three-, or four-cell packs, plus a screw
terminal five-pin connector block you can
connect to your own adapter. Adapter
cables are supplied for Thunder Power and
Electric Power packs.
The display gives you individual charge
voltages and the status of the individual
cells. The display shown is the only one
there is. You get cell-voltage readings, the
charge current, and an “okay” indication
when that cell is charged. Testing verified
the current readings for each cell in a pack
in which cells were deliberately unbalanced.
Input and output have reversal protection.
Considering the number of different balance
connector pin outs, this is essential. I let the
smoke out of one balancing charger I was
testing where the balance connector was
physically compatible but wired in reverse.
A123Systems M1 4S2P batteries installed
in the author’s Telemaster Electro.
I’m sure I’m going to get a number of
questions, such as “How does this charger
compare with the FMA Cellpro reviewed in
the September column?”
I found the cosmetics of the Cellpro’s
packaging, with overall clear heat shrink
rather than a case, a bit on the cheesy side. It
has many features including charge input with
1% accuracy, state of charge (fuel gauge)
accurate to 5%, charge time, 10 mV voltage
display accuracy, and PC viewer software, all
at a slightly lower price. On a strictly
technical basis I would give the nod to the
Cellpro.
Which Switch? As more venture into electric
power and learn that propellers on electrics
are as dangerous as those on wet-powered
models, manufacturers have come to the
conclusion that there should be some safe way
to prevent random start-ups.
Those little switches that come on some
ESCs only switch the signal lead to the
receiver. The battery is still connected. I like
to put a switch in the red lead of the battery
circuit that completely disconnects the battery.
Battery
Pack
ESC
Astro
Zero Loss connector
Astro
Flange for mounting on three-pin Zero Loss connector
fuselage wall
Charger or
Voltmeter
External battery for
bench testing
Ammeter
To left and center socket
To center and right socket
Jumper Plug
modified Zero Loss pins on
a copper-clad board
11sig4.QXD 9/26/06 9:03 AM Page 110Contrary to what you might think about
the switch rating, you don’t need a switch to
handle switching of 30 amps that your motor
might draw. One with 6 amps will be okay
since you are not actually switching that
much unless the motor happens to be on,
which it shouldn’t be.
Switches can carry much more current
than they can switch and are rated at their
switching capability—not how much current
they can carry after the switch action. I have
been using miniature toggle switches with 6-
amp ratings with no problem on models that
draw as many as 35 amps.
There are some other even more foolproof
methods that employ a shorting plug that is
accessible from outside the model to connect
the battery. A photo shows an elegant setup
that was presented on WattFlyer (www.watt
flyer.com/forums).
Is This the Battery We’ve Been Waiting
For? A thousand charge/discharge cycles,
30C continuous discharge capability, 15-
minute charge, and safe! That is quite an
order, but it is what A123Systems
(www.a123
systems.com/html/home.html) is claiming.
The company is interested in the hobby
market and sent me a couple four-cell, 2300
mAh packs for testing. The voltage delivery
is lower than with Li-Polys and they require a
different charge regime (constant current to
3.6 volts vs. the normal 4.2 volts).
112 MODEL AVIATION
With the lower voltage I used the fourcell
packs, running in parallel to replace the
3S2P 3200 Li-Polys I had been using in a
Telemaster Electro. A bench run of 29
amps (13C), the limit of my CBA II, gives
you a comparison with regular Li-Polys.
Although the voltage is approximately
.5 volt lower, the discharge is flatter than
either of the Li-Poly cells.
A123Systems has established
A123Racing (www.a123racing.com),
which focuses primarily on the car
market—at least for now. Batteries and
chargers are available from the company if
2S and 3S is all you require. I hope highercell-
count packages will be added. These
packs’ size and weight do not lend them
well to the lower-capacity flight
applications.
I am using a Vencon
(www.vencon.com) UBA4 programmable
system, checking for balance on a Cellpro
and then charging individual cells as
necessary for 3.6 volts constant voltage
with 50 mA current cutoff. So far the pack
seems to stay well balanced. If you have
access to a power supply that has voltageand
current-limit settings, that should work
also.
Sid Kauffman of SLK Electronics (the
ElectriCalc guy) is offering a modified
LiPoDapter that enables you to charge up to
6S M1 cells (this seems to be the designation
given to these cells) with your Ni-Cd charger.
I have tried the modified version, and it does
the job on the 3S and 4S packs I’m testing.
Visit Sid’s Web site at www.slk
electronics.com; some excellent Li-Poly
information is presented there—particularly
in the section on LiPoDapters.
I look forward to any input from others
who are using these cells. Accumulating
1,000 cycles is going to take me a very long
time.
Regarding the proliferation of connection
schemes, contradictory pin-out
arrangements with the same physical
connectors reversed from one vendor to the
next, and every conceivable connector ever
listed in Digi-Key and some that are not,
heaven help the poor guy (such as myself)
who has packs from more than one source
until the industry gets its act together and
standardizes balancing connectors and pinout
conventions.
Although it is obvious that battery
vendors are copying each other’s marketing
hype, they cannot be accused of copying
anyone else’s balancing-connector protocol.
We are just going to have to adapt to
sorting out pin outs, connections, pin
spacing, and all the other variables thrown
at us to make our own adapters to adapt the
other adapters.
Last month I mentioned a tour of The
Battery Clinic lab. I have not forgotten that,
but with all the important stuff hitting us
I’ll save it for when I run out of important
things to bring you.
If E-mail doesn’t do it for you, the mail
to Newberry is slower, but you can write to
me at 12219 NW 9th Ln., Newberry FL
32669. Please enclose an SASE if you want
a personalized, autographed reply. MA
Edition: Model Aviation - 2006/11
Page Numbers: 109,110,112
FL 33618; Tel.: [813] 765-0124; Web site:
www.rcaccessory.com/) imports the Bantam
line of chargers.
The BC-5 has the individual voltage
balancer that can charge and balance Li-Poly
batteries. It monitors the voltages of each
Lithium cell during the charge process to
equalize the peak voltage. No external
balancer is needed.
Up to 5S packs can be charged and
balanced at the same time. Other features
include backlit display, temperature
probe/sensor (optional), and safety timer.
This charger has gone against convention,
placing the negative
cell at the top rather
than at the bottom.
This necessitates that
one of the balance
adapter leads be
twisted to put the
negative in the right
place.
The BC-5’s
specifications are as
follows.
Operating voltage:
DC 10-15 volts
Ni-Cd/NiMH: One to
14 cells
Li-Ion/Li-Poly: One
to five cells
Charge current: 0.1-
5.0 amps
Lead acid: 2-12
volts
A close look at some new Li-Poly balancing chargers
November 2006 109
Also included in this column:
• Which switch?
• The battery we’ve been
waiting for?
• Pin schemes
The Battery Clinic Red Scholefield | [email protected]
The Bantam BC-5 multichemistry charger/balancer with adapters.
The balancing Li-Poly charger from DNPower.
IT SEEMS THAT battery and charger items
are landing at “The Battery Clinic” nearly
every time the brown UPS truck passes. This
month brings two more offerings with
balancing capability and an exciting new
battery that may tip the scales in electric vs.
glow power.
Bantam Chargers has introduced a Li-Poly
balancing charger—the BC-5—but there is
more. This charger will balance your Li-Poly
packs while it takes care of your conventional
Ni-Cd, NiMH, and lead-acid batteries. RC
Accessory, Inc. (3304 Foxridge Cir., Tampa
Cell balancer: Up to 5S Li-Poly
Weight: 12.4 ounces (350 grams)
Dimensions: 5.2 x 3.5 x 1.1 inches (130 x 90
x 28mm)
Battery temperature cutoff: 20-80 degrees
Celsius or off (temperature probe optional)
Maximum charge input limit: 10 to 9990
mAh or off
Key beep and buzzer: On or off
LCD backlight brilliance: 0%-100%
Warranty: Twelve months from date of
purchase
Price: $129.95
I put this unit through the usual tests and
found that it operates as advertised. Voltage
and current readings were within 1.5%-2.0%
when checked with a Fluke 87 digital
multimeter. Balancing is accomplished by
looking at the individual cells and discharging
each one a bit to bring them all together.
Programming is almost as simple as it
gets, with four buttons that follow
essentially the same protocol as other fourbutton
chargers. The instruction book
(which consists of 10 6 x 8-inch pages)
can be found at www.bantamtek.com/
Manual/BC5%20English.pdf. It appears to
have been written by someone who has
actually used the charger.
Ignore any reference to discharge
function; this was a glitch in the publishing.
In addition to explaining all the functions,
displays, error messages, etc., the manual
features a flow chart to act as a road map
when programming.
This is the first charger I have encountered
that addresses all the different batteries we
use and provides for Lithium balancing. For
charging there are the conventional banana
jacks.
If balancing is required, there is another
eight-pin socket to which various available
adapters may be connected for balancing
Poly-Quest, Hyperion, E-Tec, Thunder
Power, and Kokam (not FMA Direct Cellpro)
Li-Polys. Bantam Chargers can also supply
you with a pigtail with which you can make
your own adapter for other packs.
The BC-5 unit has one shortcoming: it
does not have cycling capability that you find
in the popular Triton or Multiplex LN 5014
11sig4.QXD 9/26/06 8:47 AM Page 109110 MODEL AVIATION
A discharge curve comparing Li-Poly 2100 with A123Systems’ M1 cells.
A safety switch setup schematic that was presented on the WattFlyer Web site.
chargers. If you feel that you need a charger
that is dedicated to a specific battery
chemistry, and there are a number of pros
and cons in this discussion, XUS Hobby
has an alternative.
XUS Hobby (www.xushobby.com/servlet/
StoreFront) sent me one of its new Li-Poly
balancing chargers by DNPower. The price
is $85.95. You will find the same charger
under at least two other labels: Common
Sense R/C and Tenergy.
I was immediately impressed by the
instrument’s quality metal case and the
large display. This charger is almost as
simple to use as you can get. This is
fortunate because the instructions confused
even me.
This unit is essentially four individual
chargers with currents adjustable from 200
mA to 2 A in 200 mA steps. Connect to
your 12-volt source, set the charge rate, and
hit the start button.
There are charge ports for one-, two-,
three-, or four-cell packs, plus a screw
terminal five-pin connector block you can
connect to your own adapter. Adapter
cables are supplied for Thunder Power and
Electric Power packs.
The display gives you individual charge
voltages and the status of the individual
cells. The display shown is the only one
there is. You get cell-voltage readings, the
charge current, and an “okay” indication
when that cell is charged. Testing verified
the current readings for each cell in a pack
in which cells were deliberately unbalanced.
Input and output have reversal protection.
Considering the number of different balance
connector pin outs, this is essential. I let the
smoke out of one balancing charger I was
testing where the balance connector was
physically compatible but wired in reverse.
A123Systems M1 4S2P batteries installed
in the author’s Telemaster Electro.
I’m sure I’m going to get a number of
questions, such as “How does this charger
compare with the FMA Cellpro reviewed in
the September column?”
I found the cosmetics of the Cellpro’s
packaging, with overall clear heat shrink
rather than a case, a bit on the cheesy side. It
has many features including charge input with
1% accuracy, state of charge (fuel gauge)
accurate to 5%, charge time, 10 mV voltage
display accuracy, and PC viewer software, all
at a slightly lower price. On a strictly
technical basis I would give the nod to the
Cellpro.
Which Switch? As more venture into electric
power and learn that propellers on electrics
are as dangerous as those on wet-powered
models, manufacturers have come to the
conclusion that there should be some safe way
to prevent random start-ups.
Those little switches that come on some
ESCs only switch the signal lead to the
receiver. The battery is still connected. I like
to put a switch in the red lead of the battery
circuit that completely disconnects the battery.
Battery
Pack
ESC
Astro
Zero Loss connector
Astro
Flange for mounting on three-pin Zero Loss connector
fuselage wall
Charger or
Voltmeter
External battery for
bench testing
Ammeter
To left and center socket
To center and right socket
Jumper Plug
modified Zero Loss pins on
a copper-clad board
11sig4.QXD 9/26/06 9:03 AM Page 110Contrary to what you might think about
the switch rating, you don’t need a switch to
handle switching of 30 amps that your motor
might draw. One with 6 amps will be okay
since you are not actually switching that
much unless the motor happens to be on,
which it shouldn’t be.
Switches can carry much more current
than they can switch and are rated at their
switching capability—not how much current
they can carry after the switch action. I have
been using miniature toggle switches with 6-
amp ratings with no problem on models that
draw as many as 35 amps.
There are some other even more foolproof
methods that employ a shorting plug that is
accessible from outside the model to connect
the battery. A photo shows an elegant setup
that was presented on WattFlyer (www.watt
flyer.com/forums).
Is This the Battery We’ve Been Waiting
For? A thousand charge/discharge cycles,
30C continuous discharge capability, 15-
minute charge, and safe! That is quite an
order, but it is what A123Systems
(www.a123
systems.com/html/home.html) is claiming.
The company is interested in the hobby
market and sent me a couple four-cell, 2300
mAh packs for testing. The voltage delivery
is lower than with Li-Polys and they require a
different charge regime (constant current to
3.6 volts vs. the normal 4.2 volts).
112 MODEL AVIATION
With the lower voltage I used the fourcell
packs, running in parallel to replace the
3S2P 3200 Li-Polys I had been using in a
Telemaster Electro. A bench run of 29
amps (13C), the limit of my CBA II, gives
you a comparison with regular Li-Polys.
Although the voltage is approximately
.5 volt lower, the discharge is flatter than
either of the Li-Poly cells.
A123Systems has established
A123Racing (www.a123racing.com),
which focuses primarily on the car
market—at least for now. Batteries and
chargers are available from the company if
2S and 3S is all you require. I hope highercell-
count packages will be added. These
packs’ size and weight do not lend them
well to the lower-capacity flight
applications.
I am using a Vencon
(www.vencon.com) UBA4 programmable
system, checking for balance on a Cellpro
and then charging individual cells as
necessary for 3.6 volts constant voltage
with 50 mA current cutoff. So far the pack
seems to stay well balanced. If you have
access to a power supply that has voltageand
current-limit settings, that should work
also.
Sid Kauffman of SLK Electronics (the
ElectriCalc guy) is offering a modified
LiPoDapter that enables you to charge up to
6S M1 cells (this seems to be the designation
given to these cells) with your Ni-Cd charger.
I have tried the modified version, and it does
the job on the 3S and 4S packs I’m testing.
Visit Sid’s Web site at www.slk
electronics.com; some excellent Li-Poly
information is presented there—particularly
in the section on LiPoDapters.
I look forward to any input from others
who are using these cells. Accumulating
1,000 cycles is going to take me a very long
time.
Regarding the proliferation of connection
schemes, contradictory pin-out
arrangements with the same physical
connectors reversed from one vendor to the
next, and every conceivable connector ever
listed in Digi-Key and some that are not,
heaven help the poor guy (such as myself)
who has packs from more than one source
until the industry gets its act together and
standardizes balancing connectors and pinout
conventions.
Although it is obvious that battery
vendors are copying each other’s marketing
hype, they cannot be accused of copying
anyone else’s balancing-connector protocol.
We are just going to have to adapt to
sorting out pin outs, connections, pin
spacing, and all the other variables thrown
at us to make our own adapters to adapt the
other adapters.
Last month I mentioned a tour of The
Battery Clinic lab. I have not forgotten that,
but with all the important stuff hitting us
I’ll save it for when I run out of important
things to bring you.
If E-mail doesn’t do it for you, the mail
to Newberry is slower, but you can write to
me at 12219 NW 9th Ln., Newberry FL
32669. Please enclose an SASE if you want
a personalized, autographed reply. MA