The case for standardizing Li-Poly balancers
March 2006 91
Also included in this column:
• Using Windows hibernate
functions with your chargers/
cyclers
• Possible hazards in using powertool
chargers on hobby packs
• Checking new packs for
reversed connectors
• The VoltMagic RC-system
monitor
• The first realistic test data for
battery-pack life cycle
The Battery Clinic Red Scholefield | [email protected]
Several techniques may be used to mate with balancing connectors.
Reversed wires on battery packs as they came from the factory; the top is reversed
and the bottom is correct.
THIS WILL BE a column of “do nots” and
“be carefuls.” But when you are on the
cutting edge, it is wise to exercise caution so
you don’t get cut.
Do not use Microsoft Windows hibernate or
sleep modes with your chargers/cyclers.
In certain computers and versions of
Windows the USB ports are disabled,
ignored, or somehow made inoperative
when various power-saving features
automatically activate. Disable them if you
are using your personal computer to control
your chargers.
Check those new packs before you use
them. A modeling buddy encountered that
for a power-tool manufacturer (referencing
an item in the September column).
“A reader mentioned that he was trying
to use a DeWALT drill charger to charge his
model batteries. While technically this is
possible, as long as the cells are within the
ratings on the label, you and everybody else
should know that this type of charger (same
for most tool suppliers) is non-isolated. That
means that there is no transformer inside and
that the batteries are at a potential of 120V.
“This is okay for the specially designed
drill batteries since you can’t touch the cells
or the power contacts during charging, but if
a harness is created to charge any old pack,
then the protection is gone. Any contact
with the wires or the cells can transmit 120V
just as if the plug into the wall were
touched.
“I think it would be smart to warn your
readers that using this type of charger can be
hazardous. If the charger is light in weight,
there is no transformer, and the danger
exists!”
A DeWALT instruction manual reads,
“Danger: Electrocution hazard. 120 volts
are present at charging terminals. Do not
probe with conductive objects. Electric
shock or electrocution may result.”
Please check any charger you are
working with to make sure a transformer is
being used. If you do not know how to do
that, do not try any modifications to use as a
hobby charger.
the power connector was reversed on a
newly purchased pack.
It charged fine through the charge
connector, but when he plugged it into his
four-motor B-17 made from a Guillow’s kit,
it smoked his ESC and put all the motors
into reverse, damaging the model when it
backed out of the restraints on the bench.
There is a possible hazard in using powertool
chargers on hobby packs. I received the
following note from an engineer who works
An AstroFlight 109 Lithium charger using a balancing adapter
to charge individual cell in 3S pack.
An inelegant balancing adapter made from a block of wood with
brass nails, allowing each cell to be probed.
The high-end VoltMagic battery monitor tracks in-flight glitches
as well as battery voltage.
Balancing is good! It’s so good that nearly every Lithium battery
supplier is providing balancing taps. Similarly, many companies
are releasing their own balancing devices. The bad news is that
there seems to be a contest to see how many different connectors
can be used. That makes each battery supplier’s product unique
and incompatible with other balancing devices.
If you have purchased an FMA Direct BalancePro system and
want to use it with your PolyQuest pack, you are out of luck. Until
these people get together and standardize connectors and pin-outs,
we will have to apply our creative-modeling skills.
So does the pack even need to be balanced? Yes, if you want to
maximize its service life.
That requires access to the positive and negative lead as well as
the junction between the cells. Whether you have modified your
pack with a balancing lead or have a pack with the balancing
connector provided, you need a means to check each cell’s voltage
and charge it if necessary.
The first challenge is where to find a connector to mate with
the one on the battery. Vampower packs have a small, black
connector that is incompatible with the PolyQuest system, but the
pins are on the same 0.01-inch spacing. Do not try to make
contacts by sticking pins into these connectors; the chance of
shorting is too great. (Don’t ask me how I know.)
A male JST connector (shown) fits nicely. Just add some
banana plugs to the other end, and you can measure the voltage of
each cell and charge it if necessary. Always connect the banana
plugs in first so you won’t inadvertently short the cell you are
looking at.
Pure Hobby (www.purehobby.com) sells the multipin
connector PolyQuest uses and the one to mate with it. Getting my
BalancePro HD to talk to my PolyQuest packs required another
adapter (shown). Then on a roll, I made one to balance two-cell
packs, to which I simply added a wiretap between the cells.
Earlier I had made a balancing fixture consisting of just a
wooden block (shown), into which five brass nails were evenly
spaced. Then I soldered leads from the PolyQuest connector to
them. It is not too elegant, but now I can measure each cell and
then charge individually if necessary.
Since my prototype BalancePro was back in the shop for a
firmware upgrade, I had to find a way to balance and charge the
packs. So I added another connector—the same as that used on the
BalancePro charger.
If you go this route, make sure nothing can fall on the nails to
short them out. Also, never connect two packs at once, or it can let
all the smoke out—or worse. Only if you are reasonably well
skilled in the electrical department should you attempt any of this.
Onboard Voltage Monitor on Steroids: I have been a fan of voltmonitoring
devices since they became available. I can’t count the
number of models that have been saved by these inexpensive
safeguards.
The VoltMagic R/C System Monitor, which is available at
www.voltmagic.com/, takes this device to a higher level. The
following specifications are from the VoltMagic Web site.
“Battery Voltage Indication—12 range programmable
selections for the LEDs.
The Kokam battery pack curves showing capacity and charge temperature as a
function of number of cycles.
“Peak Low Voltage (PLV)—captures
momentary low voltages hundreds of
times/sec.
“Glitch and Failsafe Counting—
Selectable PPM glitch or PCM Failsafe
counting.
“Data Logger—PLV and
Glitches/Failsafes, play back even after
power off.
“Application—4- to 5-cell Ni-Cd/NiMH
or 2-cell Li-Poly. Voltage regulators can also
be monitored.
“Connector—Universal (Futaba, JR, Z).
“Accuracy—Calibrated within 0.015 VDC.
“Weight—0.23 oz.
“Made in the USA.
“MSRP $39.95.
“Instructions—http://www.voltmagic.com
/instruction.htm.”
The voltages shown in Table 1 of the
instructions are median values—0.10 volt
per LED. There is a 0.02-volt dead band on
either side of the switch points.
If we start at 5.00 volts and increase
voltage, the LED will change at 5.07 (5.05 +
0.02). If we then decrease voltage, the LED
will change back at 5.03 (5.05 - 0.02).
Sudden voltage drops (from servo
movement) are dampened so you do not
have jittering LED indications.
The PLV in Table 2 of the instructions
lists the voltage below which the
appropriate LED blinks. At 4.51 volts
nothing will blink, but at 4.49-4.41, green
LED 5 will have one blink (indicating that
the PLV is less than 4.50 but not less than
4.40).
The sample rate actually varies
depending on the frame rate of the receiver
to optimize the PLV measurement and
glitch detection. This is a good means to
determine how your pack is performing
under maneuvering loads and gives you an
indication that you may be pushing the
edge.
Glitch (and fail-safe) detection is unique
because of the binary weighted count
scheme (see Table 3 in the instructions) and
logic to count glitches that occur within
two-thirds of a second after a bad or missing
pulse as the same glitch. Basically, the raw
data is massaged into a more meaningful
and easier-to-read format. A high count
means many glitches separated by at least
two-thirds of a second—not just a bunch
from one isolated event.
All the configuration settings are done
with your transmitter via a receiver channel.
There are no switches or jumpers to get
dirty or break on the VoltMagic. If it saves
one model it has more than paid for itself.the FMA Direct item KOK 2000 HDR pack
in 3S configuration under controlled lab
conditions using precision test equipment.
I observed the following:
1) The data is conservative, with the cells
uncooled during charge or discharge but
cooled by fan after discharge and before
charge, as one should do in the field. Any
cooling in the airplane would extend life.
2) All runs were at a constant 17.5 amps
discharge, reflecting the average current drain
for many applications in helicopters and with
the many new brushless motors that draw
roughly 15-25 amps and are replacements for
Speed 400 brushed motors.
Discharge was cut off at 3.00 volts per cell
based on individual cell voltage. Cell voltage
characteristically rebounds to the
neighborhood of 3.65-3.80 volts when the
load is removed and the cell cools a bit. This
amounts to approximately a 5% rebound of
capacity.
3) All charges were done at 3C to 94%
(1785 mAh) using the FMA Direct
BalancePro system.
4) The test pack is a 3S Cellpro pack with
tap and connector so that cell voltage could
be recorded.
5) Handling and plugging/unplugging of
the pack were minimized.
6) Cycle life as defined by international
standard 80% of base capacity was 450
cycles. The pack was run to complete death to
see what would happen. Results were
interesting. Capacity declined slowly and
steadily to 475 cycles, then plummeted.
Disassembly of cells confirms the rapid
formation of salts (dendrites) as the cell dies.
7) The peak temperature rise for each
cycle was recorded and averaged 65 degrees
Fahrenheit during the life of the pack. As cell
capacity falls gradually and run time shortens
slightly, rise temperature falls slightly as well.
Since discharge current was a constant
17.5 amps, this implies that internal resistance
was not degraded and, if anything, increased
only slightly. Although rated for high
discharge, some cells can exceed the 140
degrees Fahrenheit that is the maximum
temperature before cell life is significantly
compromised.
8) The need for and achievement of cell
balance was also recorded. Cell voltage was
brought to within plus and minus 5 millivolts
even after 450 runs. This is a powerful
testament to the desirability of cell balancing
as done by FMA Direct BalancePro systems.
9) The discharge profile matches the flight
profile for a typical Trex helicopter or any of
the new generation of brushless-motor
propulsion systems that demand an average
200 watts.
The computer challenged can reach me at
The Battery Clinic, 12219 NW 9th Ln.,
Newberry FL 32669. An SASE will get you a
timely response (but not as timely as an Email
Edition: Model Aviation - 2006/03
Page Numbers: 91,92,93,94
Edition: Model Aviation - 2006/03
Page Numbers: 91,92,93,94
The case for standardizing Li-Poly balancers
March 2006 91
Also included in this column:
• Using Windows hibernate
functions with your chargers/
cyclers
• Possible hazards in using powertool
chargers on hobby packs
• Checking new packs for
reversed connectors
• The VoltMagic RC-system
monitor
• The first realistic test data for
battery-pack life cycle
The Battery Clinic Red Scholefield | [email protected]
Several techniques may be used to mate with balancing connectors.
Reversed wires on battery packs as they came from the factory; the top is reversed
and the bottom is correct.
THIS WILL BE a column of “do nots” and
“be carefuls.” But when you are on the
cutting edge, it is wise to exercise caution so
you don’t get cut.
Do not use Microsoft Windows hibernate or
sleep modes with your chargers/cyclers.
In certain computers and versions of
Windows the USB ports are disabled,
ignored, or somehow made inoperative
when various power-saving features
automatically activate. Disable them if you
are using your personal computer to control
your chargers.
Check those new packs before you use
them. A modeling buddy encountered that
for a power-tool manufacturer (referencing
an item in the September column).
“A reader mentioned that he was trying
to use a DeWALT drill charger to charge his
model batteries. While technically this is
possible, as long as the cells are within the
ratings on the label, you and everybody else
should know that this type of charger (same
for most tool suppliers) is non-isolated. That
means that there is no transformer inside and
that the batteries are at a potential of 120V.
“This is okay for the specially designed
drill batteries since you can’t touch the cells
or the power contacts during charging, but if
a harness is created to charge any old pack,
then the protection is gone. Any contact
with the wires or the cells can transmit 120V
just as if the plug into the wall were
touched.
“I think it would be smart to warn your
readers that using this type of charger can be
hazardous. If the charger is light in weight,
there is no transformer, and the danger
exists!”
A DeWALT instruction manual reads,
“Danger: Electrocution hazard. 120 volts
are present at charging terminals. Do not
probe with conductive objects. Electric
shock or electrocution may result.”
Please check any charger you are
working with to make sure a transformer is
being used. If you do not know how to do
that, do not try any modifications to use as a
hobby charger.
the power connector was reversed on a
newly purchased pack.
It charged fine through the charge
connector, but when he plugged it into his
four-motor B-17 made from a Guillow’s kit,
it smoked his ESC and put all the motors
into reverse, damaging the model when it
backed out of the restraints on the bench.
There is a possible hazard in using powertool
chargers on hobby packs. I received the
following note from an engineer who works
An AstroFlight 109 Lithium charger using a balancing adapter
to charge individual cell in 3S pack.
An inelegant balancing adapter made from a block of wood with
brass nails, allowing each cell to be probed.
The high-end VoltMagic battery monitor tracks in-flight glitches
as well as battery voltage.
Balancing is good! It’s so good that nearly every Lithium battery
supplier is providing balancing taps. Similarly, many companies
are releasing their own balancing devices. The bad news is that
there seems to be a contest to see how many different connectors
can be used. That makes each battery supplier’s product unique
and incompatible with other balancing devices.
If you have purchased an FMA Direct BalancePro system and
want to use it with your PolyQuest pack, you are out of luck. Until
these people get together and standardize connectors and pin-outs,
we will have to apply our creative-modeling skills.
So does the pack even need to be balanced? Yes, if you want to
maximize its service life.
That requires access to the positive and negative lead as well as
the junction between the cells. Whether you have modified your
pack with a balancing lead or have a pack with the balancing
connector provided, you need a means to check each cell’s voltage
and charge it if necessary.
The first challenge is where to find a connector to mate with
the one on the battery. Vampower packs have a small, black
connector that is incompatible with the PolyQuest system, but the
pins are on the same 0.01-inch spacing. Do not try to make
contacts by sticking pins into these connectors; the chance of
shorting is too great. (Don’t ask me how I know.)
A male JST connector (shown) fits nicely. Just add some
banana plugs to the other end, and you can measure the voltage of
each cell and charge it if necessary. Always connect the banana
plugs in first so you won’t inadvertently short the cell you are
looking at.
Pure Hobby (www.purehobby.com) sells the multipin
connector PolyQuest uses and the one to mate with it. Getting my
BalancePro HD to talk to my PolyQuest packs required another
adapter (shown). Then on a roll, I made one to balance two-cell
packs, to which I simply added a wiretap between the cells.
Earlier I had made a balancing fixture consisting of just a
wooden block (shown), into which five brass nails were evenly
spaced. Then I soldered leads from the PolyQuest connector to
them. It is not too elegant, but now I can measure each cell and
then charge individually if necessary.
Since my prototype BalancePro was back in the shop for a
firmware upgrade, I had to find a way to balance and charge the
packs. So I added another connector—the same as that used on the
BalancePro charger.
If you go this route, make sure nothing can fall on the nails to
short them out. Also, never connect two packs at once, or it can let
all the smoke out—or worse. Only if you are reasonably well
skilled in the electrical department should you attempt any of this.
Onboard Voltage Monitor on Steroids: I have been a fan of voltmonitoring
devices since they became available. I can’t count the
number of models that have been saved by these inexpensive
safeguards.
The VoltMagic R/C System Monitor, which is available at
www.voltmagic.com/, takes this device to a higher level. The
following specifications are from the VoltMagic Web site.
“Battery Voltage Indication—12 range programmable
selections for the LEDs.
The Kokam battery pack curves showing capacity and charge temperature as a
function of number of cycles.
“Peak Low Voltage (PLV)—captures
momentary low voltages hundreds of
times/sec.
“Glitch and Failsafe Counting—
Selectable PPM glitch or PCM Failsafe
counting.
“Data Logger—PLV and
Glitches/Failsafes, play back even after
power off.
“Application—4- to 5-cell Ni-Cd/NiMH
or 2-cell Li-Poly. Voltage regulators can also
be monitored.
“Connector—Universal (Futaba, JR, Z).
“Accuracy—Calibrated within 0.015 VDC.
“Weight—0.23 oz.
“Made in the USA.
“MSRP $39.95.
“Instructions—http://www.voltmagic.com
/instruction.htm.”
The voltages shown in Table 1 of the
instructions are median values—0.10 volt
per LED. There is a 0.02-volt dead band on
either side of the switch points.
If we start at 5.00 volts and increase
voltage, the LED will change at 5.07 (5.05 +
0.02). If we then decrease voltage, the LED
will change back at 5.03 (5.05 - 0.02).
Sudden voltage drops (from servo
movement) are dampened so you do not
have jittering LED indications.
The PLV in Table 2 of the instructions
lists the voltage below which the
appropriate LED blinks. At 4.51 volts
nothing will blink, but at 4.49-4.41, green
LED 5 will have one blink (indicating that
the PLV is less than 4.50 but not less than
4.40).
The sample rate actually varies
depending on the frame rate of the receiver
to optimize the PLV measurement and
glitch detection. This is a good means to
determine how your pack is performing
under maneuvering loads and gives you an
indication that you may be pushing the
edge.
Glitch (and fail-safe) detection is unique
because of the binary weighted count
scheme (see Table 3 in the instructions) and
logic to count glitches that occur within
two-thirds of a second after a bad or missing
pulse as the same glitch. Basically, the raw
data is massaged into a more meaningful
and easier-to-read format. A high count
means many glitches separated by at least
two-thirds of a second—not just a bunch
from one isolated event.
All the configuration settings are done
with your transmitter via a receiver channel.
There are no switches or jumpers to get
dirty or break on the VoltMagic. If it saves
one model it has more than paid for itself.the FMA Direct item KOK 2000 HDR pack
in 3S configuration under controlled lab
conditions using precision test equipment.
I observed the following:
1) The data is conservative, with the cells
uncooled during charge or discharge but
cooled by fan after discharge and before
charge, as one should do in the field. Any
cooling in the airplane would extend life.
2) All runs were at a constant 17.5 amps
discharge, reflecting the average current drain
for many applications in helicopters and with
the many new brushless motors that draw
roughly 15-25 amps and are replacements for
Speed 400 brushed motors.
Discharge was cut off at 3.00 volts per cell
based on individual cell voltage. Cell voltage
characteristically rebounds to the
neighborhood of 3.65-3.80 volts when the
load is removed and the cell cools a bit. This
amounts to approximately a 5% rebound of
capacity.
3) All charges were done at 3C to 94%
(1785 mAh) using the FMA Direct
BalancePro system.
4) The test pack is a 3S Cellpro pack with
tap and connector so that cell voltage could
be recorded.
5) Handling and plugging/unplugging of
the pack were minimized.
6) Cycle life as defined by international
standard 80% of base capacity was 450
cycles. The pack was run to complete death to
see what would happen. Results were
interesting. Capacity declined slowly and
steadily to 475 cycles, then plummeted.
Disassembly of cells confirms the rapid
formation of salts (dendrites) as the cell dies.
7) The peak temperature rise for each
cycle was recorded and averaged 65 degrees
Fahrenheit during the life of the pack. As cell
capacity falls gradually and run time shortens
slightly, rise temperature falls slightly as well.
Since discharge current was a constant
17.5 amps, this implies that internal resistance
was not degraded and, if anything, increased
only slightly. Although rated for high
discharge, some cells can exceed the 140
degrees Fahrenheit that is the maximum
temperature before cell life is significantly
compromised.
8) The need for and achievement of cell
balance was also recorded. Cell voltage was
brought to within plus and minus 5 millivolts
even after 450 runs. This is a powerful
testament to the desirability of cell balancing
as done by FMA Direct BalancePro systems.
9) The discharge profile matches the flight
profile for a typical Trex helicopter or any of
the new generation of brushless-motor
propulsion systems that demand an average
200 watts.
The computer challenged can reach me at
The Battery Clinic, 12219 NW 9th Ln.,
Newberry FL 32669. An SASE will get you a
timely response (but not as timely as an Email
Edition: Model Aviation - 2006/03
Page Numbers: 91,92,93,94
The case for standardizing Li-Poly balancers
March 2006 91
Also included in this column:
• Using Windows hibernate
functions with your chargers/
cyclers
• Possible hazards in using powertool
chargers on hobby packs
• Checking new packs for
reversed connectors
• The VoltMagic RC-system
monitor
• The first realistic test data for
battery-pack life cycle
The Battery Clinic Red Scholefield | [email protected]
Several techniques may be used to mate with balancing connectors.
Reversed wires on battery packs as they came from the factory; the top is reversed
and the bottom is correct.
THIS WILL BE a column of “do nots” and
“be carefuls.” But when you are on the
cutting edge, it is wise to exercise caution so
you don’t get cut.
Do not use Microsoft Windows hibernate or
sleep modes with your chargers/cyclers.
In certain computers and versions of
Windows the USB ports are disabled,
ignored, or somehow made inoperative
when various power-saving features
automatically activate. Disable them if you
are using your personal computer to control
your chargers.
Check those new packs before you use
them. A modeling buddy encountered that
for a power-tool manufacturer (referencing
an item in the September column).
“A reader mentioned that he was trying
to use a DeWALT drill charger to charge his
model batteries. While technically this is
possible, as long as the cells are within the
ratings on the label, you and everybody else
should know that this type of charger (same
for most tool suppliers) is non-isolated. That
means that there is no transformer inside and
that the batteries are at a potential of 120V.
“This is okay for the specially designed
drill batteries since you can’t touch the cells
or the power contacts during charging, but if
a harness is created to charge any old pack,
then the protection is gone. Any contact
with the wires or the cells can transmit 120V
just as if the plug into the wall were
touched.
“I think it would be smart to warn your
readers that using this type of charger can be
hazardous. If the charger is light in weight,
there is no transformer, and the danger
exists!”
A DeWALT instruction manual reads,
“Danger: Electrocution hazard. 120 volts
are present at charging terminals. Do not
probe with conductive objects. Electric
shock or electrocution may result.”
Please check any charger you are
working with to make sure a transformer is
being used. If you do not know how to do
that, do not try any modifications to use as a
hobby charger.
the power connector was reversed on a
newly purchased pack.
It charged fine through the charge
connector, but when he plugged it into his
four-motor B-17 made from a Guillow’s kit,
it smoked his ESC and put all the motors
into reverse, damaging the model when it
backed out of the restraints on the bench.
There is a possible hazard in using powertool
chargers on hobby packs. I received the
following note from an engineer who works
An AstroFlight 109 Lithium charger using a balancing adapter
to charge individual cell in 3S pack.
An inelegant balancing adapter made from a block of wood with
brass nails, allowing each cell to be probed.
The high-end VoltMagic battery monitor tracks in-flight glitches
as well as battery voltage.
Balancing is good! It’s so good that nearly every Lithium battery
supplier is providing balancing taps. Similarly, many companies
are releasing their own balancing devices. The bad news is that
there seems to be a contest to see how many different connectors
can be used. That makes each battery supplier’s product unique
and incompatible with other balancing devices.
If you have purchased an FMA Direct BalancePro system and
want to use it with your PolyQuest pack, you are out of luck. Until
these people get together and standardize connectors and pin-outs,
we will have to apply our creative-modeling skills.
So does the pack even need to be balanced? Yes, if you want to
maximize its service life.
That requires access to the positive and negative lead as well as
the junction between the cells. Whether you have modified your
pack with a balancing lead or have a pack with the balancing
connector provided, you need a means to check each cell’s voltage
and charge it if necessary.
The first challenge is where to find a connector to mate with
the one on the battery. Vampower packs have a small, black
connector that is incompatible with the PolyQuest system, but the
pins are on the same 0.01-inch spacing. Do not try to make
contacts by sticking pins into these connectors; the chance of
shorting is too great. (Don’t ask me how I know.)
A male JST connector (shown) fits nicely. Just add some
banana plugs to the other end, and you can measure the voltage of
each cell and charge it if necessary. Always connect the banana
plugs in first so you won’t inadvertently short the cell you are
looking at.
Pure Hobby (www.purehobby.com) sells the multipin
connector PolyQuest uses and the one to mate with it. Getting my
BalancePro HD to talk to my PolyQuest packs required another
adapter (shown). Then on a roll, I made one to balance two-cell
packs, to which I simply added a wiretap between the cells.
Earlier I had made a balancing fixture consisting of just a
wooden block (shown), into which five brass nails were evenly
spaced. Then I soldered leads from the PolyQuest connector to
them. It is not too elegant, but now I can measure each cell and
then charge individually if necessary.
Since my prototype BalancePro was back in the shop for a
firmware upgrade, I had to find a way to balance and charge the
packs. So I added another connector—the same as that used on the
BalancePro charger.
If you go this route, make sure nothing can fall on the nails to
short them out. Also, never connect two packs at once, or it can let
all the smoke out—or worse. Only if you are reasonably well
skilled in the electrical department should you attempt any of this.
Onboard Voltage Monitor on Steroids: I have been a fan of voltmonitoring
devices since they became available. I can’t count the
number of models that have been saved by these inexpensive
safeguards.
The VoltMagic R/C System Monitor, which is available at
www.voltmagic.com/, takes this device to a higher level. The
following specifications are from the VoltMagic Web site.
“Battery Voltage Indication—12 range programmable
selections for the LEDs.
The Kokam battery pack curves showing capacity and charge temperature as a
function of number of cycles.
“Peak Low Voltage (PLV)—captures
momentary low voltages hundreds of
times/sec.
“Glitch and Failsafe Counting—
Selectable PPM glitch or PCM Failsafe
counting.
“Data Logger—PLV and
Glitches/Failsafes, play back even after
power off.
“Application—4- to 5-cell Ni-Cd/NiMH
or 2-cell Li-Poly. Voltage regulators can also
be monitored.
“Connector—Universal (Futaba, JR, Z).
“Accuracy—Calibrated within 0.015 VDC.
“Weight—0.23 oz.
“Made in the USA.
“MSRP $39.95.
“Instructions—http://www.voltmagic.com
/instruction.htm.”
The voltages shown in Table 1 of the
instructions are median values—0.10 volt
per LED. There is a 0.02-volt dead band on
either side of the switch points.
If we start at 5.00 volts and increase
voltage, the LED will change at 5.07 (5.05 +
0.02). If we then decrease voltage, the LED
will change back at 5.03 (5.05 - 0.02).
Sudden voltage drops (from servo
movement) are dampened so you do not
have jittering LED indications.
The PLV in Table 2 of the instructions
lists the voltage below which the
appropriate LED blinks. At 4.51 volts
nothing will blink, but at 4.49-4.41, green
LED 5 will have one blink (indicating that
the PLV is less than 4.50 but not less than
4.40).
The sample rate actually varies
depending on the frame rate of the receiver
to optimize the PLV measurement and
glitch detection. This is a good means to
determine how your pack is performing
under maneuvering loads and gives you an
indication that you may be pushing the
edge.
Glitch (and fail-safe) detection is unique
because of the binary weighted count
scheme (see Table 3 in the instructions) and
logic to count glitches that occur within
two-thirds of a second after a bad or missing
pulse as the same glitch. Basically, the raw
data is massaged into a more meaningful
and easier-to-read format. A high count
means many glitches separated by at least
two-thirds of a second—not just a bunch
from one isolated event.
All the configuration settings are done
with your transmitter via a receiver channel.
There are no switches or jumpers to get
dirty or break on the VoltMagic. If it saves
one model it has more than paid for itself.the FMA Direct item KOK 2000 HDR pack
in 3S configuration under controlled lab
conditions using precision test equipment.
I observed the following:
1) The data is conservative, with the cells
uncooled during charge or discharge but
cooled by fan after discharge and before
charge, as one should do in the field. Any
cooling in the airplane would extend life.
2) All runs were at a constant 17.5 amps
discharge, reflecting the average current drain
for many applications in helicopters and with
the many new brushless motors that draw
roughly 15-25 amps and are replacements for
Speed 400 brushed motors.
Discharge was cut off at 3.00 volts per cell
based on individual cell voltage. Cell voltage
characteristically rebounds to the
neighborhood of 3.65-3.80 volts when the
load is removed and the cell cools a bit. This
amounts to approximately a 5% rebound of
capacity.
3) All charges were done at 3C to 94%
(1785 mAh) using the FMA Direct
BalancePro system.
4) The test pack is a 3S Cellpro pack with
tap and connector so that cell voltage could
be recorded.
5) Handling and plugging/unplugging of
the pack were minimized.
6) Cycle life as defined by international
standard 80% of base capacity was 450
cycles. The pack was run to complete death to
see what would happen. Results were
interesting. Capacity declined slowly and
steadily to 475 cycles, then plummeted.
Disassembly of cells confirms the rapid
formation of salts (dendrites) as the cell dies.
7) The peak temperature rise for each
cycle was recorded and averaged 65 degrees
Fahrenheit during the life of the pack. As cell
capacity falls gradually and run time shortens
slightly, rise temperature falls slightly as well.
Since discharge current was a constant
17.5 amps, this implies that internal resistance
was not degraded and, if anything, increased
only slightly. Although rated for high
discharge, some cells can exceed the 140
degrees Fahrenheit that is the maximum
temperature before cell life is significantly
compromised.
8) The need for and achievement of cell
balance was also recorded. Cell voltage was
brought to within plus and minus 5 millivolts
even after 450 runs. This is a powerful
testament to the desirability of cell balancing
as done by FMA Direct BalancePro systems.
9) The discharge profile matches the flight
profile for a typical Trex helicopter or any of
the new generation of brushless-motor
propulsion systems that demand an average
200 watts.
The computer challenged can reach me at
The Battery Clinic, 12219 NW 9th Ln.,
Newberry FL 32669. An SASE will get you a
timely response (but not as timely as an Email
Edition: Model Aviation - 2006/03
Page Numbers: 91,92,93,94
The case for standardizing Li-Poly balancers
March 2006 91
Also included in this column:
• Using Windows hibernate
functions with your chargers/
cyclers
• Possible hazards in using powertool
chargers on hobby packs
• Checking new packs for
reversed connectors
• The VoltMagic RC-system
monitor
• The first realistic test data for
battery-pack life cycle
The Battery Clinic Red Scholefield | [email protected]
Several techniques may be used to mate with balancing connectors.
Reversed wires on battery packs as they came from the factory; the top is reversed
and the bottom is correct.
THIS WILL BE a column of “do nots” and
“be carefuls.” But when you are on the
cutting edge, it is wise to exercise caution so
you don’t get cut.
Do not use Microsoft Windows hibernate or
sleep modes with your chargers/cyclers.
In certain computers and versions of
Windows the USB ports are disabled,
ignored, or somehow made inoperative
when various power-saving features
automatically activate. Disable them if you
are using your personal computer to control
your chargers.
Check those new packs before you use
them. A modeling buddy encountered that
for a power-tool manufacturer (referencing
an item in the September column).
“A reader mentioned that he was trying
to use a DeWALT drill charger to charge his
model batteries. While technically this is
possible, as long as the cells are within the
ratings on the label, you and everybody else
should know that this type of charger (same
for most tool suppliers) is non-isolated. That
means that there is no transformer inside and
that the batteries are at a potential of 120V.
“This is okay for the specially designed
drill batteries since you can’t touch the cells
or the power contacts during charging, but if
a harness is created to charge any old pack,
then the protection is gone. Any contact
with the wires or the cells can transmit 120V
just as if the plug into the wall were
touched.
“I think it would be smart to warn your
readers that using this type of charger can be
hazardous. If the charger is light in weight,
there is no transformer, and the danger
exists!”
A DeWALT instruction manual reads,
“Danger: Electrocution hazard. 120 volts
are present at charging terminals. Do not
probe with conductive objects. Electric
shock or electrocution may result.”
Please check any charger you are
working with to make sure a transformer is
being used. If you do not know how to do
that, do not try any modifications to use as a
hobby charger.
the power connector was reversed on a
newly purchased pack.
It charged fine through the charge
connector, but when he plugged it into his
four-motor B-17 made from a Guillow’s kit,
it smoked his ESC and put all the motors
into reverse, damaging the model when it
backed out of the restraints on the bench.
There is a possible hazard in using powertool
chargers on hobby packs. I received the
following note from an engineer who works
An AstroFlight 109 Lithium charger using a balancing adapter
to charge individual cell in 3S pack.
An inelegant balancing adapter made from a block of wood with
brass nails, allowing each cell to be probed.
The high-end VoltMagic battery monitor tracks in-flight glitches
as well as battery voltage.
Balancing is good! It’s so good that nearly every Lithium battery
supplier is providing balancing taps. Similarly, many companies
are releasing their own balancing devices. The bad news is that
there seems to be a contest to see how many different connectors
can be used. That makes each battery supplier’s product unique
and incompatible with other balancing devices.
If you have purchased an FMA Direct BalancePro system and
want to use it with your PolyQuest pack, you are out of luck. Until
these people get together and standardize connectors and pin-outs,
we will have to apply our creative-modeling skills.
So does the pack even need to be balanced? Yes, if you want to
maximize its service life.
That requires access to the positive and negative lead as well as
the junction between the cells. Whether you have modified your
pack with a balancing lead or have a pack with the balancing
connector provided, you need a means to check each cell’s voltage
and charge it if necessary.
The first challenge is where to find a connector to mate with
the one on the battery. Vampower packs have a small, black
connector that is incompatible with the PolyQuest system, but the
pins are on the same 0.01-inch spacing. Do not try to make
contacts by sticking pins into these connectors; the chance of
shorting is too great. (Don’t ask me how I know.)
A male JST connector (shown) fits nicely. Just add some
banana plugs to the other end, and you can measure the voltage of
each cell and charge it if necessary. Always connect the banana
plugs in first so you won’t inadvertently short the cell you are
looking at.
Pure Hobby (www.purehobby.com) sells the multipin
connector PolyQuest uses and the one to mate with it. Getting my
BalancePro HD to talk to my PolyQuest packs required another
adapter (shown). Then on a roll, I made one to balance two-cell
packs, to which I simply added a wiretap between the cells.
Earlier I had made a balancing fixture consisting of just a
wooden block (shown), into which five brass nails were evenly
spaced. Then I soldered leads from the PolyQuest connector to
them. It is not too elegant, but now I can measure each cell and
then charge individually if necessary.
Since my prototype BalancePro was back in the shop for a
firmware upgrade, I had to find a way to balance and charge the
packs. So I added another connector—the same as that used on the
BalancePro charger.
If you go this route, make sure nothing can fall on the nails to
short them out. Also, never connect two packs at once, or it can let
all the smoke out—or worse. Only if you are reasonably well
skilled in the electrical department should you attempt any of this.
Onboard Voltage Monitor on Steroids: I have been a fan of voltmonitoring
devices since they became available. I can’t count the
number of models that have been saved by these inexpensive
safeguards.
The VoltMagic R/C System Monitor, which is available at
www.voltmagic.com/, takes this device to a higher level. The
following specifications are from the VoltMagic Web site.
“Battery Voltage Indication—12 range programmable
selections for the LEDs.
The Kokam battery pack curves showing capacity and charge temperature as a
function of number of cycles.
“Peak Low Voltage (PLV)—captures
momentary low voltages hundreds of
times/sec.
“Glitch and Failsafe Counting—
Selectable PPM glitch or PCM Failsafe
counting.
“Data Logger—PLV and
Glitches/Failsafes, play back even after
power off.
“Application—4- to 5-cell Ni-Cd/NiMH
or 2-cell Li-Poly. Voltage regulators can also
be monitored.
“Connector—Universal (Futaba, JR, Z).
“Accuracy—Calibrated within 0.015 VDC.
“Weight—0.23 oz.
“Made in the USA.
“MSRP $39.95.
“Instructions—http://www.voltmagic.com
/instruction.htm.”
The voltages shown in Table 1 of the
instructions are median values—0.10 volt
per LED. There is a 0.02-volt dead band on
either side of the switch points.
If we start at 5.00 volts and increase
voltage, the LED will change at 5.07 (5.05 +
0.02). If we then decrease voltage, the LED
will change back at 5.03 (5.05 - 0.02).
Sudden voltage drops (from servo
movement) are dampened so you do not
have jittering LED indications.
The PLV in Table 2 of the instructions
lists the voltage below which the
appropriate LED blinks. At 4.51 volts
nothing will blink, but at 4.49-4.41, green
LED 5 will have one blink (indicating that
the PLV is less than 4.50 but not less than
4.40).
The sample rate actually varies
depending on the frame rate of the receiver
to optimize the PLV measurement and
glitch detection. This is a good means to
determine how your pack is performing
under maneuvering loads and gives you an
indication that you may be pushing the
edge.
Glitch (and fail-safe) detection is unique
because of the binary weighted count
scheme (see Table 3 in the instructions) and
logic to count glitches that occur within
two-thirds of a second after a bad or missing
pulse as the same glitch. Basically, the raw
data is massaged into a more meaningful
and easier-to-read format. A high count
means many glitches separated by at least
two-thirds of a second—not just a bunch
from one isolated event.
All the configuration settings are done
with your transmitter via a receiver channel.
There are no switches or jumpers to get
dirty or break on the VoltMagic. If it saves
one model it has more than paid for itself.the FMA Direct item KOK 2000 HDR pack
in 3S configuration under controlled lab
conditions using precision test equipment.
I observed the following:
1) The data is conservative, with the cells
uncooled during charge or discharge but
cooled by fan after discharge and before
charge, as one should do in the field. Any
cooling in the airplane would extend life.
2) All runs were at a constant 17.5 amps
discharge, reflecting the average current drain
for many applications in helicopters and with
the many new brushless motors that draw
roughly 15-25 amps and are replacements for
Speed 400 brushed motors.
Discharge was cut off at 3.00 volts per cell
based on individual cell voltage. Cell voltage
characteristically rebounds to the
neighborhood of 3.65-3.80 volts when the
load is removed and the cell cools a bit. This
amounts to approximately a 5% rebound of
capacity.
3) All charges were done at 3C to 94%
(1785 mAh) using the FMA Direct
BalancePro system.
4) The test pack is a 3S Cellpro pack with
tap and connector so that cell voltage could
be recorded.
5) Handling and plugging/unplugging of
the pack were minimized.
6) Cycle life as defined by international
standard 80% of base capacity was 450
cycles. The pack was run to complete death to
see what would happen. Results were
interesting. Capacity declined slowly and
steadily to 475 cycles, then plummeted.
Disassembly of cells confirms the rapid
formation of salts (dendrites) as the cell dies.
7) The peak temperature rise for each
cycle was recorded and averaged 65 degrees
Fahrenheit during the life of the pack. As cell
capacity falls gradually and run time shortens
slightly, rise temperature falls slightly as well.
Since discharge current was a constant
17.5 amps, this implies that internal resistance
was not degraded and, if anything, increased
only slightly. Although rated for high
discharge, some cells can exceed the 140
degrees Fahrenheit that is the maximum
temperature before cell life is significantly
compromised.
8) The need for and achievement of cell
balance was also recorded. Cell voltage was
brought to within plus and minus 5 millivolts
even after 450 runs. This is a powerful
testament to the desirability of cell balancing
as done by FMA Direct BalancePro systems.
9) The discharge profile matches the flight
profile for a typical Trex helicopter or any of
the new generation of brushless-motor
propulsion systems that demand an average
200 watts.
The computer challenged can reach me at
The Battery Clinic, 12219 NW 9th Ln.,
Newberry FL 32669. An SASE will get you a
timely response (but not as timely as an Email