September 2008 91
The Battery Clinic Red Scholefield | [email protected]
Also included in this column:
• How High, See How, and
How Fast
• A simple propeller speed
formula
• Hughes Spectra 4
• A caveat of all chargers:
they’re loaded
Is my charger working?
1/32 plywood mount
The How Fast is set up for temporary mounting on models.
Hughes RC’s See How provides a direct reading of flight altitude
or speed.
An inexpensive
digital voltmeter,
such as this one, is
essential for the
electric-power flier.
I AM STILL perplexed by the number of
people who depend on batteries to fly their
models, yet lack even the most basic battery
test equipment. It is not as if it costs a
fortune.
You can purchase adequate digital
multimeters for less than $5 apiece. Harbor
Freight has them for as low as $3.99 ($2.99
when on sale, which is frequently). See the
source list for contact information.
Northern Tool and Equipment,
RadioShack, and eBay are other sources.
RadioShack has a multimeter that interfaces
with your PC to allow you to record
discharge voltage/current and print it out.
These tools are a great way to check your
batteries, and at a cost that is significantly
less than you will pay for some of the
hobby-specific devices.
Check out the photo with the multimeter
connected to a servo. I have found this
invaluable when setting up a model to check
for servo linkage dragging.
Cut the red wire in the middle of a servo
extension (12 inches). Add banana plugs to
the ends of the red wire, and plug these into
your digital multimeter. Polarity makes no
difference, because most meters will read in
either direction. Plug in the modified servo
extension between the battery and the
receiver or between the receiver and any
servo under investigation.
How High and See How: How about a new
fun-fly event? How high can you get your
model in a certain number of seconds from
takeoff? Winged Shadow Systems’ (see the
sources list) neat little gadget called the
How High allows you to get the exact
altitude by hooking up to your receiver and
flying the 2-gram device to altitude.
While you can get a single reading—the
maximum altitude—by waving your fingers
over the LED and counting its blinks, the
See How that the company sells lets you
take multiple altitude readings in the same
flight and displays the actual number.
Simply mate the See How with the LED on
the See High and press the button.
In less than a second, the See How
downloads the altitude data and displays it
for each segment of the flight. As many as
10 readings and nine individual flights can
be displayed.
I learned something else. At 1,000 feet,
your typical trainer is getting to the point
where orientation becomes a problem.
Would you believe that most of our flying is
done at 200-300 feet of altitude? At least
that is what How High told us.
92 MODEL AVIATION
Right: The Spectra 4’s large, backlit display
contains all pertinent battery information.
Below and below right: Brayton Paul’s
conversions to electric power.
Right: Hughes RC’s Spectra 4 addresses
popular modeling battery chemistries.
Winged Shadow Systems’ How Fast
components were fastened to 1/32 plywood to
allow it to be moved from aircraft to aircraft.
This is achieved by temporarily taping the
plate to the bottom surface of the wing and
running the leads to the receiver for power
and acquiring different altitudes by toggling
the retract switch.
The RC Reporter, also from Winged
Shadow, gives you battery voltage on the
fly. Installing this 2-gram device in your
model allows you to check the voltage while
in flight.
The unit gives you audible beeps as your
airplane flies by, while actuating a spare
channel on your transmitter. That’s another
reason to fly electric; you can hear these. It
gives you the present voltage and the lowest
voltage your pack sees during the flight.
A similar device for glow/gas-powered
models measures the receiver-pack voltage
and gives you an audio readout, but you
would not be able to hear it with the engine
running. It’s still a nice feature. Taxi back to
the pits, shut down your engine, flip the
retract switch on your transmitter, and find
out if you have enough battery for your next
flight.
Another feature is that if you turn off
your transmitter without turning off your
model, it will warn you with an audio alarm.
In addition, it’s good as a lost-aircraft finder.
Propeller Pitch Speed: I received a simple
formula from Paul. Someone always has a
better way.
“Red, I just finished reading your
column in May 2008 MA. Learned
considerable. You gave us a location for a
propeller pitch speed calculator. I find it
much simpler and quicker to use the
equation: Pitch (inches) x KRPM x 0.95 =
Speed (mph).”
The kprm is thousands; 12,450 rpm
would go into the equation as 12.54. I
checked several calculations against the
calculator with same results.
Hughes Spectra 4—A Charger for All
Reasons: Remember when the Litco Alpha
4 was the hottest item in charging? It was
so hot that you literally had to win the
Litco raffle to even get one and then be
willing to part with $300. This bought you
the capability of charging four packs at the
same time.
While the Alpha 4 has essentially
disappeared from the market, the need to
charge/cycle various kinds of packs has
not. Hughes RC has stepped forward to fill
that gap. There are other multiport
chargers available, but few, if any, give
you the charge/discharge/cycle control that
the Hughes Spectra 4 offers for all the
battery chemistries we are now employing.
One of the first things that struck me
when I got the charger was the size. This is
not a wimpy little charger you can lose on
your charging bench. Its commanding
appearance with the large heat sink on one
end says serious charging.
Turning on the Spectra 4 for the first
time is another surprise, because the
display, after showing the Hughes
welcome statement with firmware
version, scrolled to “Property of Red
Scholefield, Newberry, FL (352) 331-
8410.” The people at Hughes RC
program the owner’s information into
each charger sold and can change it if the
original owner requests it.
Following are the Spectra 4’s
specifications.
• Four outputs allow you to manage as
many as four batteries at one time (oneto
10-cell Ni-Cd/NiMH, one- to four-cell
Li-Poly/Li-Ion/A123, one- to six-cell
lead acid
• Serves as charger/cycler (for two or
more cells)/loaded voltmeter
• 50 mA-1000 mA per port (charge or
discharge)
• Input: 11-15 VDC
• 80-character, four-line backlit LCD
• Reverse polarity protection on input
and output
• Memorizes up to 20 battery pack charge
settings for “Automatic Charging”
• Remembers packs by “name”—not
number
• Each pack name can be up to 16
characters long
• Memory examples: “Futaba TX”;
“Extra 300 RX”; “CAP 232 ignition”
• Charges multiple batteries with
common grounds
• Simple four-button operation—menu
driven
• Detailed monitoring of all ports
• Audible alerts
• Battery backup in case of power failure
• Built in loaded voltmeter
• Fast charge with peak detection
(selectable rates)
• Timed charge (selectable rates)
• Topping-charge option (selectable
rates)
• Trickle-charge option (selectable rates)
• Accurate battery management
• Rugged all-metal enclosure
• One-year warranty
• Can memorize up to 20 battery-pack
charge settings for “Automatic Charging”
• Weighs 2 pounds
• Size of 8 x 5 x 3 inches
All the charge parameters measured
and recorded appeared to be well within
the accuracy limits expected for this type
of equipment. The ample display gives
you all the information about the pack.
A photo in this column shows the
“END” display for three cycles on a fourcell
Ni-Cd pack that had one flight on it
in the morning before cycling. “P3” is for
Port 3, “CYC” indicates that there were
three cycles, and the last charge was 1
hour, 7 minutes, 33 seconds with 736
mAh input. The readings at the bottom
were for the capacity delivered on each
discharge. The Spectra 4 discharges and
then charges in the cycle mode.
The Spectra 4 is shipped with a
battery backup lead. Connect a 7.2- to
12-volt Ni-Cd or NiMH pack to the jack
on the left end, near the power wire. In the
event of a power failure, the backup
battery will continue to power the
microprocessor and LCD while
terminating all other functions. When
power is restored, all functions will pick
up where they left off.
Battery backup can save you a lot of
headaches, especially if you are powering
your unit from an AC-driven power supply
that is subject to the power company’s
reliability. Your backup battery pack does
not need to be large; a 500 mAh pack
should keep you going for more than a 10-
hour power failure. When you are doing
multiple cycles, battery backup can keep
you from having to start over.
Need more power? Connect two or
more ports with a simple-to-make harness
(detailed on the Hughes RC Web site), and
you can charge/discharge at up to 4 amps
for a single pack or two packs up to 2
amps. Just set the ports to the charge
amount you want to add. If you want 3500
mA, set three ports at 1 amp and one at
500 mA.
A Caveat of All Chargers: This is the first
time I’ve seen any charger manufacturer
admit the following. The Hughes owner’s
manual read:
“Batteries should be disconnected from
the charger within a reasonable period of
time after all functions have been
completed. Once “END” is displayed there
will be a small discharge (less than 5 mA)
on the battery.”
I knew this was the case with some
chargers, such as the old ACE DVMC. But
my curiosity was aroused, so I checked a
number of other chargers in the lab. Every
one puts a small load on the battery when
the charge is complete.
So if you are using chargers that do not
have a continuous or pulsed trickle charge,
you could find a pack somewhat
discharged if it were left connected to the
charger for an extended period (such as
four or five days for a 500 mA pack).
Readers’ Conversions (Which Some
Refer to as Ugly Models): Brayton Paul
seems to favor AXi motors, as I do. It
looks like he is taking no chances on
overheating his ESC.
With all my batteries charged, I’m going
flying. You can write to me at the street
address for “The Battery Clinic,” but Email
is faster. MA
Sources:
Harbor Freight (multimeter)
(800) 444-3353
www.harborfreight.com/cpi/ctaf/Displayite
m.taf?itemnumber=92020
Winged Shadow Systems
(630) 837-6553
www.wingedshadow.com
Hughes RC
(800) 786-0802
www.hughesrc.com
The Battery Clinic
12219 NW 9th Ln.
Newberry FL 32669
Edition: Model Aviation - 2008/09
Page Numbers: 91,92,95
Edition: Model Aviation - 2008/09
Page Numbers: 91,92,95
September 2008 91
The Battery Clinic Red Scholefield | [email protected]
Also included in this column:
• How High, See How, and
How Fast
• A simple propeller speed
formula
• Hughes Spectra 4
• A caveat of all chargers:
they’re loaded
Is my charger working?
1/32 plywood mount
The How Fast is set up for temporary mounting on models.
Hughes RC’s See How provides a direct reading of flight altitude
or speed.
An inexpensive
digital voltmeter,
such as this one, is
essential for the
electric-power flier.
I AM STILL perplexed by the number of
people who depend on batteries to fly their
models, yet lack even the most basic battery
test equipment. It is not as if it costs a
fortune.
You can purchase adequate digital
multimeters for less than $5 apiece. Harbor
Freight has them for as low as $3.99 ($2.99
when on sale, which is frequently). See the
source list for contact information.
Northern Tool and Equipment,
RadioShack, and eBay are other sources.
RadioShack has a multimeter that interfaces
with your PC to allow you to record
discharge voltage/current and print it out.
These tools are a great way to check your
batteries, and at a cost that is significantly
less than you will pay for some of the
hobby-specific devices.
Check out the photo with the multimeter
connected to a servo. I have found this
invaluable when setting up a model to check
for servo linkage dragging.
Cut the red wire in the middle of a servo
extension (12 inches). Add banana plugs to
the ends of the red wire, and plug these into
your digital multimeter. Polarity makes no
difference, because most meters will read in
either direction. Plug in the modified servo
extension between the battery and the
receiver or between the receiver and any
servo under investigation.
How High and See How: How about a new
fun-fly event? How high can you get your
model in a certain number of seconds from
takeoff? Winged Shadow Systems’ (see the
sources list) neat little gadget called the
How High allows you to get the exact
altitude by hooking up to your receiver and
flying the 2-gram device to altitude.
While you can get a single reading—the
maximum altitude—by waving your fingers
over the LED and counting its blinks, the
See How that the company sells lets you
take multiple altitude readings in the same
flight and displays the actual number.
Simply mate the See How with the LED on
the See High and press the button.
In less than a second, the See How
downloads the altitude data and displays it
for each segment of the flight. As many as
10 readings and nine individual flights can
be displayed.
I learned something else. At 1,000 feet,
your typical trainer is getting to the point
where orientation becomes a problem.
Would you believe that most of our flying is
done at 200-300 feet of altitude? At least
that is what How High told us.
92 MODEL AVIATION
Right: The Spectra 4’s large, backlit display
contains all pertinent battery information.
Below and below right: Brayton Paul’s
conversions to electric power.
Right: Hughes RC’s Spectra 4 addresses
popular modeling battery chemistries.
Winged Shadow Systems’ How Fast
components were fastened to 1/32 plywood to
allow it to be moved from aircraft to aircraft.
This is achieved by temporarily taping the
plate to the bottom surface of the wing and
running the leads to the receiver for power
and acquiring different altitudes by toggling
the retract switch.
The RC Reporter, also from Winged
Shadow, gives you battery voltage on the
fly. Installing this 2-gram device in your
model allows you to check the voltage while
in flight.
The unit gives you audible beeps as your
airplane flies by, while actuating a spare
channel on your transmitter. That’s another
reason to fly electric; you can hear these. It
gives you the present voltage and the lowest
voltage your pack sees during the flight.
A similar device for glow/gas-powered
models measures the receiver-pack voltage
and gives you an audio readout, but you
would not be able to hear it with the engine
running. It’s still a nice feature. Taxi back to
the pits, shut down your engine, flip the
retract switch on your transmitter, and find
out if you have enough battery for your next
flight.
Another feature is that if you turn off
your transmitter without turning off your
model, it will warn you with an audio alarm.
In addition, it’s good as a lost-aircraft finder.
Propeller Pitch Speed: I received a simple
formula from Paul. Someone always has a
better way.
“Red, I just finished reading your
column in May 2008 MA. Learned
considerable. You gave us a location for a
propeller pitch speed calculator. I find it
much simpler and quicker to use the
equation: Pitch (inches) x KRPM x 0.95 =
Speed (mph).”
The kprm is thousands; 12,450 rpm
would go into the equation as 12.54. I
checked several calculations against the
calculator with same results.
Hughes Spectra 4—A Charger for All
Reasons: Remember when the Litco Alpha
4 was the hottest item in charging? It was
so hot that you literally had to win the
Litco raffle to even get one and then be
willing to part with $300. This bought you
the capability of charging four packs at the
same time.
While the Alpha 4 has essentially
disappeared from the market, the need to
charge/cycle various kinds of packs has
not. Hughes RC has stepped forward to fill
that gap. There are other multiport
chargers available, but few, if any, give
you the charge/discharge/cycle control that
the Hughes Spectra 4 offers for all the
battery chemistries we are now employing.
One of the first things that struck me
when I got the charger was the size. This is
not a wimpy little charger you can lose on
your charging bench. Its commanding
appearance with the large heat sink on one
end says serious charging.
Turning on the Spectra 4 for the first
time is another surprise, because the
display, after showing the Hughes
welcome statement with firmware
version, scrolled to “Property of Red
Scholefield, Newberry, FL (352) 331-
8410.” The people at Hughes RC
program the owner’s information into
each charger sold and can change it if the
original owner requests it.
Following are the Spectra 4’s
specifications.
• Four outputs allow you to manage as
many as four batteries at one time (oneto
10-cell Ni-Cd/NiMH, one- to four-cell
Li-Poly/Li-Ion/A123, one- to six-cell
lead acid
• Serves as charger/cycler (for two or
more cells)/loaded voltmeter
• 50 mA-1000 mA per port (charge or
discharge)
• Input: 11-15 VDC
• 80-character, four-line backlit LCD
• Reverse polarity protection on input
and output
• Memorizes up to 20 battery pack charge
settings for “Automatic Charging”
• Remembers packs by “name”—not
number
• Each pack name can be up to 16
characters long
• Memory examples: “Futaba TX”;
“Extra 300 RX”; “CAP 232 ignition”
• Charges multiple batteries with
common grounds
• Simple four-button operation—menu
driven
• Detailed monitoring of all ports
• Audible alerts
• Battery backup in case of power failure
• Built in loaded voltmeter
• Fast charge with peak detection
(selectable rates)
• Timed charge (selectable rates)
• Topping-charge option (selectable
rates)
• Trickle-charge option (selectable rates)
• Accurate battery management
• Rugged all-metal enclosure
• One-year warranty
• Can memorize up to 20 battery-pack
charge settings for “Automatic Charging”
• Weighs 2 pounds
• Size of 8 x 5 x 3 inches
All the charge parameters measured
and recorded appeared to be well within
the accuracy limits expected for this type
of equipment. The ample display gives
you all the information about the pack.
A photo in this column shows the
“END” display for three cycles on a fourcell
Ni-Cd pack that had one flight on it
in the morning before cycling. “P3” is for
Port 3, “CYC” indicates that there were
three cycles, and the last charge was 1
hour, 7 minutes, 33 seconds with 736
mAh input. The readings at the bottom
were for the capacity delivered on each
discharge. The Spectra 4 discharges and
then charges in the cycle mode.
The Spectra 4 is shipped with a
battery backup lead. Connect a 7.2- to
12-volt Ni-Cd or NiMH pack to the jack
on the left end, near the power wire. In the
event of a power failure, the backup
battery will continue to power the
microprocessor and LCD while
terminating all other functions. When
power is restored, all functions will pick
up where they left off.
Battery backup can save you a lot of
headaches, especially if you are powering
your unit from an AC-driven power supply
that is subject to the power company’s
reliability. Your backup battery pack does
not need to be large; a 500 mAh pack
should keep you going for more than a 10-
hour power failure. When you are doing
multiple cycles, battery backup can keep
you from having to start over.
Need more power? Connect two or
more ports with a simple-to-make harness
(detailed on the Hughes RC Web site), and
you can charge/discharge at up to 4 amps
for a single pack or two packs up to 2
amps. Just set the ports to the charge
amount you want to add. If you want 3500
mA, set three ports at 1 amp and one at
500 mA.
A Caveat of All Chargers: This is the first
time I’ve seen any charger manufacturer
admit the following. The Hughes owner’s
manual read:
“Batteries should be disconnected from
the charger within a reasonable period of
time after all functions have been
completed. Once “END” is displayed there
will be a small discharge (less than 5 mA)
on the battery.”
I knew this was the case with some
chargers, such as the old ACE DVMC. But
my curiosity was aroused, so I checked a
number of other chargers in the lab. Every
one puts a small load on the battery when
the charge is complete.
So if you are using chargers that do not
have a continuous or pulsed trickle charge,
you could find a pack somewhat
discharged if it were left connected to the
charger for an extended period (such as
four or five days for a 500 mA pack).
Readers’ Conversions (Which Some
Refer to as Ugly Models): Brayton Paul
seems to favor AXi motors, as I do. It
looks like he is taking no chances on
overheating his ESC.
With all my batteries charged, I’m going
flying. You can write to me at the street
address for “The Battery Clinic,” but Email
is faster. MA
Sources:
Harbor Freight (multimeter)
(800) 444-3353
www.harborfreight.com/cpi/ctaf/Displayite
m.taf?itemnumber=92020
Winged Shadow Systems
(630) 837-6553
www.wingedshadow.com
Hughes RC
(800) 786-0802
www.hughesrc.com
The Battery Clinic
12219 NW 9th Ln.
Newberry FL 32669
Edition: Model Aviation - 2008/09
Page Numbers: 91,92,95
September 2008 91
The Battery Clinic Red Scholefield | [email protected]
Also included in this column:
• How High, See How, and
How Fast
• A simple propeller speed
formula
• Hughes Spectra 4
• A caveat of all chargers:
they’re loaded
Is my charger working?
1/32 plywood mount
The How Fast is set up for temporary mounting on models.
Hughes RC’s See How provides a direct reading of flight altitude
or speed.
An inexpensive
digital voltmeter,
such as this one, is
essential for the
electric-power flier.
I AM STILL perplexed by the number of
people who depend on batteries to fly their
models, yet lack even the most basic battery
test equipment. It is not as if it costs a
fortune.
You can purchase adequate digital
multimeters for less than $5 apiece. Harbor
Freight has them for as low as $3.99 ($2.99
when on sale, which is frequently). See the
source list for contact information.
Northern Tool and Equipment,
RadioShack, and eBay are other sources.
RadioShack has a multimeter that interfaces
with your PC to allow you to record
discharge voltage/current and print it out.
These tools are a great way to check your
batteries, and at a cost that is significantly
less than you will pay for some of the
hobby-specific devices.
Check out the photo with the multimeter
connected to a servo. I have found this
invaluable when setting up a model to check
for servo linkage dragging.
Cut the red wire in the middle of a servo
extension (12 inches). Add banana plugs to
the ends of the red wire, and plug these into
your digital multimeter. Polarity makes no
difference, because most meters will read in
either direction. Plug in the modified servo
extension between the battery and the
receiver or between the receiver and any
servo under investigation.
How High and See How: How about a new
fun-fly event? How high can you get your
model in a certain number of seconds from
takeoff? Winged Shadow Systems’ (see the
sources list) neat little gadget called the
How High allows you to get the exact
altitude by hooking up to your receiver and
flying the 2-gram device to altitude.
While you can get a single reading—the
maximum altitude—by waving your fingers
over the LED and counting its blinks, the
See How that the company sells lets you
take multiple altitude readings in the same
flight and displays the actual number.
Simply mate the See How with the LED on
the See High and press the button.
In less than a second, the See How
downloads the altitude data and displays it
for each segment of the flight. As many as
10 readings and nine individual flights can
be displayed.
I learned something else. At 1,000 feet,
your typical trainer is getting to the point
where orientation becomes a problem.
Would you believe that most of our flying is
done at 200-300 feet of altitude? At least
that is what How High told us.
92 MODEL AVIATION
Right: The Spectra 4’s large, backlit display
contains all pertinent battery information.
Below and below right: Brayton Paul’s
conversions to electric power.
Right: Hughes RC’s Spectra 4 addresses
popular modeling battery chemistries.
Winged Shadow Systems’ How Fast
components were fastened to 1/32 plywood to
allow it to be moved from aircraft to aircraft.
This is achieved by temporarily taping the
plate to the bottom surface of the wing and
running the leads to the receiver for power
and acquiring different altitudes by toggling
the retract switch.
The RC Reporter, also from Winged
Shadow, gives you battery voltage on the
fly. Installing this 2-gram device in your
model allows you to check the voltage while
in flight.
The unit gives you audible beeps as your
airplane flies by, while actuating a spare
channel on your transmitter. That’s another
reason to fly electric; you can hear these. It
gives you the present voltage and the lowest
voltage your pack sees during the flight.
A similar device for glow/gas-powered
models measures the receiver-pack voltage
and gives you an audio readout, but you
would not be able to hear it with the engine
running. It’s still a nice feature. Taxi back to
the pits, shut down your engine, flip the
retract switch on your transmitter, and find
out if you have enough battery for your next
flight.
Another feature is that if you turn off
your transmitter without turning off your
model, it will warn you with an audio alarm.
In addition, it’s good as a lost-aircraft finder.
Propeller Pitch Speed: I received a simple
formula from Paul. Someone always has a
better way.
“Red, I just finished reading your
column in May 2008 MA. Learned
considerable. You gave us a location for a
propeller pitch speed calculator. I find it
much simpler and quicker to use the
equation: Pitch (inches) x KRPM x 0.95 =
Speed (mph).”
The kprm is thousands; 12,450 rpm
would go into the equation as 12.54. I
checked several calculations against the
calculator with same results.
Hughes Spectra 4—A Charger for All
Reasons: Remember when the Litco Alpha
4 was the hottest item in charging? It was
so hot that you literally had to win the
Litco raffle to even get one and then be
willing to part with $300. This bought you
the capability of charging four packs at the
same time.
While the Alpha 4 has essentially
disappeared from the market, the need to
charge/cycle various kinds of packs has
not. Hughes RC has stepped forward to fill
that gap. There are other multiport
chargers available, but few, if any, give
you the charge/discharge/cycle control that
the Hughes Spectra 4 offers for all the
battery chemistries we are now employing.
One of the first things that struck me
when I got the charger was the size. This is
not a wimpy little charger you can lose on
your charging bench. Its commanding
appearance with the large heat sink on one
end says serious charging.
Turning on the Spectra 4 for the first
time is another surprise, because the
display, after showing the Hughes
welcome statement with firmware
version, scrolled to “Property of Red
Scholefield, Newberry, FL (352) 331-
8410.” The people at Hughes RC
program the owner’s information into
each charger sold and can change it if the
original owner requests it.
Following are the Spectra 4’s
specifications.
• Four outputs allow you to manage as
many as four batteries at one time (oneto
10-cell Ni-Cd/NiMH, one- to four-cell
Li-Poly/Li-Ion/A123, one- to six-cell
lead acid
• Serves as charger/cycler (for two or
more cells)/loaded voltmeter
• 50 mA-1000 mA per port (charge or
discharge)
• Input: 11-15 VDC
• 80-character, four-line backlit LCD
• Reverse polarity protection on input
and output
• Memorizes up to 20 battery pack charge
settings for “Automatic Charging”
• Remembers packs by “name”—not
number
• Each pack name can be up to 16
characters long
• Memory examples: “Futaba TX”;
“Extra 300 RX”; “CAP 232 ignition”
• Charges multiple batteries with
common grounds
• Simple four-button operation—menu
driven
• Detailed monitoring of all ports
• Audible alerts
• Battery backup in case of power failure
• Built in loaded voltmeter
• Fast charge with peak detection
(selectable rates)
• Timed charge (selectable rates)
• Topping-charge option (selectable
rates)
• Trickle-charge option (selectable rates)
• Accurate battery management
• Rugged all-metal enclosure
• One-year warranty
• Can memorize up to 20 battery-pack
charge settings for “Automatic Charging”
• Weighs 2 pounds
• Size of 8 x 5 x 3 inches
All the charge parameters measured
and recorded appeared to be well within
the accuracy limits expected for this type
of equipment. The ample display gives
you all the information about the pack.
A photo in this column shows the
“END” display for three cycles on a fourcell
Ni-Cd pack that had one flight on it
in the morning before cycling. “P3” is for
Port 3, “CYC” indicates that there were
three cycles, and the last charge was 1
hour, 7 minutes, 33 seconds with 736
mAh input. The readings at the bottom
were for the capacity delivered on each
discharge. The Spectra 4 discharges and
then charges in the cycle mode.
The Spectra 4 is shipped with a
battery backup lead. Connect a 7.2- to
12-volt Ni-Cd or NiMH pack to the jack
on the left end, near the power wire. In the
event of a power failure, the backup
battery will continue to power the
microprocessor and LCD while
terminating all other functions. When
power is restored, all functions will pick
up where they left off.
Battery backup can save you a lot of
headaches, especially if you are powering
your unit from an AC-driven power supply
that is subject to the power company’s
reliability. Your backup battery pack does
not need to be large; a 500 mAh pack
should keep you going for more than a 10-
hour power failure. When you are doing
multiple cycles, battery backup can keep
you from having to start over.
Need more power? Connect two or
more ports with a simple-to-make harness
(detailed on the Hughes RC Web site), and
you can charge/discharge at up to 4 amps
for a single pack or two packs up to 2
amps. Just set the ports to the charge
amount you want to add. If you want 3500
mA, set three ports at 1 amp and one at
500 mA.
A Caveat of All Chargers: This is the first
time I’ve seen any charger manufacturer
admit the following. The Hughes owner’s
manual read:
“Batteries should be disconnected from
the charger within a reasonable period of
time after all functions have been
completed. Once “END” is displayed there
will be a small discharge (less than 5 mA)
on the battery.”
I knew this was the case with some
chargers, such as the old ACE DVMC. But
my curiosity was aroused, so I checked a
number of other chargers in the lab. Every
one puts a small load on the battery when
the charge is complete.
So if you are using chargers that do not
have a continuous or pulsed trickle charge,
you could find a pack somewhat
discharged if it were left connected to the
charger for an extended period (such as
four or five days for a 500 mA pack).
Readers’ Conversions (Which Some
Refer to as Ugly Models): Brayton Paul
seems to favor AXi motors, as I do. It
looks like he is taking no chances on
overheating his ESC.
With all my batteries charged, I’m going
flying. You can write to me at the street
address for “The Battery Clinic,” but Email
is faster. MA
Sources:
Harbor Freight (multimeter)
(800) 444-3353
www.harborfreight.com/cpi/ctaf/Displayite
m.taf?itemnumber=92020
Winged Shadow Systems
(630) 837-6553
www.wingedshadow.com
Hughes RC
(800) 786-0802
www.hughesrc.com
The Battery Clinic
12219 NW 9th Ln.
Newberry FL 32669
