|Contributed by: Greg Covey | Published: January 2005 | Views: 133975 | Email this Article
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new "Watt's Up" RC battery Watt meter
from RC Electronics measures and calculates all
the electrical parameters you need to get high performance
from your R/C cars or planes. It is an essential
tool for increasing the performance and safety of
your electric-powered R/C model. With the best balance
of specifications and features on the market, you
can stop guessing and start knowing "Watt's
Up" with your performance!
do I need a watt meter? The "Watt's Up"
watt meter helps you:
* Predict model airplane flight time
Ensure peak currents are safe for motor, wiring
Check battery health and whether battery should
Evaluate R/C battery charging efficiency
Verify that the minimum voltage while operating
is within specifications
Choose the best propeller or gearing and the
most efficient motor
Check for wiring and connector power losses
Measure power and energy consumption of ANY
device with a battery
energy (Wh), charge (Ah), power (W), current (A)
and voltage (V)
to use a receiver battery for measurement down
to 0 V
current peaks and voltage minimums(droops)
& precise - 0.01 A current and 0.01 V voltage
- handles 50 A continuous and 100 A peak at 60
ga., 7 x 37 stranded, high temp silicone rubber
insulated wire without connectors
& Light: 2.8" long x 1.7" wide x
0.83" thick (70 mm x 44 mm x 21 mm), 2.5
like a wire so doesn't affect model's performance.
Precision current sensing resistor, with only
0.001 Ohm resistance and circuitry only draws
DSP to increase ADC resolution and differential
measurement amplifiers to increase noise immunity
calibration stores constants in EEPROM to compensate
for component tolerances
0-60 V, resolution 0.01 V. That's a 14 cell series
0-100 A peak, 50 A continuous, resolution 0.01
0-65 Ah, resolution 0.001 Ah. That's ~32 Amps
for two hours!
0-6500 W, resolution 0.1 W. That's ~8.7 Horsepower!
0-6500 Wh, resolution 0.1 Wh. That's lifting a
50 pound model into outer
space (65 mi.)!
from 4.0-60 V, 0 V with optional receiver battery
16 x 2 STN LCD display
8 MIPS micro-controller
"Watt's Up" watt meter comes with a manual
but without connectors. I soldered a set of Dean's
Ultra connectors onto my meter for testing in a variety
The "Watt's Up" watt meter (bottom) goes
beyond the specifications of my original Astro Flight
I've been using other watt meters for years like the
popular Astro Flight "Super" and "Micro"
whattmeters. The single "Watt's Up" watt
meter can not only perform the range of both Astro
Flight meters but can even go beyond it for specifications
not before seen in any other unit.
the "Watt's Up" watt meter can use an
external receiver battery, it can measure a voltage
range from 0-60v with a 0.01 volt resolution and
a current range from 0-100amps with a 0.01 amp resolution.
Now, even single-cell Lithium setups can be measured
for micro-flight applications.
measurements I took on a power system that draws
first screen of my sample measurements (left)
shows that the alternating LCD display can capture
current peaks and voltage minimums (or droops).
It also measures energy used (Wh) and power in
second and third screens show the same display
alternate at different times. The charge level
(Ah), power (W), current (A) and voltage (V) are
all shown. Only the power in the lower right corner
keeps the same units.
"Watt's Up" watt meter has been optimized
for the needs of the R/Cer with added features
like charge display in Ah and power in Wh. Conventional
equipment like a DVM often has insufficient current
range and too much insertion loss due to internal
resistance or long leads.
next test of the "Watt's Up" watt
meter was to verify the voltage measurement
against a Fluke 79 series multimeter
measured 0.01v difference which was probably
correct since my Fluke meter was tapped at the
output connector side after about a 6"
wire length at 14amps
The current peak and voltage minimum
capture features allows
for hands-free measurements
can be very difficult to hold the watt meter while
holding the plane and transmitter. On larger planes,
the prop wash blows the watt meter so you can't
see it sometimes. The "Watt's Up" ability
to capture even brief current peaks and voltage
minimum values can help. The Peak Amps value and
Voltage Minimum values will be the peak and minimum
captured following the "Watt's Up" power
on sequence. Be careful in adjusting test setups
to not accidentally cause a current peak or voltage
minimum that isn't the one you are watching for.
This might happen if, for example, you connect another
component to the system while it is measuring. When
you throttle back down, your peak current reading
and lowest voltage reading will be maintained until
you disconnect the flight pack.
Peak Amps and Voltage Minimum values are cleared
whenever the "Watt's Up" watt meter turns
on (i.e. is powered up). So remove all power sources
when you need to clear them for a new measurement.
The watt meter can also be used to measure
the charge going into a flight pack
application that comes in handy is to measure
the charge going into a flight pack for the
lower-end chargers. You can monitor the charge
that you put back into the pack and keep a
closer eye on the actual current being applied
to the pack. I love the inexpensive Apache
2500 chargers for 1-4 cell Lithium packs but
often want to measure just how much I depleted
the pack after a flight. The "Watts Up"
watt meter allows me to do it if I reverse
the connector sex by using adapters. Shown
above is an already charged 2-cell Kokam 1500mAh
pack that I am just peaking up to 8.4v.
The "Watt's Up" watt meter documented
my baseline measurement for a power system
I measured the power on my new ProJeti wing
power upgrade with the "Watt's Up"
watt meter, it confirmed my suspicion with
an eyebrow raising 43amps and 440watts! The
finished wing not only balanced perfectly
with the new 3-cell Kokam 3.2AH pack but the
Lithium pack held a higher voltage at 43amps
than any other pack I own.
flight test should be fun and I'll have a
documented reading to refer back on.
racing cars or flying electric planes, there
are times when you need to verify the performance
of your power system. The "Watt's Up"
watt meter can be used to keep your power
system in top condition by measuring critical
parameters under load or battery pack capacity.
The values measured by the watt meter can
then be compared to manufacturer's specifications
or your own baseline measurements.
have been times when I have suspected poor
motor performance, when in fact, a watt meter
has proven the issue to be poor battery performance.
Fine-tuning your R/C electric model for great
performance doesn't have to be a guessing
game. The watt meter easily showed me that
the battery I was using could not deliver
the current needed for my motor. Without a
tool like the "Watt's Up" watt meter,
I would still be guessing about which component
of my power system to change.
2980 East Capitol Expy. #50-194
San Jose, CA 95148
The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.
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