RC watt's up WU100 User manual

"Watt's Up" & "Doc Wattson" Watt Meter and
Power Analyzer User's Manual
Model WU100 v2
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Revision 1 7 1
9/1/2007

Notices
Copyright
Copyright © 2004-2007 by RC Electronics, Inc All rights reserved No part of this manual
may be reproduced or transmitted in any form or by an means, analog, digital, electronic or
mechanical, including imaging, photocopying and recording, for any purpose other than the
purchaser's personal use without the written permission of RC Electronics, Inc , 2980 E
Capitol Expy #50-194, San Jose, CA 95148
Trademarks
Watt's Up and Doc Wattson are trademarks of RC Electronics, Inc
All other brand and product names mentioned in this manual are trademarks or registered
trademarks of their respective owners
Changes
The material in this manual is for information only and is subject to change without notice
While reasonable efforts have been made in the preparation of this manual to ensure its
accuracy, RC Electronics, Inc assumes no liability resulting from errors or omissions in
this manual, or from the use of information contained herein
RC Electronics, Inc reserves the right to make changes in the product design without
reservation and without notification to its users
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual RC Electronics, Inc

Table of Contents I
1 INTRODUCTION..............................................................................................................................3
1 1 WHAT IT DOES 3
1 2 BENEFITS 3
2 FEATURES AND SPECIFICATIONS............................................................................................4
2 1 FEATURES 4
2 2 SPECIFICATIONS TABLES 4
3 SAFETY PRECAUTIONS................................................................................................................5
3 1 SAFE OPERATION LIMITATIONS 5
3 2 ELECTRICAL CONNECTIONS AND WIRING 5
3 3 POWERING UP5
3 4 LIMITS OF CONNECTED EQUIPMENT 6
4 BASICS OF ELECTRICITY............................................................................................................7
4 1 CHARGE 7
4 2 CURRENT 7
4 3 VOLTAGE 8
4 4 RESISTANCE 8
4 5 POWER 9
4 6 WORK/ENERGY 9
4 7 CONSERVATION OF ENERGY 9
4 8 ABOUT UNITS 10
5 GETTING STARTED.....................................................................................................................11
5 1 MAKING CONNECTIONS 11
5 2 USING AUXILIARY POWER 11
5 3 POWER UP CHECKLIST 12
5 4 APPLYING POWER 12
5.4.1 Applying Power, Examples...................................................................................................12
5.4.2 Applying Power, Problems...................................................................................................12
6 INFORMATION DISPLAY...........................................................................................................13
6 1 STARTUP SCREEN 13
6 2 MEASUREMENT SCREEN 13
6.2.1 (Current) Amps A, Pea Amps Ap........................................................................................13
6.2.2 (Voltage) Volts V, Minimum Volts Vm..................................................................................13
6.2.3 (Energy) Watt-hours Wh.......................................................................................................13
6.2.4 (Charge) Amp-hours Ah........................................................................................................13
6.2.5 (Power) Watts W, Pea Watts Wp........................................................................................14
7 USING WATT'S UP........................................................................................................................15
7 1 WHERE DO YOU CONNECT WATT'S UP15
7 2 MAXIMUM CURRENT CAPABILITIES 15
7 3 USING A WATT METER WITH INDUCTIVE LOADS LIKE MOTORS 15
7 4 RESETTING METER AND CLEARING ACCUMULATED VALUES 16
7 5 CONNECTION DIAGRAMS 16
7 6 INCREASING TRANSIENT VOLTAGE PROTECTION 18
8 BATTERY CHARACTERI ATION............................................................................................20
8.1.1 Battery Charging..................................................................................................................20
8.1.2 Battery Discharging, Efficiency and Health.........................................................................20
8.1.3 Low Voltage Measurement...................................................................................................21
9 SYSTEM CHARACTERI ATION...............................................................................................22
9.1.1 Testing & Troubleshooting Loads........................................................................................22
9.1.2 Capturing Current Pea s, Power Pea s and Voltage Minimums (sags)..............................22
9.1.3 Bac up DC Voltmeter & DC Ammeter.................................................................................23
9.1.4 Calculating Relative Efficiency............................................................................................23
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual RC Electronics, Inc

Table of Contents II
10 WATT'S UP APPLICATIONS.......................................................................................................24
10 1 ON BOARD USE 24
10 2 FLIGHT TIME 24
10 3 BASIC COMPONENT SELECTION 24
10 4 INITIAL TESTING 24
10 5 BALANCING BATTERY PACK CELLS 24
10 6 RECEIVER AND SERVO TESTING 25
11 CARE................................................................................................................................................27
11 1 CLEANING 27
11 2 STORAGE 27
12 TROUBLESHOOTING..................................................................................................................28
13 SUPPORT.........................................................................................................................................30
14 WARRANTY....................................................................................................................................31
14 1 ONE YEAR LIMITED WARRANTY 31
14 2 LIMITS AND EXCLUSIONS 31
14 3 LIMITATION OF LIABILITY 31
14 4 ENTIRE WARRANTY 31
14 5 PROCEDURE FOR WARRANTY CLAIMS AND RETURN AUTHORIZATION 32
15 MEASUREMENT LOG..................................................................................................................33
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual RC Electronics, Inc

Introduction 3
1 INTRODUCTION
Thank you for purchasing the Watt's Up or Doc Wattson power analyzer We are confident
you will find it to be an indispensable addition to the tools you use to make your hobby
more enjoyable
While emphasizing RC modeling applications, this manual applies to the myriad
applications to which the Watt's Up or Doc Wattson meters can be applied While the
Watt's Up model will be referred to, the Doc Wattson is the same with the exception of
some the parameter ranges covered
Your Watt's Up watt meter and power analyzer is an easy-to-use precision instrument for
measuring and calculating the electrical parameters the hobbyist of electronic devices
needs to get the most from their projects
1.1 What it Does
Watt's Up measures current, voltage and time and from those measurements calculates
peak current (Amps), peak power (Watts), minimum voltage (Volts), power (Watts),
energy (Watt-hours) and charge (Amp-hours) values for you, in real-time, for the circuit in
which you connect it
1.2 Benefits
With the advent of electric power for models the hobbyist can now investigate and tune the
performance of their model in ways not possible with the traditional internal combustion
engines With Watt's Up it is now easy to determine things like:
Flight time
Current through an ESC and motor
ESC, BEC and motor efficiencies
Charge put into and removed from a battery and the performance of battery
chargers
Battery health
Presence of peak currents that can damage components
Presence of voltage sags that cause components to operate out of specification
Why power is lost during acrobatics or extreme conditions
Effect of gearing and propeller size and shape on power consumption and battery
currents
Effects of modifications, age and damage on many electrical system components
Clever RC hobbyists will, no doubt, discover new applications to further improve electric
model performance
With Watt's Up you can stop wondering what’s going on with your electric model and get
answers that allow you to apply science to your hobby The precise measurements you
collect will help you fine tune your model to get all the performance that you paid for
We know you are anxious to start using your Watt's Up and ask that you review this
manual first to get the most out of its capabilities and inform you of relevant safety
issues.
Enjoy learning Watt's Up!
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual RC Electronics, Inc

Features and Specifications 4
2 FEATURES AND SPECIFICATIONS
2.1 Features
Measures energy (Wh), charge (Ah), power (W), current (A) and voltage (V)
Connector to use an optional receiver battery for measurement down to 0 V
Accurate & precise – 0 01 A current and 0 01 V voltage resolutions
Measures peak Amps, peak Watts (except for Doc Wattson) and voltage
minimum (sag)
Rugged – handles 50 A continuous and 100 A peak at 60 V
14 ga , super fine stranded, high temperature, silicone rubber insulated wire
Small & light with a tough plastic case available in several colors
Acts like a wire so doesn't affect model's performance Precision Alu-Chrom
current sensing resistor, with only 0 001 Ohms resistance and circuitry that draws only 7 mA
Uses DSP to increase ADC resolution and differential measurement amplifiers to
increase noise immunity
Factory calibration stores constants in EEPROM to compensate for component
tolerances
Powerful, 8 MIPS micro-controller
Made in USA to ISO 9001:2000 quality standards
One-year warranty and complete user manual
2.2 Specifications Tables
Table 1 Electrical Measurement Ranges
Parameter Range Resolution Notes
Voltage 0* - 60 V 0 01 V *0 V min w/ auxiliary power
E g a receiver battery Else 4 0
V
Current 0 – 100 A peak 0 01 A 50 A continuous
Power 0 - 6554 W 0 1 W
Charge 0 - 65 Ah 0 001 Ah 0 – 6554 Ah for Doc Wattson
0 1Ah resolution
Energy 0 - 6554 Wh 0 1 Wh 0 – 655 Kwh for Doc Wattson
0 01KWh resolution
Table 2 Miscellaneous Specifications
Parameter Value Notes
Measurement Update Period 400 mS 650 mS for Doc
Wattson
Signal Sampling Rate ???? samples/s
Data Queue Sequence
time
2 seconds
In Circuit Resistance 0 001 Ohms
Operation Current 7 mA
Auxiliary Power Voltage 4 0 V - 60 V e g from a receiver
battery
Dimensions 2 8" L x 1 7" W x 0 83" D
Weight 2 3 oz 1 7 oz without case
Display Screen 16 character x 2 row STN
LCD
Nominal Operating
Conditions
0 - 50 C ambient
temperature, non
condensing humidity
Maximum
temperature must be
reduced at
maximum current
rating
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual RC Electronics, Inc

Safety Precautions 5
3 SAFETY PRECAUTIONS
CAUTION: High power electrical systems pose dangers independent of devices like the
Watt's Up and it is the user's responsibility to be familiar with these dangers and take any
necessary action to ensure safe use Shorting a rechargeable battery or a Watt's Up
connected to a rechargeable battery or battery charger can supply huge currents and have
serious consequences including explosions, causing fire, damage to equipment and
personal injury
Please carefully read the entire SAFTY PRECAUTIONS section to ensure safe
product use.
3.1 Safe Operation Limitations
The Watt's Up is designed to be safe to use when operated within the parameter limits it
was designed for Typical applications are well within these limits, but it is the user's
responsibility to be familiar with the Watt's Up specifications and ensure the unit is
operated within its limits
Table 3 Safe Operating Limits (Do Not Exceed)
Parameter Operating Range Notes
Voltage 0 V - 60 V
Current 0 - 100 A intermittent
50 A continuous
Assumes device's wires are
in free air and attached to
connections at or below
temperature of 35 C
(95 F) with adequate air
flow 100 A operation time
depends on ambient
temperature and wiring
temperature
Nominal
Operating
Conditions
0 - 50 C ambient air
temperature, non condensing
humidity
Maximum temperature must
be reduced at maximum
current rating
CAUTION: Exceeding these limits may permanently damage the Watt's Up and may
cause personal injury and may cause fire
3.2 Electrical Connections and Wiring
There are risks associated with the potentially high currents measured by the Watt's Up
These include, but are not limited to, fire, burns and personal injury The user must be
familiar with the relevant methods, procedures and connection components before using
or making any connection to the It is suggested that any connectors and wires chosen for
use be appropriately sized and rated for the intended application and attached in the
manner recommended by their respective manufacturers
CAUTION: Poor connections and reckless wire handling in electrical systems may have
serious consequences including personal injury, fire and property damage
Intermittent and loose connections can cause component damage!
3.3 Powering Up
Verify there are no exposed wires or connectors at risk for a short circuit before
connecting a battery or power source to the Watt's Up
The Red “SOURCE” and “LOAD” leads of the Watt's Up are connected to each other
and the Black leads are essentially so This means the "other" side is electrically "hot"
when a battery or other power source is connected to either side
CAUTION: Shorting a rechargeable battery or a Watt's Up connected to a rechargeable
battery or battery charger can supply huge currents and have serious consequences
including explosions, causing fire, damage to equipment and personal injury
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual RC Electronics, Inc

Safety Precautions 6
3.4 Limits of Connected Equipment
The Watt's Up may have measurement capabilities, operating ratings and electrical signal
handling abilities that exceed those of equipment to which it is connected This means the
Watt's Up may be able to make measurements on a connected component despite that
component being operated outside of its safe operating ratings
CAUTION: It is the user's responsibility to consider the limitations of any equipment
connected to the Watt's Up and not to exceed them since the Watt's Up provides no
protection for those components Examples of possible hazards include, without limitation:
charging or discharging batteries outside their voltage and current ratings, application of
excessive voltage or currents to electronic speed controls (ESC) and motors, application of
currents that cause dangerous heating or voltages that present a shock hazard Other
hazards may exist
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual RC Electronics, Inc

Basics of Electricity 7
4 BASICS OF ELECTRICITY
Understanding the basics of electricity will help you get the most out of your Watt's Up and
electric model With these concepts you can intelligently compare electrical components
and conduct experiments to maximize their performance in your electric modeling hobby
If you are new to electrical propulsion systems you may want to read through this a few
times Experts can skip it
We use the water and plumbing analogies to teach electrical concepts because people often
already have good intuition about water systems
4.1 Charge
It all starts with charge
Charge is the basic unit of electric energy Using the water analogy, charge is the “amount
of water”
Charge (electrons actually) is what gets stored in a rechargeable battery by a battery
charger Like water gets “stored” in an aquarium by a water pump a battery charger stores
charge in a battery
Asking how much charge is in a battery is like asking how much water is in an aquarium
A physicist will tell you that charge is measured in units of Coulombs (C) like water can
be measured in units of gallons It turns out that Amp-hours (Ah) is also a unit of charge
and is more familiar to RC hobbyists We’ll show why later when we discuss current
Charge = Current  Time
Charge can be measured in Amp-Hours by:
Amp-hours = Average Amps  hours of duration
4.2 Current
Current is measured as an amount of something flowing per unit of time
With electricity, the “something” flowing in a wire is charge, which is measured in
“Coulombs”
A Coulomb per second of electric charge current has a special name It is called an
Ampere (abbreviated Amps or just A) A gallon per second of water flow doesn’t have a
special name It’s just a gal/s
So 20 Amperes or Amps flowing into a motor means it has a current of 20 Coulombs of
charge flowing per second
Now we can explain why Amp-Hours is a measure of charge
An hour is 60  60 = 3600 seconds So an Amp-hour (meaning Amps times
hours)
= Ampere  Hour
And substituting the definition of an Ampere and of an hour this becomes
= (Coulomb/Second)  3600 Seconds which leaves 3600 Coulombs
Coulombs are charge so there we are -- an Amp-hour (or Ah) is 3600 Coulombs
of charge
It is common in RC modeling to discuss charge in units of mAh The m is an abbreviation
for the Greek “milli” which means “thousandth” of something So 1 mAh is 1/1000 of an
Ah Conversely, 2 Ah is the same as 2000 mAh
Here are some examples showing the important relationships between current, time and
charge
1) Charging
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual RC Electronics, Inc

Basics of Electricity 8
If you pump 1 gal/h of water into an aquarium for five hours it will contain 1
gal/h  5 h = 5 gallons Similarly a battery charging at 1500 mA for one hour
will contain 1 5 Amp  one hour = 1 5 Ah of charge Since we learned above
that there are 3600 Coulombs per Ah, the physicist would say the battery
contains 1 5 Ah  3600 C/Ah = 5400 Coulombs of charge Amp-hr versus C
They are different ways of saying the same thing
2) Discharging
If you know a battery and an aquarium are both “full” you just read their
“capacity” (volume) specification to find the stored “charge ” The aquarium
says 20 gallons and the battery says 2000 mAh The aquarium would take 4
hours to empty at a “current” of 5 gal/h and the battery would take 1 hour to
empty at a current of 2000 mA
4.3 Voltage
Something forces current to flow in a wire That something is called voltage and is
measured in Volts (abbreviated V) The pressure your hand feels pushing water out of a
pipe is the force analogous to voltage
You can’t get a current without a voltage The two are related by the concept of resistance
4.4 Resistance
Resistance is measured in Ohms (abbreviated with the Greek symbol Omega ) It is the
property that limits the current, which flows in a wire for a given voltage applied across the
wire
The very important “Ohm’s Law” summarizes this relationship
Amps = Volts  Ohms
It says the amount of current depends on the voltage applied divided by the amount of
resistance Push harder for a given amount of resistance and you get more flow
Reducing the diameter of a water pipe increases its resistance and therefore reduces the
water flowing from it for a given pressure (voltage) Similarly doubling the resistance of a
wire halves the current flowing through it for a given voltage across it
A useful thing to remember is that 1 Volt divided by 1 Ohm = 1 Amp
It says that One Amp of current will flow in wire having a resistance of one Ohm if one
Volt of voltage is applied across it
So given relatively fixed battery voltages, you need low resistance wires to allow high
currents
Resistance is a general term for a rather complex phenomenon There are different kinds of
resistance For our purposes we will mean Direct Current or DC resistance Alternating
Current or AC resistance is beyond the scope of this tutorial and is not widely discussed in
RC electrical systems
Here’s an example problem using resistance
How much voltage drop is there to a motor drawing 50 Amps if the motor is one
foot from the battery? Assume14 Ga wire has a resistance of approximately
0 0025 Ohms per foot
So we have two feet of wire total with 50 Amps flowing through them Ohms
law tells us that to get 50 Amps through a wire of 2  0 0025 Ohms requires:
Volts = Amps  Ohms, = 50  (2  0 0025) = 0 25 V
So those wires use up 0 25 V in battery voltage Our motor would receive 7 15
Volts from a 7 4 Volt battery Apparently, this motor consumes exactly 50
Amps at exactly 7 15 V
"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual RC Electronics, Inc