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Using Watt's Up

  

                                                           

  

                                                                              

  

19

1. 

Use a transient voltage suppression (TVS) zener diode across meter's leads. 

Add an 

appropriate unidirectional transient voltage suppressor (TVS) zener diode like a "Transorb"
with the "cathode" side on the meter's plus (red) lead and the other end on the negative 
<black) lead. The TVS cathode end usually has a band. Make sure the TVS turn on voltage 
is above that of the voltage being measured, but it's clamp voltage is below that of the 
meter's max rating. A higher Joule/power/energy rating is better, other things being equal.

As an example, the Diodes Inc. partnumber: 1.5KE43A  (which Digi-Key carries) is a 
unidirectional ~ 43 Volt turn on, 1500 Watt TVS Zener diode with axial leads that clamps 
voltages to less than 60V. It would not be appropriate in circuits having measured voltages 
near or greater than 43 Volts because it would start shorting them out at ~ 43 Volts.

This approach does not affect meter accuracy, but does limit the maximum applied voltage 
to somewhat less than the TVS diode's turn on voltage.

2. 

Use auxiliary power and add series resistor to measured voltage.

 Power the meter 

using the Auxiliary Connector connected to a voltage source that exceeds by one volt the 
voltage to be measured by the meter. E.g 13V to the auxiliary connector if measuring a 
12V power source. Connect the voltage to be measured to the plus lead of the meter via a 
non wirewound (they're inductive) resistor with a value of at least 270 Ohms and power 
rating of ¼ Watt or more. A 274 Ohm resistor adds ~ -0.1% error (will read low) to voltage
(not current) measurements. Higher resistance increases protection, but at increased voltage
error. E.g. a 1.3K Ohm which increases voltage error to ~ -0.5%. Digi-Key carries the 
inexpensive Yageo, MFR series metal film resistors (e.g. pn: MFR-25FBF-274R) which 
will work as will many others. The Auxiliary power source must be free of voltage 
transients itself. It can be connected through a resistor as well as long as the IR voltage 
drop from the ~7 mA meter operating current results in voltage at the meter that still 
exceeds the voltage being measured. E.g. a 270 Ohm resistor would require a minimum 15 
Volt source due to the (270 X 0.007) 1.9 V drop across the resistor.

Failure to provide sufficiently high Auxiliary voltage will result in the meter being 
powered by the measured voltage. Any added resistor will then add an IR voltage drop 
error to measured readings. E.g. ~1.9V using a 274 Ohm resistor.

3. 

Remove internal power sharing diode.

 *** 

This is an Absolutely unsupported 

modification – don't even think of getting support for this or making a warranty 
claim on a meter whose case has been opened ***. 

With the case open, carefully remove 

diode D1. Once done, this will require powering the meter through the Auxiliary 
Connector, but will also make the meter more robust against overvoltage transients and 
remove the requirement that, to be the sole power source, the Auxiliary Connector voltage 
must exceed the measured SOURCE voltage.

The following diagram shows components added to increase transient voltage protection as
well as the use of a pushbutton switch to reset meter readings.

"Watt's Up" & "Doc Wattson" Watt Meter and Power Analyzer User's Manual

RC Electronics, Inc.

L o a d s

P o w e r  S o u r c e s

L e g e n d

P l u g  c o n n e c t o r

S o c k e t  c o n n e c t o r

M e a s u r e d

P o w e r

S o u r c e

L o a d

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t r a n s i e n t  p r o t e c t i o n  c o m p o n e n t s  a n d

r e s e t  s w i t c h  c o n n e c t i o n

m e t e r

+

-

S

O

U

R

C

E

L

O

A

D

X

M a k e  n o
c o n n e c t i o n

A u x i l i a r y

P o w e r

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O p t i o n a l ,
n o r m a l l y  o p e n ,
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p u s h b u t t o n
s w i t c h  t o  r e s e t
m e t e r  r e a d i n g s

T V S

P r o t e c t i o n
R e s i s t o r

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-

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c a t h o d e  e n d

N e g a t i v e  L e a d
C u r r e n t  F l o w

©  c o p y r i g h t  2 0 0 4 - 2 0 0 7  R C  E l e c t r o n i c s ,  I n c .  A l l  r i g h t s  r e s e r v e d

Summary of Contents for Doc Wattson

Page 1: ...ttson Watt Meter and Power Analyzer User s Manual Model WU100 v2 Please visit our website for the latest version of this manual Visit our website Watt s Up Watt meter www rc electronics usa com Revisi...

Page 2: ...l 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 t...

Page 3: ...CREEN 13 6 2 1 Current Amps A Peak 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 Peak Watts Wp 14 7 USING WATT S U...

Page 4: ...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 LIAB...

Page 5: ...ir 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 eff...

Page 6: ...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 Vo...

Page 7: ...nt 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...

Page 8: ...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 ha...

Page 9: ...C 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 amoun...

Page 10: ...e 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 th...

Page 11: ...d chosen at a particular time depends on the point of view being emphasized by an author Hopefully this will become clear as you read on People often incorrectly mix the concepts of power and energy w...

Page 12: ...delivered to the prop In battery charging energy from the charger is delivered as a current into a battery where it is converted to a charge stored in the battery s chemistry In a perfect rechargeabl...

Page 13: ...Loose and intermittent connections can cause component damage 5 2 Using Auxiliary Power By connecting a receiver battery pack of at least 4 0 V or other power source to the 3 pin connector on the SOU...

Page 14: ...auxiliary 3 pin SOURCE power input connector If you connect an auxiliary power source of 4 0 V or more e g small receiver battery pack the Watt s Up operates independently of power sources on the LOA...

Page 15: ...s a slight amount of current 7 mA from the SOURCE side Being hundreds of times less current than is drawn by typical loads this slight additional current can be ignored and the SOURCE s current be con...

Page 16: ...er delivered in Watts over the last screen update interval The displayed Peak Watts value Wp is the maximum power drawn on the LOAD side since the startup screen ended Watts values are measured on the...

Page 17: ...ng connectors etc have resistance subject to the same resistance based heating The high current handing capabilities of Watt s Up will be maximized when the Watt s Up s SOURCE and LOAD wires are kept...

Page 18: ...le connections between the Watt s Up and various Sources and Loads using a four wire connection A three wire connection only connects the meter s red plus lead at the LOAD or the SOURCE but not both A...

Page 19: ...t t s U p w a t t m e t e r B a t t e r y 0 6 0 V D i s c h a r g e L o a d SOURCE LOAD B a t t e r y C h a r g i n g B a t t e r y D i s c h a r g i n g L o a d s P o w e r S o u r c e s L e g e n d...

Page 20: ...t c h t o r e s e t m e t e r r e a d i n g s b y r e m o v i n g p o w e r c o p y r i g h t 2 0 0 4 2 0 0 7 R C E l e c t r o n i c s I n c A l l r i g h t s r e s e r v e d O p t i o n a l n o r m...

Page 21: ...transients itself It can be connected through a resistor as well as long as the IR voltage drop from the 7 mA meter operating current results in voltage at the meter that still exceeds the voltage bei...

Page 22: ...eived as well as the peak Amps Ap and peak Watts Wp used and the minimum voltage on the battery during the charging process Make a note of these final values as they can be used to determine charger e...

Page 23: ...nce it can be difficult to get manufacturer specifications to match test results it is often simpler and just as useful to record the capacity value of a new battery and save that as a baseline Note t...

Page 24: ...Watt s Up readings exercise the system by varying things like throttle settings gearbox ratios motor type ESC setup propeller type battery voltage and type drive train type etc Watt s Up allows you to...

Page 25: ...onents of the system for comparison Start by taking a baseline measurement to compare against Run the prop up to its typical operating RPM using your tachometer and make note of the Watts reading on t...

Page 26: ...Now choose a suitable ESC and battery pack of the appropriate voltage 10 4 Initial Testing Now that you have chosen components to start with it s time to bench test things and do some tuning Keep in...

Page 27: ...t the value you calculate from the pack voltage minus a cell or two may be inaccurate to a degree that interferes with your cell balancing We therefore recommend you measure each cell independently Be...

Page 28: ...exercise your servos simultaneously if possible to create the maximum load on the battery or BEC Monitor the peak Amps peak Watts and minimum Volts to verify acceptable values Unexpected peaks may be...

Page 29: ...in a cup of lukewarm water Do not apply the detergent directly to your Watt s Up Instead moisten a cloth with the solution and gently wipe your Watt s Up clean CAUTION Do not exert too much pressure o...

Page 30: ...low voltage Check you have a power source battery or charger supplying at least 4 0 V connected to the SOURCE side wires or to the Auxiliary Power Connector Only have volt readings no Amps Power or o...

Page 31: ...lue is more than the Peak Amps value the Peak Amps value will match it The Peak Watts value is determined the same way Similarly any time the Volts value is less than the Minimum Volts value the Minim...

Page 32: ...l Expy 50 194 San Jose CA 95148 Phone 408 705 1980 Fax 408 834 7413 Technical Support Email rc_support rc electronics usa com Customer Service Email rc_customerservice rc electronics usa com Websites...

Page 33: ...e iv Damage from immersion or cleaning with other than the described procedure v Damaged as a consequence of any repair modification alteration or conversion not performed by RC Electronics Inc This w...

Page 34: ...our sales invoice Please contact RC Electronics Inc directly to get a RMA and return instructions Carefully pack the Watt s Up and return to the address you are provided The RMA must be clearly labele...

Page 35: ...Make photocopies so they re always handy Amps Amps Volts Volts Watts Watts Ah Ah Wh Wh Ap Ap Vm Vm Wp Wp Amps Amps Volts Volts Watts Watts Ah Ah Wh Wh Ap Ap Vm Vm Wp Wp Amps Amps Volts Volts Watts Wa...

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