At the recient meeting there were several great questions that I did my best to answer and peaked me to do more reading. There are some great resources available to us as electric flyers thanks to some very bright people involved in the hobby and using the search function. I found one thread/post in particular that answered several of these questions AND in easy to understand terms. Please take the time to look over the post as It might answer some of your questions and help us all to build/fly better performing models. Win Win!
You dont have to go on the wild chase following the links the post provides the mainstay of the information. That is unless you want to! PS the link has some great photos if interested.
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http://www.rcgroups.com/forums/showpost.php?p=10926525&postcount=1)
Quote origional post in link provided:
too long battery wires will kill ESC over time: precautions, solutions & workarounds
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I have copied (parts of) useful posts in this thread into this opening post.
Problem
Solution
Rule of thumb
Capacitor type
Capacitor polarity!
How to add extra capacitors
Expert/manufacturer opinions, rules of thumb, installation
Explanation/theory
Measurements
DIY pictures
Problem
Conclusion from the links below, all controller manufacturers say the same:
Too long battery wires will kill your ESC over time!
The standard input capacitors (large cylindrical thingies in thin shrink wrap) will be destroyed over time because they get warmer/hotter. Using thicker wire will not help, it's mainly a wire inductance problem, not a resistance problem.
This goes for all makes, they all use the same principle (except Sinus controllers, they use sinusoidal commutation instead of trapezoid, they tested 70 meters without capacitors). However, lengthening the motor wires may lead to radio interference. Give the three of them a twist to prevent this.
Solution
Lengthen the motor wires, not the battery wires. That's hardly critical because there's already a lot of wire in the motor itself. If the motor-ESC wire eventually gets too long, it will not harm motor and/or controller. May cause interference though, give the motor-ESC wires a twist. Always a good idea to do that anyway.
Rule of thumb
If you have to lengthen the battery wires, add extra electrolytic capacitors in parallel with ESC, never in series with ESC. As a rule of thumb, for every 4inch/10cm extra length/distance between battery and ESC, add an 220uF extra capacitance near the controller (electrolytic condensators, voltage the same as the capacitors already installed, low ESR type) (Ludwich Retzbach, German e-flight author&editor, the 'R' in LRK).
Better to use several smaller caps (in parallel) instead of one biggie. Smaller caps can shed more heat and total inductance will be lower (inductance per cap is lower and those inductances are paralled to boot ). See attached pictures below.
Also keep the positive and negative wires as close to each other as possible, eg. by twisting and/or taping them together. If the wires are close to each other then the series inductance will be reduced, because the current is going in opposite directions in each wire (and therefore producing opposite polarity magnetic fields which cancel out). For example, 13AWG wires separated from each other by 1 inch have about 4 times higher inductance than if they are bound together. (Bruce Abbott in
www.rcgroups.com/forums/showthread.php?p=11594609#post11594609)
Capacitor type
The main spec you need is low impedance and low ESR(equivalent series resistance). I think the only thing you will find at radio shack will be general purpose caps, not low ESR. The ESR of a cap won't be printed on it, you will have to look up the manufacturers spec sheet. The Rubicon ZL series mentioned in the Schulze instructions is a good one and is available from newark/farnell. The Panasonic FM series is another good low impedance cap and is available from digikey
www.farnell.com/datasheets/2161.pdfindustrial.panasonic.com/www-data/pdf/ABA0000/ABA0000CE108.pdf
PS You would want the voltage rating on the caps to be significantly higher than the battery voltage. Same voltage rating is the installed caps. Higher rating is no problem. (thanks jeffs555, from
www.rcgroups.com/forums/showthread.php?p=11971048#post11971048)
If you try it with longer wires and no extra low esr caps it may work for a while, but the longer wires put an extra load on the original cap. The extra load shortens the life of the original cap and it will eventually fail, probably catastrophically. (thanks jeffs555, from
www.rcgroups.com/forums/showthread.php?p=11996840#post11996840.
Capacitor polarity!
Electrolytic capacitors, like batteries, have a (+) and (-) lead! Solder them in the wrong way and they will got hot, pop open or even explode. Nasty fumes and the liquid stains. Don't ask how I know
How to add extra capacitors (English and German)
www.schulze-elektronik-gmbh.de/guide/gfutc-de.pdfYGE controllers, extra capacitors and their location, nice pics, click to enlarge:
www.yge.de/caps2.phpExpert opinions, rules of thumb, installation
Schulze controllers and battery lead length
www.schulze-elektronik-gmbh.de/tips_e.htm (English)
www.schulze-elektronik-gmbh.de/tips_d.htm (German)
Castle Controllers about battery lead length
www.rcgroups.com/forums/showpost.php?p=1537846&postcount=28www.rcgroups.com/forums/showpost.php?p=4833040&postcount=5www.rcgroups.com/forums/showpost.php?p=1531363&postcount=25www.rcgroups.com/forums/showthread.php?t=1095329Bob Boucher (Astrobob,
www.astroflight.com) on long battery leads
www.rcgroups.com/forums/showpost.php?p=2988042&postcount=32Hacker on long battery wires:
www.hacker-motoren.de/images/Master-manual-Engl.pdf (English)
-> Safety and operating instructions
www.hacker-motoren.de/images/MASTER-Manualgerman.pdf (German)
-> Sicherheits- und Betriebshinweise
Novak
www.teamnovak.com/tech_info/power_caps/power_caps.htmPaul Daniels
www.rcgroups.com/forums/showthread.php?p=11297012#post11297012Explanation/theory
First a watery analogy, water running in a pipe and through a tap. Now turn off the tap quickly. You'll hear a loud knock/shock sound in the pipe. The water wants to continu flowing but it can't, for a moment the water pressure is much higher than the static water pressure. It's the same for a current that's switched off, because of the inductance it wants to keep on flowing, voltage gets higher. This is also what causes sparks (brush fire) in a brushed motor.
The controller is like a watertap that's switched off (and on) very fast (8,16, 32kHz PWM) to get the desired current. Turning off the current, in combination with the battery wire inductance, causes voltage spikes because the current wants to continue on its course (ref. inertia of the moving watercolumn). Those voltages are higher than the battery voltage. The input capacitors (cylindrical) takes care of these spikes (they reduce the wire inductance). The longer the wires, the higher the voltage spikes induced in the wires, the harder on the input capacitors. They will get warmer, heat up and explode. This is caused by the wire inductance, not by wire resistance. Therefore, using thicker wire will not help much, it's not a bad idea either, but extra capacitors are the solution, thus reducing/compensating the wire inductance. Or longer motor wires instead of long battery wires.
www.s4a.ch/eflight/reglerleistung.pdf (German)
-> Akkukabellänge und seine tödliche Auswirkung
The coils switching off create the high voltage spikes in the battery wires:
www.rcgroups.com/forums/showthread.php?p=10940134#post10940134In depth discussion
www.aerodesign.de/peter/2001/LRK350/SPEEDY-BL_eng.htmlwww.aerodesign.de/peter/2001/LRK350/Warum_dreht_er_so_eng.htmlwww.rcgroups.com/forums/showpost.php?p=10028325&postcount=2661www.rcgroups.com/forums/showthread.php?p=1518827#post1518827Measurements
By RCGroups user Peter D Rieden
www.rcmf.co.uk/4um/index.php/topic,50366.msg569630.html#msg569630Vriendelijke groeten Ron van Sommeren
• brushless motor building tips & tricks
• diy brushless motor discussion group
• Drive Calculator download & discussion group
• int. electric fly-in, Nijmegen, the Netherlands
DIY pictures
more pictures at
www.YGE.de controllers
Han Witteveen (Netherlands ) posted his diy solutions in post #49
Building the Haviland DH-84 VH-UXG 'Riama' workshop cam
Topic: Power Systems (Read 34003 times)