 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| HomeDiscussion Groups General ModelsRailroadsRocketsRadio Controlled Air ModelsHelicoptersLand ModelsWater ModelsModelGeeks.com Contact UsLink To UsSearch & Site Map |
Model Forum / Radio Controlled / Air Models / July 2009Dead electric motor.
Flew my Greensleeves electric glider today, with a new battery, new (2.4) receiver. I bought the new LiPo (3 cell) to replace a heavy NiCd/NiMh (7 cell). New battery was charged last month but never flew (weather too bad). So I discharged it a bit. And recharged it fully this morning. Flight was OK but no lift whatsoever so it was pretty much on full power for the whole flight. Suddenly, with no warning, I had no control, no power, no nothing. Felt like someone had unplugged the battery. Normally when the battery gets low the ESC turns off power to the motor but I still get control to the flying surfaces (is this the BEC thing?). But today I had nothing. Luckily the landing was better than I usually manage when I do have power! and there was no damage, except a bent spinner. Now at home I've recharged the battery OK; I now have control but no motor power at all. I did get one little blip, for half a second, but no more. My current theories are 1. dodgy connection at the battery, switch or r/x. 2. dodgy brand new, expensive receiver. 3. I've burned out the motor using 11V instead of 8.4V (but why the total loss of control?) 4. none of the above. Any clues? >Flew my Greensleeves electric glider today, with a new battery, new (2.4) >receiver. [quoted text clipped - 20 lines] > >Any clues? Eliminate one thing at a time. If you have one, replace the motor temporarily to troubleshoot your system. If I were to guess, I'd say your had a failure in your ESC but changing the motor is the easiest option to test both. If it doesn't work with a known good motor, it's probably your ESC. If it does work, it's probably your motor. If you don't have a spare motor, run the entire thing down to your local hobby shop. In exchange for your continued support of their business many shops offer free help in testing. You did buy your gear from the local shop and not the cheapest place you could find it on the Internet. Right? -- Ray My father had a problem that sounds pretty similar. His motor would just twitch a bit but power to the servos was normal. What it turned out to be (twice) was one lead from the motor breaking off at the solder point in the plug to the ESC. Visually, it looked fine due to the shrinkwrap but was broken inside. This happened twice. We figure it was vibration so he fastened down the loose leads to keep them from flexing in flight and that solved the problem. > On Sat, 27 Jun 2009 17:54:07 +0100, "Martyn" > [quoted text clipped - 38 lines] > -- > Ray I bought the plane/motor second hand, then took it to the local shop and bought the battery/ESC together. I was going to buy a motor at the time, but he advised then that motors are so cheap it would make sense to try it and see. Don't have any spares. Guess I'll take it bake to the shop and see what he says. > Flew my Greensleeves electric glider today, with a new battery, new (2.4) > receiver. [quoted text clipped - 22 lines] > > Any clues? I'm going to say you blew the motor and when the voltage dropped it made the RX reboot. I really don't know much about 2.4 radios except that I'm not ready for one. mk If you didn't change the prop when you increased the voltage, the odds are extremely high that you pulled too many amps for the ESC and fried it. You have to use a smaller prop when you increase the voltage to keep the amp draw down. Some of the better ESC's have current limiting, but most don't. You would lose the BEC if the ESC fried. At least you didn't have to watch your plane sail into the sunset in a thermal with no control. Best Guess, none of the below: ESC bad... PCPhill > Flew my Greensleeves electric glider today, with a new battery, new (2.4) > receiver. [quoted text clipped - 22 lines] > > Any clues? > If you didn't change the prop when you increased the voltage, the odds > are extremely high that you pulled too many amps for the ESC ... Note that current wants to go up *squared* with voltage! Going from 8.4Volt to 11.1Volt would give an increase in current by a factor 1.3, 30%extra (assuming motor, controller and battery are perfect, zero resistance) Dry testing brushless motors http://www.wattflyer.com/forums/showthread.php?t=35216 http://www.rcgroups.com/forums/showthread.php?t=240993 About de-rating controllers and motors, starting at 'for everyone else': http://www.rcgroups.com/forums/showthread.php?p=11476940#post11476940 Vriendelijke groeten ;-) Ron near Nijmegen, Netherlands It would never have occured to me to change the prop. Especially to make it smaller! You'd have thought that having more power available (bigger battery) would allow a bigger prop. This is why I've never understood electrics. > This is why I've never understood electrics. For a rainy day. * Presentation: de-mystifying Electric Flight www.rcaircrafters.org/The%20Electric%20Show.pdf * Brushless motor animations and simulations. Mostly outrunners but inrunners are just outrunners turned inside out. www.rcgroups.com/forums/showthread.php?t=216928 * www.wattflyer.com/forums/forumdisplay.php?f=3 -> Everything You Wanted To Know About Electric Powered Flight * www.ampaviators.com -> Beginner Guide * www.ezonemag.com -> Faq * Choosing a power setup www.rcgroups.com/forums/showthread.php?t=739069 www.wattflyer.com/forums/showthread.php?t=27019 * Current, voltage, Watt, battery-types and -C-rating explained www.rcgroups.com/forums/showthread.php?t=417868 * Motor_internals_101, about poles, winds, delta, star www.gobrushless.com -> knowledge base -> basic overview (1-5) All things being equal, it should and does to a point. The problem is that the current draw goes up at the same time. Propping down lets the RPM go up dramatically without increasing the current, giving you more output power from the bigger battery without killing the ESC. You can still have problems if the ESC or motor isn't rated for the higher voltage. PCPhill > It would never have occured to me to change the prop. > Especially to make it smaller! > You'd have thought that having more power available (bigger battery) > would allow a bigger prop. > This is why I've never understood electrics. > It would never have occured to me to change the prop. > Especially to make it smaller! > You'd have thought that having more power available (bigger battery) > would allow a bigger prop. Current wants to go up squared with voltage! Explanation http://www.wattflyer.com/forums/showthread.php?p=594945#post594945 http://www.wattflyer.com/forums/showthread.php?p=591935#post591935 Prettig weekend ;) Ron |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2012 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.