Alex Leigh Posted June 23, 2009 Share Posted June 23, 2009 After my ESC caught fire, I was looking for a replacement, and was reading on a website that the recommendation is 50% headroom. So if your motor draws 28a (as mine does with the standard prop), should I be buying a 40A ESC rather than a 30? Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted June 23, 2009 Share Posted June 23, 2009 Yes, I would Alex. I always try and leave a bit of headroom - most of my ESCs seem to be 40amp versions which comfortably covers most 20-30amp draw set-ups. Edited By David Ashby - RCME moderator on 23/06/2009 09:50:45 Quote Link to comment Share on other sites More sharing options...
Alex Leigh Posted June 23, 2009 Author Share Posted June 23, 2009 Thanks David... I'll go with a 40. And I've bought myself one of those funky ocean tree monitors that show the amperage ratings of the motor/prop combination. I also noticed with the "s" that is has a cooling inlet but no outlet! Is it worth chopping one in? Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted June 23, 2009 Share Posted June 23, 2009 LOL, Chopping, Chopping!! Is that a technical aeromodelling term? I didn't seem to need that on mine Alex but you could cut a small outlet so long as the structure isn't compromised, won't do any harm at all and will help keep the bits cool. I haven't any experience of the data loggers, didn't Timbo have one? Edited By David Ashby - RCME moderator on 23/06/2009 11:02:28 Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted June 23, 2009 Share Posted June 23, 2009 If you mean an EAGLE tree logger Alex...yes I use one. Quote Link to comment Share on other sites More sharing options...
Alex Leigh Posted June 23, 2009 Author Share Posted June 23, 2009 I do, Frank had one and he even sent me a funky PDF afterwards. Very useful and I'd like to be sure that I've matched all my components correctly. Although in the case of the burned ESC, there was no issue in terms of max amps. That is a technical term David. It's in "Al's manual of percussive engineering" between sections on Light Hammering and Bashing the offending article with a tyre iron I'll have a look at a possible chop later. Or fly with the canopy off Quote Link to comment Share on other sites More sharing options...
steve cotterell Posted June 27, 2009 Share Posted June 27, 2009 Hi please help!!! I have a turnigy 17ookv brushless motor - gws 15amp esc and dualsky 3 cell 450 11.1v lipo. The recommended prop is 8-4 . Whilst running up after three quarters throttle it cuts out i have down propped to a stupid size and its ok but not for the 3d slofly i intend.. Any ideas PLEASE.. Steve Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted June 27, 2009 Share Posted June 27, 2009 Probably the battery is too small in capacity and is sagging to a very low voltage under load - try a larger maybe 800+mahr battery. Of course you dont say WHICH 1700 kv moor you are using - if its the tiny 2211 one then this is only designed for 2s battery not a 3s, and maximum curent of only around 3 - 4 A with a 3s battery you may well be exceeding the ESC rating and causing shutdown Edited By Timbo - Moderator on 27/06/2009 15:13:57 Quote Link to comment Share on other sites More sharing options...
Pete Rieden Posted July 6, 2009 Share Posted July 6, 2009 Posted by Alex Leigh on 23/06/2009 09:41:01: After my ESC caught fire, I was looking for a replacement, and was reading on a website that the recommendation is 50% headroom. So if your motor draws 28a (as mine does with the standard prop), should I be buying a 40A ESC rather than a 30? In my experience this is a "you get what you pay for" thing. Almost all of my ESCs are Jeti or Hacker (which are mostly the same hardware with different software). I routinely run these at or slightly above their stated ratings at full throttle - for example I run my Jeti Advance 40-3p controllers at between 40 and 45 Amps because that's what their specifications state they can achieve. Several of these are over 5 years old and have over 500 flights on them, and they are still going strong. I actually use the over-current protection of the ESC to protect the batteries. Likewise my 18A ESCs are run at 18-20A and my 12A ones are run at up to 14A. I have an ancient Modelmotors 55A Opto ESC that spends most of its time at 60-65A (but only for bursts, because it's used in a hotliner). Now I've read this theory put out by the cheaper suppliers that to run at 40Amps you need a 60 Amp ESC (actually an ESC whose advertised rating is "60 Amps continuous, 90 Amps burst") and as far as I'm concerned that simply means they lied about the ratings. If it can't take 40Amps then it's not a 40Amp ESC. But I can understand the temptation to buy the cheap stuff and tollerate the snake-oil in the instructions! £0.03 supplied, PDR Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted July 6, 2009 Share Posted July 6, 2009 Well have to say that in my experience...most fliers today do not splash the cash on expensive Jeti and Hacker ESCs - the days of the cheap yet perfectly reloiable and functional ESC are here, and even allowing for the extra headroom of larger capacity, they are still better VFM.The "add 50%" for headroom guide is proably wise withthese cheaper brands. Just my £0.01 worth, as I cant afford 3p. Quote Link to comment Share on other sites More sharing options...
Pete Rieden Posted July 7, 2009 Share Posted July 7, 2009 True enough, but most of these ESCs were bought many years ago when there were no "cheap" options - and as they're still going I have no need to consider replacing them. So for me they are excellent VFM, although I can see that the decision isn't as clear cut for someone looking to buy new ones today. PDR Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted July 7, 2009 Share Posted July 7, 2009 I only build headroom into my ESC's if I think I'm going to struggle with cooling, I find in a EDF model having the ESC dangling behind the motor inside the duct works quite well Also ESC's get hotter at low throttle settings as they are switching on and off a lot, generating heat and generally being inefficient, going WOT they generally just switch on and run cooler or more efficiently so it pays to match the battery, motor, amp draw and ESC to get them all running at their most efficient. Tom Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted July 8, 2009 Share Posted July 8, 2009 basic---no frill's controller's 60 amp....£20.00 from up here in god's country.........beat that........ ken anderson......... Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted July 8, 2009 Share Posted July 8, 2009 A pal returned from Weston with 2 X 60A jobbies @ 8£ each brand new !!Edited By Timbo - Moderator on 08/07/2009 09:41:19 Quote Link to comment Share on other sites More sharing options...
Allan Bowker Posted July 8, 2009 Share Posted July 8, 2009 I leave about 80% headroom based on advice from many sources (including this forum). Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted July 25, 2009 Share Posted July 25, 2009 Just think about this. The world speed record for a full size electric powered aircraft has been set at 135 MPH. The power is provided by a 75 KILOWATT motor. I wonder what the batteries are and what they cost and what the speed controller is like. Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted July 25, 2009 Share Posted July 25, 2009 lma are taking the speed controller's out of toyota prius car's for the large model project's peter................'sssss ken anderson...who nearly set fire to his transmitter...... Quote Link to comment Share on other sites More sharing options...
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