HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Aug 21, 2013, 11:57 AM
I live on LiPos
RcAirplaneNoob's Avatar
United States, DE
Joined Jul 2012
691 Posts
Help!
Motor Issues with my UM SUK26xp PLEASE HELP

Hello I flew my sukhoi a few times in the spring and it flew great. This morning i took it out a burned through a few packs at full throttle. Eventually my flight times got shorter and the plane lost power even with a full pack. I thought the AAs in my chargers were low and i changed them but i still had the same issue. I checked the voltage in a "charged" pack (according to my AA parkzone chargers) and it read 4.2V I don't know if that is actually a full charge or not. I use E-flite 150mah, Turnigy nanotech 160mah and Thunder Power 160mah in the sukhoi. I don't know if the brand matters or not. I removed the top half of the fuse and checked out the motor and added some oil to the bearings and it didnt make a difference. I did crash it into the dewy grass and it did the fire its throttle up right away it pulsed but after a bit it flew normal except for the power level. I flew my flights WOT and I don't know if I could have burned the motor up and caused it to lose power. I also trimmed out the foam near the motor in case it was grinding on the gear and losing power because of friction. I'm out of ideas please help!
RcAirplaneNoob is offline Find More Posts by RcAirplaneNoob
Last edited by RcAirplaneNoob; Aug 21, 2013 at 12:08 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Aug 21, 2013, 12:09 PM
Deviant
sbstnp's Avatar
Joined Jul 2012
1,179 Posts
Probably the motor is burnt out. You should let the motor cool for 2-3 minutes between flights, otherwise you greatly shorten it's lifespan.

Other cause could be the lipos, if you don't time your flights and reach LVC too many times then not put lipos in storage mode they will be gone sooner or later. Indeed 4.2V is fully charged, but that doesn't mean much, you should check how much voltage sags during load in order to assess the state of a lipo.
sbstnp is online now Find More Posts by sbstnp
Reply With Quote
Old Aug 21, 2013, 12:14 PM
I live on LiPos
RcAirplaneNoob's Avatar
United States, DE
Joined Jul 2012
691 Posts
i do hit lvc alot and i dont know how to put the 1 cells in storage
RcAirplaneNoob is offline Find More Posts by RcAirplaneNoob
Reply With Quote
Old Aug 21, 2013, 12:38 PM
Playing with AutoCAD!
PiperCub49's Avatar
United States, ME
Joined Oct 2008
2,654 Posts
Quote:
Originally Posted by sbstnp View Post
Probably the motor is burnt out. You should let the motor cool for 2-3 minutes between flights, otherwise you greatly shorten it's lifespan.

Other cause could be the lipos, if you don't time your flights and reach LVC too many times then not put lipos in storage mode they will be gone sooner or later. Indeed 4.2V is fully charged, but that doesn't mean much, you should check how much voltage sags during load in order to assess the state of a lipo.
I've always wanted to do this, but I didn't know how to check the voltage when everything is plugged in. All I have is a multimeter. How do you read the voltage and what sort of sag in voltage should I expect? Do I read the sag in voltage at full throttle?

Thanks,
Kody
PiperCub49 is offline Find More Posts by PiperCub49
Reply With Quote
Old Aug 21, 2013, 12:59 PM
Power Wheels Guru
UNGN's Avatar
Southlake, TX
Joined Jan 2008
7,327 Posts
The 8.4mm pager motors don't last forever. Good thing they are easy to swap.

open the fuselage and use needle nosed pliers to twist it out of the mount.

Slide it under the brick and then out the side between the gearbox and the brick.

Any of the Mustang Spec motors will work. The 4-site motor is usually the cheapest (EFL9052)

When you plug the motor back in, the black wire goes in the furthest Right hole in the motor block (looking forward)
UNGN is offline Find More Posts by UNGN
Reply With Quote
Old Aug 21, 2013, 01:01 PM
Deviant
sbstnp's Avatar
Joined Jul 2012
1,179 Posts
Quote:
Originally Posted by PiperCub49 View Post
I've always wanted to do this, but I didn't know how to check the voltage when everything is plugged in. All I have is a multimeter. How do you read the voltage and what sort of sag in voltage should I expect? Do I read the sag in voltage at full throttle?

Thanks,
Kody
Yes. You can use a watter meter (power meter) or a DMM. Static wattage will be higher, but it does give one a good perspective on motor/esc combination.

I wouldn't worry about watts on the brushed micros/rtf/bnf models though, only on the custom builds.
sbstnp is online now Find More Posts by sbstnp
Reply With Quote
Old Aug 21, 2013, 01:05 PM
Deviant
sbstnp's Avatar
Joined Jul 2012
1,179 Posts
Quote:
Originally Posted by RcAirplaneNoob View Post
i do hit lvc alot and i dont know how to put the 1 cells in storage
If you do hit LVC then your batts are not in good shape either. I would replace the motor then buy some new batteries and start to time my flights. Fly for 1 minute then check voltage and calculate how many mah are left. Try to end flights at around 3.7V resting voltage.

To put batteries at storage charge you would need a computerized charger (a $30 IMAX B6 will do the job on these small packs). The are other methods but this is the best. Storage charge means anything between 3.75V to probably 3.9V.
sbstnp is online now Find More Posts by sbstnp
Reply With Quote
Old Aug 21, 2013, 01:13 PM
Playing with AutoCAD!
PiperCub49's Avatar
United States, ME
Joined Oct 2008
2,654 Posts
Quote:
Originally Posted by sbstnp View Post
Yes. You can use a watter meter (power meter) or a DMM. Static wattage will be higher, but it does give one a good perspective on motor/esc combination.

I wouldn't worry about watts on the brushed micros/rtf/bnf models though, only on the custom builds.
Alright. And what kind of voltage am I looking for?

I bet that I can also read the amp draw using the same method. Now THAT would be incredibly useful!
PiperCub49 is offline Find More Posts by PiperCub49
Reply With Quote
Old Aug 21, 2013, 01:20 PM
Deviant
sbstnp's Avatar
Joined Jul 2012
1,179 Posts
Quote:
Originally Posted by PiperCub49 View Post
Alright. And what kind of voltage am I looking for?

I bet that I can also read the amp draw using the same method. Now THAT would be incredibly useful!
I can't tell you exctly, but as a general rule if a fully charged 4.2V battery while resting goes down to 3.5V right away when under load then something's really fishy.

A watt meter usually tell the amps too. I personally have this:
http://www.hobbyking.com/hobbyking/s...r_1_5_TFT.html

I have never used it on 1S applications though, only on 2S and above.
sbstnp is online now Find More Posts by sbstnp
Reply With Quote
Old Aug 21, 2013, 01:47 PM
Playing with AutoCAD!
PiperCub49's Avatar
United States, ME
Joined Oct 2008
2,654 Posts
Quote:
Originally Posted by sbstnp View Post
I can't tell you exctly, but as a general rule if a fully charged 4.2V battery while resting goes down to 3.5V right away when under load then something's really fishy.

A watt meter usually tell the amps too. I personally have this:
http://www.hobbyking.com/hobbyking/s...r_1_5_TFT.html

I have never used it on 1S applications though, only on 2S and above.
Great! Thanks for all the help.
PiperCub49 is offline Find More Posts by PiperCub49
Reply With Quote
Old Aug 21, 2013, 02:54 PM
Registered User
Vince Herman's Avatar
United States, OH, Strongsville
Joined Nov 2000
2,703 Posts
Kody,
I have a different set of advice from the others. Oh, they all give good advice, but I wanted to let you know how I handle a similar situation.

1. The motor is suspect? Buy another. It is a consumable part, and if you are having this much fun, you will likely run your existing motor down.
2. The batteries are suspect? Buy more. HK has them at the USA warehouse for $1.47 I buy a new batch every year for the indoor season. I got 70 this year. My Dad, 2 brothers, 2 girlfriends (1 mine, 1 my brother's) and I all fly together at the weekly indoor meet. We sell many to the other pilots. I still use last year's batteries, but the ones that are 2 years old are given away to young pilots (lesser flight time is better than no flight time when their one battery is sitting on the charger)
Vince Herman is online now Find More Posts by Vince Herman
Reply With Quote
Old Aug 22, 2013, 06:38 AM
Registered User
Petefoss's Avatar
Oxford, Michigan, United States
Joined Aug 1999
2,390 Posts
Quote:
Originally Posted by sbstnp View Post
A watt meter usually tell the amps too. I personally have this:
http://www.hobbyking.com/hobbyking/s...r_1_5_TFT.html

I have never used it on 1S applications though, only on 2S and above.
Cool little device. I may have to order one.
Petefoss is online now Find More Posts by Petefoss
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Binding issue with my AR400?? Stradawhovious Beginner Training Area (Aircraft-Electric) 8 Aug 01, 2013 10:07 AM
Discussion issues with my first quadcopter elmacjunkie Multirotor Talk 9 May 18, 2013 11:48 AM
Help! Issue with my HK Boscam 5.8 tx help please jlcamp7 FPV Talk 2 May 13, 2013 11:06 AM
Rant My biggest issue with the hobby. btown2 Electric Plane Talk 143 Feb 17, 2013 01:47 AM
Help! DJI NAZA-H Setup issues with my ESC... jhebbel Electric Heli Talk 0 Feb 16, 2013 08:36 PM