HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 09, 2005, 02:02 PM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
What am i doing wrong, im almost ready to give up. :( 1 Min flight times.

Hey all, im getting pretty frustrated over here. I bought a Gp Electricub (41") a while ago and its been hell trying to get it to fly well. The stock setup (geared 280, 5amp esc, 8cell 650mah) was just too underpowered.

I put a 3:1 geared 400 size (380) with a 30A esc from a great planes supersportster, and a GP (not greatplanes) 8x1100mah batt pack that i just got brand new from cheapbatterypacks.com. This all on a 10x7 Slowflyer prop. (Which will soon be switched out for a 9x6SF prop.

It flies GREAT (mucho power)! But only for about a min or two. A couple passes around the pattern at 60-75% throttle and its dead and ready to glide in.

Ive speant WAY more money on this plane than i originally wanted to, and im really getting frustrated. Anyone want to buy a 41" cub? Lol

Could it be the 30A esc? Even though i fly @ 60-70% throttle?

Grrr

[/rant]
gotime242 is offline Find More Posts by gotime242
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 09, 2005, 02:09 PM
Master of 1 point landing
Naperville, IL
Joined Jul 2005
2,841 Posts
I would test your bat pack. Charge the way you normally do, run 2-3 12 volt auto light bulbs while measuring amp draw with a multimeter. If the capacity is there, I would think that it is just a crap pack and the voltage is sagging to LVC. Unless you have a shunt, you can not really measure WOT power as most cheap multimeters only go to 10amps before the blow the fuse. How are you charging it - automatic charger? if so, how long does it take and what amperage are you pumping into it.
ImaBiggles is offline Find More Posts by ImaBiggles
Reply With Quote
Old Dec 09, 2005, 02:24 PM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
Quote:
Originally Posted by ImaBiggles
I would test your bat pack. Charge the way you normally do, run 2-3 12 volt auto light bulbs while measuring amp draw with a multimeter. If the capacity is there, I would think that it is just a crap pack and the voltage is sagging to LVC. Unless you have a shunt, you can not really measure WOT power as most cheap multimeters only go to 10amps before the blow the fuse. How are you charging it - automatic charger? if so, how long does it take and what amperage are you pumping into it.
Right now im charging it on a peak detection charger (Hitec). The first charge was @ .5 Amp, im not sure how long it took. And now i am doing it at 1C (Approx 1.1A) and it seems to be taking a bit. I will run it dead and charge/time it again.

Like i said, its a brand new pack. I also have another ooolldd 1100mah pack (7cell) that did the same thing.

Edit: Ok, its charging right now at like 1.2/1.3A. It has been for a while, it seems this is taking waaayyyy longer than the first charge @ .5A. Do batteries ever need to just get cycles a time or two before they start to cycle properly?
gotime242 is offline Find More Posts by gotime242
Last edited by gotime242; Dec 09, 2005 at 02:38 PM.
Reply With Quote
Old Dec 09, 2005, 03:02 PM
E-Flight Addict
ronin8451's Avatar
Weatherford, Tx.
Joined Oct 2003
1,329 Posts
NiMh batteries tend to take 4 or 5 complete cycles to get up to capacity and be fully broken in. Cycle them completely a few more times and they should be better, but don't expect more that 4 or 5 minutes flying at 75-80% throttle.
ronin8451 is offline Find More Posts by ronin8451
Reply With Quote
Old Dec 09, 2005, 03:17 PM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
Thats good to hear. Right now it just finished charging and im running it at approx 60% Throttle. So far its been 2:15. It might have taken a better charge this time, since it took a really long time to charge @ 1.3a.

Ill report back in a min.

Edit #1: I dont know whats going on, lol. Its going on 6+ min now, and can still burst WOT well.

Edit #2: Ok, looks like there is possibly 7 min of flight time now with bursts of wot for t/o and etc.

Ill have to fly again and see what happens.
gotime242 is offline Find More Posts by gotime242
Last edited by gotime242; Dec 09, 2005 at 03:23 PM.
Reply With Quote
Old Dec 09, 2005, 04:40 PM
Registered User
vintage1's Avatar
East Anglia, UK
Joined Sep 2002
29,687 Posts
sounds like you got it sorted. NiMh self discharge HORRIBLY - always use the pack hot off the charger.
vintage1 is offline Find More Posts by vintage1
Reply With Quote
Old Dec 10, 2005, 01:01 AM
Permanently Banned
Larry3215's Avatar
Gig Harbor, Washington, United States
Joined Sep 2003
8,434 Posts
Temps have a lot to do with it too.

If your flying outside in very cold weather the batts will sag very fast compared to inside testing.

Larry
Larry3215 is offline Find More Posts by Larry3215
Reply With Quote
Old Dec 10, 2005, 06:47 AM
Formerly of mcba fame
Matthew Allen's Avatar
Luxembourg
Joined Apr 2001
3,007 Posts
Quote:
Originally Posted by gotime242
Right now im charging it on a peak detection charger (Hitec). The first charge was @ .5 Amp, im not sure how long it took. And now i am doing it at 1C (Approx 1.1A) and it seems to be taking a bit. I will run it dead and charge/time it again.
It sounds like you've solved your problem, I'd just thought I 'd throw something in for future reference.

It's not supposed to be very good for your batteries to run them 'dead'. Cycling doesn't involve totally flattening them, you shouldn't go below (I forget the exact figure) about 0.75v per cell. This is why it's better to use a proper discharger as opposed to running them dead with a light bulb or something.

Btw, this is not a reference to the technique Imabiggles was talking about - that makes perfect sense for testing a pack.

Matthew
Matthew Allen is offline Find More Posts by Matthew Allen
Reply With Quote
Old Dec 10, 2005, 07:13 AM
I don't want to "Switch Now"
pmackenzie's Avatar
Toronto (Don Mills), Canada
Joined Dec 2002
16,428 Posts
Nimh cells should be charged the first time at C/10 for 14-16 hours.
This gets them all evenly charged, while a fast charge could cause problems due to the different charge states when the pack is assembled.
It is also a good idea to do this if the pack is unused for as while.
Pat MacKenzie
pmackenzie is online now Find More Posts by pmackenzie
Reply With Quote
Old Dec 11, 2005, 11:28 AM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
omg....i was doing another batt cycle and i hear it go wot (when it was running at 60%)....and i go over to see the esc melting down.

It was burning hot, and not taking order from the radio anymore. All the rubber melted off... I stop it and let it cool down...try it again and it doesnt work.

W T F


I swear this plane is not meant to be.

Im going to try my old 5a esc because i have nothing left to try and i dont want to spend anymore money on it.
gotime242 is offline Find More Posts by gotime242
Reply With Quote
Old Dec 11, 2005, 11:56 AM
Suspended Account
Silent's Avatar
New York City
Joined May 2005
698 Posts
Quote:
This plane is not meant to be
ROFLMAO. It's not the plane, it's YOU.
Silent is offline Find More Posts by Silent
Reply With Quote
Old Dec 11, 2005, 12:05 PM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
LOL what did i do?!!? lol

How is it my fault the dang 30a esc decided it was going to explode for no stupid reason.
gotime242 is offline Find More Posts by gotime242
Reply With Quote
Old Dec 11, 2005, 01:21 PM
Permanently Banned
Larry3215's Avatar
Gig Harbor, Washington, United States
Joined Sep 2003
8,434 Posts
Many esc's run much hotter at partial throttle - 60% say - than they do at full throttle.

Sitting on the ground the esc probably has less cooling air flow than in the air - did it have any cooling air flow?

If the 30A esc melted, how could the 5amp one possibly handle the current?

Have you actually measured the current?

Good luck!

Larry
Larry3215 is offline Find More Posts by Larry3215
Reply With Quote
Old Dec 11, 2005, 01:35 PM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
Quote:
Originally Posted by Larry3215
Many esc's run much hotter at partial throttle - 60% say - than they do at full throttle.

Sitting on the ground the esc probably has less cooling air flow than in the air - did it have any cooling air flow?

If the 30A esc melted, how could the 5amp one possibly handle the current?

Have you actually measured the current?
Yeah, it had the wind from the prop, lol. But i dont think that was it, i think it was faulty or something to begin with.

I havnt measured the current yet.
gotime242 is offline Find More Posts by gotime242
Reply With Quote
Old Dec 11, 2005, 08:31 PM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
Welp, its not the batt. I just got like a 10+ min flight on my little helicopter (ESky HoneyBee), and it all worked well. Maybe it was just that esc. Ill try it tomorrow with the plane again and a diff esc...see how it comes out.
gotime242 is offline Find More Posts by gotime242
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
What am I doing Wrong? kushal_22 Batteries and Chargers 10 Jun 27, 2003 06:53 PM
GWS Tiger Moth and M100. What am I doing wrong? HardLander Foamies (Kits) 16 Jan 08, 2003 06:28 PM
What am I doing wrong? (1500mah LiOn & Qualcomm desktop charger) thwang99 Batteries and Chargers 4 Dec 26, 2002 05:16 AM
What am I doing wrong? hkowalczyk Beginner Training Area (Aircraft-Electric) 31 Jun 23, 2002 06:47 PM
NMH Batteries: what am I doing wrong. rcav8r2 Parkflyers 2 Mar 12, 2002 03:26 PM