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Old Dec 09, 2005, 03:02 PM
gotime242 is offline
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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]
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Old Dec 09, 2005, 03:09 PM
ImaBiggles is offline
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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.
Old Dec 09, 2005, 03:24 PM
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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?
Last edited by gotime242; Dec 09, 2005 at 03:38 PM.
Old Dec 09, 2005, 04:02 PM
ronin8451 is offline
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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.
Old Dec 09, 2005, 04:17 PM
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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.
Last edited by gotime242; Dec 09, 2005 at 04:23 PM.
Old Dec 09, 2005, 05:40 PM
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sounds like you got it sorted. NiMh self discharge HORRIBLY - always use the pack hot off the charger.
Old Dec 10, 2005, 02:01 AM
Larry3215 is offline
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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
Old Dec 10, 2005, 07:47 AM
Matthew Allen is offline
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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
Old Dec 10, 2005, 08:13 AM
pmackenzie is online now
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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
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Old Dec 11, 2005, 12:28 PM
gotime242 is offline
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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.
Old Dec 11, 2005, 12:56 PM
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This plane is not meant to be
ROFLMAO. It's not the plane, it's YOU.
Old Dec 11, 2005, 01:05 PM
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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.
Old Dec 11, 2005, 02:21 PM
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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
Old Dec 11, 2005, 02:35 PM
gotime242 is offline
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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.
Old Dec 11, 2005, 09:31 PM
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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.


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