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EP Expectation Questions

Old 02-17-2004, 06:36 PM
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ke5in
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Default EP Expectation Questions

I just put together my first electric and I’m not sure if I have unreasonably high expectations.

The plane is a Thunder Tiger Windstar and it came with what they call a “Speed 540” motor. I bought a “Super 30” FMAdirect speed controller and a 7.2V 2000mAh 6 cell NiCad pack.

I set it all up, initialized the speed controller and gave it a test. On a fully charged battery I can go full throttle for 45 seconds and then I’m cut off. The speed controller manual says I can expect 2 restarts on a good battery. I’ve got a brand new battery and I can’t even get a single restart.

My questions are:

1) Is 45 seconds of run time normal for this type of configuration? Will adding another cell make much of a difference?
2) Any idea on why I can’t get a restart?
3) Should I not run the plane a full throttle in order to get more restarts?

Thanks,
Kevin
Old 02-17-2004, 07:32 PM
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A1RENCH
 
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Default RE: EP Expectation Questions

Did you cycle the batteries? This is a must for Nicd's! The batteries should be subjected to three
charge/discharge cycles to produce the best power. 45 seconds,even with a green pack doesn't
sound reasonable. It sounds like your charger is not giving you a full charge.
Bud
Old 02-17-2004, 07:43 PM
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ke5in
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Default RE: EP Expectation Questions

Yeah, I cycled them but only twice. I will try one more cycle.

Here is something else.... what should I set my custom LVC to be? Right now it is set at 5.3V can i go lower with NiCads?
Old 02-17-2004, 07:50 PM
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Jim Finn
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Default RE: EP Expectation Questions

Whenever you buy a plane with an engine or a motor included you get the minimum motor that will make the plane fly. Your motor will just barely fly the plane on that $12 motor. Seven cells would be better but a better motor will do a lot more to help fly the plane. 45 seconds is too short a motor run. Did you break in the motor? cycle the battery pack? are you sure the pack is getting fully charged? The cells should be almost too hot to hold after the motor run. If not I am guessing they were not fully charged. In the air (flying) the motor will run longer than in a static test. When i furst got into electrics I charged my pack a few times and each time the run was shorter. Wondered why untill I tried to start the car. I almost killed the car battery! After charging the car battery it charged the plane battery pack fully.
Old 02-17-2004, 07:58 PM
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ke5in
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Default RE: EP Expectation Questions

Jim,

After i charge the batteries should they be warm / really warm / hot? My charger has a 15 minute timer and that is the only way to "turn it on" and the battery pack is slightly warmer than body temperature after a 15 minute cycle. I heard everybody talking about the temperature of the batteries as being pretty warm after charging but mine aren’t. I figured that was because they were new. The charger was a freebee that somebody gave me (no manual). Perhaps its not working. Can new Nicad 6 cells be charged in 15 minutes?

Thanks,
Kevin
Old 02-17-2004, 08:21 PM
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Jim Finn
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Default RE: EP Expectation Questions

After charging the batterys they should be quite warm (Not hot). With that little charger try charging it for 15 min then set it for anothor 15 min and hold it in your hand. When it starts to get really warm it is charged. That is the best you can do without getting a better charger.
Old 02-17-2004, 09:29 PM
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Dr Kiwi
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Default RE: EP Expectation Questions

Won't that "540" be trying to pull at least 10-20A? If it is, then it is no wonder it is flattening semi-charged batteries, AND dropping the voltage to below 5.3v (from only 7.2v) in a hurry.

Cheers, Phil
Old 02-17-2004, 09:45 PM
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Default RE: EP Expectation Questions

Did you say what prop you are using? Anything larger that a 7x4 will over amp that motor and drain the batt. pack quickly and damage the motor too.
Old 02-18-2004, 07:43 AM
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Default RE: EP Expectation Questions

That charger is surely your biggest problem! What you need to do is invest $40.00-$50.00 bucks in an entry level peak charger. The timer style charger your using is obviously not doing the job. If you know anyone with a peak charger, give that a try. I think you'll be amazed at the difference in performance. Throw the timer charger away before you destroy your battery pack!
Good flying!
Bud
Old 02-18-2004, 08:26 AM
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Matt Kirsch
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Default RE: EP Expectation Questions

Good advice here. Definitely get yourself a peak-detect charger. It's the only way to charge batteries. Any other way is just guessing; you either overcharge the battery and damage it, or undercharge the battery and end up with a crappy-flying plane or a short run time.

When you buy a glow plane kit or ARF, it doesn't come with the engine. I'm not sure why people expect the motor that comes with a LESS EXPENSIVE electric kit to be anything useful. A direct drive 540 car motor on a 6-cell car pack is just about the worst electric power system out there. Notice the copious use of the word CAR. It's a CAR power system. This is an airplane. It didn't work 20 years ago, yet manufacturers continue to sell planes "designed" for it and recommend it. Two minutes of lackluster performance and equipment hot enough to cook a steak over after a flight is not what I'd call efficient.

Could you describe this Thunder Tiger Windstar, give it's specifications? Perhaps we can suggest a better power system for it, and you can put your motor and battery back in your 1/10 scale buggy.

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