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Old Mar 15, 2011, 01:46 PM
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1: if your Tx cells are down, and you are charging with it, the battery in the copter is now down too far, likely for good.
-It may be possible you've missed the Tx's light blinking, this means the cells are too dead for charging.

2: Is a BIG TV set on while you are flying?
Interference is a documented malady with IR birds, and they go dead in mid-flight as a result.

3: The ONLY "Upgrade" you should do concerning the S107 battery is a higher "C" rating, period.
Removing weight to compensate for more mAh is only half the equation: the lenght of flight, and the heat generated by a motor set that MAY have more current and or resistance than intended will result in an assembly that may not survive as many flight cycles.
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Old Mar 15, 2011, 02:22 PM
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Killbucket

There's a blue/red light flashing on the nose. There's a green light at the back. This light flashes at first, then stays on. When the chopper cuts out all lights are dead.

This happens with the TV on or off.

The chopper is new.
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Old Mar 15, 2011, 02:28 PM
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Sure sounds like the battery protection circuit is cutting off on overdraw/undervoltage to me. That or a switch/soldering issue? Didn't you say turning it off then on and it "flies" again?
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Old Mar 15, 2011, 02:56 PM
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Didn't you say turning it off then on and it "flies" again?
Yes that is correct.

It actually flew once for about 20 seconds in the 10 times I tried it just now.
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Old Mar 15, 2011, 03:08 PM
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I found this on Helipal.com:

Quote:
Itīs a great heli, only have a one problem, the throttle stick is defective, lets see, if the stick donīt go all way down when the transmiter is turn on, (you must first turn tx on and move throttle stick up and down again) then the heli falls, the solution is simple, open the transm. take a dremel and rebate or cut a little below the window of throttle stick, Presto! no more problems!
What does that mean exactly?
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Old Mar 15, 2011, 03:21 PM
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Just that his Tx's plastic case cutout for the left stick wasn't cut right or the case didn't fit together right.

Also sounds like something else, not an S107.
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Old Mar 15, 2011, 03:27 PM
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http://www.helipal.com/product_revie...vc8dchliidu1c1
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Old Mar 15, 2011, 03:43 PM
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Quote:
Originally Posted by killbucket View Post
1: if your Tx cells are down, and you are charging with it, the battery in the copter is now down too far, likely for good.
-It may be possible you've missed the Tx's light blinking, this means the cells are too dead for charging.

2: Is a BIG TV set on while you are flying?
Interference is a documented malady with IR birds, and they go dead in mid-flight as a result.

3: The ONLY "Upgrade" you should do concerning the S107 battery is a higher "C" rating, period.
Removing weight to compensate for more mAh is only half the equation: the lenght of flight, and the heat generated by a motor set that MAY have more current and or resistance than intended will result in an assembly that may not survive as many flight cycles.
I disagree with 3. Higher battery capacity (mAh) is a perfectly valid upgrade. C is a funny rating and it is a relationship between mAh and time. By my calculations, the stock 150 mAh battery with a 30 C rating can supply a theoretical peak of 4500 mAh. As long as the new battery can also supply that, you're good.

Ohm's law says that any identical two loads (motors) with the same voltage across them, will have the same current. The source of the electricity doesn't matter. They could be AAA batteries, LiPos or bar batteries. Ohm's law applies. Period. If you don't like it, take it up with God. See http://www.allaboutcircuits.com/vol_1/chpt_2/1.html for a writeup.

But there is a catch to the principle above. It applies when the *same* voltage is applied. If you are maxing out a battery's ability to supply current, which the helicopter might, the voltage will fall. Ohm's law still applies, but since the voltage is lower, the current will also be less.

If a motor system were designed to max out the battery, which the heli might, putting in a battery with a higher discharge rate might be able to supply more current without dropping the voltage. Since the voltage stays up, so does the current, and the motors get more power. More power does mean more heat, and that will have an effect on the lifetime of the motors.

If it were my heli, I would totally go for the capacity (mAh) upgrade, considering weight and mounting and all.

There is a nice writeup of how mAh and C work at http://www.engineersedge.com/battery...ry_ratings.htm.

***Let's not forget that companies lie through their teeth about max ratings, including mAh, C, horsepower, torque, watts, etc. The ratings may be 50% wishful thinking in the first place.

Michael
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Old Mar 15, 2011, 03:49 PM
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Michael does have some valid points. I've spent LOTS of investivative time with LiPos.
Batteries have an internal resistance. That internal resistance is lowest typically when you buy the batteries and they have broken in. Lower IR the better. Lower IR means battery drops less voltage under load. Higher IR means battery drops more voltage under load and motor max power goes down. Over time and with abuse, that IR increases.
This is one way the battery feels sluggish over time. mAhr capcity also tends to go down over time too.
Not all batteries are rated equal. (Like Michael says at the end of his post). One company C rating may be different than the other. In general for a new battery from the same company, higher C or higher mAhr for the same cell count means lower IR.

Wait, What? we are futzing over batteries for a $30 helicopter right?????
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Old Mar 15, 2011, 03:58 PM
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Originally Posted by Trailrider View Post
Trailrider,

I could think of a few things that could be wrong with your heli.

The battery could be bad in a couple different ways. You could also easily have a bad solder joint somewhere. Vibration from the motors could be rattling it and causing power to cut or at least resetting the microcontroller. The IR thing is a remote but real possibility (hey, that's punny!).

Try this: take the rotors off so that the motor spin freely and don't vibrate the heli so much. Set it set it down on something soft and hold it there. Fire it up and see if it runs properly. This will tell whether it has something to do with the IR system or if it has something to do with loaded motors.

I've looked very hard at the circuit board and I don't see any thermal cutouts or power components with temperature sensors. The microcontroller has one, but it isn't where the heat would be. remember, these things are dirt cheap. Almost disposable, I think.

Hopin' for the best,

Michael
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Old Mar 15, 2011, 04:17 PM
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Actually, its not difficult to put all this to a test. Buy 2 separate motors for the S107, 2 240 mah batteries, well, try charging them both and do the test while plugging the second battery right after the first is done (maybe attach both together and plug and play), and see how the motors will handle all the continuous time from BOTH batteries with very short break while switching one battery to the other. It should give them a good 20 to 30 minutes of almost non-stop run.
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Old Mar 15, 2011, 04:39 PM
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Originally Posted by Trailrider View Post
I still think it's wrong. You don't need to move the throttle stick up/down for an S107. But case-fit could have been an issue with getting the throttle fully to "zero."

I remember seeing this same "I hadda cut out the case" thing mentioned for an S032 somewhere though, which is a different matter.
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Old Mar 15, 2011, 04:40 PM
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Wait, What? we are futzing over batteries for a $30 helicopter right?????
Amen. Let's go fly some! Life is too short for hacking and modding perfectly good helicopters.
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Old Mar 15, 2011, 04:55 PM
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Amen. Let's go fly some! Life is too short for hacking and modding perfectly good helicopters.
Perfectly good Hellis with a perfectly bad and short flying time you should add...
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Old Mar 15, 2011, 05:02 PM
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Originally Posted by RCHeli11 View Post
Perfectly good Hellis with a perfectly bad and short flying time you should add...
How much flight time are you expecting? Hobby-grade electric helis have similar flight times.

The weight vs. battery capacity trade-off is the basic engineering question with rc helis of all levels, hobby-grade or toys. Current LiPo technology is the limiting factor. Unlike rc cars, the batteries' weight must be lifted. The gravity force vector is constant and vertical in helis, whereas in rc cars the entirety of that force need not be overcome.
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