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Batteries, voltage, mah,c ratings ?


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andy ching
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Joined: 21 Sep 2011
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Location: nz

PostPosted: Mon Sep 26, 2011 8:33 pm
PostPost subject: Batteries, voltage, mah,c ratings ?
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Hi everyone, im still a little confused with the battery theories, did some reading on the forum re which type to use. The battery with the iron horse 9104 is ok for now but i need(want) more power, its 7.4 V ,1300 mah not sure the c rate. As i understand the motors voltage is a constant , meaning if i run a larger one 11v for example it will destroy motor and main board ? So for more power some recommend a 2200mah for this model. Is increasing the mah too high dangerous for the motor etc if so how high can you go with mah as i've seen some as high as 10000 mah. also what c rating is recommended to improve flight times as i understand it the higher the c rate the quicker you burn through the juice. P.s second flight ever and it still works sooo much fun i want 100 batteries. Thanks Andy Ching Idea
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pjdog
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Joined: 12 Jan 2010
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Location: Hudson, Florida, USA

PostPosted: Mon Sep 26, 2011 11:07 pm
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Hey Andy:

When you increase the mah rating your going to increase the weight of the battery. When you increase the weight of the battery your motor has to work harder to lift the bigger battery and you defect the purpose of having a bigger battery.

Most RC helicopter manufacturs have balanced out what size battery to use. It's normally best to stick with what size mah the helicopter came with.

Just my thoughts.

I do know a ESKY Big Lama that flew for 20 minutes with a 2200 mah rather than the 800 mah that came with it but that's not the norm. Also the motors had been replaced with ball bearing motors rather than the stock bushing motors.

Jack
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magyarbacsi
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Joined: 04 Aug 2011
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Location: seattle

PostPosted: Tue Sep 27, 2011 12:43 am
PostPost subject: batteries, voltage, mah
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Andy, I have the Double Horse 9104 that was my introduction into helicopters. I can say one thing about the 9104 is that it is built like a tank. It has survived numerous impacts in the beginning and even the blades survived I have now given it to my son and went through the FP 4chs and now working toward a 450 size cp. Sorry for the deviation.Just wanted to warn you about the addiction.

The 9104 is very robust, also means it is a bit on the heavy side and thus uses a lot of amps. I have never gotten more than 5-6 min of constant flying with mine and sometimes even less. Its the nature of that heavy copter. Running longer may burn the motor out. The Big Lama is a lighter bird and maybe able to fly extended time. I think the stock battery is bulky and heavier than the flat pack ones. Not sure as I have not weighed it. If u burn the motor, it is cheap to replace. They go for $5 or so and u can buy a bunch as a spare. The pc board is about $11. I replaced mine once when the bird would not stop spinning and thinking the pc went out. It was the tail rotor gear, got stripped and the blade could not turn fast enough to counter the torque.
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nick_onelove
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Joined: 01 May 2011
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Location: Mendocino County, CA, United States 21 years old

PostPosted: Tue Sep 27, 2011 1:26 am
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I agree with the two above. Sometimes a slightly higher-mAh batteries will increase flight times a little bit, but for the most part it's best to stick with the mAh/weight the designer's chose.

I'm pretty sure a higher C rating does not mean reduced flight times. I think it just means the battery has less internal resistance so that more power is available at any given moment and the battery doesn't get as hot.
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tombo242
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Joined: 04 Nov 2008
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Location: Santo Estêvão, East Algarve, Portugal. Now 82, but still feels 22.

PostPosted: Tue Sep 27, 2011 3:20 am
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Hi Andy,

That was my Big Lama that did the 20 min flight. Here's the video.


Link


Like Jack said it was not standard, as well as the ball bearing motors it had high lift aerofoil section blades (Clark Y) and a lot of tweaking with a DX6i Tx/Rx. I believe that something would have burned out if I had tried this with a stock Big Lama. I was setting this up for aerial photography and the big battery was was really a lifting test to see what could be done.


The advice you have on this thread is exactly what I would give you. Stick with the stock rated batteries and the heli will be fine. It is quite usual to have 4 batteries charged and ready for flight. Hardly anyone flies with just one charged battery. However, remember to let the heli cool between flights. Plugging in a replacement battery and flying immediately is not recommended.

Tom.
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andy ching
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Joined: 21 Sep 2011
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Location: nz

PostPosted: Tue Sep 27, 2011 7:27 am
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Thanks people your'e all brilliant for your comments, funny story 2nd flight in the dark, (can you tell im new to this) but you are right its very addictive. mostly it went really well and kept it close-ish. Then it started to get away from me couldn,t tell if it was facing me or not 30 meters and near some power lines so i floored the throttle cleared them upwards jumped four fences while flying it landed it nicely in a field 100 m away. Then coming back over the fence got a little zap from an electric fence !! no harm done but lesson learned ! Will get new batteries cheers
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nick_onelove
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Joined: 01 May 2011
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Location: Mendocino County, CA, United States 21 years old

PostPosted: Tue Sep 27, 2011 7:36 am
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Hah, good story; electrical shocks are no fun. Laughing

Unfortunately at my new place I've trespassed into private property a few times myself to retrieve a heli, in my case an industrial complex. Rolling Eyes
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platinum
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Joined: 31 May 2011
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Location: Bangkok Thailand

PostPosted: Tue Sep 27, 2011 2:56 pm
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andy ching wrote:
Thanks people your'e all brilliant for your comments, funny story 2nd flight in the dark, (can you tell im new to this) but you are right its very addictive. mostly it went really well and kept it close-ish. Then it started to get away from me couldn,t tell if it was facing me or not 30 meters and near some power lines so i floored the throttle cleared them upwards jumped four fences while flying it landed it nicely in a field 100 m away. Then coming back over the fence got a little zap from an electric fence !! no harm done but lesson learned ! Will get new batteries cheers


I believe the 100m away landing, I had that experience with my 9104 (3CH), it is no roll channel so it landed streight to the ground softly when reduce throttle. After I mod to 4 channel suprisingly I need more careful to control the roll when near the ground! Rolling Eyes

For the battery issue :
9104 stock battery is Li-ion 7.4V 1300mAh weight approx 90g.
I bought spare battery Li-po 7.4V 1300mAh weight approx 80g.
I tried using Li-po 11.1V 950mAh weight approx 70g. The 3 in 1 is OK.(Big lama use 11.1V 800mAh) more powerful but the 9104 tail motor is worked harder and not last long, also the tail heavy occured.

So I prefer to use the Li-po 7.4V 1300mAh with put a little bit forward location.

platinum
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