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02-15-2021 04:55 PM  9 days ago
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Peter Wales

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Orlando Fl

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What battery?
I am building a 3 blade Kraken. My ESC does not have a BEC so I want to use a 2s battery. The problem is that SAB have provided a very small plate to use if I want to use a battery so I need a small battery.

I have found some small 2000maH batteries which will fit but am concerned about voltage drop. I got low battery warnings while just cruising around the other day.

Worse was when I landed, I had adjusted the bottom stick pitch up slightly and not the off pitch so when I turned the switch from flight to shut down the blades went from slightly negative to more negative, then the blades went to full negative as the battery did not power the servos enough to stop it. A second or two later it went back to normal operation as the motor slowed down.

I am concerned about this happening if I went from positive to negative pitch in something as simple as a loop.
Peter Wales
http://scalehelicopters.org
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02-15-2021 05:21 PM  9 days ago
helitom

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Pine Grove, Calif, USA

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Let me start by noting that I have never seen the set up to which you refer. If the battery mount plate is small, is there room to stack upward? If so, you could stack two 2000''s and wire them up in parallel to make a 4000 pack.The older I get, the fewer things seem worth waiting in line for.
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02-15-2021 06:00 PM  9 days ago
youngbuck

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Maine

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Have u looked into that scorpion back up battery thingy? I’m not a very experienced heli guy but from the info I’ve gathered, it may work?
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02-15-2021 08:42 PM  9 days ago
Rojoalfa

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Punta de Mata, Monagas-Venezuela

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/
/

A single 2500 mAH, 7.4 volts, 10C should be enough for electronic, if you are running HV servos.

If you think this is not enough, run a 15 amps BEC!

There is no difference in term of requeriment of power between that kraken and a raptor 90.

It is a old design in a new box and pretty face.

/
Saludos cordiales,
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02-16-2021 02:45 AM  8 days ago
Peter Wales

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Orlando Fl

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I am still nervous of those batteries. I dont care how many c's it says on them, they are probably lying. The cells inside the batteries are round so they are probably 18650 cells which should be good for 20 amps surge. The plate to put them on only supports half of the length of one battery.

I haven't looked the the scorpion battery back up. I imagine it is a very large capacitor or capacitors and I have some Castle ones and some from the ESC I am using. I'll look into it, thanks for the tip
Peter Wales
http://scalehelicopters.org
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02-16-2021 02:25 PM  8 days ago
v22chap

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Granger, Indiana

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Peter .. check that your power is going directly to the FC . Most tell you to go direct to it and not thru the RX first . I have had trouble with this very item and it sounds just like what you discribe .Once I found that in the manual and did it .. my little 2000 mah 15 C battery flies for 4 or 5 flights with no problems .Larry C ----------Bergen R/C helicopters
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02-16-2021 08:48 PM  8 days ago
Rojoalfa

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That is correct.

Let's do an absurd calculation...

You are going to fly an electric helicopter with 8 HV servos, each one is going to take 4 amps.

So, 8 x 4 = 32 amps peak.

With a lipo of 2500, 30C, it is going to give 2.5x30, 75 amps but... Sorry... I don't believe that... Ok! Take a half... 75/2, 37.5 amps... Good.

This lipo is going to handle that 37.5 amps peak without problem in our hypothetical helicopter.

So, for our helicopter with 8 hungry servos consuming 32 amps peak, a lipo pack 7.4 volts, 2500 mAH, 30C is going to work without problems.

Now, for our little "kraken" that only have 4 servos, you only need half of the calculation of our hypothetical helicopter... Instead of a 30C, you may have 10C... You know... A safety factor...

So, a 7.4 volts, 2500 mAH, 10C is going to give you 5 flights between charges.

/
Saludos cordiales,
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02-16-2021 09:08 PM  8 days ago
Peter Wales

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Orlando Fl

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Thanks Larry, it did occur to me last night that I was feeding all the power through one single UDI line to the Axon.
Then this morning I forgot all about it. I guess my little 2000maH battery could do the job after all.
The biggest problem is the wires dont reach so now I have to figure something else. I am using a switch with a Deans connector on one end and two servo style wires on the other end. Moving it is something I don't want to do. Some thinking is required here.
Peter Wales
http://scalehelicopters.org
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02-16-2021 09:11 PM  8 days ago
v22chap

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Granger, Indiana

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Yep ,, there is always something right

Good luck on the relocation
Larry C ----------Bergen R/C helicopters
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