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How to determine the right batteries ?

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Old 01-09-2014, 04:19 PM
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jmpups
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Default How to determine the right batteries ?

I have recently purchased a Phoenix Edge 540. I am planning on going electric for the first time, since I found that my OS120FS won't fit without modifying the firewall. I am planning to go with a GP Rimfire120 and A Phoenix Edge100 ESC.The motor calls for A lipo battery 5s-6s. My question is do I use one 6s battery or two 3s batteries? And what mhp rating should I be looking for. The plane should weigh approx 5-7 lbs. Any input is appreciated.
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Old 01-09-2014, 05:08 PM
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Well , if there is room in the battery compartment it's easier to spread the weight and to get a better CG using two packs as opposed to one . You should have the room in a 120 size plane. We are talking about the Edge 91/120 size correct?
Now what has me concerned is a 6 cell lipo flying a 120 size plane. That Edge looks like it will come in around 11 pounds. It would need around 2000 watts of power . I would install an Eflite Power 110 or a Monster Power 110 motor and power it with an 8 cell 5500mah 40c lipo pack or (2) 4 cell packs wired in series.
I have a 120 size Sukhoi running 10 cells and it pulls it around with plenty of spare power.
A 6 cell pack is what you would use for a 60 size 7 pound electric plane using an Eflite Power 60 for example.
I don't think the Rimfire specs are correct but I've never used any of their large motors.

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Old 02-03-2014, 12:24 PM
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This will be helpful:

EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT
http://www.rcuniverse.com/forum/m_7100376/tm.htm

There is a chapter on sizing electric power systems.

Short form -

look at the max amp your motor is rated for
Look for a battery that can handle that at 80% of its continuous C rating

As for using 1 6S or 2 3S in series, that is up to you. But the packs should be of the same size and C rating. A 6S pack is just 2 3S packs soldered together.
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Old 02-04-2014, 04:32 PM
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Dr Kiwi
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We really need to know which model Edge 540 we are discussing...the 120 size is 65"?

Wingspan: 65 in (1660 mm), Weight: 8.8-9.3 lb (4000-4200 g)

5lb-7lb by OP, 11lb by Brian Ray.... ????????????

Last edited by Dr Kiwi; 02-04-2014 at 04:35 PM.
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Old 02-08-2014, 12:45 AM
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"The plane should weigh approx 5-7 lbs"
150-200W per pound
Lets take the high road 200W per pound
equals 1400W At maximum, An E-Flite 52 draws/is rated at 1650W
I have a 10-11 lb P51 that uses the 52 and a 6S 5000mah lipo.
Static test current was about 78A with a freshly charged battery. Flying current at full throttle just within motor spec.
Compare that against the rimfire motor you mentioned.
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