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Old Jan 22, 2012, 06:55 PM
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Joined Apr 2009
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how do you match motors to esc's and batteries?

say i have a eflight power 110 brushless out runner rated at 295 Kv...

how do i know without a doubt....which battery i should use?
i'd like to run lipo's due to their lower weights.

i'm not interested in tandem 2 or more batteries together to achieve the required voltage....

I ONLY WANT TO USE AND CHARGE (!) ONE BATTERY!

(i'm yelling that because some of the more fluent guys here will chime in with...
"heres how i do it i get a 2& a 4 cell wire them together...then i might also use the 2 in another plane and ...." yada yada yada.

no offense but i want to be as simple as possible.

thanks in advance!




i think i have the right "esc"...its a phoenix hv-85)
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Old Jan 22, 2012, 07:19 PM
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bartricky's Avatar
United States, FL, Monroe
Joined Jan 2008
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Product Specifications
Type: Brushless outrunner
Size: Equivalent to or surpassing the power of a 1.10 size 2-sroke glow engine
Bearings or Bushings: One 8 x 19 x 6mm Bearing, and Two 8 x 16 x 5mm Bearings
Wire Gauge: 13
Recommended Prop Range: 17x8 to 19x10
Voltage: 28.238.4
RPM/Volt (Kv): 295
Resistance (Ri): .03 ohms
Idle Current (Io): 1.20A @ 10V
Continuous Current: 55A
Maximum Burst Current: 65A (15 sec)
Cells: 2432 Ni-MH/Ni-Cd or 8S9S Li-Po
Speed Control: 85A High Voltage Brushless
Weight: 490 g (17.5 oz)
Overall Diameter: 63mm (2.50 in)
Shaft Diameter: 8mm (.3 in) (Includes two 12mm threaded prop shaft adapters with 1.5 pitch)
Overall Length: 54mm (2.10 in)

That's what is recommended... You may get one made, I'm not sure about a charger for a 8S.
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Old Jan 22, 2012, 07:26 PM
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It's impossible to say what battery is best without knowing what plane it's going in, what kind of performance you want, and how much flight time you need.

For all we know you could be bolting the thing to an electric bike or using it as a ceiling fan. Application details are important
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Old Jan 22, 2012, 07:49 PM
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Quote:
Originally Posted by TP16 View Post
It's impossible to say what battery is best without knowing what plane it's going in, what kind of performance you want, and how much flight time you need.

For all we know you could be bolting the thing to an electric bike or using it as a ceiling fan. Application details are important
What he said...also using multiple batteries has some advantages. Flexibility, its nice to have two 5s batteries that can be put in series to make a 10s. A single 10S would be a dedicated battery for that motor. Also, if you loose a cell in a 10S, its a bigger loss than if you loose a cell in a 5S.
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Old Jan 22, 2012, 07:58 PM
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United States, NE, Kearney
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Quote:
Originally Posted by TP16 View Post
It's impossible to say what battery is best without knowing what plane it's going in, what kind of performance you want, and how much flight time you need.

For all we know you could be bolting the thing to an electric bike or using it as a ceiling fan. Application details are important
See... I want my ceiling fan to make 73 mph of wind.

Now what?

DON'T TELL ME I HAVE TO USE MULTIPLE COMBINATIONS OF BATTERIES!
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Old Jan 22, 2012, 10:06 PM
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You can use a calc program like this one.

http://www.s4a.ch/eflight/motorcalc_e.htm

So, Eflite 110. Uses 8s lipos.

Giving a very generic setup here that would work in a Cub, trainer on up.

Batteries, do you want a short wide or long and narrow?

http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

Reason people say to use two batteries is getting (2) 4s batteries is easier then getting a single 8s. Plus you can move them around to balance the plane.


Many things go into making up a power package. Is it on a giant foam slow flyer or a sleek pylon racer?


Buzz.

P.S. if I ran a 32X2 prop, it might make a good ceiling fan?
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Old Jan 22, 2012, 11:16 PM
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United States, NE, Kearney
Joined Dec 2011
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Quote:
Originally Posted by blvdbuzzard View Post
You can use a calc program like this one.

http://www.s4a.ch/eflight/motorcalc_e.htm

So, Eflite 110. Uses 8s lipos.

Giving a very generic setup here that would work in a Cub, trainer on up.

Batteries, do you want a short wide or long and narrow?

http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

Reason people say to use two batteries is getting (2) 4s batteries is easier then getting a single 8s. Plus you can move them around to balance the plane.


Many things go into making up a power package. Is it on a giant foam slow flyer or a sleek pylon racer?


Buzz.

P.S. if I ran a 32X2 prop, it might make a good ceiling fan?
Only if it the winds stay at tropical level without becoming a hurricane.
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Old Jan 23, 2012, 03:08 AM
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Australia, ACT, Kambah
Joined Feb 2001
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Quote:
Originally Posted by mozeppa View Post
say i have a eflight power 110 brushless out runner rated at 295 Kv...

how do i know without a doubt....which battery i should use?
i'd like to run lipo's due to their lower weights.

i'm not interested in tandem 2 or more batteries together to achieve the required voltage....

I ONLY WANT TO USE AND CHARGE (!) ONE BATTERY!

(i'm yelling that because some of the more fluent guys here will chime in with...
"heres how i do it i get a 2& a 4 cell wire them together...then i might also use the 2 in another plane and ...." yada yada yada.

no offense but i want to be as simple as possible.

thanks in advance!




i think i have the right "esc"...its a phoenix hv-85)
I'm gonna be picky here, but seeing as you're asking some pretty fundamental questions, I think it might help to get some of your concepts straight up front.

The motor is not "rated" at 295Kv; one of its characteristics is its Kv and that happens to equal 295. It's like saying it is rated at 490g when it weighs 490g. I raise this because there is a key rating for the motor, and that is the maximum current the manufacturer says it can handle: 55A cont, 65A burst. By handle, I mean how much power the battery delivers to the motor. The motor doesn't deliver or develop any power, just converts hopefully a large percentage of what comes out of the battery into rotation of the prop at the desired speed. The max current also implies max power handling. It says the motor is for 8-9S. 9S at 55A is nominally about 1830W.

Now we're getting closer to your actual question. You honestly can't ask the question which battery for a motor without talking about what size prop you want to run, as the motor Kv, cell count and prop size form an interdependent power system. I can take a Power 110, run it on 3 cells with a 12" prop, and the system will develop negligible thrust (about 10oz). The motor name, ie the "110" bit, is only relevant if you happen to use a big enough prop with enough cells to end up with similar thrust to a 1.10 glow. The motor on its own is only 1 part of the puzzle, which is why particularly for glow conversions, many on here will say figure out the prop size first - don't buy a motor just on its label or power rating. There's no such thing as an 1800w motor - there's an 1800W power system, and part of that is a motor that can handle 1800W without frying.

Now you've got to decide what you want to do with your system. You could run it up to 1700W peak input power on a big 3D model, using 8S and a 19 x8 prop at 63A, in which case you'd want at probably a 5000mAh pack to cope with the peak loads and high power use throughout the flight. Or you might want a bigger slow turning prop for a scale WWI warbird, but only need to put say 1100W in (6S, 21x8, 54A), and at relatively low power cruising around most of each flight you might get away with as small as a 3300mAh pack. The motor doesn't really care as long as you don't exceed the maximum limits, and you get the prop rpm which via prop diameter and pitch give you the thrust and top speed you want. WebOCalc (software tab) helps you relate the model and how you want to fly it to motor Kv and battery cell count.

For this motor, the blurb suggests 8 or 9S, which is going to be a good start point for using a motor calculator like eCalc. The blurb also suggests props 17x8 to 19x10. Often that means no bigger than the bigger prop on the lower cell count, and no bigger than the smaller prop on the higher cell count, not the whole range of prop sizes on either 8s or 9S. (19x10 on 9S is WAY over the max burst current - I rest my case). A bit of trial and error in the motor calc goes a long way to figuring out a good system, and will give you much more info than the vendor's blurb. Once you have decided on the prop size and cell count that get you the sort of performance you're looking for, then you're just left with deciding on battery capacity and current rating. You'll need to have enough at least enough capacity to support the current the motor wants to draw and for your desired flight time, and again ecalc can provide a reasonable guide as to how long the pack will last. Space, weight and balance will also be factors - sometimes you might use an oversize battery because it balances the model better and extra flight time or less stress on the battery is probably better than dead lead (but more expensive)

So in a shedload more words than probably necessary, the answer is just the same as TP16's: it depends on what you want to do with it. But hopefully I've given you a better idea of why it depends. And once you start talking about what you want to do with your motor in a bit more detail, we can give you a lot more detailed advice.
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Old Jan 23, 2012, 07:35 AM
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Charlotte, NC
Joined Jan 2004
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Very good shed load, but kV is a rating as many motors can be very different than their manufacturer rates them. I've seen motors off 20%.
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Old Jan 23, 2012, 08:02 AM
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Joined Apr 2009
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okay...its going in the space walker II 73.7" wing span.

i have a venom pro charger (new) and from the looks of the top panel ...it looks like it services up to 6 cell (2-3-4-5-6 from a single port)

i'm intending to use a 18/8" zinger.

it appears i may have to use 2 batteries, 4 cells each. (for the sake of charging them.)

i'm looking for good power for take offs ...throttle back for comfortable flying with enough power to do some aerobatics (should i get brave enough.)

and flight time? ....oh 2 or 3 hours in the air is good, any more than that ...i'd just get tired.

(kidding!)

around 10 min. is ideal.
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Last edited by mozeppa; Jan 23, 2012 at 08:11 AM. Reason: flight time
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Old Jan 23, 2012, 09:28 AM
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Charlotte, NC
Joined Jan 2004
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The Space Walker has a big wing. You just found a big reason why we use multiple packs in series. I suggest two 5000mA 4S 25 or 30C packs in series.
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Old Jan 23, 2012, 10:33 AM
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Thomas B's Avatar
United States, TX, Fort Worth
Joined Jun 2000
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Quote:
Originally Posted by DustBen View Post
See... I want my ceiling fan to make 73 mph of wind.

Now what?

DON'T TELL ME I HAVE TO USE MULTIPLE COMBINATIONS OF BATTERIES!
You certainly do not HAVE to use multiple batteries, but it is the way the majority of use get to large cell counts and it is the smart way to go.

Dozens of reasons not to use a single large cell count battery and just the single arbitrary reason you have in favor of the single battery.

Personally, it makes a lot more sense to have batteries that are useable in multiple models with different cell count requirements.
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Old Jan 23, 2012, 12:33 PM
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Moab, Utah, USA
Joined Apr 2003
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The only difference between a single eight cell battery and two four cell batteries connected in series is the shrink wrap around the batteries.

Larry
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Old Jan 23, 2012, 01:36 PM
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And the extra wires, connectors, and how you charge them...

And they may be different weight and size or not be available one way or the other. I use two 25C 5000mA 4S Flightmax packs for a P-47 I have and the 25C 5000mA 8S packs are listed as much larger for some reason.
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