ECK

This is the plane:
CAmodel Epsilon
Fuselage: 65''
Wing Span: 63"
Engine (glow): 60 - 90
Weight: 7.5 Lbs.

I plan to fit an 18 x 10 prop and the Hacker C50-12XL + 6.7:1 ACRO on my plane, but have absolutely NO idea what lipo pack to use to make this bird fly like an eagle.

Also got a newbie question: I notice people describing their batteries for instance like: 5s3p. This can tell me the voltage, but not the amps, right? And will a 8 amp battery perform better than a 5 amp battery? Or only increase duration of flight?

Also, I can't seem to find any bigger packs than 5sXp? Why is this?

Thanks for any input!

Regards,
Oystein

RC Extreme power

My Feedback: (24)

Have read a lot about the pattern flying and the set up that they use
The amount of amps that a battery will give is from it's C rating
The new Thunder power batteries 1900 mAh are putting out about 19 amps
They sell batteries packs from 11.1 volts to 37 volts and from 1200 mAh to 8000 mAh.
From what I have read this is what most are using.
A 6000 mAh pack will put out 60 amps
A 8000 mAh pack will put out 80 amps

Milton

RC Extreme power

My Feedback: (24)

This site might help you out
Milton


http://www.motocalc.com/motodown.htm

Matt Kirsch

My Feedback: (21)

ECK,

See? I told I'd find your thread and if I had anything useful, I'd add it. BTW, you sent me two PMs, but one of them said "Dear Greg?"

The 5S3P notation can be easily remembered like this: S(C)ells in Series, Packs in Parallel. The series number does tell you the voltage, and the parallel number INDIRECTLY tells you the capacity and current rating of the entire pack:

Multiply the parallel number by the mAh rating of one of the "sub packs" to get the total capacity of the entire pack. Take that number, multiply it by the "C" rating of the individual cells, and divide by 1000 to get the total capacity in Amps that the pack can handle.

Without more information, I wouldn't even hazard a guess as to what LiPoly pack you need for your plane. Do you know how many NiCd cells would be necessary to run your power setup? That would help trememdously.

You can connect multiple packs in series to get more than 5SXP, as long as X is the same for all the packs you're connecting together. For example, a 5S4P and a 3S4P can be connected + to -, in series, to make an 8S4P pack. I personally don't like having large single packs of cells. Multiple smaller packs are more versatile, and less likely to end up out of balance, IMHO.

Please make sure you're aware of all the issues surrounding LiPoly packs. With 5 times the energy density of NiCd, you're packing a tremendous amount of energy in a small space, and that requires some extra precautions.

Greg Covey

The Hacker C50 ACRO motor with 6.7:1 gear drive typically uses a 30-cell NiCd or NiMH pack capable of delivering 40amps continuous and 60amps burst current.

A 30-cell NiCd pack is equivalent to a 10s (10 cells in series) Lithium pack. The amount a cells in parallel are determined by the type of cell choosen.

Typically, I prefer to design a Lithium pack in which the continuous current rating is equal to the burst current needed in the setup.

ThunderPower makes some 10s packs for this job. You can also put two 5s packs in series. Call ZeeBee at [link=http://espritmodel.com/]Esprit Model[/link] in Arizona at 321-729-4287.

There are other alternatives new to the market like the Kokam (20C) 2AH packs. Each cell can deliver 40amps continuous so you'll only need 2 cells in parallel or 20 cells total.

Good luck!

ECK

Thanks ya' all for very useful info. I'm a newbie to electrics so all help come in handy.
From what I've read here at RCU 2meter pattern planes with the c50 Acro uses 10S configs for their planes.
And I've read somewhere the 40 size pattern planes uses 5S packs.
So I belive mine is somewhere in the middle, for instance 7 og 8S
But I dont want to guess, I want to know. I dont feel like trial and error with the prices on them lipos, dont wanna buy to many or to few.
I've looked at MotoCalc, perhaps thats the way to go. Can this program be trusted? Is it accurate to "real life" experiences?

I wish my question would have an easy answer like "Go buy a 6s3p 6amps package" based on the planes weight and size, and chosen motor.

ECK

No I'm sorry. Only reference I've got is the it's ment for 60 to 90 size IC engine. And the size/weight above.
To make a good guess, what more of info would be helpful to know?

Thanks for all input!

brg.
Oystein

Matt Kirsch

My Feedback: (21)

Greg already pretty much summed up what you need. Regardless of what brand LiPoly you get, you'll need a 10S pack, because Volts are Volts. How many packs you need in parallel depend on the brand and model of LiPoly you buy.

For Kokam 1500 8C cells, for example, you need 10S4P to meet Greg's requirements of 40 Amps constant, 60 Amps burst. 10S5P would allow constant full-throttle operation, which would fit Greg's philosophy of having enough to handle the full power (burst) for the entire flight.

For the new Thunder Power 1900 10C cells, you want 10S3P.

ECK

Thanks for your replies! Starting to understand the basics now.
I now feel more confident to make the right choice.

I kind of like Greg's philosophy too.[8D]