bobbart

I need help on getting the best RC Electric Flight Accessories for my C-130, see site below.
http://www.rcgroups.com/links/index.php?id=4546

I need to purchase an ESC, a Battery that has the power to run four Motors that are Graupner SPEED 400 6V Electric Watts=65 Volts=8.4 Amps=10 Thrust=10 oz.

I also need to purchase a 6 Channel Radio with 6 micro servos....looking to spend under $200 for radio.
To round it off, I need an ESC, I decided to go with a LiPoly cell Battery and Radio.....please reply back with you suggestions and sites to purchase them.
Thanks so much or your help and time
Bob

PS..I have 5% of the plane completed at this time.

Matt Kirsch

My Feedback: (21)

I thought we had this all hashed out at least once before. What happened?

bobbart

Hi Matt,
I decided that I want to go with a LiPoly cell and a 6 Channel Radio, so the last configuration changed
I still need help on this one.
ESC
LiPoly
6 channel Radio

Thanks
Bob

Matt Kirsch

My Feedback: (21)

Well, you've got four motors rated at 10 Amps on 8.4 Volts. That's 40 Amps at 8.4 Volts (7 NiCd or NiMH cells) for all four motors together. There's your criteria for an ESC in a nutshell. I'm not going to tell you what or where... We've got to leave SOMETHING for you to do in this project You really can't go wrong with an ESC if you use your head. If a vendor seems shady, or the brand of ESC is something you've never heard of, steer clear. Castle Creations is a good brand, as is Great Planes and GWS. Just go shopping at some of the sponsors you see in the banner ads above.

It just so happens that a 2S, or 2 cells in series, LiPoly pack is exactly 8.4 Volts fully charged, and acts like an 8.4V (7-cell) NiCd or NiMH when properly sized. You're going to want a 2S?P LiPoly pack that can handle 40 Amps. It's going to be pretty expensive.

Here's where we learn about C. C is quite simply the Capacity of the pack. All LiPoly cells come with a discharge rating expressed in terms of C. A 1500mAh pack rated at 8C, for example, can handle a (8C * 1500mAh = 12000mA = 12A) 12 Amp discharge.

Using this example pack above, a Kokam 1500 BTW, you would need FOUR of these packs connected in parallel to withstand the estimated 40 Amps being drawn by the four motors. Connecting in parallel combines the packs' capacities, so you'd have one mega-pack capable of a 48 Amp draw with a capacity of 6000mAh.

bobbart

Matt thanks for the info.
Matt, I don't want to purchase the wrong battery and waste my money because I purchase the wrong battery, can you just point me to at lease two LiPoly batteries models that will work with the 4 motors and I will do the rest. The motors will be in series.
Thanks
Bob

Matt Kirsch

My Feedback: (21)

You want the motors in parallel, believe me.

In series, you would need a brushed ESC capable of withstanding an 8S LiPoly, roughly 28 cells. These are neither inexpensive nor easy to find. Most brushed ESCs top out at around 10 cells. 10-cell brushed ESCs like the Castle Creations Griffin 55 and Great Planes C50 are both inexpensive and plentiful.

I've already given you one solution, four 2-cell Kokam 1500 packs in parallel. That's 2S4P in LiPoly notation.

Another solution would be to use ThunderPower Gen2 packs. What's nice is that ThunderPower offers the packs pre-built in parallel configurations, where you'd have to build a parallel harness for the Kokams. From www.thunderpower-batteries.com, either their TP4000-2S2P model or TP4200-2S2P model would be just fine for your setup.

bobbart

Matt.....Ok I will purchase the ThunderPower TP4200-2S2P model for for $99.95. Is this all I need with a battery? PLEASE explain how I would wire this in parallel with the 4 motors, never did it.
Thanks
Bob

bobbart

Matt, I understand how parallel works, but how does it connect with a pre-built in parallel ?
Thanks
Bob

Matt Kirsch

My Feedback: (21)

You don't wire the battery in parallel with the motors.

The motors connect to the motor wires on the ESC.

The battery connects to the battery wires on the ESC.

[four motors in parallel]=====[ESC]=====[ThunderPower battery pack]

The four motors, in and of themselves, are connected in parallel.

Inside the Thunderpower pack, there are really two "sub-packs" or "packlets" connected together in parallel. That's what the "2P" part means.