dual power source (Full Version)

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joseph185 -> dual power source (1/10/2008 2:46 AM)

Do most use dual battery packs for receiver-servos in larger gas planes and also are 2 switches required or is there another method that is better to perform this task. Dont they make dual battery plug single switches ?



altavillan -> RE: dual power source (1/10/2008 3:12 AM)

For 35% planes I use a dual set of 2800 mah lipos with 2 switches and a power expander, but the expander isn't really necessary. Y connections to get multiple battery connections to the reciever is all thats necessary.
33% plane gets one 2800mah to dual connections to the reciever and one switch.



camss69 -> RE: dual power source (1/10/2008 3:39 AM)

The Wolverine switch by Fromeco is a pretty sweet dual battery solution.

I would recommend dual A123 -2300 mah batts into the wolverine, and then out of the wolverine into your RX.

The Wolverine has built in battery sharing circuitry, can isolate a bad battery, will draw from both batteries equally, even batteries of different capacities. It also has dual switches and dual charging jacks built in.

It works really well.




Rcpilot -> RE: dual power source (1/10/2008 5:31 AM)

Simple redundancy for 27% and 28% planes. 5 digital servos on the control surfaces.

2 of these:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRJT9&P=

2 of these:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVJ44&P=

Plug each one into a different port on the RX. Go fly it.

On 30% up to 35%, I start using bigger packs with heavy duty leads and either the same switches or something from Smart-Fly.

I have recently realized that I've been WAY overbuilding the power systems in my planes. Better safe than sorry, but I'm scaling back a little. Thanks to Tom @ Wildhare for the load testing he did on our standard connectors. That test data is what made me realize just how much I'd been overbuilding my airplanes. I once set up a 28% plane with 4 battery connectors plugged into Y-harness' to power a plane with 5 servos on the surfaces. It was a wiring rats nest and looked like a 3yr old built my plane. No way to really clean up 4 y-harness' into a RX. [8|]

Keep it simple. My moto for 2008. [&:]



Rockyaged -> RE: dual power source (1/10/2008 6:36 AM)

Most RC modelers prefer the redundacy in their models. Not so necessary on the 27 to 30 percent size
aircraft. The bigger in size of the model, the more value it has, and redundancy becomes more attractive.
Using a two battery system also cuts down on charge time, if you have a charger that will charge multiple
packs. We are currently in the beginning of a major new battery upgrade, with the new A123 batteries.
If you use one switch with one imput and two outputs, there is no redundancy if the switch itself fails.
Today's equipment, overall, is reliable. I believe the electronic get blamed for failures not of electrical
origin in many cases to hide errors made by builders of the airplanes.
On a Extreme Flight Yak 54, 30%, I am using two Fromeco 2600Mah batteries with regulators, one for radio
and one for motor ignition. This plane has about 30 flights with no electrical problems.
On a Aeroworks 35% 260, I have two Fromeco 5200 batteries, thru a Smart-Fly BatShare, which equalizies
battery drain, thru regulators to a Smart fly Power Expander. The power expander sends the servo voltage
directly to the servos, rather than acroos the small copper strip in the reciever that serces as a bus bar.
Then there is a 2600MAH battery, thru a regulator, to the motor ignition system.
There are seven high current servos that can draw alot of current when performing a snaproll. 40% models
and larger use more servos yet. and draw even more current. Go to a IMAC contest and see what the competitors
use in their setups. You'll see alot of power expanders of different types. Competitors like bigger models.
This should give you some idea of what you may want to do. There's a saying.....KISS... Keep it simple stupid.
Easier said than done, but it does apply. Instead of using extensions to reach the battery locations from the switches
and reciever, I solder in longer wiring to eliminate as many connector as I can, as connectors are a weaker link
in the chain, so to speak.
I hope this makes sense to you and I have helped you. Don't be afraid to approach a giant scale flyer at your
flying site. It'll be the best info gathering, as you'll see what we're talking about.

Gerald



Dave Wilshere -> RE: dual power source (1/10/2008 7:58 AM)

I use the Powerbox Sensor switch or Gemini unit for smaller models.
Fail safe switches with real dual redundancy.

Dave Wilshere



rctom -> RE: dual power source (1/10/2008 3:45 PM)

quote:

ORIGINAL: joseph185

Do most use dual battery packs for receiver-servos in larger gas planes and also are 2 switches required or is there another method that is better to perform this task. Dont they make dual battery plug single switches ?


This is really a huge question. There are several things at work here. Also there is a difference between "need" and "want". Below is what you "need", but you may "want" additional stuff for redundancy and/or because it's shiny and cool.

First, you need to define the size of the plane. A 50cc plane will require as much as 9 amps at peak. A 35% will need 12+ during the moments of peak draw. A 40% plane can draw 20 amps for short times. Average draw during normal flight will be in the range of 1 to 5 amps. A 35% plane (in the middle of the range) will use approximately 250-350mah of power in the course of a 10 minute flight.

All these numbers are from actual testing that I have done.

Once you know what you will need, you can decide how to get it.

The first requirement is the battery. If you use Nimh or Li-Ion your current capacity is restricted to about 3C or 3 times the mah capacity of the pack/cell. For example a 2400mah Liion pack will only produce about 7 amps, so for a 50cc you would really need 2 of them, and so on. A 2400mah Lipo or A123 will supply all the current you need, they are both able to generate 10C+, so 24 amps is readily available.

Second is the switch. Mechanical switches like the MPI or Cermark/JR switch are spec'd at 5 amps but will handle bursts much larger. 1 switch is needed for a 50cc, at least 2 are needed for a 35%. For a 40% you should be using something besides these small mechanical switches. Smart-Fly has a single switch with 1 HD input and dual outputs, this is a pretty good solution for a 50cc plane. Above that the current capacity is a little limited. I'm not real familiar with all the other switches on the market, be sure to ask about current carrying capacity.

There are at least two receivers on the market that do not use switches. There is the Weatronic receiver for 72mhz and the Spektrum AR9100 for 2.4. Both of these accept power directly from the battery source through hevay duty connections without a switch, a definite plus. They integrate a soft switch which is not in line and if it fails defaults to ON. Batteries must be disconnected when being stored as a small amount of current is consumed by the switch itself.

If you are using Li-Ion or Lipo you will need voltage regulator(s). Again these must be sized for the application. Nimh and A123 do not require regulators, one more thing that won't go wrong and that you do not need to buy.

Finally you need to consider connectors. The small JR type servo connectors can carry 3-4 amps continuously and 6+ amps in burst without getting warm. Two of these is enough for a 50cc or 100cc plane. Larger than that and you should either have 4 connections or 1 or 2 heavy duty connecors. Keep in mind that each connector introduces resistance, so the fewer connectors in line the better.

My favorite setup for up to a 35% plane is a single 2300mah A123 pack with two HD outputs into two switches that go into a standard receiver. Larger than 35% and you should have either 2 receivers, a Weatronic or Ar9100 receiver, or a power box.

Whether you use 2 batteries for redundancy depends on how much you trust your setup. I would never trust a single Lipo or a single voltage regulator, I am comfortable with the reliability of a single A123 or Nimh pack that has sufficient capacity. Liions are reliable enough but do not have enough surge power to be used alone.

YMMV

Tom Fawcett
Wild Hare R/C



yarom -> RE: dual power source (1/10/2008 5:23 PM)


I found that the Smartfly equipment is particularly well suited for these applications.

On 30% planes, the SuperReg works well for the power requirements, provide redundancy and supports a single safety switch.

On 35% planes, the TurboReg (combined with Power Expander), does the same job and provides the same features with higher current draw.


One of the complicating factor is that SmartFly has a host of new products that unify the fuctions of several products into one board, like the EQ10, Power System Plus and the new EQ6. These provide the dual regulator, battery redundancy, safety switch, power expander and optical ignition cutoff, all in one product.

They are quite expensive and have not used them because I favor the distributed approach of not having all the components in one place. I also like the flexibility to install them where I want in the fuselage.

All of their products I used (SuperReg, BattShare, TurboReg, safety switch, various Power Expanders, optical cutoff, servo equalizers) however, have been extremely reliable for me.

The other complicating factor is the advent of A123 batteries. They are 6.6volt, so a bit high for some systems, but do not require regulators and are free from the various afflictions LiPos normally bring with them. So they can be plugged directly through a BattShare to the receiver, or through a Power expander (that will regulate down the receiver voltage to 5.1v).

Hope this helps...



joseph185 -> RE: dual power source (1/10/2008 5:59 PM)

Let me start with this RC MODELERS are like a BAND OF BROTHERS whom without each individual would not make it very far. Just about every question I have posted has brought great reply. Thanks for all these great Ideas, but what I have absorbed from this equation is keep it as simple as possible, it take less time to trouble shoot should a problem arise. THANKS again for all this great info. It is greatly appreciated. I will use most of these ideas. There are not many large gas fliers in my area mostly nitro guys flying smaller planes and it is nice to know I can draw from this vast pool of wealth called "you guys".



rctom -> RE: dual power source (1/10/2008 11:32 PM)


quote:


Thanks for all these great Ideas, but what I have absorbed from this equation is keep it as simple as possible, it take less time to trouble shoot should a problem arise.


Bless you.

TF







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