rmh

Iwas once given a double set of regs n batteries -I gave em away -I won another set - I traded em off
The "why"? was because of the batteries included .
Tho the sales pitch which went with them made sense to some of my friends --It did NOT to me. Not for a second--
If the devices were being used to feed a low current ,lower voltage load -then I would have said " OK so now you have proper voltage ".
But how does the Voltage Reg do that job???
That was the rub.
I know that my TX (X9303)has a simple linear reg in it - and to me, THAT application works-- tho I wonder why they just did not opt for a big lower voltage pack -Oh well--- marketing -
My tiny flat foam models use ESC with linear BEC-(voltage regs ) for the itsy bitsy servos - that's ok.
My larger Electrics use External OR Internal switching regs- because the servo loads exceed the linear types abilities --even the dual types
My othe models?-- simple .
A123 cells - no regs used or needed . and the cell durability of these is faaar in excess of any of the other stuff - either from a electrical or mechanical viewpoint .
Some see this approach as "just anothe approach - Not me - I see it as a giant tep away from problems that have plagued models for years .

Flyfast1

My Feedback: (1)

So if a single cell opens, the voltage for that pack drops to zero. How does that affect the other pack? If it fails open, it's not going to sink current. If a single cell fails short, then the voltage for that pack drops by one cell. As proven in many tests, that pack will not drain the good pack in any significant amount of time. So, it appears that with both of these failure modes, the second pack does its job. Am I missing something?

-Ed B.

Flying Geezer

My Feedback: (14)

I don't think so. So many of us have used 2 packs and 2 switches without ever having a failure, that it has proven to be a very, very, reliable system. There are other systems that seem to work well, it's a matter of choice.

For me, I can't see adding the additional link in the chain of failure by using regulators. I can see it's necessary with lipos which I don't use. I don't want to add diodes and their voltage drop either, just my choice.

Dick's A123's have a lot of promise. I'm sort of waiting for the price to come down in manufactured packs. I don't think the A123 folk's are really interest in the RC community, yet.

Ed

"I don't think so. So many of us have used 2 packs and 2 switches without ever having a failure, that it has proven to be a very, very, reliable system. "

Right-on Geezer. I've been using 2 packs, 2 switches, and no diodes per Red Scholefield http://www.rcbatteryclinic.com/ for over 12 years now with zero failures.

> Jim

nonstoprc

My Feedback: (90)

Yes, that is where the second battery provides the redundency and prevents the total power failure. I just do not understand why people do not want to do it.

For A123 cells, the reduendency is still achievable. For example, the black&deck's VPX A123 1100mah cells weights about 1.5 oz per cell. One can get 2200mah 2S2P redundent configuration @ 6 oz. The weight saving over Nicad/Nimh cmopariable is about 3oz.

dirtybird

My Feedback: (5)

Because it is money spent and extra complexity that is not necessary.
I might consider it if I were flying gliders and expected long term flights.
But for my short term power flights (<15 min) a 10 sec voltage check before a flight is all thats needed.

DadsToysBG

My Feedback: (35)

This is what Spektrum and JR has said all along. Match the battery system needs to the airplane. Dennis

dirtybird

My Feedback: (5)

Fortunately I don't use Spectrum or JR. With one of those, and heavy drain servos and then a 4 cell NIMH battery you might have a formula for disaster. I am not sure an extra battery would help in that case.

rlmcnii

My Feedback: (3)

Fortunately I don't use Spectrum or JR. With one of those, and heavy drain servos and then a 4 cell NIMH battery you might have a formula for disaster. I am not sure an extra battery would help in that case.
[/quote]


A 4-cell, high-capacity, AA pack is a real formula for disaster in that case.

DadsToysBG

My Feedback: (35)

Dirtybird, my statement stands. If you need the extra power you put in in, if not then don't. Radio types aside, this rule applies to all RC planes and radio. No one set up works for all planes. I had a small combat plane and used a 250ma battery. The plane was a three ch. Charged after each 10 min. flight. Worked fine. Wouldn't want to try that with my 40%. Dennis

JohnMac

My 4 metre glider went in with circa ten minutes elapsed time on the screen! Choice is yours.

John

nonstoprc

My Feedback: (90)

Well, the choice is yours: battery redundency or not. The big picture is clear as well. Redundency, which costs almost nothing comparing to the value of the model and liability, works and can prevent total power failure.

dirtybird

My Feedback: (5)

Where do you get your batteries? A battery that fails after a 10 minute flight in a non vibration environment has to be a real dog. I'd like to stay away from that.

Flying Geezer

My Feedback: (14)

Dirtybird,

Voltage drop is determined by two factors. (1) The load on the power source. (2) The current capability of the power source.

Two 500 mAh battery packs in paralell will provide more than twice the current of the single pack. Consequently, under the same load, the redundant system will have much less voltage drop. This is because of the greater combined capacity of the dual packs, and the reduced internal resistance of the paralell packs.

Low voltage causes the computer to reboot in spectrum radios, giving you a temporary black-out. With our traditional 72mHz systems the plane just gets a little mushy under a low voltage spike.

Of course 5 cell packs are extra insurance, too.

dirtybird

My Feedback: (5)

Thirty seven years ago GE at Gainsville Fla was the big supplier of NICDs. Suddenly we started having all kinds of problems under vibration. It seems GE in the interest of economy had stopped connecting the cells internally depending on pressure alone to make the connection. Redundant packs made a lot of sense then.
Once we started getting cells from Japan all of the battery problems went away. It seems they welded the internal cell connections. They also welded a tab to the end cells and crimped the output wire to it. Since then I have never used redundant packs. I have had a lot of crashes since then but it usually is caused by my domb thumbs or some other stupid thing I have done. I have never had a battery failure but I am just one small blip on the radar.
I really don't care what you do. I just like to argue about it since some of you act like I have violated your religeon.

Flying Geezer

My Feedback: (14)

It's not a religon with me to have redundant packs. I don't use them on smaller craft. On large expensive craft where there is several thousand dollars in the air, and greater potential of personal and property damage, I use the redundant system. Also, with the great vibration forces of the gasoline engines, the extra switch is a good back up. I have seen a few switch failure.

JohnMac

JR! Sanyo cells inside. Nothing wrong with the choice, fitment, treatment. I was just unlucky, but then isn't that the whole point of this thread?
Regards,

John