Ernie Misner

Greetings, I have been running 5 cell AAA (that's triple A) Nimh packs in my small profile planes with good success. I can get at least 4 flights if not more out of these little 700mah Sanyo's which is not too bad at all.

Question is...... has anyone gone to the A123's (LiFe) packs? I like the idea of them being 1100mah but they are advertised to weigh 3.0 ounces which seems heavier than the 5 cell AAA packs which I think are just over 2 ounces.

Thanks for any feedback!

Ernie

gene6029

I have run Li-ion packs in my profile planes. They are 2600 2 cell and weigh just under 4 0z. I can charge & fly all day practically, but top em off occasionaly between flights. You might be able to loose the extra oz or so by changeing to lighter wheels. I run them only because my Hobbico Accu cycle charger can be used to charge them & i didnt have to buy another charger. To answer your question if they are the best choice, well for me it was.....Gene

ThumbSkull

My Feedback: (57)

1100mAh A123 is all I will use. No regulator and they deliver the current needed. I get 7 flights on a charge and the charge only takes 20 minutes.

GarySS

My Feedback: (13)

Where to you get those 1100s Thumbskull? Hangtime?

RC MANIAC119

My Feedback: (14)

Rule #1 with any RC bird is
LIGHTER IS BETTER!!!!

I would keep what you have, or maybe get the same pack with a little more MaH's.....
Just my $.02

Ernie Misner

Thanks ThumbSkull and all. Maybe I was being too critical worrying about the extra ounce or so of the A123's. If ThumbSkull runs 'em I know they are an upgrade. The AAA Nimh's are definitely more fragile than the AA's...... AND we have a new and much better product in the A123's. It would be nice to fly all day without worrying about charging. Also, going to digital servos seems to suck a bit more power.

What charger are you using ThumbSkull????

Thanks loads to everyone,

Ernie

ThumbSkull

My Feedback: (57)

I built my first few from the B&D VPX packs that were discontinued. Now I am getting my individual cells from [link=http://www.hobbyking.com/hobbyking/store/__6563__GENUINE_A123_Systems_18650_LiFePo4_Cell_w_ tabs_GENUINE_.html]HK[/link] when they are in stock or from Richard at [link=http://www.shop.kavarootusa.com/category.sc?categoryId=10]WWRC[/link]


I have a couple of chargers from [link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7386]HK[/link] that do a good job quick charging them.
They work well on LiPo's too. Another great choice is the CellPro 4S.

Ernie Misner

Ahh, so you are building your own A123 packs from those cells w/tabs. Very cool and half the price when they are in stock at HK huh? I would definitely have to learn a little more about how to hook up the balancing wiring.

Thanks loads,

Ernie

Ernie Misner

One more question, the digital standard servos are quite affordable now...... but they take more amperage to run, right? So are you still using standard analog servos in your 40 size profiles??

Thanks,

Ernie

ThumbSkull

My Feedback: (57)

There is a ton of mythology about digital servos and how much current they draw.

I built a test bed a few years ago to compare the 965 against the 5965 and the results were that the idle current
was very similar and the amount of current required to move the same force was the identical.

Can a digital use more current in an airframe?
Yes it's possible if your linkage or hinges bind as the digital will fight harder to maintain center.
Under normal circumstances though, the digital uses no more current than an analog doing the same amount of work.

This bears out in real world in-flight numbers as well.
I'm using the [link=http://www.savoxusa.com/Savox_SC1251MG_Digital_Servo_p/savsc1251mg.htm]Savox 1251MG's[/link] in a 40 size profile that used to have 645's in it, the mAh's I put back in the battery
after 10 minutes of 3D is within 10 mAh. I attribute the extra 10 mAh to the servos being more than twice as fast
and able to hold better because they are stronger, not because they are digital.
BTW, I really like these servos for 40 size stuff and really enjoy the speed and precision.

ThumbSkull

My Feedback: (57)

The wiring for a123's is very easy especially with tabs already on the cells.

Starting with the positive lead of the first cell, the red wire for the load and the red wire for the balance lead.
The negative of the above battery is attached to the positive of the second cell and the middle balance lead.
On the negative of the second cell you attach the black load wire and the black balance lead.

Ernie Misner

Wow, not too hard at all. Wiring the 2 cells in series (for 6.6V) I could have done but thanks for the balancing info. If I'm reading it right, there are just 3 balance leads then, right? (2 separate hot ones and a common ground ?)

Man this is exciting that it can be done cheaply and is so much better than the Nimh's. Hey, have you figured out anything about the 2 small A123's that Tower Hobbies sells? One is an 1100mah and the other is a 1350mah. What's funny is their 1350 is 2.5 oz and the 1100 is 3.0 oz. Wierd, huh? I think it is because the 1350 one comes with less leads. AND where are they getting the 1350 cells? I haven't seen anything but 1100mah cells any place else in the world have you?

Thanks,

Ernie

ThumbSkull

My Feedback: (57)

Balance connectors always have one more pin than the number of cells. I picked up some 700mAh LiFe flat packs to try in a 40 size.
I'm expecting to get about 4 flights before needing to charge and save a few grams. I have not tried the Tower stuff yet.

The main reason to go with genuine a123 cells is that it's very well proven technology and patented.
The other LiFe cells are copies that probably won't deliver as much current or charge safely as fast.

Genuine a123 cells come in only 2 cylindrical sizes, 1100 and 2300mAh.

One thing I have noticed is that the a123 1100's are really only about 950mAh of actual usable capacity.
That said, it's still the best thing going for RX batteries. No regulator required.

Ernie Misner

Holy!!**^^%$!, you must be pretty demanding of your servos in a 40 size profile. I just checked out that Savox 1251. It's a $62 servo and man does it have the torque and speed. I know you are one of the best 3D pilots so apparently you feel this does give you an edge over the standard sevos. And the HS 645's that you had before is what most of us put in a 90 size plane. I thought the standard servos were cool because they are so light in the small profiles but you are demanding of the more speed and power, right? Please talk to me.....

Thanks again,

Ernie

ThumbSkull

My Feedback: (57)

The most often used servo I've seen used and have used myself is the DS-821. For $30 or less, they are adequate for most.
It is just enough for all but a few high throttle maneuvers like climbing flat spins, pinwheels, knife slide, knife loops, and a few without names.
The most demanding surface is the rudder and there the DS-821 falls a little short. It's a tad slow especially under load.

Keep in mind that the 40 size profiles have more moving surface area than many 90 size aerobats.
Servos usually outlast many airframes so I don't skimp there.

Ernie Misner

Thanks for the servo update. Looks like I should take another look at the standard type I am using. I've lost track of any of your videos. Do you have a link to some????

Thanks!

Ernie

Kevins_RC

My Feedback: (1)

I recently got back into the hobby after being out for about 8 yrs. I've had / have all kinds of issues with my 2.4 GHz systems. I bought a HiTec Auroa 9. I'm running the Optima 6 and Optima 7 receivers. I also bought a conversion module for my Futaba 9C since I had so many HiTec receivers. I'm running software version 1.07 on my Auroa 9. I've set-up a couple of profiles with the Optima 6 receivers, and after linking, the control surfaces goes nuts - just like interference with the old 72 Mhz systems. I talked with HiTec, and they told me not to run anything less than 1200 mA pack because the HiTec receiver consumes energy since it transmits as well. HiTec said that their receivers consume energy just like another servo. I installed all new HiTec 225MG servos in a profile, and got the interference issue. I changed the battery pack to a 4.8V 2500 mA pack - same problem. I changed the receiver - same. Changed the transmitter - same.
I set-up a new profile with Spectrum A6060 digital servos except for the throttle. I installed a 2300 mA A123 battery pack. Same interference issue. Changed the receiver (NIB) - same. I unplugged all of the servos except 1 - same issue. The only servo that I do not have an issue with is the throttle servo. I am waiting on an order of new servos to come to the house. I do not have these issues with my giant scale aircraft, only my 40 size aircraft. Any other ideas?
Thanks!
Kevin

ThumbSkull

My Feedback: (57)

HS-225's are terribly unreliable and over rated by Hi-tec.

Ernie Misner

Hey guys, on your A123 rx packs, do you just charge through the balance connector and that's it? I saw some Lipo chargers that required the main hot lead be connected to the charger as well as the balance lead. Also, do you use a charge jack or just leave the balance connector hanging out a little bit like I do on my profiles....?

Thanks again,

Ernie

Kevins_RC

My Feedback: (1)

You're missing the point, whether the HS-225's are over rated or not is not the issue at hand. Has anyone seen this interference type issue and if so, how did they get around it?

daveopam

My Feedback: (9)

Never skimp on servos. I used 130oz servos on a 40 size profile and never regretted it. You will never get full potential out of a 3D plane with lesser servos. At least IMHO.


david

Ernie Misner

Thanks David, .... so I think you are saying that don't worry about the extra weight, just go with powerful servos. I think that some, like the HS 645 would require opening up the mounting holes.

Thanks,

Ernie

daveopam

My Feedback: (9)

I never like to add weight Ernie, but in this case it's a fair trade. It would be different if we were talking about fun fly planes of old where every once made a difference. Todays profiles have such a light wing loading for the most part. The average flyer will never know the difference.

just my .02 david

Dave McDonald

My Feedback: (19)

I ran 5 cell Walmart NiMH AAA receiver batteries for many years in 40 size 3D profiles with no problems, even with digital servos. They would last for many flghts before needing to be recharged. But their downfall was that under a load, the Walmart AAA NiMH batteries couldn't maintain the voltage you would expect from a 5 cell battery. In one particular plane, with all of the servos moving, the voltage dropped to slightly under 4 volts. Even a good 4 cell NiCd won't drop that low under a load. But the FM receivers didn't mind, so I just kept flying them.

Then I got a Spektrum 2.4 DX7. With the Spektrum receiver, dropping down to 4 volts was no longer acceptable. That's when I started replacing the 5 cell AAA NiMH batteries with 1100 A123 batteries from Hobby King. The slight weight increase was easily justified by the ability of the A123 to maintain 6 volts or higher no matter how many servos were moving.

The voltage drop of the 5 cell AAA NiMH under a load also made me reconsider going back to 5 cell NiCad batteries in some other planes simply because of the ability of the NiCad to maintain a high voltage.

Today all of my 3D profile planes have either 1100 A123 batteries or Tower Hobbies LIFE batteries. Most of my non-3D planes have either TH LIFE batteries or NiCads. The only planes I have that still use 5 cell NiMH AAA batteries are two PBFs, and a Q-500 used for sport flying. The Q-500 has them simply because the A123 and LIFE batteries won't fit in the plane, and I didn't have a small 5 cell NiCad handy at the time the plane was built.

wyo69cowboy

My Feedback: (2)

I am using a 1200mah 5cell nimh pack; they are the 2/3A cells. Do these style cells have the voltage sag under load the AAA cells have? I have a couple of these packs in different planes, running on Futaba 2.4. Just don't want to get into brownout situations. The Futaba 2.4's don't seem to brown out as soon as Spektrum, but I have seen it happen, usually down under 4V...