iflyg450

New to electric flying. I have a GP riot 3d using a 640mah packs and was wondering is cell balancing really that important?

[]TEX[]

If it's not a Lipo then no.

If it is a Lipo then balancing the cells will give you longer run times and longer battery life.

jmir

My Feedback: (1)

Yes, it is.
Your battery pack will be as strong as your weakest cell. So, it is better to have them balanced so flights can last longer.

jmir

My Feedback: (1)

Yes, it is.
Your battery pack will be as strong as your weakest cell. So, it is better to have them balanced so flights can last longer.

I understand a balancer will drain the strongest cell(s) to equal the weakest cell, so that charging can continue until all cells are fully charged. Hope this makes sense.

You don't really have to balance them on every charge. I just check them after each flight to see if the cells are in balance. If not, I then use a balancer next time I charge them. I only have one balancer and I can charge up to four batteries at once.

iflyg450

My packs manual say to only use a balancer when charging they are the Great Planes Balance pack. Is this correct Is balancing every charge bad?

guver

My Feedback: (325)

I'd say it like this:

Cell balance is very important , balancing may be on a "as needed" basis.

It's kinda like airing up car tires, where "correct air pressure" is very important, yet "airing up tires" may or may not be.

patnchris

When I first started flying, my LHS told me that balancing was a waste of time and money. At that time I was flying ThunderPower 3s 1350ma lipos. After a couple months of charging every day, I noticed a distinct decrease in flight times and capacity. My LHS told me that this was normal, and I'd need to purchase new batteries. I disposed of them and bought new ones. By this time I'd moved to some larger planes and was also using Thunder Power 3s 2100ma's. The same thing happened..After a few months I noticed a distinct drop in capacity. I was "wearing out" $70 batteries. So I bought more, figuring that by spreading out the flights over more batteries, I'd get them to last longer.....But after a couple of months the new ones were losing power, and the older ones were almost unuseable. I started reading threads, here on balancing, and decided that I'd give it a try. If I'd get a little more life out of my existing batteries, I'd have more time to accumulate new ones.....Well, the results were absolutely amazing. It took several cycles, but soon the old batteries were performing as well or better than the new ones were, before balancing....I now have many batteries, many in the 3s and 4s 4200ma size and at least 16 of the ThunderPower 3s2100's and 10 of the Thunder Power 3s 1350's.....I balance every charge. I started dating and numbering them and have many that are over a year old with over 100 charges on them...I've noticed a slight difference, between the new ones vs. the old ones....But you'd really need to monitor closely to tell the difference. I've deliberately used the older one, first, to save the newer ones, and they still perform admirably.....A few weeks back I thought I'd lost a couple, only to find that what actually happened was my balancer died........I picked up an Astro Blinky to replace it, and find it works as well or better than the Thunder Power balancer....So when the Thunder Power balancer comes back, I'll have two, allowing me to use two chargers at the same time. I try to fly alot. If I don't get lazy, and the weather co-operates, I can get 6 flights in the morning, before work, at a park, close to there....One weekends I can easily get in 20 or more flights of my larger planes, at our club field....It seems that I have batteries charging all the time....The addition of a secong charging/balancing station, will be very welcome........IS BALANCING IMPORTANT???....Only if you want to save money that would be spent on batteries, and buy more planes, instead.......JMHO....Pat

vega2614

Both the lipo chargers I own are "balancing" chargers. Is this enough of a measure to ensure that the batteries are being balanced? Or do I need a separate balancer, to balance, and then charge? Some of my lipos definitely have reduced performance (about a half a year old and heavily used).

captinjohn

Where do I find a asto Blinky??? Thanks Capt,n

mrasmm

www.commonsenserc.com has the same thing just a different name, your LHS, or there is another site for the blinky that I don't remember right now =)


there are great planes packs with overcharging circuitry in them, I dunno if that is what you are talking about. I also don't know if there is any special charging considerations for these safecharge packs, but I would guess that any normal lipo charger could charge them correctly. From the sounds of the description though, they do not balance themselves, but rather just prevent overcharge.
http://www.electrifly.com/powersyste...ries-lipo.html

dcnpaulk

The Astro blinky is produced and distributed by....who else?...Astroflight. Here is the link: http://www.astroflight.com/store/sto...MvxxLsnBk3u6O3 . I am relatively new to e-flight, so have been doing a lot of reading and study on this matter. The subject of balancing is one on which there is a lot of diverse viewpoints, from "balancing, I don't need no freakin' balancing" to obsession with PC-based graphing, etc. From the theoretical point of view, all I have read suggests that balancing is highly preferable from both efficiency and, if you use LiPo's, a safety consideration. On this last point, after much reading on the subject, I have decided to go with A123's since I have no prior investment in LiPo technology, and these batteries, while having a slight weight penalty over LiPo's are by far the safest Li ion technology, rugged, ultra-fast charging (10A, ~15 minute charge time), 70C discharge and over 1000 charge cycle life. I plan to balance these also, although there is no danger of fire or explosion from an inadvertant overcharge. If you are committed to LiPo's I think Pat's real life experience speaks volumes from the practical side, which only supports what I have learned theoretically.

Paul K.

patnchris

There are many tings that contribute to battery life. Balancing is only one of them. What balancing does is insure that all the cells are fully charged, instead of one being 120% and another being 80%......The other thing that will contribute to the early demise of Lipo's is over driving them. By this I mean running them all the way out to cut off, constantly and constantly over drawing them. If the batteries are constantly coming out of the plane hot, then you need a battery with a higher "C" rating. If you are running marginally on the amp draw, you will find that the further down you draw them, the hotter they get. This is because as the voltage starts to drop off, the motor will automatically draw more amps. I could show the formula, but to save from boring ya, you can just take my word for it, that for a given performance the motor will draw less amps at the beginning of a flight than it will at the end. If you over tax them they will definately swell. You may not notice it, but you can definately measure it. Use a calipers to measure the thickness of the battery at the beginning of a flight, then measure it again at the end. If the measurement is substantially different, your batteries are generating tooo much internal heat, and their life will be shortened. I have recently started switching over to 25C batteries as I've noticed that many of mine are coming down warm. I'm not sure if it's just the batteries getting old, or that as I get better at flying, I'm pushing them harder. Possibly a combination of both.......Another thing I think is confusing tis the whole "C" rating system on lipos.....They give a "C" rating which is actually the continuous discharge rating. This usually doubles for the Maximun discharge and them goes even higher for the "BURST" rating. The reality of it is that if you have a motor that draws 20 amps during normal flight and you're using a battery that is rated at 15C....Then you have a problem.....While the plane will fly, and the battery will work, you are exceeding the continuous discharge rate....If the motor draws 15 amps during normal flight. and then you punch the throttle to do some aerobatic stuff, the amp draw may go to 25 amps for that period of time, but then you return the throttle to normal and return to the 15 amp draw for a while.....Then you are within the operating limits of the battery, and you're doing just fine.....I've always used this to determine my battery needs and conditions, and it's never given me any grief. I've never had a battery explode, burn, or any of the other thing lipo batteries are given a bad name for. I firmly believe that it's not the battery that's dangerous, it's the user......Pat

davidgeorge212

I have a question. I just got a Thunder Power 3cell 730mah lipo and I am wondering on how to balance it. All my other lipos have balancing leads but this particular battery does not. Does anyone have an idea on how to balance such a battery, if so please let me know.

I have a super brain 989 charger and a Thunder power Balancer that can balance up to 10 cells. Do I need something else to balance it.

mrasmm

basically if it doesn't have balance leads then you can't balance it. The only way to balance it is to add the leads, and basically if you don't know what you are doing you can really mess things up. It's all up to you what you do. You can leave it alone, and take the gamble that way, although TP's are better at keeping balance over lots of cycles, or you can try to get someone else to add balance taps, you could try to add the taps yourself, or sell it to someone that wants it or knows how to add the taps or whatever and get you a new pack. Just whatever you want to do. Good luck

davidgeorge212

I have had other lipos (not Thunder Power Brand) puff on me and I had been balancing them so I thought it was a critical step to alwasy keep them balanced. I was looking at this one and it cant be balanced. I wonder if that is the way thunder power purposely engineered it. I guess I will just use this battery stock until it dies or puffs. I hope it works ok not getting balanced.

captinjohn

Pat: I have a E-flight Cap 232 with 425 square inches of wing area. Is it possible to have good performance with this plane with A123 cells and the right motor ..ect. Thanks, Capt,n

patnchris

Cap,
I think you are right on the edge. While the A123 cells do have distinct advantages, one of the disadvantages is weight. You are basically looking at a wing that is 40 inches long and 10 inches wide. I'm afraid thatby the time you get enough voltage you will be weighing the the plane down. One of the reasons a CAP or any other extreme sport plane performs the way it does, is because the are light. While I don't use any A123's , yet, there some in my clubs using them. From what I gather they are using them in .40 sized planes and larger. I'm assuming that this is because the larger planes can overcome the weight difference better without affecting the performance. I don't feel I have enough knowledge to make recommendations on A123's yet......Talk to me about it next summer as I intend to build a couple .60 sized planes over the winter, and A123's will definately be a consideration........Pat

Matt14x

Pat
I would sure like to have that formula were less voltage equal more current draw.

I need to prove a point at my club.

Matt

patnchris

Simply put.....If a plane flying through the air requires 300 watts to maintain a given speed, then as the voltage drops the amps must go up.
W= I X E where W = watts, I = amps, and E = Volts.....This is known as Watts Law......Pretty simple formula....It is WATTS (Power) that spins the prop, not volts or amps. and the watts to spin the prop doesn't change as long as the prop is spinning at the same speed....Therfore on a fully charged 3s battery, you are starting out at 12.6 volts.....however as you continue to fly, the voltage continues to drop. since the WATTS to spin the prop at a given speed doesn't change and the voltage is dropping, the only way to maintain the power (WATTS) is to increase the current (amps)...

Matt14x

Pat

I see your point. Thank You.

W=IXE still means , less volts=less amps=less watts.

Matt

a1atom12

My Feedback: (1)

The derivation is from Ohm's Law V=I*R and the definiton of power (P= I * V)
Where:
V= volts I=current R= resistance P= Watts...........P=power (Watts),

Using good ol' algebra you can rearrange the formula to solve for any needed value:

V= I * R P= I * V

I= R / V and I= V / P Now you have all sorts of cool relationships between power, voltage, current, and resistance.

R= V / I V= P / I

You can combine any or all of these to suit your needs, solving for knowns and unknowns and plugging them into each other.
Ex.

V= I * R and V= P / I so P/I=I*R solving for P yeilds P=I^2*R
and
I=R/V and I= V/P so R/V=V/P solve for R= yeilds R=V^2*P of P=R/V^2


This is a very handy equation that most RC enthusiasts should add to their mental tookit.
It's extremely useful and has a wide variety of applications:

-battery (power and current) design and selection
-sizing resistors for LEDs
-altering/computing voltage outputs
-setting up (simple) discharge curcuits
-approx. run times
-and much much more!

You can have all this and much much more for the 1 time Super Special Extreme Deal
of only a few bytes of Memory

V= I * R
P= I * V

Knowledge is power, you can never have too much!!
I hope this proves useful to someone somewhere, its my first post ever so I'm a little green.
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