I am building a flamewheel 550 with dji 2212-920kv motors and 30A opto esc,and APM 2.6....I have the choice of 3 or 4 cell lipo....what will give me the longest flight-time of 5000mah 3c and 3800mah 4c (ca same weight)?
Edgar - I tried Hobby Town USA. No luck. Do you know where to buy AGA batteries? I'd like to test the AGA 4500 3S 25C.
Really nice reply, showing the pros/cons of many system aspects that vary with cell count.
Also watch out for the current crop of HK Zippy's using 8ga wire. Egad! That's a lot of wasted copper and weight.
Well put Graham. I sell batteries for a living, and for the life of me I cannot fathom why people buy Zippy, Rhino, Turnigy, Kongpower and similar chinese cheapies purely based on price. These brands have over time PROVEN that they puff after a few cycles, their capacities and c ratings are grossly overstated, and they are a waste of money in the purest form.
Drone Zone lists five batteries for sale, and three of them are brands you mentioned in your post as being a bit crap? Isn't DZ your shop?
Beside the fact that is completely off point and irrelevant, yes, I AM involved in DroneZone, and yes, we do STILL have tose batteries that we inherited when we bought over the stock 2 YEARS ago, because people here know better than to buy those brands. Others dont learn....
You really want to know if your battery is good quality or not? Measure its internal resistance, and compare to QUALITY brands like Hyperion, Thunder Power, XPower and the like. then measure again after 200 cycles, IF your chinese cheapie even gets that far.
In the end its up to you what you want to buy, some people have budget issues, people with experience can advise you untill they are blue in the face, if you dont take the advice, you will miost likely learn the expensive lessons for yourself, that is after all why they call it school fees.
I agree completely on the quality with Chinese off-brand packs, especially zippy. Turnigy, however, has actually worked for me surprisingly. I have packs with 200-300 cycles on them, with a 3% loss in capacity. If you buy with an extra 25%-35% C rating in mind, and you take good care of them (which most people don't) you're fine. That being said, I would not trust a $2000 multicopter on their quality. A $250 build? Sure. A carbon fiber $2500 hexa with a camera? Not even a consideration. Buy the packs guaranteed to work.
As much as I hate anything that comes from HobbyKing, I will concede that from customer reports, the New high C Turnigy Nanotecs do seem to be the best of the worst. (Although still not as good as the name brand ones IMHO) I have had quite a few mixed reviews, they certainly start off quite well, not sure if they go the distance, I dont personally own any of them. It would be good to hear from Nanotec owners after 200 cycles, be it good or bad experiences.
I don't even use the nanotecs, just the regular Turnigy packs. The picture I attached is a 2 1/2 year old pack that has around 400 cycles on it. I've used it on both planes and a 3D heli, and it only recently puffed when I put too much draw on it on a new airframe. They're cheap, simple, fairly efficient and consistent, and I have 15 packs from them because of that. But you are definitely right, for any larger builds, especially with the increased cost and danger from a larger airframe, use brand name, tried and true, and consistently reliable packs.
I'll be testing
o Zippy Compact 5000
o Zippy Compact 3700
o Zippy FlightMax 5000
o Turnigy Nano-Tech 3000
o MaxAmp 11000 (possibly)
There is only one criteria in my mind for copters: discharge-capacity per gram tested at the amp rate required by the ship. Each battery will be tested over approximately 15 cycles.
Weight is critical. Many batteries add mass where where it isn't needed for my application because they make batteries for the general market. A battery might force on me to a 12 gauge wire when a 14 gauge wire works for a copter not flying as hard.
Here is where they add mass:
o tab material (copper or aluminum)
o tab cross section (width and thickness)
o less-cubic shape (takes more aluminum and plastic to wrap to contain the LIPO)
o wire size connecting the tabs together
o size of the primary cables
The above list of batteries were chosen because they appear to have the most optimal combination of capacity for their weight (but as you said, don't believe it, which is why we are testing).
The most efficient battery out there for multi-copters would be one built after mother nature's ... the onion. Minimal skin, maximum density.
So in your opinion, if you had to pick one battery to win this contest, what would it be for a multicopter running at 3S, 3C, at a total paylode of about 15000mAh in batteries.
What I mean by 3C is the amps it take to fly the copter relative to the capacity of the battery. So about 22 amps flying a 12 Ah battery. At max thrust (versus hover) figure 6C. This is a photography platform so it's never at max thrust.
Do you have a battery in mind?
Mark: He is right though. A lot of Chinese packs have been... incredibly unreliable over the years. Some are a LOT better than others, and they have been getting better over time, but in a lot of cases, the reported capacities and discharge rates have been off a bit. I personally have a competition aircraft for a UAS competition next summer, and we put $300 into batteries alone, just to ensure the extra quality. If you've ever seen a low end lipo go off mid-air, you'd understand why. Giant foam flying wings exploding in mid air are quite spectacular ;)
That being said, I have 15 Turnigy packs I use for quadcopters and smaller planes, and have only ever had a problem once. If it works for you, it works for you! Just make sure to give yourself extra room on the discharge rated, just to make sure. And that's true of any lipo's, not just lower price packs.And keep them well maintained! Discharge them fully, charge and balance every time, and don't use them puffed, and you shouldn't have any problems! Happy flying :)