After 30+ years of flying Nitro fixed wings, NiMh cars and cheep RTF helicopters I find myself lacking on the large battery LiPo side of things. With that I went to a trusted hobby shop for advice and to purchase a battery for the y6 that is already ordered from 3dr. This created more questions than answers.
1) What is the "best" voltage for a Hex? - # of cells - using 3dr esc's, transponder and standard r/c receiver.
2) Where is the sweet spot for mAh for a Hex?
3) There is a rating of "c" that indicates the available discharge amps (as per the owner of the shop) He recommended/guesstimated that it be greater than 40 because of the size and draw from motors based on the props being used. My question is how best to calculate the requirements so that the battery is not fried because of an over draw?
4) A point of observation in his selection of 8 to 10 brands is that given the same spec the price was similar... Given this quick observation is there a brand that has shown to out perform others?
5) Is there something unforeseen in battery choice.
I found this site that assisted, but thought I would check with those that have gone down this path...
http://www.rchelicopterfun.com/rc-lipo-batteries.html
Thanks,
Dan
Replies
Ive flown a lot of my multirotors using 3S 6000mAh Nanotechs and they work really well so don't really agree with you there. If you want a sporty acro flying style then agree a 4S is the way to go. If your doing aerial photograph and filming then you don't really need a 4S type of performance for carrying cameras under 500gms.
Over all its a sliding scale of performance v cost. My hex at 2.5kgs fly's for 10-12min on 3S 6000mAh nano's when new in their first 20-30 cycles. They cost about $45pc. By the time I stop using them for the long flights is about 40cycles So I'm only paying less than $1 a flight. My view is I dont care to run then out lower than most people if I can comfortably get 30-40 cycles of good flight times out of them, then I am way ahead.
Soon as you jump up into 4S-6S or higher the cost of the batteries is double or more, yet your not getting double the economy of flight out of them at all when you consider the extra weight as well.
Also there always the voltage compatibility issues for telemetry, gimbal controllers, cameras HDMI converters and triggers etc etc,. I wont list the number of items Ive blown up over the years forgetting the battery is 4S and not 3S
This trend to go for very lower KV motors and using high voltages of 4S-12S batteries yet flight times are not showing to be that much more in flight time seem very uneconomical to me, when the cost for those motors, batteries, props and ESC in those size specs is 3 to 4 time the cost that to build a 3S system that only marginally gives a lower flight time. I don't feel the extra $1-2K in cost is worth 3-7 min more flight time when i just fly twice at so much less cost.
Now day I only run 6000mAh 3S for anything up to 2.5kgs and only use the 4S for the bigger rigs 3-4Kgs. My small FPV DJI450 quad I use for fun and crashing testing also runs off 3S and I get 12-14min on it.
Good points and of course to each their own :)
I'm curious to see what your mid (hover) throttle is on your camera/gimbal 3S rigs. For me, it's about staying as close to 50% throttle at hover, because by the time you are towards the end of the battery, you will not have much power on 3S in case you need to punch it. 4S does not inhibit you from flying slow and smooth.
On a 450 that's another story, 3S would be fun and fine - in my recommendation i'm talking about a Y6 with camera & gimbal.
Interestingly, I had my first lipo fire with a turnigy nano-tech 3s 5000mah battery following a crash. The crash was caused by an ESCfailure and the battery split in half along the horizontal.
I had previously been flying dualskys and they would keep it together even after a decent spill.
The fire was quite spectacular indeed and luckily it was outside on a cricket oval. Pics below.
Great info Ralph! I just ordered a RMRC 8000 mah 3S battery. Its total weight is 560g which is pretty light for that sized battery. I'll compare it the Turnigy Nanotech 5000 mah and RMRC 5100 mah batteries that I'm using now and post some results.
Just wanted to update everyone on more battery tests. Keep in mind I have 850 motors and am carrying a gimbal + go pro + telem + fpv equipment. AUW is around 2200g
First off my 2 Zippy 3S 5800 batteries are barely flyable now (60 cycles approx). They both drop voltage significantly under load (ie: under 40amp draw they go to 10.5v on a full charge). To be safe I only run them for about 6-7 minutes. I had a 3rd which I decommissioned as it was not safe to fly. People recommended them here which is why I bought them, but I definitely will not be giving this company anymore business. Stay away is my suggestion if you want something that will last.
I purchased a Thunder Power 3S 6600mah 35-70c. This battery, so far, has been the best performer. Voltage drop under load is minimal, and flies for a solid 10 minutes, and 13 minutes if you're in a bind with some to spare (voltage around 10.2v under load). I have flown it over 20 cycles with no performance or capacity degradation. So expensive though - $149.
Lastly I tried a Turnigy Nanotech 3S 6000mah. This battery performs great; holds it's voltage well under load and flies for 9-10min. I have only done 10-15 cycles, but I detect no degradation yet. So far best bang for the buck. Hoping it will last! $49 + $10-$15 shipping.
Best,
Raph
Adding my observations to this discussion. I've only just started with my Y6 and I am using a Zippy Compact 5800mAh 4s. Today was the first time I measured flight time. I got 14 mins of easy flight mostly in loiter, including getting to 150m altitude. I guess it takes a fair bit of juice to get it up there. It was at 18% by the time I landed. My Y6 is pretty much standard weighing 1.98kg with battery but no camera. I use the 880kV motors. I haven't tried using a 3s yet but there doesn't seem to be a good reason to use one. The only bigger 4s at hobbyking is 8000mAh and weighs >1kg. Ouch!
I guess you have to be a bit careful with batteries like this one because there is almost no physical protection. I feel like I could squeeze it like plasticine.
So i ended up getting a zippy 3S 8000mah to testhttp://www.hobbyking.com/hobbyking/store/__16225__zippy_flightmax_8...
With the gimbal + camera, it maxes out the recommended weight for the 3DR Y6 of 2500g. I plan to remove my bullet connectors and shave off some weight. Someone mentioned about 100G savings with this.
-I got about 13 minutes of hover only, and 9.5 minutes of mixed flight under low wind conditions. Mixed flight meaning, flying about 1 mile away and back (10000 feet traveled)
-40amp draw for hover @ 65% throttle.
-Once the voltage reaches below 10v, you begin to feel the weight. Fast descents are very hard to recover from.
-Only been able to charge 7000mah into this battery. This is from stopping at 9.6v under load, and 15% battery shown left on my OSD.
I really can't say I recommend this battery unless you fly with no gimbal or go pro. If you are just flying around and don't have the FPV weight (or just are using a small camera to FPV), it would fare quite well. Otherwise, flying around at 2500g does feel sluggish.
now waiting for a nanotech 3S 6400mah. let's see how that does!
Yes, sorry guys. Believe it or not, the 5.0 batteries were just Turnigy 5000mah 30-40C. I ran two batteries through and was able to get at least 14 minutes from them. I also had some Zippy 5000mah 40C and Dualsky 4000mah 30C.
However, I tried to reduce the weight / draw where I could just to see what 'normal' was. So this was without camera, no nav lights, no telemetry and very steady (almost grandma like) powering up and loitering. I also made sure that my CoG was spot on so it didn't fight itself. This was with stock PIDs.
I'm about to head to work, but will post the params later.
I finally had time and nice weather to go out and do some battery tests. Pleasingly, with brand new 5000mah batteries I was able to get over 14 minutes of loiter 'flying' time. This was in 35km/h wind so it was fighting to stay in position a little, but still very pleasing.
With my 4000mah batteries, I could only manage 8-10 minutes.
I was looking into this battery - anyone tried it or use anything close?
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=21945
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