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Still building my quad.. Waiting for some connectors and a new video Tx..
I'm wondering where to place the battery. Presumably the quad should balance close to its centre but the FC should also be at the centre for its inertial stabilizers. I'll start with a 3S 2700 battery but might want to use 4S 4000 later - so I want to plan for a heavier battery from the start. How important is balancing a quad in the horizontal plane? I'm guessing very important. How important in the vertical plane? Maybe I could put the battery right on the top? Any thoughts gratefully received. |
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They need to be balaced latterally and longitudinally. It isn't super critical as the flight controller will counteract, however you don't want it to be working harder than it needs to. That just uses more battery by making the motors work harder stabilising it.
I have a strap and my battery is underneath. I use a 3S 2200 because a 3S 3300 or a 4S dont give you any more flight time due to the extra weight. But I guess you will find that out in time. I have a range of 4 klm max @ 15 meters per second. (54 kph) This can be stretched out by flying a bit slower. e.g. 8 meters per sec. (28 kph) |
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Last edited by Grantham Kid; Jan 23, 2019 at 04:20 AM.
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If you want, you mentioned you bought 2 frames?
I doubled up the length of the legs by using the extra legs in my spare kit. This gives it heaps of ground clearance if you undersling the battery. I din't bother with my other 2 quads as it isn't really a problem. If you decide to, make sure you put some glue on the legs where they join because they can come loose. I watched a leg fall off one day when it was flying across in front of me. Lucky I saw it drop. |
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Yes, I like the idea of doubling up on the legs and slinging the battery underneath. That will leave loads of space for gear in/on the green cage. And keeps the weight very centralised.
I'll saw up some long M3 bolts to make a stud to join the legs. Plus glue as you say. Thanks for that. Just need the nice Mr Postman to deliver the rest of the bits I need now..... |
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Finished and flying.
Early days but flies nicely. Just need some decent weather and more practice. Thanks for your help on this Grantham Kid. |
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Fabulous! It is a great little frame to work with. I have a buddy bringing his around today so I can help him set it up. Keep us updated.
Cheers GK |
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I see what you mean about adding battery capacity for longer endurance. The extra weight cancels out a lot of the additional mAh available.
I've compared flying one 2700 3S 40C battery with flying with two of the same. The weight of the whole craft only goes up 16% while the energy available is doubled. And yet the endurance only increases by 44% (theoretical max judging by current draw in a hover). I think I'll get two 3000mAh 3S 10C batteries and run them in parallel. Should weigh about the same (or less) as a pair of 2700mAh 3S 40C batteries. I think that will give me a practical max flight time with this machine and I'm hoping for a safe 10 mins. |
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I had no luck with those Multistar 10C batteries.. They failed on my quads in the first 3-4 flights. They caused crashes.
One cell died in each of them and couldnt be restored so be careful. Those green things are crap in my opinion. I still have 2 x 1400 65C Green Multistars that perform quite well on my quads believe it or not. |
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Yup, I've had dodgy batteries like that too. Low C rating might suggest low quality I guess.
After your comment and after another test flight yesterday I've had a rethink on batteries.. My pair of 2700mAh 3S 40C batteries in parallel gave me 10 minutes hovering in a 10->20 mph wind yesterday. Batteries were down to 3.7v. Thats good enough for me for now. I'll just get some more of the same batteries. They have been reliable and they are multi-purpose - I can use them in my Tundra and I can use them for my goggles. |
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Quote:
Or are there packs out there which are already connected up in series & parallel to make them suitable for a quad? |
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Only pre-made packs I'm aware of are these: https://www.readymaderc.com/products...50-li-ion-xt30 But they're only 2s.
Yeah, best is to spot weld them as soldering directly to the battery poles is not easy without overheating the battery. I buy mine at nkon.nl, they offer to have solder tabs spot-welded to the batteries as an option. Then you can solder wires to the tabs easily. I have these: https://eu.nkon.nl/rechargeable/1865...18650vtc6.html |
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Last edited by Rodizio; Feb 18, 2019 at 11:47 AM.
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