Hi, I'm after a bit of help, I am trying to run dual batteries, but am having very ordinary performance when I do. Today I tried flying with dual batteries, and when I did, the flight times where much improved, (24min with a D800) however the copter would constantly fly off to the left when flying manually. I tried trimming the roll and nick, which would level it out for a second or two, and then it would start to fly off to the left again. I thought it may be a weight and balance issue, yet when I yawed through 180 degrees, it would still head off in the same direction. (My left not copter left) When I engaged PH it would just sit in the sky in the right spot, as it should, however when I would fly manually it took a lot of stick input to stay in position. To trouble shoot, I went back to flying with one battery, and flight performance was excellent. I have a gryphon power distribution board, with two power leads on it. I flew with the battery connected to the aft power lead and it performed perfectly, I then carried out a the same flight with the battery connected to the forward power lead and it worked perfectly. At this point I started walking around in circles scratching my head ..... I then tried to fly with two batteries again, the power leads we're twisted, the batteries were balanced over the copter, and as soon as I took off again, it wanted to start flying off to the left again. This makes me think that it is some sort of interference issue, rather than a weight and balance issue. So my question is has has anyone seen this type of behavior before, and if so where should I start looking to resolve it? Some more details of my copter ... FF 6S 9000mah batteries CS8, 500mm booms MT3515-15 motors, 15" props MK flight controller HW 2.2 SW 0.90j Nav Controller + GPS Two axis gimbal, driven from the MK flight controller Gryphon PDB 40a esc And an i2c converter just to finish it off When I was flying with two batteries, the gimbal would roll off level as well, which is what makes me think that I somehow confused the MK board ..... Any advice would be appreciated, I want to get the dual battery thing sorted for when I attach the MōVI on Wednesday
Do you have a GPX file? There may be some pearls of information in there. And have you tried disconnecting the gimbal?
Yep, I have a GPX, but I'm bumbling my way on the forums on an iPad .... No sd slot in this thing .... Doh. I'll get the file onto the inter web in about 9hrs
Chris: did you try flying with two batteries mounted but only one connected? That would eliminate balance. Also, it might be worth trying to recalibrate the ACC (FC board level, left stick on Tx up to the top right hand corner to write the settings). Why that should depend on the number of batteries escapes me, though. Also, using MK Tool, on the Misc window, try setting the Compass Effect to zero -- effectively disabling the compass -- if it is a magnetic effect, that would eliminate that. Andy.
And lastly check that the sticks are calibrated on you transmitter and not off center by default and that all trims are centered.
I've attached to GPX files, the both from the dual battery setup, the same flight I just landed, shut down the motors and reinitialised the the board and took off again to see if that would help, but it didn't. The sticks on the transmitter are calibrated, I've checked it, but I would expect that would show up as a problem with dual batteries or single wouldn't it? the ACC was calibrated a couple of weeks ago with an inclinometer to find level, and a lot of post it notes (aka Andy's Video style) I will try that again though, and see, I'll also try flying with two batteries and only one plugged in .... if thats the case then it would have to make it a weight an balance issue if the problem persists. I'm trying to get the dual batteries sorted before I bolt up the MōVI to the setup on Wednesday. Thanks for the ideas so far.
Chris Do you have any pictures you can share? Adding the parallel cable adds a lot of extra wire to the equation. Personallly I think the QC cable is just a tad too long. If it appears that your cables are long enough that they can just flop around with the parallel cable added I would suggest to tie it down slightly with a velcro wrap. I'm not saying to have it extremely tight just enough so that the battery cables are not flopping around. Also on my parallel cable I electrical tape the red and black together. I make sure there is no air gaps between any red and black connections. I also think its a good idea to recalibrate the ACC with both batteries powered up. Lastly do yourself a favor and check the motor alignments and make sure the booms are out exactly equal length. I know your probably saying that its not doing it with one battery but I would eliminate all of the basic issues that can cause it.
G'Day Gents, Thanks for the pointers so far, I have just come back from doing a series of test flights. All flights had the two axis gimbal and a D800 on board. First flight, was with two batteries on board mounted transversely, but only one battery connected to the rear power lead. The result was the copter trying to run away to the left again, it pitched and actively flew away when I put the sticks in the neutral position, so it did that with the extra weight on top, I'm guessing not an emi issue. Second flight only one battery on board transversely mounted and connected in the rear position, on the rear lead, it flew like a dream Third flight, only battery in the transversely mounted in forward position, and flew like a dream. Fourth flight. Two batteries on board, only one connected to the rear power lead, transversely mounted and I disconnected the gimbal roll and pitch servo leads from the flight controller, so it just hung as a dead weight. The copter pitched over to the left and flew like a dog. Fifth flight, one battery mounted longitudinally, and it flew like a dream. So I'm thinking it is a weight issue too top heavy, or something bending and moving the flight control board when the weight of two batteries is on top ...... I'm really scratching my head here ..... And would you believe it I'm supposed to be an aeronautical engineer .... Obviously I'm not working at NASA or Boeing. Here some pics of the flight controller and PDB
Chris do you have a wireless Xbee system so that you could see the balance in MK tools in the 3d window. That might also help. FYI I realize you are from the land down under and are used to viewing pictures upside down but for us Yankees hard to tell what is going on
It could be a weight/balance issue. If I was you, I would velcro a 3rd big LiPo to the camera gimbal and try flying again like that to balance the second battery on top. You indicated you have more than enough power based on your flight times. But I just looked at your GPX file, and the first thing that jumps out at me is this: "Errors / warnings: Compass is disturbed by magnetic fields!" This is a clue, as something is messing with the Navi board, which could easily lead to what you're seeing. You have a lot of voltage going through the system, and if any of your components (like the ESCs) are too close to the Navi board, that could cause what you're experiencing. The MK stack is well-known to be somewhat marginally engineered, and I don't know too many people who have had good results pushing it beyond its design limits. Can you take another photo (sorry) of the top of the copter looking directly downward showing two batteries and the Navi/GPS boards?
If it related to the compass, Chris, (and I'm not sure it is), then can you confirm that you set the Compass Effect in the Misc window of MK Tool to zero? Thanks Andy.
I think I have the australian version of the iphone, where iOS automatically inverts every photo when viewed from the Northern hemishpere ..... pretty clever really I have the MK wireless thingy, so I'll have a look at what the balance window says. when static and in flight. I now just have to wait until Wednesday, as everything is broken down into pelicases for the plane tomorrow.
G'Day Andy, I haven't adjusted the compass values, at all, they are stock for 0.90j I'm not sure it could be the compass as it flies perfectly when only loaded with one battery ..... but I will give it a go on Wed when I'm flying with the computer handy. THanks
Well all of this did not end very well. On the first flight with the MōVI onboard the copter flew for a bit, then rolled over onto its back and headed for the centre of the earth .... The flight control board has been sent to an independent investigator, who has developed a hypothesis that the soldering of ACC upgrade may have cracked one of the ceramic capacitors on the board, and upset the reference voltage used for the signal processing of the flight controller .... So now I'm hoping the move to V2.5 of the FC will resolve this in its entirety. stay tuned for the results of the copter building commencing this week. I'm building two identical HL machines side by side, with the new flight controller, and hopefully the new firmware operates well with the new FC. Is anyone running V2.5 of the FC yet?
Sorry to hear. I"m waiting to build a new Heavy lifter myself but I won't use MK with the I2C converter. I'm trying to see if Synapse will come out in the next 3 months or I'll be using DJI.
the MōVI disassembled itself. the MR kit and pan boom were toast, the tilt carbon tubes let go from the clamps on the motor and pivot, But I reassembled the tilt bars, and replaced the pan boom with a new carbon tube, and powered it up in the M10 configuration holding my breath ..... and holding it bit longer as the lights blinked .... and .... turned to solid green and it runs just fine, so I was shooting hand held the following day .... Now it is onto building a the replacement copters ..... only 6 booms, and maybe the navigation board and GPS survived from the original, I'm glad I bought RTF to start with, as now I am in a better position to see what works well and what I would do differently for the next two. I'm hopping to have the next two built this week.