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Dual batteries

Discussion in 'General Discussion' started by Sokol, Jan 28, 2014.

  1. Sokol

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    Just received my CF dual battery mount and Y-cable for flying with two batteries, got everything set, and went out for a test. With two batteries, anti-jello mount and NO camera I only got 5 1/2 minutes flying time, compared to 8 minutes on a single battery. Thinking I had mad a mistake, I did it again with the same result. This makes absolutely no sense to me...I knew I wouldn't double the flight time but I did think I would get a few extra minutes. Any ideas?
     
  2. DeweyAXD

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    A few things to test:

    1) Voltage of both batts after the flight and ideally how many MAH you put back in. You may have your voltage limits a little too high.
    2) The Paralel cable... make sure it is actually sending power from the second battery! (unlikely that is the issue but it would still power on if one leg wasn't doing anything).

    These CF mounts are also really bad for eating battery life in GPS mode. They throw the weight (and hence CG) all over the place and cause a pendulum effect. To explain:

    Phantom rolls left, CG sways too far, NAZA compensates (based on what it thinks the CG was... not what it is). In its compensation it throws a control to roll it back but it rolls it too far... this cycle causes an instability that uses a lot more motor power than a well balanced Phantom with the weight down the centre axis.

    If you've seen my shapeways parts you will know I've done a fair bit of testing on dual battery setups. I found that you get a much more stable craft keeping one batt in the shell and one under the body down the axis. Maybe not the news you want here.

    The other thing to be aware of is the prop wash can hit the batts so some lift efficiency is lost. This is of course worse if you have 9" props?
     
  3. Sokol

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    I have CF props but they are not oversized and the aircraft handled normally...no swaying effect that I could see. The way that the Y cable is made precludes one battery not feeding the drone so I know that's not the case. I can see that the downdraft could be a problem since it would be pushing the craft down as the props are trying to lift it ...that might be part of the problem. I checked the voltage on the batteries when I finished and the were at 11.4---does that sound right? Since I'm new to this, I don't know what you're referring to when you mention MAH and having the voltage limits too high. What I don't understand is the fact that it actually lowered the flight time by 21/2 minutes instead of adding a little...it doesn't seem like the aerodynamic difference could account for this. I'll check out your Shapeways videos and see what you offer..I'd like to run two batteries for more flight time but how does it work underneath if you have a camera rig? Thanks for your reply..l need all the help I can get..I'm an old retired guy that got this to occupy his time and I'm trying to learn as much as possible
     
  4. ElGuano

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    11.4 immediately after flight is too high. Duals will behave differently to the low voltage alarm than single but in any case you're ending on something like 10.9-11.0 loaded.
     
  5. Sokol

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    I hate to be a pest but I am really new to this. Does this mean the point at which the Phantom decides the batteries are near depletion and starts to power down and how do you change the voltage limits ?
     
  6. OI Photography

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    I'm curious what you meant by that...? Are you sure you have parallel cable and not a serial cable? If you have a pic of the one you have or a link to where you bought it we can tell easily.

    Setting the voltage limits (which is how the Phantom knows when to warn you through the LED and eventually land on its own) is done through the NAZA Assistant software, which is something you should get familiar with. The instructions for checking/setting the voltage limits are in there, along with a lot of other functions that can be useful for you.
     
  7. Sokol

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    Thank you very much for the info...it was very helpful. I have downloaded the assistant software but it won't let me do anything until I update the firmware. After asking on here, I decided not to do that because the Phantom is flying perfectly and I am afraid to mess with it and I have been told that it's not necessary yet. I am not very computer savvy and I'm afraid if doing something that I can't easily fix.... ( I only have an old, slow laptop to work with...my good computer is an iPad ). The y cable that I am using came with a bundle purchased on Amazon---the wires that come from the single connector and go to the double connectors are together in the connector so I don't see how one could work and not the other. After the flight, I checked the voltage in both batteries and the values were the same and I know both were fully charged because I always check the batteries before I fly. Any other ideas you have would really be appreciated because, as I said, I am new to this and I would really like to fly with two batteries....and learn all I can in the process. Thanks again !
     
  8. OI Photography

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    Ok, it sounds like you do have a parallel cable, which is what you need. It will work with only one of the two batteries connected, you can test it that way to verify ;)

    You can (and should) still use the assistant software without updating the firmware of the Phantom...but it will force you to update the Assistant software itself before proceeding. It'll also prompt you to upgrade the Firmware, but you can click past that and use the Assistant software anyway. However...if the firmware on your Phantom isn't 4.02 I'd recommend going ahead and upgrading to it. But even if you don't, the Assistant software is what you may need to use to address issues like the one you're having trying to use dual batteries.

    The software will let you look at the voltage settings we've mentioned, which is the first step in trying to figure out why your batteries seem to have too much remaining charge on them when the Phantom is thinking it needs to land. My guess is that your voltage load with that much weight is higher than the stock settings and those will need to be adjusted.

    If you need visual assistance, there's tons of videos on youtube, just search for "Adjusting voltage settings in NAZA v2"
     
  9. Sokol

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    Thanks again but here's the problem about the assistant software...it will not let me do anything until I update the firmware ! I have tried everything to get past that and it won't let me..it recognizes the Phantom but will not let me cycle the controls or any other function. If I could use the assistant without updating the firmware, I'd be a happy camper but it won't let me! Any ideas?? By the way , I didn't get this thing til after Xmas, so I would have thought that it would have the latest...any way to tell without the computer?
     
  10. OI Photography

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    I admit it's been a while since I updated mine, but I could swear I was able to see/adjust settings before updating the firmware. It did force me to update the software first, but that's a different thing than the firmware.

    To be honest, I'd just go ahead and do the upgrade. It'll let you have access to the settings you need (and if you didn't need them now, you probably would at some point in the future), and I believe 4.02 (the latest for version 1 Phantoms) is as stable and safe as any...no version seems to be immune to the worst type of failure, a total flyaway. I've used it for a few months with no issues, and many can say the same.

    If you ever want to add groundstation capability in the future, which will allow you to use a PC or iPad to pre-program an automated flight path for the Phantom, you'll need that newer firmware anyway.
     
  11. ElGuano

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    Updating the software on a Phantom is pretty easy, you shouldn't fear taking the plunge on that one. But if you really don't want to update your firmware, all you need to do is find and download the older version of the assistant that goes with your particular firmware--that will prompt you to update, but won't force it. You'll probably have to google the download file, but it's out there on the webz.
     
  12. Sokol

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    Well, today has been the Phantom day from hell. I couldn't sleep last night thinking about this problem and got up at 0430 and started fooling with it, trying to figure out how to change the battery limits. The assistant software absolutely would not let me access the aircraft unless I did the firmware upgrade, so I thought, to hell with it, I'll give it a a shot.....what's the worst that can happen? Well, I found out ! The download seemed to go okay, I changed the limits on the batteries and took it out for a trial. Takeoff normal, hover normal but when I backed it up a bit, it just kept going and before I could react it was heading toward the neighbors garage so I got it on the ground where it flipped over and mowed the grass. I picked it up, recycled everything and tried again with the same result. Third time I just let it hover and it was drifting all over the place. Thinking that I had somehow turned on the IOC, screwed up the IMU or messed up the compass I went back in and tried to recalibrate everything. Long story short, I couldn't do anything...the controllers wouldn't cycle, the IMU wouldn't calibrate and kept getting a message the there was an error of disparity in the controller setting and I needed to recalibrate the transmitter. After fooling with it for half a day, I finally got through to DJI support who talked me through getting everything reset. While I had him, I went through all the values and everything was, in his words, excellent. When I went outside, I calibrated the compass successfully, and lo and behold, it wouldn't start...nothing. Back inside, go through everything again, and after several more tries, and transmitter calibrations, I got it to start. Back out side, normal startup and same thing, give it a little forward or back and away it goes. That's where it stands right now...I had a perfectly performing Phantom, did what I was advised and now I have a Phantom that I can hardly control. I sure wish that I had followed my first instinct and left it alone but it's too late now. Sorry to be so wordy but I had to describe what happened. Any ideas, comments or suggestions?
     
  13. OI Photography

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    1. It sounds like the transmitter setting had to be changed to "D-bus" after the update of the firmware, and I absolutely take credit for not warning you about that ahead of time, I should have thought of that. Same goes for applying the default Phantom settings after the upgrade, which is what I'm guessing the DJI support person (you really got through..? and they didn't refer you to a dealer..?) walked you through.

    2. Now it sounds like the Phantom might not be in the right mode (GPS vs Atti or manual), but that's only one possibility. Do you have the ability to take screenshots of your current settings in the NAZA Assistant software while the Phantom is connected (and the transmitter powered on)? That will help us check a number of things to try to find the source of why it's not holding position like it should. Also details on what lights you noticed on the LED on the back when it was misbehaving that way.

    I feel confident there's just a setting out of place somewhere, I've never heard of the firmware upgrade directly causing what you're experiencing.
     
  14. Sokol

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    Actually, you hit the nail on the head with one of the problems. When I finally got through to DJI( 27 minute wait)he started walking me through everything and the first thing he asked me what the controller type showed and it was PPM so we set that back to DBUS and then proceeded to go through getting the sticks calibrated, IMU recalibration and so on. He told me , after I asked him to let me go trough all the relevant values, that everything was in an excellent range and that I was good to go after a compass recalibration. That's when it wouldn't start. By the way, they are on a 10 minute limit per call so you have to have your ducks in a row when you call. I can take shots if the settings but I don't know how to upload them to the forum...I'm sorta technologically challenged. Would it be possible for me to call you. If so PM me a number..if not, I'll take some pictures and try to figure out how to get them uploaded. Which values would be important for you to see?
     
  15. Sokol

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  16. TechJunkieRC

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    Not sure if you did this after the update but somewhere I read to upload the Phantom Default Configuration Parameters from DJI's website back into the Phantom after the update. You might have already done this, just thought I would throw it out there. After the update and after uploading the parameter file into the Phantom I remember having to do a compass calibration. Somewhere I read or watched a video which suggested doing an advanced IMU calibration after updates. I figured what could it hurt and did that as well as ensured that transmitter was D-BUS and that it was calibrated.

    You have probably done all of this already, just thought I would put the path I took out there. I am no expert, whether by design or by accident this process worked fine on my Phantom.
     
  17. Sokol

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  18. Sokol

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    I did everything the tech support guy told me and he said I was good to go. I did all the things you said, per the tech advisor, and he thought it was fixed but it wasn't. He said all the values and settings are where they should be...but it still won't fly right after I finally got the engines to start.
     
  19. Sokol

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  20. ElGuano

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    This isn't your main problem, but those low voltage alarms are extremely low. You're running past the ragged edge. To start out, set your level 2 alarm at 10.6 or so; you can always lower it later if you want.