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Newbie question on Low battery RTH feature

Discussion in 'Phantom 2 Help' started by dlambfra, Aug 25, 2015.

  1. dlambfra

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    Hello! I recently became the (proud - and somewhat poorer) owner of a DJI Phantom 2, just starting to get to grips with it :)

    I have a short question regarding the low battery/RTH feature. I did a quick search on the web, but didn't find a direct response to the question, although I imagine that I'm not the first person to ask it by any means, so my apologies for no doubt repeating an oft-posed question.
    Basically I assumed (wrongly, it would appear) that when the Phantom reached low battery level, then critical low battery, at some point it would automatically land or return to home, depending on how it's configured (a check box in the Assistant software for the latter if I understand correctly). So yesterday I kept my Phantom flying, through the red flashing Low battery warning, and then the faster flashing 'Critically low' warning, expecting the Phantom to land of its own accord at some point (like I said, I'm a newbie). I did however take the precaution of flying it only a couple of feet above the ground at this stage. So the battery finally emptied completely and the Phantom dropped dead to the ground (with a disturbing bump - thankfully it was on pretty soft grassy ground). So the lesson I learned from this is that as long as you don't relinquish control on the remote during the low battery phases it'll keep flying (albeit a bit less energetically), thus overrding any auto-land/RTH procedure, it's only when you release the sticks that it'll land or RTH automatically?

    I'd really like to know if I'm missing a configuration parameter somewhere, or if normal operation is that use of the RC does indeed override any auto 'low battery' mechanisms and you have to 'relinquish control' for them to kick in!
     
  2. kenjancef

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    I'm sorta new too, and I haven't had the chance (thankfully) to test this feature, but one question: how far away were you from your starting point? I would think that if you were within 5-10 feet or so then it would think it's back where it started. If you're in a big field, I would have it take off from a far corner, then fly it to the longest end, then let it hover from there. Then see if it goes back.

    I'm sure the awesome folk here can chime in to see if I'm right, or wrong... :)
     
  3. jason

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    The first low battery warning is set at 30% and the second is at 15% at which point it will automatically land where it is at the time which could several hundred yards away. While RTH works like the failsafe position on switch S!. The problem I have with RTH is that when it gets to the critical low battery it will ascend quickly to the same altitude as failsafe and the craft may be under some trees. Guess what happens next!! You do have the option to turn off RTH and it's best to do so. Now If you have FPV with mini iOSD on board then you know when your close to the first warning and that it's time to return other wise be prepared to do some walking when it reaches the second warning.
     
  4. dlambfra

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    Thanks for the responses. When I tested it out, the Phantom was indeed very close - and maybe even at (or at least slightly above) - its start point. Although only a couple of feet off the ground, since I wasn't sure what would happen!
    When you say - 'it will automatically land', that's what I thought, but that didn't happen - as long as I kept moving the sticks it stayed airborne, and when the battery died it simply dropped to the ground. Perhaps this behaviour was because it was so close to the ground and to the start point? I really thought that at some stage I could do what I liked with the sticks, but the Phantom would no longer respond to the controls and land by itself. I think I had the 'RTH' feature activated also, and at no point did it ascend to the 20m default height to then return home. So I'm still a little perplexed - is this normal, or am I missing something configuration-wise?

    I take the point regarding turning RTH off, but so far I've only flown in open spaces, and in fact when I did my little test I was beside a small lake, so I certainly wouldn't have liked the Phantom to simply land when the battery was flat - although rest assured, I wasn't daft enough to do my little test over the water! Duh!

    I don't have any FPV gear or iOSD, so am flying in line of sight. I've yet to really test the RTH feature, although I've programmed the S1 switch for it. How far away from the home point does the Phantom have to be for it to work? I believe that if you're within a certain distance of your start point flicking the switch doesn't do anything.

    Please excuse these (very) newbie questions, I've only done two 20-minute flights so far (very tentatively, given that I wasn't 100% sure the failsafe/RTH mechanisms were correctly configured), so have a lot to learn!
     
  5. jason

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    First of all sit down and reread the users manual. The reason it fell to the ground because you simply refused to let it autoland until it didn't have enough voltage to sustain flight. DJI's minimum failsafe setting is is 20m (60 feet) But mature forest can be much higher then that I set mine 36m (118 feet). Here is what happens when failsafe triggered the quad will begin to turn and face the home point as it ascends to the set altitude then fly toward the home point it will hover over the HP for a few seconds then descend land and shut down. So if you have failsafe set in the software fly out in open field about 100 feet or so and put switch S1 to the bottom position and watch what it does and you can take back control at any time by moving the switch back to the top in GPS it will stop and hover.All of this information is in the manual so take the time to read it.
     
  6. evman

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    Well yesterday I had my Failsafe low voltage option unticked (in NAZA mode). The battery went into low voltage warning (red LEDs flashing) while I was a hovering few feet from the ground and me (i was just waiting to for the battery to drain to the final led), and it decided to do a return to home on me. I checked the setting after just be sure. So I don't know if it can be trusted.

    Now, the battery I was using was an aftermarket one, and it seemed to drop very quickly, so it's possible there was there was another issue, maybe a battery error. But my point is, remember RTH can still be activated unexpectedly, so beware of trees even if you have the low voltage option off.
     
  7. dlambfra

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    Thanks for the responses. In fact I did read the manual quite thoroughly, and think I understand the RTH feature, although as I said I haven't tested it yet. When you flick the S1 switch to Failsafe mode, that is a clear user intervention asking the Phantom to go home.

    The grey area for me - and what I can't find any clear information on - is the behaviour of the Phantom in Low battery mode. From what I've seen, if you do not relinquish control of the Phantom during this phase it will simply keep flying until the battery dies, neither returning to home nor landing (depending on what you've configured it to do). I assumed that at some point you would no longer have any choice in the matter, and that the auto-land/RTH feature would kick in regardless of what you do with the RC, but in my test this wasn't the case.

    So that's what my question is - I understand the behaviour when you voluntarily initiate RTH mode with the S1 switch, but once in Low Battery mode, regardless of whether it's configured just to land where it is or RTH in this state, unless you relinquish control and stop moving the control sticks you can 'fly until you drop' and no override to land kicks in. Is this the case?
     
  8. Discoverydave

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    This is what should happen when your battery goes critical. Thought I had enough batery left for a quick flight and video. Nope wrong! Look at where it headed! Lesson Learned
     
  9. dlambfra

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    Hmm.. but in the description you say 'No controls worked', and that's just the thing - in my case the controls DID keep working until I'd exhausted the battery. That's what I don't get :-(
     
  10. jason

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    Seems you know more then some who has more experience then yourself so you'll just have to learn the hard way..
     
  11. Discoverydave

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    I would recheck all settings in Naza mode and make sure your failsafe modes are on. As a newbie myself, I foolisly thought I had enough battery for a quick flight (35%) but did not realize that the battery drops quickly. Mine did what it was supposed to do. I had no control whatsoever.
    Hope you solve the problem.
     
  12. dlambfra

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    Sheesh, I hope that my post didn't come over as me trying to be some kind of smart-***, which was certainly not my intention. With only two flights so far - to be honest I'm a little scared of my Phantom right now! - I was indeed hoping to find people with more experience than me (which equals just about everyone at this stage) and who have perhaps been through the same learning curve. The reason I'm a little scared of my Phantom at the moment is because I'm not 100% sure of the features I can use that might save my *** (or rather its ***) in the event of a problem. I understand the theory of RTH/Failsafe by itself - but as I say haven't had the time to test it yet - but the nuances of what happens in a Low battery state escape me so far, as my perhaps my misguided test and 'drop from the sky' prove :-(
     
  13. dlambfra

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    I've been using mine in Phantom 2 mode so far, do I need to switch to Naza mode to check those settings too? Thanks :)
     
  14. jason

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    Look when you battery gets to 30% the LED's turn to red and flash slow but when the battery hits 15% the LED's flash faster and it will begin to land where ever it is. Now if the P2 is close to you and it is descending to fast give some up throttle to slow the decent so it land softly. Just do not hold the throttle up until it runs below 10.65 volts because you've already done that and it will fall. Now if you had a gimbal and camera on board it could cost between $290-$800 depending on the equipment attached from a fall because you lacked the knowledge in how it works.
     
    TeamYankee likes this.
  15. Discoverydave

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    I would switch to Naza and do the checks there. Have you downloaded the Naza m Assistant and the Phantom Assistant software? Here is a link dji . Also search google for setup Naza m lots of videos out there. The only functions I changed was checking the box IOC and the failsafe modes.
     
  16. dlambfra

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    I'll have a look at the settings in Naza mode then, up until now I thought that you could fly the Phantom in two modes - Phantom mode and Naza mode, and that Naza was reserved for experienced users. Therefore in Phantom mode it was only settings in this mode that 'counted'. Having read the overview page at DJI on Naza-M - which seems to consist of several pieces of additional hardware that I don't have - I guess some of the 'basic' Naza features are available in the Phantom 2 even without the additional modules? So then switching to Naza mode simply provides finer control over the Phantom's features than Phantom mode does?
    Sorry if this is all no-brainer stuff to some...

    Anyway, many thanks for the tips, I'll have a look at my settings and do some more reading on this feature on the web, and post back when I've had a chance to test the results :)
     
    #16 dlambfra, Aug 27, 2015
    Last edited: Aug 27, 2015
  17. TeamYankee

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    Take a look at this.. it explains the two modes:
    One thing to Note: On the switch settings - DO NOT USE MANUAL MODE - there, it's been said!

     
  18. dlambfra

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    Great video, very informative, clears up a lot of the queries I had, so thanks a lot for that! :)

    Won't have the opportunity to look at settings or fly over the next few days, but will definitely post back when I've had the time to delve a bit deeper, so thanks again.
     
  19. SteveMann

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    RTH won't do anything if you are within 10 meters of your home point.
     
  20. jason

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    That is an incorrect statement Steve. If you were in IOC's home lock then RTH would not work until the craft was beyond 10 meters. Phantom-Intelligent Orientation Control (IOC) Flight - DJI Wiki

    In the OP's case he was in Phantom mode and the failsafe/RTH will work at 10 meters or less. Here's a video to make my point.


     
    #20 jason, Aug 28, 2015
    Last edited: Aug 28, 2015