Battery failsafe: RTL vs Land

It appears hitting the battery failsafe will initiate LAND rather than RTL.  Is there any way to make it RTL instead?  I realize landing is better than falling out of the sky.  But not if it landing on Grumpy Aunt Bertha out for her morning walk.  I set my battery threshold essentially as bingo fuel.  Always enough left to come back for a normal landing based on where I'm flying.  If I'm not paying attention failsafe initiates, I don't want it to land itself in my lake. I want it to come home.

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  • Thanks for the input Pedals2Paddles. I don't know what I'm doing wrong then, I have it set in the full parameter menu list, as well as elsewhere that I found it, and it just lands, always. Not such a big problem, but I would rather it have worked as I'd hoped. I just nipped out and tried again. See settings below, copied from full parameter list, and sadly, once again it just landed. Note high 3S cut off voltage is due to wanting a very early reaction whilst purely under test.

    FS_BATT_ENABLE 2 0:Disabled 1:Land 2:RTL Controls whether failsafe will be invoked when battery voltage or current runs low
    FS_BATT_MAH 0 mAh Battery capacity remaining to trigger failsafe. Set to 0 to disable battery remaining failsafe. If the battery remaining drops below this level then the copter will RTL
    FS_BATT_VOLTAGE 11.8 Volts Battery voltage to trigger failsafe. Set to 0 to disable battery voltage failsafe. If the battery voltage drops below this voltage then the copter will RTL
    FS_BATT_ENABLE 2 0:Disabled 1:Land 2:RTL Controls whether failsafe will be invoked when battery voltage or current runs low
    FS_BATT_MAH 0 mAh Battery capacity remaining to trigger failsafe. Set to 0 to disable battery remaining failsafe. If the battery remaining drops below this level then the copter will RTL
    FS_BATT_VOLTAGE 11.8 Volts Battery voltage to trigger failsafe. Set to 0 to disable battery voltage failsafe. If the battery voltage drops below this voltage then the copter will RTL

    Sorry about the text alignment and formatting, I didn't know how esle to put it in here.

    Regards

    Sutty

  • The wiki is incorrect (still).  You can set the battery failsafe to RTL in the full parameter list.  It works lovely.  I have mine go into failsafe with about 4 minutes of flying time left, or about 25%.  I also have a LiPo beeper on the batteries that will start beeping around the same time.  Plus I have Mission Planner blabbing away about it  I always try to make a point of landing or being in the area to land with that kinds of battery life left anyway.  At which point I either let it land itself, or I takeover and enjoy the last few minutes and land myself.

    • With a single 5000mah 4S battery, I try to be on final approach around 13-14 minutes.  With (2) 5000mah batteries in parallel, more like 18-29 minutes.  But I find it flies better with a single battery (weight) so that's usually what I do.

      • That is really good flight times.   What equipment do you have.   I had the gimbal, Gopro, and extended legs but could not get good times.  The worst part was how fast the power would drop when it approached the time to land.  It seems as if you have things working well.  

    • I like the caution you use. nothing worse than trying to find your equipment that may be successful or not if the power goes too low before it is insight. may I ask what flight times you are getting for a usable mission away from your landing spot before your 4 minute saftey window. and what equipment are you flying with.
  • Hi Guys

    Brand new member, and interested in this debate with regard to RTL vs Land. Like Pedals2Paddles I too have been trying to configure my controller to default to RTL on low battery failsafe. I was curious to see the harsh reaction of some to this request, but that's by the by, I have what I believe are logical reasons for wanting the behaviour to be RTL and not Land.

    I have and will be flying FPV, under goggles, on my own land, and for the majority of the time within LOS. So far I have no interest in autonomous flight, as to me, at the moment, it is all about learning to fly FPV. I am flying close to the ground, or over small trees, as this seems to give me the most thrill of motion and flight. If I make a mistake with my radio timer, or have a battery issue, by far the best course of action for my craft would be for it to climb to the RTL altitude, and begin the return journey. During this time I would then take over, by toggling the flight mode switch, and doing a very fast manual return to base. The only time I am actually likely not to be LOS is if I enabled battery fail safe, with the default Land behaviour, and it went down behind a tree, so this is not the behaviour I desire.

    If, as it stands, the default behaviour for all modes, other than Auto, is Land, then I could be over a pond, a stream, a tree, a big bush, or similar unsuitable landing area, and Land may not give me time to overule it before it actually does land, or more likely crashes.

    My plan for setting it up was to add to safety, not reduce it, and RTL, in my opinion would have done that. Sure, I shouldn't make a mistake. Sure if all my batteries are in tip top condition then I should have no need, and yes, Land is better than a plummet, but RTL would be better for me, in my opinion.

    As soon as the autonomous climb began, I would remove my goggles, aquire the craft visually, toggle flight modes, and then either land it safely, where it stands, or fly it back really quickly.

    As mentioned by Pedals2Paddles the wiki says this cannot be done, and my tests would confirm this as every time it simply lands even though the parameter settings appear to have been done correctly, by choosing the RTL option. If you're still checking this thread Peddals2Paddles could you let me know if you mean it worked for you in autonomous mode, or if you somehow got it to work in the other modes too.

    Here is a quick snippet from the wiki that suggests that it cannot be done.

    Battery Failsafe

    • If enabled and set-up correctly the battery failsafe will trigger if:
      • your battery voltage becomes low for more than 10 seconds
      • your estimated current consumed passes your battery capacity (set on the power module set-up page)
    • When a battery failsafe is triggered one of the following will happen:
      • Disarm motors – if you are in stabilize or acro mode and your throttle is zero
      • RTL – if you are in AUTO mode, have a GPS lock and are at least 2 meters from your home position
      • LAND – in all other cases

    Thanks for any and all thoughts.

    Best regards

    Sutty

  • Despite the abuse you suffered in this thread, I too have had the same issue several times.  The configuration is correct, the threshold for triggering the RTL is 10.7 and yet this bird land hard and fast with no warning.  The latest case MAY have been traced to a bad battery as it is now bloated and needs to be replaced.  The other times, it was not the battery - no warning and it just lands wherever it is which is NOT good. 

  • New to this lingo, what does RTL stand for.

  • As a follow up, I found what appears to be a bug or oversight in Mission Planner on this matter.  if you're in the failsafe settings screen, there is no option to select LAND vs RTL for the battery failsafe.  The wiki page states that it will just LAND, and that it will only RTL if already in Auto mode.

    However, if you go to the full parameter list and look at the battery failsafe parameter, there is an option for OFF, LAND, and RTL!  So, it can do exactly what I want.  I set it for RTL and tested it.  It did indeed initiate an RTL when either the MAH setting or voltage setting was exceeded.

    • I would say the battery failsafe RTL when in Auto is not always the best solution. If you are in auto and pretty far from home location, a try to RTL (with a low battery) will fail.

      Maybe is better the system to compute the time/resource to go to destination. If enough battery, then RTL, if not, Land.

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