FailSafe mode at 25% battery

I am currently using the Iris with a GoPro on the front. This is roughly my 5th flight and every time the battery gets to 25% it starts a failsafe mode and beeps. One flight it landing on its own, another flight I landed it while still having control. Today, I had control and attempted to land, but then I didn’t have control as it was attempting to land. From a few feet up it dropped to the ground and I attempted to shut down by holding left stick to the left, but it didn’t initiate the shut down and the props kept spinning into the ground.

I inserted a new battery and took my second flight. The second flight with over 50% battery somehow initiated a different ‘failsafe’ mode and started to beep. I luckily landing but it had the same issue with turning off. I’ve attached the Tlog. I had the DronePlanner2 with me on my Nexus 7 to monitor the flight.

Also, I would really love to disable this feature of automatically landing at 25% and going into this failsafe mode. I monitor my battery with the DronePlanner and would love to turn this off. Does anyone know how?

You can configure all of this… … failsafes/

There’s also a throttle failsafe, and may be more. I’m still learning myself…

Can you tell which failsafe was trigger on my second battery from the logs? The first one was from the battery, but the second battery I used had over 50% when it went into failsafe.

In both cases your failsafe was triggered by a low battery. The low battery failsafe is not based on battery percentage, but kicks in when the voltage is below 10.5V for more than 10secs. The voltage level itself can be configured, but I strongly recommend against decreasing it.

You might even want to increase it! Here is why:
When looking at the voltage of the batteries for your two flights, the voltage drops extremely fast once below 10.5.

In your case the voltage drops even down to 7 - 7.5V. That’s below 3V per cell or 9V for the pack. You are basically in a range where you might have permanently damaged the pack.
See here: for more.

Were you using the stock 3DR batteries?
There are other folks complaining about the poor performance of the 3DR batteries:

Especially the really fast dropping of the voltage once you hit 10.5V is a problem that is described in the other post.

For the second flight, it looks like you started flying with an half-empty pack. That’s why the battery percentage displayed was telling you garbage.

Well it’s yours to disable, but I fully agree with Kanga, I would push that up to 10.7 so that there’s enough time to land under control, otherwise you run the risk of destroying the iris when the motor cuts out.
Apparently the stock battery’s can be somewhat unpredictable, you definitely run the risk of the IRIS dropping like a rock once you discharge past 10.5 v.

You do not want to fully discharge a lipoy battery, you will likely destroy the battery and from what I’ve read fully discharging it increases the likelyhood of it exploding and catching fire.

First, thank you for the replies. This information has been very beneficial.

I’m using the stock 3DRobotics batteries, but I have read a few posts of issues with the batteries. My second battery doesn’t charge and only shows ‘discharging’ when I plug it in. So that was why it was only at 50% when I flew (the second flight). I will not use this battery until I get an answer from 3DRobotics, which they are working with me on it now.

My last question, on my first flight with what I believe to be my good battery, it went into fail safe mode because the battery hit 25%, but why did I have the issue with turning the Iris off? When it landed it dropped from a foot or two up and then disarming did not work for at least 15-30 seconds.

Also, Kangajump mentioned it does not initiate fail safe mode because of battery percentage, but so far every time DroidPlanner2 says I get to 25% it initiates. Can I monitor battery voltage in DroidPlanner?

Once again, thanks for checking out my logs and giving me some dialogue. I look forward to adding to the community as well.