Thoughts? crash and critically low power @ 38%

ByronH · May 14, 2016

Thoughts on the following?

At 9 minutes 37 seconds I received a critically low power warning and aircraft landing warning.
Battery percentage was 38%.
Did not receive a Low Battery Warning (RTH) prior to this.

In 22 seconds following warning:
- Inspire dropped approx 160 feet
- Battery only dropped from 38% to 35%
- Motors were UP 20-36% the entire time
Background Info:

DJI Inspire V1.0
Firmware: 1.08.01
Battery: TB47 with 5-10 charges
Fully charged TB47 battery taken off charger 1 hour prior to flight
Outside temperature approx 40 degrees F. Wind was minimal.
Compass calibrated prior to flight. Strong signals.
Low Battery Warning set at 30%, Critical Battery Warning at 11%.
Battery kept warm until flight time and was at 100% charge.
Throughout the flight I monitored the battery status/temp. All systems appeared normal.

Anyone have this experience and had DJI not warranty? Any advice on how to go about dealing with DJI?

The Editor · May 14, 2016

ByronH said:
Thoughts on the following?

At 9 minutes 37 seconds I received a critically low power warning and aircraft landing warning.
Battery percentage was 38%.
Did not receive a Low Battery Warning (RTH) prior to this.

In 22 seconds following warning:
- Inspire dropped approx 160 feet
- Battery only dropped from 38% to 35%
- Motors were UP 20-36% the entire time
Background Info:

DJI Inspire V1.0

Firmware: 1.08.01

Battery: TB47 with 5-10 charges

Fully charged TB47 battery taken off charger 1 hour prior to flight

Outside temperature approx 40 degrees F. Wind was minimal.

Compass calibrated prior to flight. Strong signals.

Low Battery Warning set at 30%, Critical Battery Warning at 11%.

Battery kept warm until flight time and was at 100% charge.

Throughout the flight I monitored the battery status/temp. All systems appeared normal.

Anyone have this experience and had DJI not warranty? Any advice on how to go about dealing with DJI?

Any idea what your lowest cell voltage was when this occured?

ByronH · May 14, 2016

Is there a way to find that info without downloading it from the inspire via USB

IrishSights · May 15, 2016

Did you fully recalibrate your battery (down to 3.3v) after the last firmware update? This similar to what it would look like if you didn't. You didn't mention this in your background info.

Flying Monkey · May 21, 2016

ByronH said:
Thoughts on the following?

At 9 minutes 37 seconds I received a critically low power warning and aircraft landing warning.
Battery percentage was 38%.
Did not receive a Low Battery Warning (RTH) prior to this.

In 22 seconds following warning:
- Inspire dropped approx 160 feet
- Battery only dropped from 38% to 35%
- Motors were UP 20-36% the entire time
Background Info:

DJI Inspire V1.0

Firmware: 1.08.01

Battery: TB47 with 5-10 charges

Fully charged TB47 battery taken off charger 1 hour prior to flight

Outside temperature approx 40 degrees F. Wind was minimal.

Compass calibrated prior to flight. Strong signals.

Low Battery Warning set at 30%, Critical Battery Warning at 11%.

Battery kept warm until flight time and was at 100% charge.

Throughout the flight I monitored the battery status/temp. All systems appeared normal.

Anyone have this experience and had DJI not warranty? Any advice on how to go about dealing with DJI?

Unfortunately you have no recourse with DJI. I too have an inspire 1 and the prop lock failed. The props were the 1345 s quick release prop. Problem is that the plastic lock would break in half with the break running from one screw to the spindle Andover to the second screw splitting the lock in half. DJI was aware of the issue and introduced the 1345 t prop and lock assembly. Unfortunately they sent out no warnings or recalls for the 1345 s. I actually have to inspire ones with those props on them and the first one crashed and we did not know why I put out $800 in repairs. Then the same thing happened to our second Inspire 1 this time in front of a crowd. I sent it in to DJI and they sent me a repair bill for $2,000. I wholeheartedly plan to notify the FAA about DJI selling an unsafe uas knowing about the prop lock problem. So good luck. I am getting both units back from DJI in Los Angeles and we'll let the lawyers deal with their unsavory business practices

Bryan Conover · May 21, 2016

IrishSights said:
Did you fully recalibrate your battery (down to 3.3v) after the last firmware update? This similar to what it would look like if you didn't. You didn't mention this in your background info.

Where does it state you need to recalibrate (drain) the battery after each firmware update?...if that's the case we'd be draining every 20 flights and every time DJI drops a firmware update. Who has the time for this with 6 batteries.

The Editor · May 21, 2016

Bryan Conover said:
Where does it state you need to recalibrate (drain) the battery after each firmware update?...if that's the case we'd be draining every 20 flights and every time DJI drops a firmware update. Who has the time for this with 6 batteries.

Because any firmware update that involves a battery update can have different algorithms written into it meaning that any 'fuel guage' indication may well be inaccurate until you recalibrate the packs on the new firmware.
However, if you have 'no time' for that then that's fine, it's your Inspire.........

The Editor · May 21, 2016

ByronH said:
Is there a way to find that info without downloading it from the inspire via USB

I'm afraid not but you should be monitoring your pack voltage during flight no? As soon as anything strange happened with pack levels the first thing you should be aware of is your lowest cell voltage.
Mine is checked regularly during the course of every flight.

BudWalker · May 21, 2016

ByronH said:
Is there a way to find that info without downloading it from the inspire via USB

If you want to know about battery info go here. You'll need to get the .txt of of your tablet and upload it to that site. You can find the instructions on how to retrieve the .txt at that site.

IrishSights · May 21, 2016

Bryan Conover said:
Where does it state you need to recalibrate (drain) the battery after each firmware update?...if that's the case we'd be draining every 20 flights and every time DJI drops a firmware update. Who has the time for this with 6 batteries.

Like the @The Editor said after every battery firmware update I recalibrate down to 3.3v. I have tested it and the 1.8 firmware showed big discrepancies between % and voltage. It was easily noticeable as I watch both values before and during flight. Misbehaving batteries due to lack of care and observance to displayed value discrepancies is a sure point of failure at some point.

Checklists rule!

Bryan Conover · May 22, 2016

I'm dumping my Inspire soon anyways...tired of wondering when it will fall out of the sky. I'll be lucky if I get $1000 as the values have cratered.

offshorecl1 · May 22, 2016

Bryan Conover said:
I'm dumping my Inspire soon anyways...tired of wondering when it will fall out of the sky. I'll be lucky if I get $1000 as the values have cratered.

Maybe you're right? I will never update new FW, and stay now on FW 1.3

Larr2000 · Sep 3, 2016

ByronH said:
Thoughts on the following?

At 9 minutes 37 seconds I received a critically low power warning and aircraft landing warning.
Battery percentage was 38%.
Did not receive a Low Battery Warning (RTH) prior to this.

In 22 seconds following warning:
- Inspire dropped approx 160 feet
- Battery only dropped from 38% to 35%
- Motors were UP 20-36% the entire time
Background Info:

DJI Inspire V1.0

Firmware: 1.08.01

Battery: TB47 with 5-10 charges

Fully charged TB47 battery taken off charger 1 hour prior to flight

Outside temperature approx 40 degrees F. Wind was minimal.

Compass calibrated prior to flight. Strong signals.

Low Battery Warning set at 30%, Critical Battery Warning at 11%.

Battery kept warm until flight time and was at 100% charge.

Throughout the flight I monitored the battery status/temp. All systems appeared normal.

Anyone have this experience and had DJI not warranty? Any advice on how to go about dealing with DJI?

Hi Byron,
I did have a Critical Battery Low issue but slightly different than yours.
Here is the backstory:
While practicing “follow me mode”, I received “battery low warning” with 30% battery left and immediately switched to manual mode. Descended the aircraft to a hover 18” above ground level with landing gear down. While lowering for the final landing I got the “critical low battery” announcement and the aircraft rapidly rose (and crashed) even with the controller stick attempting to land.

tech support (Oscar) confirmed that the DJI go app is programmed to “go home” in the event of any low battery message.

recommendation: please add an option to “hover” in the event of any critical battery low condition and give the pilot the opportunity to recover the aircraft.

DJI Inspire V1.0
Firmware: AC 1.9.1.30 / RC 1.6.0 / APP 2.8.4 / Camera 1.8.00 - 18 July 2016
Battery: TB47 with 10-15 charges
Fully charged TB47 battery taken off charger 1 day prior to flight
Outside temperature ~ 40 degrees F. Wind was minimal.
Compass calibrated prior to flight. Strong signals.
Low Battery Warning set at 30%, Critical Battery Warning at 11%.
- DJI Inspire V1.0
- Firmware: 1.08.01
- Battery: TB47 with 5-10 charges
- Fully charged TB47 battery taken off charger 1 hour prior to flight
- Outside temperature approx 40 degrees F. Wind was minimal.
- Compass calibrated prior to flight. Strong signals.
- Low Battery Warning set at 30%, Critical Battery Warning at 11%.

I was fortunate that the aircraft rose only several feet into a low branch, so my damages were low, by comparison (any Inspire crash = $1K).

Have you had any encounters with Critical Low Battery over-riding manual mode when attempting a landing?
Any feedback would be helpful. Thanks