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Critically Low Power @ 57% remaining
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Central Maine D
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Took my Phantom 3 Pro up today.  Started out with battery at 68%.  Climbed to 165 feet without using forward motion.  Proceeded to fly North, forward throttle @73%, vertical @61% trying to climb while moving forward.  Received warning "Motor overloaded.  Aircraft will decelerate to ensure safety".  Reduced rate of climb to 68% forward throttle at 40%.  Altitide was 324 feet, distance 1261 feet.  Warning displayed "Critically Low Power.  Aircraft Landing. Throttle up to reduce the speed of descent and use sticks to avoid obstacles".  Battery was at 57%.   Was able to fly aircraft to side of road where it landed, nothing broken.   This was my third flight since it came back from DJI for repairs.  Two prior flights were 1845 feet using Ground Station Pro duration 7 minutes then DJI Go for a 10132 foot flight which lasted 10 minutes.  

I don't understand how I can get a Critically Low Power warning when the battery is at 57%, the "aircraft battery" settings are 10% for Critical.  



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2017-3-6
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Mark The Droner
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The problem is in your second sentence.  
2017-3-6
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Daroga
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Mark is referring to "Motor overloaded.  Aircraft will decelerate to ensure safety".  It wasn't a battery issue but a motor issue. These birds need all four to fly safely. You were losing at least one motor, so it correctly tried to land.

Immediate action should have been to flip the camera to looking straight down and find a place to land....
Sounds like you did that correctly.

Check you motors for debris or did you recently add prop guards or anything that could bind one or more motors?
2017-3-6
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Mark The Droner
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If you look at your AC documentation, it states you must always launch with a fully charged battery.  When you don't do that, weird unexplainable things happen.  
2017-3-6
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RonBurk
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Yep - "Started out with battery at 68%" is likely the reason. I've had this happen twice over a year's time with my P3P, both times I started with a battery less than fully charged. Otherwise the aircraft was (and still is) in perfect working order.
2017-3-6
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WilliamM
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Daroga Posted at 2017-3-6 13:36
Mark is referring to "Motor overloaded.  Aircraft will decelerate to ensure safety".  It wasn't a battery issue but a motor issue. These birds need all four to fly safely. You were losing at least one motor, so it correctly tried to land.

Immediate action should have been to flip the camera to looking straight down and find a place to land....

No, he was referring to the second sentence "Started out with battery at 68%"
2017-3-6
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WilliamM
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"Started out with battery at 68%" Starting to fly with less than fully charged (at least in the 90%) batteries can cause this. The manual does state to fully charge battery before flight. If it's cold outside this issue will be even more an issue.
2017-3-6
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Daroga
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WilliamM Posted at 2017-3-6 17:47
No, he was referring to the second sentence "Started out with battery at 68%"

Sorry Mark and thanks William! You are of course correct.

DJI changed the P3 power profile so that low voltage battery sags would not cause the P3 to shutdown in flight. Instead, they reduce power consumption and alert the pilot as Central Maine D observed....

Out of habit, all my flights are with 100% charged batteries. Thanks for setting things straight!
2017-3-6
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blackcrusader
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RonBurk Posted at 2017-3-6 17:11
Yep - "Started out with battery at 68%" is likely the reason. I've had this happen twice over a year's time with my P3P, both times I started with a battery less than fully charged. Otherwise the aircraft was (and still is) in perfect working order.

The warning is because of the distance and height your software will advise you that you need to return home.  It also calculates to your low battery setting.

So it's a  system designed to prevent people flying beyond their batteries flight capability.

Here is my flight record, I am 9,922ft from home point and get a low battery warning at 52%
Now I had been meandering around and also into a headwind of 15 - 19mph.  I went into RTH but gave my drone full throttle.  I went into the equivalent of warp drive in RTH mode... 42mph with the tail wind. I got back to my home point with 35% battery remaining so did some more flying around my home point.  Totally mileage just under 25,000ft.   

10m 4.9s        Go Home        11satellites        1,104.7ft        0mph        9,921.7ft        52%        14.751V        3.681V        3.691V        3.697V        3.682V        0.016V        Returning Home

http://www.phantomhelp.com/LogViewer/46YA1Z6WZHS00OQNLEFF/

2017-3-6
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Ahmet67
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Charge your batteries before everyflight, dont use them after 2 days of storaging. It auto discharges for safety.
2017-3-7
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DJI Natalia
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Please try to fully-discharge it then charge it again, and check the battery info through APP.
If you always get the notification on the screen, please sync your flight records and provide us your account username (e-mail address), we'll help you check it.
2017-3-7
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Central Maine D
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DJI Natalia Posted at 2017-3-7 01:29
Please try to fully-discharge it then charge it again, and check the battery info through APP.
If you always get the notification on the screen, please sync your flight records and provide us your account username (e-mail address), we'll help you check it.

I completely drained the battery after cleaning the aircraft.  I had it sit on the floor occasionally starting motors, revving them then shutting them down.  Had camera take videos when power below 10%.  Now fully charged but it's raining out.  It will rain for another day so no flying.  
2017-3-7
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Central Maine D
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blackcrusader Posted at 2017-3-6 21:09
The warning is because of the distance and height your software will advise you that you need to return home.  It also calculates to your low battery setting.

So it's a  system designed to prevent people flying beyond their batteries flight capability.

I'm familiar with the system returning to home when it detects conditions, distances and battery life remaining.  I've had flights exceeding 25000 feet in total distance.  When the aircraft got to 15000 feet away (68% battery remaining) it automatically started the return trip home.  It got back with 16% battery remaining.  This occurrence did not invoke the return to home but emergency landing after flying only 1200 feet + 300 feet altitude, a far cry from the 25000 feet I've gone before.  By the way, there was no wind yesterday at ground level (can't say what wind was at 300+ feet).  From the camera view it wasn't being buffeted by wind.  
2017-3-7
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Central Maine D
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WilliamM Posted at 2017-3-6 17:53
"Started out with battery at 68%" Starting to fly with less than fully charged (at least in the 90%) batteries can cause this. The manual does state to fully charge battery before flight. If it's cold outside this issue will be even more an issue.

It was 44 degrees F yesterday, manual says 0 - 44C so I was 12 degrees above minimum temp.  I'm in Maine so 44 degrees seems like summer.  I typically charge my batteries after they've cooled down after flying then put them in the carrying case rotating them so as to not use one battery more than others.  If I don't fly for several days you're saying I have to recharge even if they're at 80 or 70%.  I think that would be detrimental to batteries.  Should I not recharge after flying?  Should I charge, store, then top off before flying?  I've got 6 batteries and three chargers.
2017-3-7
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digdat
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blackcrusader Posted at 2017-3-6 21:09
The warning is because of the distance and height your software will advise you that you need to return home.  It also calculates to your low battery setting.

So it's a  system designed to prevent people flying beyond their batteries flight capability.

The first part of your statement is not correct, that is a feature of "Smart RTH" which invokes return to home, not critically low power resulting in landing.
2017-3-7
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digdat
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Central Maine D Posted at 2017-3-7 13:35
It was 44 degrees F yesterday, manual says 0 - 44C so I was 12 degrees above minimum temp.  I'm in Maine so 44 degrees seems like summer.  I typically charge my batteries after they've cooled down after flying then put them in the carrying case rotating them so as to not use one battery more than others.  If I don't fly for several days you're saying I have to recharge even if they're at 80 or 70%.  I think that would be detrimental to batteries.  Should I not recharge after flying?  Should I charge, store, then top off before flying?  I've got 6 batteries and three chargers.

Always top off before flying. Batteries shouldn't lower by 20% by sitting for a day or three though. Its always wise to top them off before going out.
2017-3-7
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Labroides
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Central Maine D Posted at 2017-3-7 13:27
I'm familiar with the system returning to home when it detects conditions, distances and battery life remaining.  I've had flights exceeding 25000 feet in total distance.  When the aircraft got to 15000 feet away (68% battery remaining) it automatically started the return trip home.  It got back with 16% battery remaining.  This occurrence did not invoke the return to home but emergency landing after flying only 1200 feet + 300 feet altitude, a far cry from the 25000 feet I've gone before.  By the way, there was no wind yesterday at ground level (can't say what wind was at 300+ feet).  From the camera view it wasn't being buffeted by wind.

Because your battery had been sitting and slowly discharging it was not able to deliver the required voltage and although the % indicator showed 57%, you did not have the power you thought.
If you looked at the voltage in your flight record, you would see that it fell to dangerously low levels despite the % indicator.

Check by going to http://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight record.
2017-3-7
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Central Maine D
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Daroga Posted at 2017-3-6 13:36
Mark is referring to "Motor overloaded.  Aircraft will decelerate to ensure safety".  It wasn't a battery issue but a motor issue. These birds need all four to fly safely. You were losing at least one motor, so it correctly tried to land.

Immediate action should have been to flip the camera to looking straight down and find a place to land....

This was the third time flying since the aircraft came back from DJI because of "motor idling, loose or missing propeller", weak GPS signal (showing 17 satellites) and compass error (drone flew 500 feet on it's own until regained control).  DJI replaced the main logic board and 1 motor.   One flight was 10,000 feet, the other around 1000 from what I recall and this one that went 1200 then the emergency landing.  No motor warning message.  Yes I had it going upwards and forward at the same time, 67% forward propulsion, 49% up but I've flown faster while climbing without errors before.   Looking over my flight records I've flown at 100% forward throttle for 5500 feet, 25 miles per hour without any motor warnings.  
2017-3-7
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Central Maine D
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Labroides Posted at 2017-3-7 13:47
Because your battery had been sitting and slowly discharging it was not able to deliver the required voltage and although the % indicator showed 57%, you did not have the power you thought.
If you looked at the voltage in your flight record, you would see that it fell to dangerously low levels despite the % indicator.

I am replaying the flight record, the indicator on the screen never changes from green and lands with 54%, where else would I see an indication battery fell to dangerously low level other than the on screen indicator?
2017-3-7
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Central Maine D
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Having just looked at the flight record again the take off voltage was 61%, not 68% as originally posted.
2017-3-7
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WilliamM
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Central Maine D Posted at 2017-3-7 13:35
It was 44 degrees F yesterday, manual says 0 - 44C so I was 12 degrees above minimum temp.  I'm in Maine so 44 degrees seems like summer.  I typically charge my batteries after they've cooled down after flying then put them in the carrying case rotating them so as to not use one battery more than others.  If I don't fly for several days you're saying I have to recharge even if they're at 80 or 70%.  I think that would be detrimental to batteries.  Should I not recharge after flying?  Should I charge, store, then top off before flying?  I've got 6 batteries and three chargers.

Your doing what I did when a newbie, it's the other way around.  Always charge your batteries fully right before going out, or no more than 24 hours before. Never charge them right after unless your going back out the very next day. Also if your not planning to fly again for a week or so, and after your day out any of your batteries are less than 25%, it's a good idea (for the health of the battery) to partly charge them to about 50% for storage. Then fully charge only when needed for that day.
2017-3-7
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Labroides
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Central Maine D Posted at 2017-3-7 14:21
Having just looked at the flight record again the take off voltage was 61%, not 68% as originally posted.

No it wasn't.
The voltage is a number with V or Volts after it and has nothing to do with the notional percentage indicated which assumes you started with a full battery.
Post your flight data and I'll show you the difference between your battery level and a full battery
2017-3-7
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WilliamM
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Central Maine D Posted at 2017-3-7 14:18
I am replaying the flight record, the indicator on the screen never changes from green and lands with 54%, where else would I see an indication battery fell to dangerously low level other than the on screen indicator?

The Go app playback feature does not show voltage, only battery %. You need to upload your flight log to a on-line viewer, like the one in Labroides's post.
2017-3-7
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Central Maine D
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Labroides Posted at 2017-3-7 14:43
No it wasn't.
The voltage is a number with V or Volts after it and has nothing to do with the notional percentage indicated which assumes you started with a full battery.
Post your flight data and I'll show you the difference between your battery level and a full battery

Sorry.  I'll post once I figure out link.
2017-3-8
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Central Maine D
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WilliamM Posted at 2017-3-7 14:42
The Go app playback feature does not show voltage, only battery %. You need to upload your flight log to a on-line viewer, like the one in Labroides's post.

I'd never used this tool, it's very helpful.  I've done a screen capture of when the critical event was recorded, batteries aren't red.  Can you explain why it would go to emergency landing?
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2017-3-8
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Sloan Fischer
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Have to start with higher battery percentages or else it is too hard on the battery
2017-3-8
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WilliamM
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Central Maine D Posted at 2017-3-8 09:52
I'd never used this tool, it's very helpful.  I've done a screen capture of when the critical event was recorded, batteries aren't red.  Can you explain why it would go to emergency landing?

Can you post the link to the full log from that site, not just a screen print. From this image it looks like the voltage is too low.
Anything under 3.4 is not good, per cell. I think the flight controller's critical low battery threshold is 13.5 volts.



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WilliamM
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Central Maine D Posted at 2017-3-8 09:52
I'd never used this tool, it's very helpful.  I've done a screen capture of when the critical event was recorded, batteries aren't red.  Can you explain why it would go to emergency landing?

Here is something I found on the PP site.

It's important to monitor the battery voltage in each cell of the DJI smart battery. Be aware of the following:

1) Monitor the battery to ensure all cells maintain a similar voltage.
2) Do not allow any of the battery cells to drop below 3.3V.
3) Consider landing your Phantom when (or before) the first battery cell reaches 3.4V.
4) Your battery will shut off mid-flight if the voltage drops below 3.0V.

You can display the voltage of the lowest battery cell on the main screen of the DJI GO application. To do so, enable the "Show Voltage On Main Screen" setting in the "Aircraft Battery" --> "Advanced Settings" section of the DJI GO settings.
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Central Maine D
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WilliamM Posted at 2017-3-8 10:40
Can you post the link to the full log from that site, not just a screen print. But from this image it looks like the voltage is too low, Anything under 3.4 is not good.And I think the flight controller's critical low battery voltage threshold is 13.5V.

I didn't know the log would be publicly viewable.  Here's the link  http://www.phantomhelp.com/LogViewer/1F30Y8BMWRXQWYVDIOK5/
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WilliamM
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Central Maine D Posted at 2017-3-8 11:18
I didn't know the log would be publicly viewable.  Here's the link  http://www.phantomhelp.com/LogViewer/1F30Y8BMWRXQWYVDIOK5/

OMG, you had some very low battery voltage numbers there. I very surprised it didn't land sooner. You might not have had red numbers when it went into auto land, but you sure had red voltage numbers all over the place before that.  Once even down to 3.3 on cell 4.  Try learning to keep an eye on total voltage as well as lowest cell voltage while in flight.
2017-3-8
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Central Maine D
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WilliamM Posted at 2017-3-8 11:06
Here is something I found on the PP site.

It's important to monitor the battery voltage in each cell of the DJI smart battery. Be aware of the following:

I had monitor battery on screen already.  I don't see how I can monitor individual cells though.
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WilliamM
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Central Maine D Posted at 2017-3-8 12:31
I had monitor battery on screen already.  I don't see how I can monitor individual cells though.

Do you have the cell voltage set to display on screen too? Not % only.
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Central Maine D
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WilliamM Posted at 2017-3-8 12:34
Do you have the cell voltage set to display on screen too? Not % only.

I only see one number, not individual cells.
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WilliamM
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Central Maine D Posted at 2017-3-8 13:03
I only see one number, not individual cells.

Yes, that's good. It's the one cell with the lowest voltage. You can also go to the battery page within settings to view all four cells during flight if you want.
2017-3-8
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Quamera
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Central Maine D Posted at 2017-3-8 13:03
I only see one number, not individual cells.

Not sure about your controller but on the P4 (GL 300C) if you touch the battery symbol you are given the 4 individual cell voltages on the screen. If that doesn't work there are 2 programmable buttons (C1 & C2) on the back of the controller that can be made do the same thing (on the GL 300C) instead of having to wade through the app.

If the 300A/B can't do either then you still have a better controller because the "C" has the weakest TX RF output of all DJIs controllers and that is the most important thing IMHO.
2017-3-8
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Labroides
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Central Maine D Posted at 2017-3-8 11:18
I didn't know the log would be publicly viewable.  Here's the link  http://www.phantomhelp.com/LogViewer/1F30Y8BMWRXQWYVDIOK5/

Looking at your numbers, you started with a partially discharged battery showing 61%
at 61% and before takeoff with no load you had 15.5V which immediately fell to 13.5V when you took off.
At 30 secs your battery is down in the red at 13.08V (below 3.3V per cell).
After this your battery is in the red whenever you ask it to climb.
At 1:08.9 (57%) the flight controller recognised the critical low power situation and initiated autoland.

A freshly charged battery has 17.3V at 100% and by the time it is at 61% this is down to 15.3V
This is why you should never launch with a battery that has partially discharged.
2017-3-8
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blackcrusader
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WilliamM Posted at 2017-3-8 14:00
Yes, that's good. It's the one cell with the lowest voltage. You can also go to the battery page within settings to view all four cells during flight if you want.

Yes you just click on the battery icon ( power level remaining % icon ) and it shows the 4 cells. In your photo the 89% is your battery icon link. Even with a fully charged battery I always check my cell levels as my aircraft is warming up before launch.
I also check inflight as well.  Thanks for your post as others who do not understand can now learn something.  I errered in thinking you had just had low battery level so RTH due to distance to home point but did not have your battery levels to look at. You came close to a complete battery shutdown in flight.  Drones don't drift to the ground with no power unfortunately.

battery levels

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2017-3-8
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WilliamM
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blackcrusader Posted at 2017-3-8 16:46
Yes you just click on the battery icon ( power level remaining % icon ) and it shows the 4 cells. In your photo the 89% is your battery icon link. Even with a fully charged battery I always check my cell levels as my aircraft is warming up before launch.
I also check inflight as well.  Thanks for your post as others who do not understand can now learn something.  I errered in thinking you had just had low battery level so RTH due to distance to home point but did not have your battery levels to look at. You came close to a complete battery shutdown in flight.  Drones don't drift to the ground with no power unfortunately.

I believe your post was meant for "Central Maine D", but I'm sure he'll see your post.
2017-3-8
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Central Maine D
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Thanks all.  I touched the spot on the screen and it displays the 4 cell levels in the battery.  I won't take off again with battery below 90% charged.  And the flight log analyzing web site is great.  
2017-3-9
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