Battery Issue

[Tonysbird]

Thanks W. T. B to be honest I get nothing on screen about voltage or battery warnings. And I do get standard flight times (about 16 mins before I land around 30%) I only get the voltage turning from green, yellow then red. From now on I will just fly at a casual speed (not full throttle) and try to keep the voltage in green at all times, as soon as it goes yellow I will slow down. Sometimes it can go from green to red, but I think that's me pushing it fast catching wind towards the drone. I still have no idea on voltage numbers. Is there a simple link you could paste to explain?

You only have 30% after 16 minutes? Are you running wide open the whole 16 minutes? That seems like a short amount of flight time to me.

 

[The Famous]

I've never seen a cell suddenly die and go open circuit, you shouldn't fear that.

What is something to fear is one cell going eroding too fast, deviating rapidly under load, especially in cold weather. You can monitor that if you want to continue using it, which I deem fairly safe for now, unless something changes. I wouldn't send that battery on long missions anymore, or missions over water.

What I would do is put a special red tag on the battery and use it less than the others, since it's higher risk. If you fly it, you'll need to monitor that cell. The voltage displayed in the upper right corner (if you have enabled the battery voltage to display) of the Go4 app is the voltage of your weakest cell, and in this case that would be cell #4. If it ever gets close to 3.2V at the end of a flight, I would retire it. Never fly this battery in super cold weather, as a marginal battery can decrease momentarily in voltage more rapidly than in pleasant weather. If the weakest cell ever hits 2.99V, the motors will shut down mid-flight, that's why you want to retire a battery with a huge deviation. Right now I would classify this as a mild deviation, one to watch going forward if you need to fly with it.

You might see an improvement if you deep cycled the battery, but generally speaking that doesn't work most the time.

Happened to me! #1 cell shut down "instantly", crashing my drone!

 

[John Locke]

Happened to me! #1 cell shut down "instantly", crashing my drone!

Wow, that's a first. What model DJI done was that?

 

[Calsun]

You have to assume that the drone voltage sensors are accurate to 0.001 volt and that is highly unlikely. Just because a digital display shows these values does not mean that the accuracy is at this level. I would worry when one cell is at 90% or less of the other cells as it is dragging down the overall voltage from the battery pack.

With lithium-ion battery packs they get their longest life by being fully charged after each use. Unfortunately DJI recommends not doing this so one is left in a gray area and the probable battery pack life is going to be significantly reduced. For DJI the concern is naturally one of avoiding a battery pack bursting into flames and so they go with the safest strategy and one I think is prudent. There is a cost but I view shorter battery pack life as cheap insurance to keep my house and its contents safe.

The aircraft is dependent on total voltage received from the battery pack and not an individual cell so if the drone is happy I would not worry about the individual cell voltage unless you see a truly significant drop in a particular cell. Appreciate also that a no load voltage level is not a great indicator of how well a battery will power a drone. The batteries are designed to provide full voltage until the end so you get a sharp drop-off in voltage with a lithium-ion battery and so without a load applied you have no real idea as to the health of such a battery.

 

[With The Birds]

You have to assume that the drone voltage sensors are accurate to 0.001 volt and that is highly unlikely. Just because a digital display shows these values does not mean that the accuracy is at this level. I would worry when one cell is at 90% or less of the other cells as it is dragging down the overall voltage from the battery pack.

With lithium-ion battery packs they get their longest life by being fully charged after each use. Unfortunately DJI recommends not doing this so one is left in a gray area and the probable battery pack life is going to be significantly reduced. For DJI the concern is naturally one of avoiding a battery pack bursting into flames and so they go with the safest strategy and one I think is prudent. There is a cost but I view shorter battery pack life as cheap insurance to keep my house and its contents safe.

The aircraft is dependent on total voltage received from the battery pack and not an individual cell so if the drone is happy I would not worry about the individual cell voltage unless you see a truly significant drop in a particular cell. Appreciate also that a no load voltage level is not a great indicator of how well a battery will power a drone. The batteries are designed to provide full voltage until the end so you get a sharp drop-off in voltage with a lithium-ion battery and so without a load applied you have no real idea as to the health of such a battery.

You are giving poor advice here- Contrary to your belief LiION chemistry is actually most unstable and will age faster when kept at full charge.

To say a 10% variance in cell voltages within a pack is acceptable if ridiculous. With the highest cell at 4v this would mean a 400mv imbalance. At this level the low cell would be delivering significantly higher current and would fail quickly under load. You should consider 100mv as a safe limit in a 3C average load application (which is the case with the phantoms).

As to your claim of the voltage measurement being innacurate there may be an absolute error however consistency between cells is very good, the ADC’s all reside in the same package and calibration is performed when the cells are first connected to the electronics.

 

[The Famous]

Wow, that's a first. What model DJI done was that?

Go here: 175 feet straight down slamming onto a frozen lake!