As I follow the drone crash website, more than 10% drone crashes duo to the malfunction of battery. A reliable and safe battery is the first step of a safe fly. As I know that the imbalance of voltages from each cell are the major indicator of battery dead or malfunction, but no detail official criterial showed the formal suggestion. After 50 or 100 circles of charges, I can always see some imbalance in my P4P+, Mavic Platinum or Mavic 2. For example, the voltages of each one of my 4 of P4P+ batteries variance between 4.22 volts and 4.24 volts, even though it flies normal (performance, distance and duration). I always check the voltage balance before fly, but I always worry about it, because I saw somebody crashed the drone duo to voltage deviation (voltage variance between 4.20 and 4.24). Someone knows the battery dead and discard immediately.

  

My questions are:

  

1.       What the exact voltage imbalance indicates the battery malfunction?

  

2.       Whether it is possible for DJI to design a firmware, in which allows the user to find the malfunctional battery out?

  

3.       What are other good suggestions to exclude the bad battery?

  

Aloha djiuser_PE,

     Those numbers are in the normal range.  The firmware does give you warnings about battery problems, in fact the warnings jump the gun on the side of safety.  There are a number of contributors that know more about this than I do, but I just wanted to respond quickly to your concern.

     If you ever do have a battery warning that the drone is landing due to a battery problem, push the left stick upward so the drone maintains altitude enough to come home and land.  This way the drone will hold its altitude on the way back (and is not very far away).

     Make sure your batteries are topped off to over 95% minimum before you fly.  Most of the crashes you read about do not tell you that the flight started with a 50% to 80% charge on the battery (we usually find that out later).  The cell variations at that level do not allow a smooth transition of charge between cells when the overall charge is that low.  The firmware is designed for higher charges before starting a flight.

     If you store your batteries for a month or two (or more), fly close and run down the battery, or just run the battery down at idle without using the props.  Then charge the battery so all the cells get an even charge and transitions between cells can be smooth.

     BTW, you can have the voltages displayed on the On-Screen-Display.  It is a setting.

     Hope this helps!

Aloha and Drone On!

1.  There is no exact number.  There are ranges and also there are opinions among those of us who have flown for a while and have a sound understanding of what keeps the AC aloft.  Since the AC will auto land when any particular cell reaches less than 3.3 volts, and since the battery will shut off if any particular cell reaches less than 3.0 volts, if you give it a little thought, it becomes obvious that you want balanced cells.  My opinion is you want no more than .07 volt deviation from the lowest cell to the second lowest cell, and also you want no more than .1 volt deviation from the lowest cell to the highest cell.  Other people will have other opinions.  Know that an occasional imbalance during a flight is normal.  A constant imbalance for an extended period is not.  

As Cetacean states above, the main thing you want to do is ALWAYS launch with a fully charged battery.  Also, it's a good idea to keep an eye on the behavior of your battery cells via the flight log afterwards.  That way, you'll know to retire it if/when you think it's time.  

Good luck

Mark The Droner Posted at 3-12 03:27
1.  There is no exact number.  There are ranges and also there are opinions among those of us who have flown for a while and have a sound understanding of what keeps the AC aloft.  Since the AC will auto land when any particular cell reaches less than 3.3 volts, and since the battery will shut off if any particular cell reaches less than 3.0 volts, if you give it a little thought, it becomes obvious that you want balanced cells.  My opinion is you want no more than .07 volt deviation from the lowest cell to the second lowest cell, and also you want no more than .1 volt deviation from the lowest cell to the highest cell.  Other people will have other opinions.  Know that an occasional imbalance during a flight is normal.  A constant imbalance for an extended period is not.  

As Cetacean states above, the main thing you want to do is ALWAYS launch with a fully charged battery.  Also, it's a good idea to keep an eye on the behavior of your battery cells via the flight log afterwards.  That way, you'll know to retire it if/when you think it's time.  

Thanks for your reply.

The key point is that there is no sign of battery draining fast, even it gets fully charged.  Sometime even directly from 90% to 0%. We always get kinds of warning: High percentage doesn't mean the battery is normal.

djiuser_PEp4mLwh74c7 Posted at 3-12 06:32
Thanks for your reply.

The key point is that there is no sign of battery draining fast, even it gets fully charged.  Sometime even directly from 90% to 0%. We always get kinds of warning: High percentage doesn't mean the battery is normal.

90% to 0%?  Do you have a link?

A battery can autoland or turn itself off earlier than expected and above the expected percentages if it is damaged; for example if it is swollen or it has unbalanced cells.  

This can also happen if one makes the mistake of launching with a partially charged battery.  

Cetacean Posted at 3-12 01:52
Aloha djiuser_PE,

     Those numbers are in the normal range.  The firmware does give you warnings about battery problems, in fact the warnings jump the gun on the side of safety.  There are a number of contributors that know more about this than I do, but I just wanted to respond quickly to your concern.

Thanks!

Which is better, or which is good for the battery? Running the battery down then making a full charge, or just charge the battery from the current level.

Mark The Droner Posted at 3-12 06:55
90% to 0%?  Do you have a link?

A battery can autoland or turn itself off earlier than expected and above the expected percentages if it is damaged; for example if it is swollen or it has unbalanced cells.  

That's a Chinese website.

djiuser_PEp4mLwh74c7 Posted at 3-12 06:56
Thanks!

Which is better, or which is good for the battery? Running the battery down then making a full charge, or just charge the battery from the current level.

Aloha djiuser_PE,

     Those are "Intelligent Flight Batteries".  They have firmware that sometimes gets updated.  If you are down to 95%, you are generally safe to fly if the battery has never shown any problems (but I would top it off if there is time).  Down to 90%, it is best to charge (top-off) the battery with the battery turned on so the firmware can distribute the fresh charge evenly.  It is best to always top off the batteries you will be flying with, while the battery is turned on, the day or night before you fly.

     If you have any problems at all, enable the voltage display on the "On-Screen-Display".  This will allow you to easily monitor your battery.

     Some have reported that it is best to turn on the battery every time you charge the battery.  But I would think that any light display where the first LED has gone dark, or lower, charge, would indicate that charging the battery without starting the battery is not a problem since the manual does not say to charge all batteries while they are turned on.

     Hope this helps!

Aloha and Drone On!