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OK to discharge the battery to 0% ?

boblui

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This test has probably been done by the others before but I haven't come across any reports yet.

Today I made my M2P hovering about 1 meter above the ground until the battery dropped to 0% and then I kept it hovering until I felt uncomfortable which is about one minute afterwards.

Upon checking the flight log ( attached ). This is what I get :

1595952387766.png

It turns out that 0% refers to the point where the battery voltage starts to drop more rapidly. In the test the drone was forced to keep hovering for 77 seconds after the battery has dropped to 0%. At the end of the flight, the battery voltage was about 3.5 volts.

I read from the internet that it is safe to discharge LiPo battery to 3V but I have to admit that I have not done a very thorough search so I am not sure whether the information is reliable. If this is true then it will be perfectly safe to discharge the battery of M2 to 0% which corresponds to about 3.6 V.

What do you guys think ?
 

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  • hover batt SN 534038B DJIFlightRecord_2020-07-28_[16-41-02].txt
    2.4 MB · Views: 19
A measure of absolute, last gasp, get it over land otherwise go for a swim, last resort I suspect.
Not recommended but useful to know that you can fly down to zero, and don't necessarily have to kiss it good bye at 10%.
There's a couple of videos on youtube were folks have been caught out by wind etc. and at 10% their drone was still over water.
It's cheaper to replace the battery than the drone
 
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There's a couple of videos on youtube were folks have been caught out by wind etc. and at 10% their drone was still over water.

Yes, those things have happen from time to time, especially to pilots who do not plan before the flight.

What I am trying to understand here is whether it's safe to discharge the battery of M2 to 0%. I have repetitively heard that doing so will harm the battery but I have not seen any convincing evidence so far.
 
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Probably a decent answer to battery drain may be this one.
The lower the battery percentage, the higher the risk of a problem?
I do some risk while flying, but not when it involves batteries.
 
because I want to be able to make my own decision base on proven facts instead of hearsays.

I can assure you DJI have their facts straight regarding battery useage. They have extensive experience as a supplier (not manufacturer) of the battery cells over many years. Reducing LiPo’s close to 3V will ultimately cause premature failure. The nominal voltage per cell is 3.7V and reach full charge at 4.2V. Multiply each cell voltage by 3 for the Air2 and 4 for the M2’s for the actual intelligent battery voltage.
 
Yes, those things have happen from time to time, especially to pilots who do not plan before the flight.

What I am trying to understand here is whether it's safe to discharge the battery of M2 to 0%. I have repetitively heard that doing so will harm the battery but I have not seen any convincing evidence so far.

Have done the same experiment with keeping the drone in the air until the battery is down to zero, this happened about when I had 100 charges of the batteries, now I am on over 200 charges and the batteries still work OK, but of course they have lost some over time in the maximum flight time.
 
@boblui one other thing to consider as well is the fact that at lower voltages ,lipos tend to drop power quicker than when they are 50% plus charged, this is to do with the way the battery provides the current draw to the motors through the ESCs,its not really good practice to drain them down to low voltages as it can cause damage to the cells, really there is no need to push the boundaries of the batteries, just obtain extra ones and treat them with care ,and you will get a lot more life span out of them ,after over 400 flights and 20 months of use my four batteries are still in great condition, no swelling and they still get 98 to 100% charge according to airdata , my first battery warning is set for 40% then critical is set at 25% ,i am normally on the ground shortly after the 40% warning i can get 18 to 20 mins flight time depending on conditions and i find that is plenty for me per battery ,also it gives me some wriggle room if i have to delay my landing for some reason
 
because I want to be able to make my own decision base on proven facts instead of hearsays.

The following shows a typical voltage/% used chart. Note that below 3.7 volts per cell you are starting to reduce lifespan of the battery. The 3S column is for the Air2 and 4S column for the M2’s.


DroneGirl has a good 15-point list for LiPo battery use.

 
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October 2019 I posted a thread called: Battery life
Good or bad to fly until the battery is at 0%?

Trying and testing things myself is my and many others' way of developing our knowledge and skills. Making mistakes is one of the better ways to expand your knowledge and experience, we all remember what Mr Goldfinger said about mistakes.

In the above mentioned thread, the conclusion was probably not to drain your batteries too hard, I myself now have a 20% limit when I fly over land, but I always have the drone in VLOS. When I fly over water, something I have to do today, I have a bigger margin.
 
One interesting thing to note is that when you fly your batteries down to 0% and maybe a little less, you begin to get very close to the flight times that DJI seems to state in their specifications. I normally fly down to 30% since I have 4 batteries each for my M2P and MA2, but occasionally, I land at 10%, and I saw 0% the other day with the M2P after a long timelapse that I did. I think DJI builds a bit of fudge factor into their batteries, and although I don't know this for sure, I'm fairly confident that you can run their OEM batteries down to 0% every flight if you wanted, and all it would cost you is more time to re-charge.
 
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One interesting thing to note is that when you fly your batteries down to 0% and maybe a little less, you begin to get very close to the flight times that DJI seems to state in their specifications. I normally fly down to 30% since I have 4 batteries each for my M2P and MA2, but occasionally, I land at 10%, and I saw 0% the other day with the M2P after a long timelapse that I did. I think DJI builds a bit of fudge factor into their batteries, and although I don't know this for sure, I'm fairly confident that you can run their OEM batteries down to 0% every flight if you wanted, and all it would cost you is more time to re-charge.

Agree with you that DJI has a certain safety capacity built in, have mentioned this before, then if it is so wise to run the batteries down to zero every flight, the battery experts may dispute.
 
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Agree with you that DJI has a certain safety capacity built in, have mentioned this before, then if it is so wise to run the batteries down to zero every flight, the battery experts may dispute.
I've had the iPhone 6S for coming up on 3 years now, and I've run it down to auto shutdown countless times. The thing just keeps going as it did when it was new as far as battery life, and I think DJI's batteries are even smarter.
 
because I want to be able to make my own decision base on proven facts instead of hearsays.
Than I would recommend that you do intensive studies on batteries in general. You should also be careful with your expressions because you frequently mention 0%. What do you actually mean ? 0% voltage ? 0% capacity ? If you want to make your own decisions get your own knowledge based on facts first before you bother people with trash.
 
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.... What do you actually mean ? 0% voltage ? 0% capacity ?

I think it's obvious that I am referring to the percentage figure displayed on the DJI GO APP . 0% voltage is complete nonsense BTW. It just reflects you ignorance on the subject.
 
I encourage you to do further research on battery life. Good to contact DJI for info. I have been flying with the same battery's for 3 years now, always leaving 20 to 30 % charge 1 or 2 blinking lights on the battery. All good, I store them in safe bags, I have a rule of thumb, when I get 3 or more people agree on how to do something. Usually, I do it, depending on what it is, and the cost involved. I see old man mavic has good success with his batterys and his method. I did a intensive study myself, came up this method. Let us know what you came up with, always interested in other research. Not hear say, but facts.
 
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I think it's obvious that I am referring to the percentage figure displayed on the DJI GO APP . 0% voltage is complete nonsense BTW. It just reflects you ignorance on the subject.
Actually, I had the same question for you. Makes sense now. Have you figured out what "physical" parameters of the battery coincide with the app zero percentage?

I'm not sure how "smart" the batteries are since I've had to rebalance two of my four with a $40 RC charger after DJI reports them unusable. Hopefully they're smart enough to shut down before permanent damage occurs. (hence my question to you :)
 
I can reply not specific to Mavic batteries but to lithium batteries in general.
Lithium batteries are made up of many cells and not all the cells are created equally. So it you read 3.6 volts that is the average voltage of the cells and approx 1/2 will be less. So every cell below 3 volts will probably get damaged and every time it happens the damage accumulates. This will not kill the battery but reduce it's longevity/voltage output.
General Motors found that when letting the lithium battery in their Chevy Volt get below 30% greatly reduced it's battery life so the generator kicked in at 30%.. On 1/19 GM reported not having to replace one Chevy Volt battery in 9 years. Now obviously, GM was ultraconservative to protect it's battery which contained over a thousand more cells than the Mavic.
I have an Apple Ipad that is 10 years old and I have only allowed the battery to get below 30% several times and the battery is > 90% today.
I have a large 17.4 amp battery on an ebike that when charged is 54.4 volts and the manufacturer has set the shutoff for use at 41 volts to protect the battery life and strongly states it should never be run at < 41%.
So NEVER let your battery get anywhere near 0% unless you love buying new batteries.
Voltage is the best way to monitor your battery.
 
Just don’t store it at zero after. Charge it to 50% to store
 
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