I left my drone on until the battery shutdown. The Mavic battery bottom meter light flashes 16 times when checking charge. When i place the battery on DJI chargers it will not charge and also flashes 16 times. Keep in mind i did not store it this way and the battery depleted this low in the past 24 hours. Is there a way to force the battery to charge up from a depleted shutdown state?
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4 Answers
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5
Short answer. Buy a new battery.
I heavily researched this and although there may be another solution I will share my experience.
The Mavic batteries have complex circuitry in them to maintain stability and longevity. This is partly why the Mavic charger will not revive the battery.
Is there a way to manually charge it? Well the answer is yes and no. The cells inside the battery are probably okay if the battery did not deplete this far while in storage. The problem is the circuitry will not allow a manual charge above failsafe levels restoring to a functioning DJI battery. There are some videos and reports of people cracking open their batteries and doing various physical things to the circuitry to fix this issue. I do not recommend this. I found that opening the Mavic battery was not easy and left the battery case in disrepair due to it being glued or affixed with single use fasteners. If there is a tool that can open the battery case gracefully i don’t believe it is something in a standard tool box. On top of that the Mavic circuitry is precise to avoid radio interference and modding that could increase radio interference.
Once the battery was open, poorly, I was able to charge directly to the main leads. The battery stack read about 10.5 to 10.6 volts on 3 cells. Very low. My hobby charger pulled it up to 11.1 volts static. I was still unable to charge using the Mavic charger. This led me to believe the circuitry remembers the charge state of the battery and will not continue if that battery has inconsistent untracked voltage changes.
I saw another video that shows desoldering the positive terminal while the balance lines are disconnected. Then soldering it back. I tried this and it did seem to refresh the charge level readout, but i still could not charge using the Mavic charger. With my battery split open and looking like it would never be allowed in checked or carry on baggage i gave up and decommissioned the battery using a method that worked for me. Once the battery became inert it could be disposed of properly.
I suggest contacting DJI before opening the case. Maybe they have a trade in policy or something when the Mavic depletes the battery too low?
Best bet is to get a new battery.
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2$\begingroup$ "decommissioned the battery by placing it in a bucket of salted water" Please don't recommend this method as it brings a lot of risks while not even being a good method to start with. $\endgroup$– Num LockAug 31, 2020 at 9:39
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1$\begingroup$ Why is that? Explain the risks. If the battery is discharged to sub usable voltages, “over-discharged”, what are the risks to depleting the battery to zero volts in a controlled reaction? Please explain the risks since we are all about learning here. I want to know the details. Thanks. $\endgroup$ Aug 31, 2020 at 16:48
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$\begingroup$ Important to note that a fully depleted battery or one in a similar state should not be considered flight safe as it will have sag issues, voltage will drop very fast and unexpected, some risk of fire, risk of component damage, and the drone will not perform the same with a compromised battery. There is nothing you can do to the chemistry (that is reasonable) to change this fact. Generally we keep old batteries for desk use, better ones to scout with (short flight), and recycle the chemistry. $\endgroup$ Sep 1, 2020 at 19:32
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1$\begingroup$ @cliffclof Dumping an over-discharged LiPo battery into a bucked of salt water is far from a controlled reaction. The general idea is old and predates back to the first months of consumer available LiPo batteries. A lot of (post-)accidents happened using this seemingly sound method and Fred Marks (FMA) himself, from whom this idea originated and was made popular in those early days, no longer recommends this. At least wear safety glasses. Or even better, bring them to an expert for disposal. Almost any electronics shop will also take LiPo batteries. $\endgroup$– Num LockSep 2, 2020 at 6:23
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1$\begingroup$ Right on and thanks for sharing. I’ve been doing it for a while and you led me to look into other ways. I read a lightbulb method that sounds pretty good. Given my motivation to bring a single battery to a disposal facility I mostly want a way to set it and forget it. Until i get enough to send to the recycler/destroyer. You make some excellent points. $\endgroup$ Sep 2, 2020 at 6:30
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I just had this experience with my first generation Mavic Pro. I have very low charge counts on the batteries. I flew it last a week ago, and when I went to charge one of the batteries, I saw the dreaded rapidly flashing lights. I wasn't sure what to do, so I plugged in my other batteries that had not been charged or flown recently. The others charged normally, and as the problem battery was awaiting it's turn to charge, the multi charger indicator light die turn green. I was thinking this may be some sort of trickle charge. I cannot confirm that, however the battery that would not accept a charge did accept a charge after the first battery was done. I do not know if I was just lucky.
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For a normal, "raw", unprotected LiPo you just hook it up to a charger and select the NiCad or NiMh setting (yes, for a LiPo), and set it to 1/20C charge rate (Capacity / 20). Then, you charge it until it's > 3.0V/cell. Then, you switch to 1/10 C until past 3.5V/cell or so, then maybe do 0.5C until full. I wrote extensively about that on my personal website here in 2014: www.ElectricRCAircraftGuy.com: Restoring/Recharging Over-discharged LiPo (Lithium Polymer) Batteries!.
For a Mavic battery, however, it has protection circuitry and may stop that. You might try my approach above anyway, or you might try bypassing the circuitry to hook up to the raw battery cells to do my approach, but be careful and study my article first.
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DJI Mavic batteries include a firmware self-destruct switch; if the battery becomes "unsafe" (according to the software - e.g. - charge drops too low) or if it is disconnected from the circuit - this trips the fuse and from then-on it will never work again (even if the batteries are OK or replaced with good ones).
DJI say this is for "safety", but it also effectively blocks repairs, forcing you to buy new DJI batteries of course.
There are some hacks around where you can pull dead batteries apart and re-flash the fuse manually, but they're hard to find and very difficult to perform.
