Hi, this is my first time posting on this forum. I recently swapped my Mavic Pro with someone in my town for a Mini. I had the pro for 3 years with no issues and everything was purchased from the DJI store. The person who bought the Pro said he crashed it today and that one of the batteries I gave was defective. I have never had a problem with the batteries and if there was an issue wouldn't there be a warning? He provided this log, anyone have an idea if this is legit and is this something I could have known?
Sold my Mavic & buyer crashed - how to check on batteries
- Thread starter TropicalDronie
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- batteries
Hi there, welcome to the forum ? 
So the battery is ... 3 years old also ?
No way for an outsider to tell how that battery have had it during that time regarding storage care, charge cycles & general use ... but all LiPo batteries will eventually go down this route, they will not last forever.
The pic from the Airdata.com Power tab shows that the battery was in duty until cell 2 failed ... DJI drones will initiate a force landing when a cell goes under 3 volts so that must have happened here. A LiPo cell going under approx 2,7 volts will usually sustain permanent damage ... so that battery is forever shot.
It's hard to judge when a battery cell will fail before hand ... thus give an app time to put up a warning, a warning will come up usually seconds before Force landing starts, so way out it's not much to do then aim for a flat spot. Only way to take a battery off duty before this happens is to monitor the trends of cell deviation & flight time ... with a paid subscription on Airdata.com you can do that for the logs you have uploaded there ...
Buying a 3 year old drone with equal old batteries should mean that the battery value is 0 ... they should be very near end of life usually.
Below two graphs from Airdata.com showing the trend from one of my batteries ... from this it's on me to judge when to ground a battery.
So the battery is ... 3 years old also ?
No way for an outsider to tell how that battery have had it during that time regarding storage care, charge cycles & general use ... but all LiPo batteries will eventually go down this route, they will not last forever.
The pic from the Airdata.com Power tab shows that the battery was in duty until cell 2 failed ... DJI drones will initiate a force landing when a cell goes under 3 volts so that must have happened here. A LiPo cell going under approx 2,7 volts will usually sustain permanent damage ... so that battery is forever shot.
It's hard to judge when a battery cell will fail before hand ... thus give an app time to put up a warning, a warning will come up usually seconds before Force landing starts, so way out it's not much to do then aim for a flat spot. Only way to take a battery off duty before this happens is to monitor the trends of cell deviation & flight time ... with a paid subscription on Airdata.com you can do that for the logs you have uploaded there ...
Buying a 3 year old drone with equal old batteries should mean that the battery value is 0 ... they should be very near end of life usually.
Below two graphs from Airdata.com showing the trend from one of my batteries ... from this it's on me to judge when to ground a battery.
Last edited:
THE CYBORG
Well-Known Member
Ninjad by slup & he gives a more in depth answer than me
Hi TropicalDronie welcome to Mavic Pilots.
Firstly.
Do you know for certain the battery in question was actually one of yours & not one he got elsewhere ?
Secondly.
If the buyer is capable of checking the health of a battery as he obviously is if he sent you the log then he should have done that before doing the trade.
This may sound harsh but say I bought a used car in a private sale then found out it had faults I would have no comeback on the seller because I should have looked for faults before parting with my cash.
Hi TropicalDronie welcome to Mavic Pilots.
Firstly.
Do you know for certain the battery in question was actually one of yours & not one he got elsewhere ?
Secondly.
If the buyer is capable of checking the health of a battery as he obviously is if he sent you the log then he should have done that before doing the trade.
This may sound harsh but say I bought a used car in a private sale then found out it had faults I would have no comeback on the seller because I should have looked for faults before parting with my cash.
Thanks a lot for this info, I've definitely learned from poking around this forum on my issue. Yes, the batteries were 3 years old as well and I gave the buyer a copy of my receipts so he knew. So I guess it is possible this would have happened to me at some point too...may deserve a refund.
I am wondering this part, how hard would it have been for him to use this app to test my battery quality? I sent a message to this app (Airdata) to see if it's possible to test without flying for a long time. We met up to test and to be honest I didn't know the batteries were this fickle so I just tested it by flying it in the air for a few minutes.
I have to assume it was one of my batteries...if he knew enough to get a new battery he probably would have been more careful to test fly.
welcome to the forum,he had all the info about the batteries and he should have checked them out before the purchase ,if you had a bill of sale in writing ,stating that you were doing a direct swap and to the best of your knowledge both drones had been test flown,then if the person in question is a good friend then you might decide to assist him with replacing the battery ,if you did the swap on a hand shake then he has no recourse any more than you have if the MM develops a fault ,
i think that there should be ,when a drone is sold or swapped something written down that if the buyer wants the drone, then the batteries can not be guaranteed and are sold as such either that or do not include them as part of the sale
i think that there should be ,when a drone is sold or swapped something written down that if the buyer wants the drone, then the batteries can not be guaranteed and are sold as such either that or do not include them as part of the sale
As mentioned above with the selling of a second hand car, it's the same with the drone. You sold it with all good intention, you didnt (I assume) sell the drone or batteries knowing the battery was defective. You performed a test flight to show all was working correctly, the buyer was happy and handed over the money. As also mentioned, is that battery information from one of your batteries? Its sold as seen, you didnt provide a personal warranty did you? No. "Sorry mate, sold as seen"
brett8883
Well-Known Member
My two cents is that if you told him the drone and batteries were in working order, even if you were unaware, they were not.
There are not enough data there to determine the problem. For example, that could have resulted from using a partially discharged battery. You should ask him for the flight log, which will show whether it is really a defective battery or whether he didn't understand that MP batteries are a quite different beast than MM batteries, and need to be treated differently.
The batteries were in working order when he sold it as far as the seller knew. Other than breaking open the battery packs to show the buyer that the cells weren't swollen, what was he meant to do? That's the risk you take when buying secondhand 3 year old lipo batteries. I'm sure most secondhand drone buyers, buying a 3 yr old battery, would have concerns about the batteries and would of bought new batteries to reassure themselves. I'm sure if you sold a secondhand car privately, a week later the buyer came back saying "the battery is flat and wont take a charge" you wouldn't take the car back or give him money to buy a new battery would you? That's just the chance you take with private secondhand purchases.
To the op. Dont give in. The buyer just wants to blame somebody for his errors.
If you had it for 3 years and in those three years you never had a problem with it, yet alone battery problems.
Then id expect that it should work fine with the next owner. Atleast for a couple of days week or even months of flying til eventually battery expires.
If you had it for 3 years and in those three years you never had a problem with it, yet alone battery problems.
Then id expect that it should work fine with the next owner. Atleast for a couple of days week or even months of flying til eventually battery expires.
I agree the batts are on the buyer I'd never trust three-year-old batts I'd treat them as bad and buy good ones.
You need to see data for the full flight, rather than just the end.
The battery's state of charge at the start of the flight is very important.
Lastrexking
Well-Known Member
How many cycles do the mavic pro one batteries last for? assuming normal use and never over discharged below 20% my drone is a 2017 model with 45 cycles per battery and i get 17 minutes flight time landing and power off at 25%
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