Disable forced landing
- Thread starter alexsh1
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DroneTats
Well-Known Member
Aside from the risk to the drone, isn't there also a risk to the smart battery when levels get too low? I've had several "new" batteries just die completely and have been told it's because levels get too low and that causes them to completely fail to charge. I know a little off topic here but curious if that's been an issue for others as well.
Just out of curiosity, if forced landing was disabled, down to what 'percentage' or voltage would you expect the drone to fly?
Would you also want the low-voltage drone-switch-off or the low-voltage motor-stop disabled?
I think you said it is possible to disable forced landing for a mini 3 pro, if so where is this documented please?
The attached picture below represent a LiPo battery (non high volt (HV))... the redder the color is, the more wear/damage will occur.
A LiPo as such can be used between 3,0V-4,2V/cell without real major damage... the problem is that the discharge rate isn't linear the whole way from 4,2V to 3,0V (see pic. below)... the rate is somewhat linear from 4,2V down to 3,5V, but then down to 3,0V the discharge rate will have a major increase. So... for instance, if it takes 20 minutes to discharge the battery from 4,2V down to 3,5V... it will then just take a couple minutes for the battery to reach 3,0V, & there maybe also continue down below into the "permanent damage zone".
A DJI battery operates between 100%-0%, which is 4,2V-3,5V... discharging a LiPo battery to 3,5V will not harm it or put on extreme wear, but going much lower can mean that you might not have time to get it shut off before it reaches below 3,0V.
So if you precisely can get your battery shut off at 0% (or 3,5V)... it will not be harmed at all & it will not cause the batteries to die prematurely. The tricky here, if you regularly fly your batteries down this low, is that it's most probably just a matter of time before you misjudge the timing & the battery falls below 3,0V... & there you will have permanent damage & possibly a total cell failure. All this is why you should aim to have your drone landed & shut off around 15% at the lowest, then you have some wiggle time if something unforeseen happens.
What harms the battery is to leave it in a low state of charge... from there it can self discharge down to damaging levels... or leaving it fully charged which will speed up the breakdown of the chemicals in the battery which both harms the maximum storage capacity & can generate gassing which makes the battery swell. If the battery shall be stored longer than 2 days, place it on storage voltage (3,7V-3,8V or 40%-60%)... there the battery is mainly inactive & can be stored without degradation.
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Droning on and on...
Well-Known Member
Depends on what is meant by "low".
You can not damage a DJI battery by simply running the drone to the point it force-lands. When safely back on the ground, the battery will still have more than enough charge to be well above the cell voltages where damage occurs.
However, leaving a battery depleted and then storing it for months can result in dropping to damaging voltage levels through natural self-discharge, damaging one or more cells in the module.
The BMS in a DJI Intelligent Battery will usually detect this, put the pack in a failed state, and refuse to charge.
"...very long haul flights ..."
With that comment you will attract some very polarised opinions in this thread. Every time someone heads out on a long range jolly, all they're doing is passing a handful of nails to the bodies that write and enforce regulations, so that they can hammer them into everyone else's coffin. Even now the main rules are painfully simple.
1. Don't fly so far away that you can't see your drone.
2. Don't fly higher than 400 feet above what you stand on.
If you want to flip The Man the bird and do your own 'thing', fine. Just don't advertise it on public forums or YouTube.
DroneTats
Well-Known Member
I set mine to 18% to signal RTH. That's been fine for me for the past couple years but prior to that I lost several batteries and I'm assuming it was due to storage when low on charge as you mentioned above. Thanks!
I think the lowest was 3% and it was due to a strong wind which I did not expect.
In any case I am trying to come back before 7%
Well, thanks for your comments, but this is NOT what I was asking.
I am flying as far away as 12km. and Yes I am doing my own thing and I am not putting it on YouTube.
I never have had issues with the original DJI batteries. On mini 2 once I discharge the battery down to 0% and still was able to return safely.
With other batteries I have seen the battery % (aka voltage) dropping from 40% down to 5% in a few seconds.
We all are going to die at the end you know...
Batteries are not forever either. DJI is also implementing something into the battery controller "to age" batteries quicker.
Nobody is leaving the battery depleted. Why making tons of assumptions?
I am charging the battery always after usage to 60% before putting it into a storage.
I have a special charger which can charge the batteries to 60% or 100% (available on Aliexpress if you are interested)
Wrong.
The controller is locking the battery if the voltage dropped below a certain level.
However, it is possible to open the battery and charge it directly a bit and then unlocking the battery controller using CP2112
See this video
A Lithium battery isn't just "another piece of hardware"... that can be "fixed" if the voltage have been allowed to fall too low.
Furthermore, the BMS doesn't "lock the battery" in terms of preventing further self discharge & permanent damage... it only deactivate the BMS & by that stop it from draw a small current & prolong the time until the battery gets too damaged.
------------------
A LiPo allowed to fall below 3.0V will sustain permanent damage... the effect of this damage is a increased internal resistance which in turn will generate excessive heat during both charge & discharge. Another even more serious effect is that lithium metal starts to plate out on the anode. This causes dendrite structures to form, which can puncture the separator, causing an internal short-circuit.
If looking at the span between 0V & 3.0V, the amount of damage isn't linear, a battery on 1.0V is far worse than a battery on 2,5V... & one on 0,5V is far worse than one on 1.0V.
Most chargers will not charge LiPo's lower than 2,5V... the reason for this is that, the higher the internal resistance is, the greater the risk is for that the battery goes up in flames due to the heat generated from the higher internal resistance during the charge cycle.
It's possible to bring back a LiPo above 3.0V which only have a couple of mV, this by charging with a very very low current, but it's a very high risk of that the battery catch fire. Trying this out require a hand on the battery the whole time to detect if the battery starts to develop a increased heat build-up which can ignite the battery. BUT this will not in any way revert the damage that the battery sustained by being allowed to fall below 3.0V... the increased internal resistance & the dendrite structures on the anode will remain.
This damaged battery will onward pose a serious threat if you continue to use it...
1. The internal resistance will make that battery very prone to major voltage drops during amp draw, which increases the risk for it to again drop below 3.0V where a DJI drone initiate a forced auto landing.
2. Further more, the extra heat generation most probably soon make the battery swell as the heat will increase the electrolyte decomposition which generates gasses.
3. This battery will continue to be prone to catch fire during use, especially during charging... & from a very high risk of internal short-circuits.
You will never ever be able to trust this battery again...
Droning on and on...
Well-Known Member
Well, no BMS really locks the battery. The battery looks dead until dismantled and charged manually.
Really I do not understand why you are doing all this write up, nobody is discharging batteries to even 3.0V.
In terms of voltage the battery goes own to 3.2V
1. Ok, Ohm's law. And? mini 3 pro had some issues with burning PCB traces due to high current, but mini 4 pro does not have this issue
2. There is no extra heat at around 10%. Generally speaking batteries swell due to not properly stored or charged.
3. Seriously? Fire hazard mostly due to incorrect charging or physical damage. The battery won't be prone to catch fire just because it was discharged to 3.2V.
Again, batteries are serving the purpose. And if I have to change the battery after 80 cycles instead of 200 cycles, that's fine
Do not comment on the subject if you have no idea.
These are not just my observations. I'll give you example on Mavic 3 and Mini 3 batteries (the same goes for mini 4 batteries), which were released in 2022. In the settings, the charging thresholds decreased themselves. The Mavic 3 battery lowered the threshold from 4400 mV to 4310 mV. On the Mini 3 battery - from 4250 to 4150 mV. Accordingly, the battery capacity decreases not only due to cell degradation, but also due to a decrease in the charging threshold.
And now please do not tell me this is not done by DJI???
THREAD CLOSED!
Sorry folks but we are not going start being rude, condescending, and TROLLING each other.
We are better than this!!
Allen
Sorry folks but we are not going start being rude, condescending, and TROLLING each other.
We are better than this!!
Allen
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