One of my batteries showed cell deviation like that once. Flew normally. I keep my eye on it, but it hasn't did it since.
P3A tried to autoland with a battery critical warning.
- Thread starter peter west nz
- Start date
I have left the AC on with my lights also turned on to give a reasonable load, until it self disconnects. That should be a proper cycle.
More people might look at your flight log if you took the time to upload to HealthyDrones and paste the link here.
I will give it a complete charge cycle & try again. It seems to totally ignore the sudden drop below 3.3v in the %charge. What?
The battery percentage you see on the App uses the Mah remaining to calculate not the voltage. For example 4480 is 100% and 2240 is 50%...That readout doesn't care about the voltage...You should always check your voltage before you fly and the app allows you to display that info on the main screen...you should have around 4.35v give or take per cell before you take off...I don't know why that batt had only 3.5v while showing full Mah to start...Perhaps something happened during the charging cycle or the battery is scrap but if it was me i would try charging it again and check the voltages on the app and if it has around 4.35v per cell id try it ..Or if you don't trust it throw it out and buy a new one....
We see around 3.9v/cell with 73% cap depicted at T=1s in the log file posted (a reasonable voltage for the SOC) so quite possible see the expected 3.35v/cell at full charge. This is not a clear bill of health as you likely know and crook packs will often appear normal with respect to voltage readings straight off the charger. The significant cell balance issues and outright low readings for single cells suggest this pack under load suggest this pack is damaged beyond usability. The most likely culprit would be allowing to drop below 3v/cell for a significant period. The best known way to destroy a LiPO cell.
Honestly i didn't look at the logs i just look at the pic on the first page showing 3.5v at 23sec and assumed it started from there...I personally had to go by voltage for a while to calculate my flights and not Mah percentage for some reasons but 3.9V was around 78% remaining for me if i remember correctly which doesn't really matter but i guess the conclusion is to toss this battery...
Last edited:
I see what you are all saying. This is the perfect test case for all of this theory. I have just given it a full charge from lov dropout. Let's see what happens. I will fly it again tomorrow, weather gods permitting. is there any way of showing current from the log? Do they have any current sensors? There is useful stuff to learn here. Actually, thinking about it, we can work out the mah by the area under the voltage curve for the battery, if we knew the current.
Obviously, I am not going to do 7km journeys over water, like the 2 batteries before it. It is now a test battery.
A great suggestion to show the battery state on c1 or c2 - but my dji doesn't seem to give me the option.
Obviously, I am not going to do 7km journeys over water, like the 2 batteries before it. It is now a test battery.
A great suggestion to show the battery state on c1 or c2 - but my dji doesn't seem to give me the option.
Last edited:
I'm pretty sure you can check the current on the logs that are stored on the bird using DatCon you can try searching it...If you want to see the voltage on the main screen goto the battery setting page advanced \ show voltage on main screen. at least that's where its at on my version of the app...
If you upload the flight log from your controller to healthy drones it will show you the battery current under load throughout the flight. The most accurate way to check usable capacity is to monitor mah returned to the pack while charging, the smart board in the battery logs this. You can find it in Healthy drones as last recorded mah.
Few questions for ya just so there isn't something I'm missin and i could be checkin out... Is the current under load your talking about that's shown on healthy drones on the Volts and Amps page that tells you your under 15amps or within a range somewhere and not the ACTUAL amp draw? And the last recorded Mah you mention is the "initial capacity" under Battery Info, right?
My limited understanding is that the current draw you are looking at in Airdata reflects the performance of the drone at those stages of flight as indicated. My experience when reviewing the data roughly ties in with what I'm doing e.g. sport mode, flying into the wind, climbing or just cruising around. I'm more interested in any significant battery voltage changes than current draw to give me an idea of something not being right with one of my batteries. @With The Birds will probably jump in with a more detailed and experienced response.
Yeah i understand what your sayin i was just asking him to make sure i understood what he was...
- Joined
- May 9, 2017
- Messages
- 13
- Reaction score
- 4
- Age
- 66
I would like to reinforce this sage advice to add that it is wise to discharge each battery completely as close to 0% as practical before fully charging, again, instead of discharging partially & then charging. Also, only charge batteries that are room temperature or cooler. Per AirDataUAV, I have tracked my now ~90 flights including battery details & my current, primary battery is indicating that it is at the 97% point of its lifespan after 45 charges. Although I'm not banking on a straight-line battery wear on the remainder of it's useful life, if the since it has degraded a mere 3% for 45 charges, it will have to deteriorate at a rate of +2.75% per charge the rate of deterioration I've experienced to date to die at 80 charges, (assuming the AirDataUAV battery analytics are accurate otherwise this battery should be good for well over the stated 80 charge life span (unless DJI builds in a counter which self-destructs a battery at the 80th charge).
My $0.02
There is absolutely no benefit to LiION chemistry to perform a full discharge before recharging. The best you can hope for is to unduly stress and damage the cells and reduce lifespan. The 80 charge cycle figure you are quoting is fiction, a well cared for pack will get significantly more cycles.
I fully recharged, and it hovered it until it landed on 10%. @ 17 minutes.
I will upload the log stuff, but haven't had a chance to look at at it yet.
I watched the battery all the way down.
The no 4 cell was well above 3.3v all the way. Still the lowest, but by a lot less.
To me, this suggests that the actual voltage across was not below 3.3, but only that the controller thinks that it is, then the fault must lie in the way the separate cells are being measured, or because of an accumulating error in the storage of the data. If the mah counter is only reset when you perform some particular action - like have a 10% , automatic landing event, then any rounding errors may add up to give a mah which is maybe 20% out over the charging life of the batteries. Maybe that is why DJI recomend doing it?
As some one so rightly pointed out - real life below 3.3v is short & possibly spectacular as well. I have had a lipo cause a ducted fan to burn & crash, rather than the more normal method.
I will upload the log stuff, but haven't had a chance to look at at it yet.
I watched the battery all the way down.
The no 4 cell was well above 3.3v all the way. Still the lowest, but by a lot less.
To me, this suggests that the actual voltage across was not below 3.3, but only that the controller thinks that it is, then the fault must lie in the way the separate cells are being measured, or because of an accumulating error in the storage of the data. If the mah counter is only reset when you perform some particular action - like have a 10% , automatic landing event, then any rounding errors may add up to give a mah which is maybe 20% out over the charging life of the batteries. Maybe that is why DJI recomend doing it?
As some one so rightly pointed out - real life below 3.3v is short & possibly spectacular as well. I have had a lipo cause a ducted fan to burn & crash, rather than the more normal method.
I had this happen once. I was over a field of tall reeds and managed to get it back to an open area before it landed. I restarted the battery and have never had an further problems with that battery.
I have taken this to cut off again & I will cycle it once more. My guess it that it will give about 20min next time.
Any bets?
Any bets?
Similar threads
