I finally lost my Phantom - not a "flyaway"
- Thread starter Gnormand
- Start date
Kind of. My understanding is a cycle is at least half a charge. So if your battery is at 70% and you charge it fully, that doesn't count as a cycle. If your battery is at 30% and you charge it fully, that counts as a cycle.
OK...I registered with Healthy Drones and researched my flight...I see the voltage discrepancies...but got no warning on the controller until
it was already too late. relatively new battery- charged 24 times. What could I have done or known before the flight that would have changed
the situation? How do you check a battery to see if it might go bad after the bird is launched?
it was already too late. relatively new battery- charged 24 times. What could I have done or known before the flight that would have changed
the situation? How do you check a battery to see if it might go bad after the bird is launched?
From my understanding of the situation you would improve the number of cycles but not double them, the data I have seen kept the same low voltage level cutoff so therefore reduced the effective power of the battery by 14% by reducing the charged voltage by 0.1V. Remember the battery life is also affected by the DoD (depth of discharge) and part of the increased cycle life was gained from also reducing that DoD.
Your scenario keeps the same DoD although it is the higher voltages that have more effect on battery life than lower ones so they would be some increase in life but I can't say how much. The maximum cumulative amount of power that can be stored and retrieved from a Lithium battery over its life uses a 50% DoD from approximately 20% to 70% but no one only wants 50% of available power if they can have double that without a drastic reduction in life.
The manufacturers (not just DJI) have tried to achieve a balance between battery life and power with their smart control systems and have succeeded. If you want to you can extract 50% more power from a Lithium battery by raising the fully charged voltage by 0.2v and lowering the minimum voltage by the same amount but you would shorten the its life by a factor of 16!!
Remember the best way to have long and useful life from your battery is to store it below 3.92V (58%) (but above 3.0V) and below 30 C (86 F). Ignoring both of these guidelines simultaneously will SEVERELY shorten battery life. Heat and high voltage will put your battery in the recycle bin, one or the other will just land it there a bit sooner than planned.
That's not a bad way of looking at it. A battery can have 2000 to 2500 25% DoD cycles so you could nearly ignore them!! It can have 1200 to 1500 50% DoD cycles so that's fairly good too but only 300 to 500 100% DoD because we all want to fly for as long as we can.
Sorry charge and discharge is a cycle. For ease of measurement they are assumed to be the same percentage where in the real world they will often be different.
I don't even have my Phantom yet so others maybe able to help there but from my battery knowledge I suspect that cell 1 would have been dragging the chain for at least last couple of flights assuming they were recent ones. Cell 4 was only just starting to go so may not have been noticeable previously.
Only 24 cycles, that's horrific, assuming the battery hasn't been abused that would have to be worth a claim from DJI but I guess you have to find it first.
If strong winds are suspected a quick flick to "atti" mode as soon as you had reached your flight altitude would have determined which way the wind was blowing and how strongly so you could be more prepared for what lay ahead.
That was my point earlier, you MIGHT get 40% more cycles form a pack by limiting DOD to 50% (in reality most won't run down to 100% DOD and your numbers, with respect to DJI packs, are academic only as the smart board won't allow 100% dod).
And yes we all want longer air time and if that means we get 200 good flights as opposed to hovering awound in close with one eye on the battery % and spreadsheeting battery cost per flight I know which I'm going with.
So Gnormands battery is cactus after 24 cycles, does anyone else want to share their battery experiences. Perhaps you could also share if you use you batteries conservatively or not and whether you have made some mistakes with storage.
I would call that 2 x 50% DoD cycles which reduces your battery life by about half the amount of 1 x 100% DoD cycle.
You call it whatever you like, DJI calls both scenarios one cycle. Not everything you read on battery university is current for the new HV LiPO's.
Fair enough, due you know of any real world battery life experiences that you can share with us.
You have covered most, in fact probably all the relavent LiPO chemistry considerations. From a practical perspective I charge as close as possible to when I propose to fly, that often means i stick four packs on the charging hub with a timer before going to bed. I usually plan to land with somewhere above 20% charge although more than once I have been below 3% when I judged poorly. I store packs at 50%. I keep track of the mah put into packs and use that, along with cell variations as the key indicators of condition. I favor my strongest packs for flights out over water or in other circumstances where a mishap may see me loose the AC (no opportunity to recover following a forced landing).
Can you check these batteries with a voltage tester before employing them for flight to make sure they read 15.2 v ? What voltage are the prop motors rated for? From my experience with wet cell batteries, the older or more used the battery, the faster they discharge and the more difficult it is to reach full voltage charge .
Meta4
Premium Pilot
- Joined
- Jan 8, 2014
- Messages
- 15,303
- Reaction score
- 9,247
I doubt if anyone could go wrong with that advice, I expect you extract a long and healthy life from your batteries. May I ask two questions and anyone else please feel free to add your own answers.
Q1 As a battery ages do you have to put more mAh in to give you the same charge level or does the mAh in and indicated charge level stay constant with the amount of output power decreasing.
Q2 The most important question, how many cycles do you obtain out of a new battery before it is not worth using, is there much variation between the life of different packs and if there is a variation is it due to different treatment or just random.
For those that fly near tall buildings, set the RTH to 100m - 200m. In the case of losing signal, it maybe able to ascend high enough to regain. It wont help if your battery is low though.
And if you are struggling with head winds, use ATTI/Sports mode to get more angle/speed and try to get low for less wind (make sure you are in visual range).
And if you are struggling with head winds, use ATTI/Sports mode to get more angle/speed and try to get low for less wind (make sure you are in visual range).
OK guys-I posted the original thread . I'm trying to figure out what I could have done differently, so this doesn't happen again.
1. Yes, I was high...but no higher than I've done in that location several times before-my quest was to get the perfect shot of the sun rising behind this tall building.
2. Yes, the wind was high...but no higher than I've flown easily in before.
3. The way I see it-when I got to altitude, and as I was changing settings on the camera, I noticed the bird moving North with the wind...I DID NOT send it that direction..apparently,
some sensor in the aircraft saw a 0.1 to 0.2 volt discrepancy between cells-and must have cut power to the motors. That is the problem...a bird going 5-7 mph is not gonna overcome
a wind of 20+ mph....but HOW was I supposed to know the cell was going to drop voltage at that time and that altitude? I looked at the DJI go app...the voltages looked good, and there
was not a warning until it was too late.
4. The aircraft going behind the other tall buildings was not my instruction...it did it because the "smart" sensors in the bird reduced power...thereby creating a situation where
I couldn't bring it home.
5. When an aircraft is no longer in control by the pilot (me) who is trying to bring it back, and it is not doing as instructed-it is a flyaway....what else could it be? It's gone...
to the person running this forum who changed my title....I've read all the highly technical posts regarding charging and discharging, and how many cycles, etc...
this was a relatively new battery with 24 cycles......please tell me what YOU would have done in the same situation that would have resulted in a better outcome.
1. Yes, I was high...but no higher than I've done in that location several times before-my quest was to get the perfect shot of the sun rising behind this tall building.
2. Yes, the wind was high...but no higher than I've flown easily in before.
3. The way I see it-when I got to altitude, and as I was changing settings on the camera, I noticed the bird moving North with the wind...I DID NOT send it that direction..apparently,
some sensor in the aircraft saw a 0.1 to 0.2 volt discrepancy between cells-and must have cut power to the motors. That is the problem...a bird going 5-7 mph is not gonna overcome
a wind of 20+ mph....but HOW was I supposed to know the cell was going to drop voltage at that time and that altitude? I looked at the DJI go app...the voltages looked good, and there
was not a warning until it was too late.
4. The aircraft going behind the other tall buildings was not my instruction...it did it because the "smart" sensors in the bird reduced power...thereby creating a situation where
I couldn't bring it home.
5. When an aircraft is no longer in control by the pilot (me) who is trying to bring it back, and it is not doing as instructed-it is a flyaway....what else could it be? It's gone...
to the person running this forum who changed my title....I've read all the highly technical posts regarding charging and discharging, and how many cycles, etc...
this was a relatively new battery with 24 cycles......please tell me what YOU would have done in the same situation that would have resulted in a better outcome.
Similar threads
