Mini 2 and battery maintenance

[4 inch pistons]

So I got the fly more with the multiple battery charger but I know LiPos need maintenance. So when I charge both and only use one, what do I do? What do you do?

 

[slup]

Below is from page 21 in the user manual...


But if you often have this problem with returning with fully charged batteries, the auto discharge function isn't the best for your battery... a battery should as quickly as possible return to storage voltage level (at least within 48h), meaning be placed on 3,8v/cell. That correlates to 50% charged, but anywhere between 30-60% is good enough. So as you see...the auto discharge both take too long & places the battery on a too high charge level.

If too high, hover it down... too low, charge it & take it off the charger between one solid LED + one blinking up to two solid LED's + one blinking.

 

[GadgetGuy]

Below is from page 21 in the user manual...
View attachment 157417

But if you often have this problem with returning with fully charged batteries, the auto discharge function isn't the best for your battery... a battery should as quickly as possible return to storage voltage level (at least within 48h), meaning be placed on 3,8v/cell. That correlates to 50% charged, but anywhere between 30-60% is good enough. So as you see...the auto discharge both take too long & places the battery on a too high charge level.

If too high, hover it down... too low, charge it & take it off the charger between one solid LED + one blinking up to two solid LED's + one blinking.

Or, just let DJI's Auto-Discharge Function do its thing. That's what most of us do. These batteries are items of consumption, and should be good for 200+ full cycles. Every time you charge them up and then bleed them down to 50% without using them to fly is using up an extra half cycle. So fly with them instead of bleeding them down! That's what they are for! You have 9 days to do so!

 

[slup]

...let DJI's Auto-Discharge Function do its thing. That's what most of us do...

How do you know that?

But pure logical it's plausible as it's the default action if not doing anything. But it's hardly due to that's the best for the batteries, it's more of a failsafe no more... the reason is rather due to that the "average Joe" doesn't know better & lack deeper knowledge.

These batteries are items of consumption, and should be good for 200+ full cycles...

Consumables ... agreed. But an important one as it keeps your craft airborne.

Batteries will never be a problem if you're upgrading yearly & never experience the batteries end of life... batteries have a limited life span, how you treat them will determine both how long service life you will get out of them & more important HOW the service life will be ended.

Either the battery slowly degrades giving you shorter & shorter usable airtime until you buy a new one... or it gives up mid air with failing cells dropping below 3V/cell triggering a forced low battery voltage auto landing you can't stop in the worst possible place or rapidly swells during flight causing a disconnect with a freefall as a consequence. The later disastrous events is in most cases caused by how the battery have been treated.

Unfortunately we see far too many incidents here at the forum coming from battery failures to say "don't worry just be happy".

 

[GadgetGuy]

How do you know that?

But pure logical it's plausible as it's the default action if not doing anything. But it's hardly due to that's the best for the batteries, it's more of a failsafe no more... the reason is rather due to that the "average Joe" doesn't know better & lack deeper knowledge.


Consumables ... agreed. But an important one as it keeps your craft airborne.

Batteries will never be a problem if you're upgrading yearly & never experience the batteries end of life... batteries have a limited life span, how you treat them will determine both how long service life you will get out of them & more important HOW the service life will be ended.

Either the battery slowly degrades giving you shorter & shorter usable airtime until you buy a new one... or it gives up mid air with failing cells dropping below 3V/cell triggering a forced low battery voltage auto landing you can't stop in the worst possible place or rapidly swells during flight causing a disconnect with a freefall as a consequence. The later disastrous events is in most cases caused by how the battery have been treated.

Unfortunately we see far too many incidents here at the forum coming from battery failures to say "don't worry just be happy".

I know that because most of us just leave the batteries alone to do their thing because most don't know any different, or are happy to leave it as is, like I am. DJI's current default action is a areasonable compromise that involves no user battery maintenance, other than recharging them after use.

Using it alone, I still have P3P and P4P batteries that I only need to top off every few months when they drop below two bars. They are now 3-6 years old and still performing well, albeit with less flight time, exactly as expected. No catastrophic failures from doing so.

Concluding that the rare, disastrous battery failures you describe are in most cases caused by letting DJI batteries auto-discharge is completely unfounded. They are usually caused by not properly topping off the batteries before flight to 100% which includes rebalancing the cells. I've had such a battery failure, due to a cold P3P battery, and assuming that an 80% readout in the app was accurate, and an immediate ascension to 400 feet. To protect the battery, the algorithm at the time would shut off the battery, even in flight, when any cell even momentarily dropped below 3.0V. That has fortunately been changed to a forced Auto Land.

Most of us do upgrade our aircraft every few years, making the absolute best battery maintenance unnecessary, and overkill. It may slow down the degradation in flight time, and might extend the useful life, but you failed to address that deliberately reducing the battery from 100% to 50% manually is also using up a half charge cycle of the total useful charge cycles, that could be used for flight, any time within the next 10 days, which is also reducing the useful life of the battery.???

Everything is a compromise. Each user has to decide for themselves what works best. No battery will last forever, and neither technique will lead to crashes! DJI's current algorithm works best for almost everyone.

 

[slup]

...Everything is a compromise. Each user has to decide for themselves what works best...

Here we are fully in agreement without a doubt... but I add "with knowledge" better decisions can be made & consequences from compromises can better be understood.

What degrades LiPo & LiIon batteries are repeated "abuse"... that includes a lot of thing's with different severity, some only affect the capacity which leads to shorter flight times, other speed up the electrolyte breakdown causing swelling & some treatment cause increased internal resistance... which heats up the battery more than normal & cause rapid & deeper voltage drops during load... which increases the risk for swelling & further electrolyte breakdown.

...Concluding that the rare, disastrous battery failures you describe are in most cases caused by letting DJI batteries auto-discharge is completely unfounded...

Never said that... I said treatment.

Abuse is rarely deliberate... it comes with ignorance that affects how the battery will be treated overall. Having a automated process is nice, it will save the batteries enough long until knowledge have been gained... but the automated process isn't the best way if you want to care for your batteries & prevent mishaps as much as you can.

So the OP does the right thing with his post... he's learning & by that is better suited to treat his batteries based on knowledge.

...disastrous battery failures... are usually caused by not properly topping off the batteries before flight to 100% which includes rebalancing the cells.

Have investigated nearly all incidents here at the forum during almost 3 years now, & can't recall that, as a most common cause. Usually the root cause is unknown & all that can be said is that the battery possibly have been badly treated in the past... & very often it turns out that the OP's have very little knowledge about battery care & haven't paying attention to all the earlier signs of a failing battery.

An unbalanced cell is in it's own an early sign of a failing cell... no matter if it became unbalanced during flight, during storage or during the automated discharge. A healthy cell shouldn't deviate more than max 0,1V no matter what.

Just recently got twenty new 850mAh 4S 95C Tattu R-Line batteries replaced for free as most of them showed cell deviations up to 0,07V ... & that after being used & discharged to 3,5V/cell where the deviation is expected to be worst.

So if a cell falls rapidly due to that the battery wasn't fully charged... the root cause wasn't "not fully charged" it was due to a weak bad cell that needed a balance cycle to work over that single flight.

...you failed to address that deliberately reducing the battery from 100% to 50% manually is also using up a half charge cycle of the total useful charge cycles...

OK, fair... let me correct that then.
The number of charge cycles aren't even close to be in the same ballpark as other mistreatments when it comes to wear that can degrade batteries to a level where they no longer keep the drone airborne & instead suddenly fails. If comparing a repeated full SOC storage during 10 days with a prolonged heating with a battery perhaps stored in a closed bag with a half charge cycle, the later is negligible when it comes to a increased risk for a sudden battery failure... it will at most affect the capacity & thereby only the flight time.

...I still have P3P and P4P batteries that I only need to top off every few months when they drop below two bars. They are now 3-6 years old and still performing well, albeit with less flight time, exactly as expected. No catastrophic failures from doing so...

I'm not especially surprised... larger capacity & number of cells are usually much more resilient towards wear & tear.

1S low capacity batteries can easily be killed if leaving them out of storage voltage level between 2 flight occasions one time... if unlucky.

A P3 or P4 battery is like 4500-5500+mAh... so if the general treatment & battery knowledge is overall good & the battery is monitored in a good way regarding voltage drops, remaining capacity, cell deviations during use, rarely left empty longer periods & topped up during long term storage... a failure shouldn't come unannounced.

 

[GadgetGuy]

Here we are fully in agreement without a doubt... but I add "with knowledge" better decisions can be made & consequences from compromises can better be understood.

What degrades LiPo & LiIon batteries are repeated "abuse"... that includes a lot of thing's with different severity, some only affect the capacity which leads to shorter flight times, other speed up the electrolyte breakdown causing swelling & some treatment cause increased internal resistance... which heats up the battery more than normal & cause rapid & deeper voltage drops during load... which increases the risk for swelling & further electrolyte breakdown.


Never said that... I said treatment.

Abuse is rarely deliberate... it comes with ignorance that affects how the battery will be treated overall. Having a automated process is nice, it will save the batteries enough long until knowledge have been gained... but the automated process isn't the best way if you want to care for your batteries & prevent mishaps as much as you can.

So the OP does the right thing with his post... he's learning & by that is better suited to treat his batteries based on knowledge.


Have investigated nearly all incidents here at the forum during almost 3 years now, & can't recall that, as a most common cause. Usually the root cause is unknown & all that can be said is that the battery possibly have been badly treated in the past... & very often it turns out that the OP's have very little knowledge about battery care & haven't paying attention to all the earlier signs of a failing battery.

An unbalanced cell is in it's own an early sign of a failing cell... no matter if it became unbalanced during flight, during storage or during the automated discharge. A healthy cell shouldn't deviate more than max 0,1V no matter what.

Just recently got twenty new 850mAh 4S 95C Tattu R-Line batteries replaced for free as most of them showed cell deviations up to 0,07V ... & that after being used & discharged to 3,5V/cell where the deviation is expected to be worst.

So if a cell falls rapidly due to that the battery wasn't fully charged... the root cause wasn't "not fully charged" it was due to a weak bad cell that needed a balance cycle to work over that single flight.


OK, fair... let me correct that then.
The number of charge cycles aren't even close to be in the same ballpark as other mistreatments when it comes to wear that can degrade batteries to a level where they no longer keep the drone airborne & instead suddenly fails. If comparing a repeated full SOC storage during 10 days with a prolonged heating with a battery perhaps stored in a closed bag with a half charge cycle, the later is negligible when it comes to a increased risk for a sudden battery failure... it will at most affect the capacity & thereby only the flight time.


I'm not especially surprised... larger capacity & number of cells are usually much more resilient towards wear & tear.

1S low capacity batteries can easily be killed if leaving them out of storage voltage level between 2 flight occasions one time... if unlucky.

A P3 or P4 battery is like 4500-5500+mAh... so if the general treatment & battery knowledge is overall good & the battery is monitored in a good way regarding voltage drops, remaining capacity, cell deviations during use, rarely left empty longer periods & topped up during long term storage... a failure shouldn't come unannounced.

With all due respect, I haven't seen anything to indicate that anyone's DJI batteries are failing as a result of letting DJI's auto-discharge algorithms manage them, which is my main point. Surely, you aren't suggesting that doing so is abuse. It may not be optimal to maximize battery life, but it is optimal for flying, which should be the real priority for a drone used for spontaneously capturing decisive moments. Cell failures happen completely independently of how batteries are maintained. Your points appear to be more relevant to batteries in general, while mine are specifically limited to DJI batteries (larger capacity and number of cells, that are more resilient towards wear and tear) where they are promptly recharged after use, and the user lets the battery algorithms manage the batteries until next use, where they are then topped off before flight. Battery voltage is also easily monitored in the app, where the lowest cell voltage can be compared to the other cells, and deviations noted, and using AirData can also flag failing batteries, no matter how they are maintained, before a catastrophic failure occurs.

Bottom line: one has to prioritize either battery life or readiness for flight, and they are mutually exclusive. Readiness for flight requires fully charged batteries at all times. Optimal battery storage requires storing all batteries at 50%, which then requires time to charge them to 100% before use, meaning spontaneous flight is not possible. DJI's battery auto discharge algorithm provides a reasonable compromise that prioritizes flight readiness over optimal battery life. Works for me, and everyone else who lets DJI manage their batteries. I also buy new batteries any time flight time deteriorates below what I need. They are consumables, and not collectibles to be saved posterity, beyond the useful life of the drone for which they were designed.

 

[slup]

...letting DJI's auto-discharge algorithms manage them...Surely, you aren't suggesting that doing so is abuse...

If I had suggested that I wouldn't have included that cutout from the manual in my first post... but depending on the OP's unknown knowledge level I also included a more thorough method with the battery health in focus to spark an interest in getting more knowledge & a better understanding of that batteries aren't just any hardware which lasts as long he wants to use the equipment... hopefully our discussion have given him something which possibly will gain him in the long run...

...It may not be optimal to maximize battery life, but it is optimal for flying, which should be the real priority for a drone used for spontaneously capturing decisive moments...

...Your points appear to be more relevant to batteries in general, while mine are specifically limited to DJI batteries

The OP isn't describing any kind of use case including readiness for flight or spontaneity, he's just wondering what to do with fully charged unused batteries... this together with being a new member here at the forum & otherwise might be new in the hobby... but granted, readiness & spontaneity is valid thing's to consider when value the consequences.

...I instead try to give deeper knowledge about Lithium batteries, both in general & specific to DJI ones so the OP gets knowledge about the different alternatives & possible impact on the batteries depending on different treatment.

A DJI battery isn't much else than an ordinary generic LiPo battery pack besides that is has a BMS chip... nothing magic about it. The auto discharge is a "better than nothing" failsafe slightly lessen the most impacting misuse... storage with a high SOC.

Unfortunately DJI have stepwise made this functionality worse over time... in the past you could turn down the time as low as 2 days if I'm remembering it correctly, if that was still possible nowadays on the newer crafts it would be much better... & even better if the percentage level also could be manually set... why place it at 72%?

...Cell failures happen completely independently of how batteries are maintained...

In this we need to agree that we disagrees... besides occasional manufacturing errors, how you use them, how you handle them & age means almost everything when it comes to an increased risk of cell failures.

I also buy new batteries any time flight time deteriorates below what I need. They are consumables, and not collectibles

All my points have nothing to do with prolonging the battery life ... that only comes as a positive consequence.

It's all about how they possibly might end their life... in a sudden catastrophic event where you maybe lose the drone & damage something or someone... or a slow capacity degradation ending with short flight times that dissatisfy.

 

[4 inch pistons]

Thanks so much for all of the responses. I must confess, I am not new to RC and batteries, only new to quads and their unique power requirements.

I flew RC airplanes of every size and shape from twin cylinder gasoline giant scale to .40 glow planes for about 20 years. Back then if was NiCads---then NiMH---then Lithium ion---then A123 and even some LiPo, but they were all for the receiver and servos. I never really flew electric as that was just getting popular as I was getting out.

But all of these brushless motors and ESC and cameras have different requirements. The charges I had back in the day, were expensive but they were also "maintainers" and not just chargers. I am still just feeling my way around. I get so excited learning this stuff all over again.

Thanks again.

 

[GadgetGuy]

If I had suggested that I wouldn't have included that cutout from the manual in my first post... but depending on the OP's unknown knowledge level I also included a more thorough method with the battery health in focus to spark an interest in getting more knowledge & a better understanding of that batteries aren't just any hardware which lasts as long he wants to use the equipment... hopefully our discussion have given him something which possibly will gain him in the long run...


The OP isn't describing any kind of use case including readiness for flight or spontaneity, he's just wondering what to do with fully charged unused batteries... this together with being a new member here at the forum & otherwise might be new in the hobby... but granted, readiness & spontaneity is valid thing's to consider when value the consequences.

...I instead try to give deeper knowledge about Lithium batteries, both in general & specific to DJI ones so the OP gets knowledge about the different alternatives & possible impact on the batteries depending on different treatment.

A DJI battery isn't much else than an ordinary generic LiPo battery pack besides that is has a BMS chip... nothing magic about it. The auto discharge is a "better than nothing" failsafe slightly lessen the most impacting misuse... storage with a high SOC.

Unfortunately DJI have stepwise made this functionality worse over time... in the past you could turn down the time as low as 2 days if I'm remembering it correctly, if that was still possible nowadays on the newer crafts it would be much better... & even better if the percentage level also could be manually set... why place it at 72%?


In this we need to agree that we disagrees... besides occasional manufacturing errors, how you use them, how you handle them & age means almost everything when it comes to an increased risk of cell failures.


All my points have nothing to do with prolonging the battery life ... that only comes as a positive consequence.

It's all about how they possibly might end their life... in a sudden catastrophic event where you maybe lose the drone & damage something or someone... or a slow capacity degradation ending with short flight times that dissatisfy.

Between the two of us, I think we have covered the subject well, from both perspectives, with respect.

 

[thomasoes]

 

[Suzygs1000]

Well, I think but not sure the pp3 and 994 batteries are Lion? The batteries in the newer drones are lipo's, which are nowhere near as stable as Lion . (the reason they are not being considered for electric vehicles at this stage ).. There have been experiments with Lion 4 cell packs for RC airplanes which have been fairly successful, tho the batteries ( which I recall were 10C) were twice the price of equivalent Lipo's, and had fairly regular failures in one or more cells. I have one 4 cell Lion pack which I have been using for three years, don't look after it, don't discharge it, it just sits, and is always ready to go. All of my other batteries are lipos, and I have to say that trying to pull too much current from them, or leaving them fully charged, stuffs them up pretty quick. Both my Mavic SE and Mini 2 fly perfectly on the original Mini (Li-on) battery, with very little reduction in flight times, and no NOTICEABLE loss of power. If I need to replace my Mini Li-po's in the future, I will be buying the Mini Li-on's, as long as they are still available.