Battery Discharge

[moparherb]

I believe I saw a video on Facebook (skeptical already) that the batteries in the Mini 2 three bay charger will not self discharge if left in the normal storage position. This video suggested that you turn the batteries around so that their contact area is not in the normal storage position. I often go many weeks between Mini 2 flights and I guess I want to take as good a care of my batteries as I can. I also know it is advisable for LIPO batteries to be storage charged. Anyone else see this and is it true or just Facebook junk. Thanks to any who respond.

 

[tibzee]

This time it sounds correct. I keep the batteries in the 3-bay charger with small rubber band on them so they are inside but disconnected. I have read official statement from DJI's support member that batteries must be disconnected/removed from the 3-bay charger/drone to allow them to discharge, as described in the Mini2's manual.

 

[ATP]

I have the Mavic Mini and the Mini 2.
I read on this forum that with the Mavic Mini the battery charging hub will self discharge the batteries to a level suitable for storage, (I never tested this out as I flew it almost daily).
With my Mini 2 however I did go 4 weeks without flying, the batteries were in the charging hub. When I went flying yesterday, I did not top off the batteries charge because I read that the Mini 2 did not discharge the batteries.
After flying over a dam and deep gorge (read, unable to retrieve if anything went wrong), all three batteries showed 3 dots of battery charge and the controller indicated 20 minutes of flight time.
After 2 minutes of hovering over the spillway it displayed “Low battery”!!!!!!!!, with my wife yelling “Get it back, get it back!), I immediately moved away from the unable to retrieve area and landed, now the flight time remaining displayed 2 minutes, yikes!! All 3 of the batteries gave the same results.
Lesson learned, top off the charge prior to flight.
The voltage may have caused the controller to show 20 minutes of flying available but the charge (amps) is not providing that.
Took some time for the adrenaline to subside.

 

[old man mavic]

just store them at between 50 to 65% and always top them up before flying ,this allows the cells to get balanced

 

[moparherb]

How are you supposed to know if they are between 50-65%?

 

[old man mavic]

when they are in the hub its two solid = around 50% two solid + one flashing = 55 to 65% these are approximate readings

 

[Yogi053]

Good reminder OMM!

 

[stuka75]

Do they self discharge if left in the aircraft?

 

[moparherb]

The way I read it no. Now this is just my take and I’m referring to the Mini 2

 

[GadgetGuy]

The batteries discharge to 96% from 100% within 24 hours and to a 72% storage charge within 5 days, no matter how you store them, in or out of the aircraft, and in or out of the hub. However, turning the batteries completely on and then off during the 5 days will reset the 5 day timer to 5 more days. Merely checking the charge condition, without fully powering the battery on, is insufficient to reset the 5 day timer.

 

[Ashjuk]

The batteries discharge to 96% from 100% within 24 hours and to a roughly 60% storage charge within 5 days, no matter how you store them, in or out of the aircraft, and in or out of the hub. However, turning the batteries completely on and then off during the 5 days will reset the 5 day timer to 5 more days. Merely checking the charge condition, without fully powering the battery on, is insufficient to reset the 5 day timer.

I think you will find that's not so.

DJI have admitted that if you store your Mini 2 batteries in the hub or drone they will NOT self-discharge, which is contrary to what is in the user manual.

See this -

 

[jweaver]

The batteries discharge to 96% from 100% within 24 hours and to a roughly 60% storage charge within 5 days, no matter how you store them, in or out of the aircraft, and in or out of the hub. However, turning the batteries completely on and then off during the 5 days will reset the 5 day timer to 5 more days. Merely checking the charge condition, without fully powering the battery on, is insufficient to reset the 5 day timer.

The whole point of this discussion is the fact that this i NOT whats happening.. It seems (confirmed by DJI) that the discharge logic doesn't kick in if the battery is in the Charger or Drone.. You have to take them out for them to self discharge.

If you leave them in the charger or in the Mini2, they will stay at what ever % they were when you put them in and there is no self discharge.

 

[GadgetGuy]

The whole point of this discussion is the fact that this i NOT whats happening.. It seems (confirmed by DJI) that the discharge logic doesn't kick in if the battery is in the Charger or Drone.. You have to take them out for them to self discharge.

If you leave them in the charger or in the Mini2, they will stay at what ever % they were when you put them in and there is no self discharge.

I fully charged all three Mini 2 batteries 2 months ago to 100%, leaving two in the hub and the third in the drone. I just checked all three. The two in the hub are showing a single light and the one in the drone is showing 2 of 4 lights. This is inconsistent with the auto discharge not working. For the two in the charger to be at 25%, they must have first auto discharged to 72% after 5 days. Same with the one in the drone that only had two lights. Clearly, they are discharging. Also, prior to this, I flew the drone for several weeks and the batteries always auto discharged according to the manual, while stored in the drone and the hub. Perhaps there are different FW versions? I also would not trust any reply from DJI. They don't have any idea what they are talking about most of the time!

"...the battery will be THINKING it will be used soon and will not enter into self-discharge."

Seriously? One battery is always stored in the drone. I truly wished I could stop the auto-discharge, so I hope you are right, but my own experience says otherwise. Will do more testing. All batteries are now on the hub charging!

 

[jweaver]

I fully charged all three Mini 2 batteries 2 months ago to 100%, leaving two in the hub and the third in the drone. I just checked all three. The two in the hub are showing a single light and the one in the drone is showing 2 of 4 lights. This is inconsistent with the auto discharge not working. For the two in the charger to be at 25%, they must have first auto discharged to 72% after 5 days. Same with the one in the drone that only had two lights. Clearly, they are discharging. Also, prior to this, I flew the drone for several weeks and the batteries always auto discharged according to the manual, while stored in the drone and the hub. Perhaps there are different FW versions? I also would not trust any reply from DJI. They don't have any idea what they are talking about most of the time!

"...the battery will be THINKING it will be used soon and will not enter into self-discharge."

Seriously? One battery is always stored in the drone. I truly wished I could stop the auto-discharge, so I hope you are right, but my own experience says otherwise. Will do more testing. All batteries are now on the hub charging!

I still don't think we (or even DJI) understand how this works.

All i know is that I had all 3 batteries in my hub for several weeks as I havn't flown for a while, and they are all still showing 4 LEDs.. At first I was checking them regularly and I get this resets the timer.. But then I left them for over a week, and there was no sign of a discharge, which is inline with what DJI say.

So I have removed all 3 now and will check the capacity at some point.. But for now, I am just letting them do their thing.

 

[GadgetGuy]

I think you will find that's not so.

DJI have admitted that if you store your Mini 2 batteries in the hub or drone they will NOT self-discharge, which is contrary to what is in the user manual.

See this -

See my reply above. DJI often has no clue what they are talking about. This is hardly an admission by the company. It's a lone rep just making stuff up! The batteries don't "think!" They are programmed with an algorithm which is properly described in the manual. How does the battery "know" it is stored in the hub or in the drone to "think" it will be used soon? The power is off!

 

[jweaver]

See my reply above. DJI often has no clue what they are talking about. This is hardly an admission by the company. It's a lone rep just making stuff up! The batteries don't "think!" They are programmed with an algorithm which is properly described in the manual. How does the battery "know" it is stored in the hub or in the drone to "think" it will be used soon? The power is off!

I do agree with you.. Although they should "know" when they are installed in the hub or drone, as there is a TINY amount of current draw.. There isn't a physical power switch on these devices, so they are always in "standby" taking some current.

The issue is that your experience differs from many (including myself).. So right now, there is confusion as DJI claim that they only way the discharge feature works is by removing the batteries so they are PHYSICALLY disconnected from any device.

I assume they are aware of this confusion and are working to clarify this, whethre in an update to the docs, or by a firmware change.

 

[GadgetGuy]

I still don't think we (or even DJI) understand how this works.

All i know is that I had all 3 batteries in my hub for several weeks as I havn't flown for a while, and they are all still showing 4 LEDs.. At first I was checking them regularly and I get this resets the timer.. But then I left them for over a week, and there was no sign of a discharge, which is inline with what DJI say.

So I have removed all 3 now and will check the capacity at some point.. But for now, I am just letting them do their thing.

Agreed! Trust the written manual over what any DJI rep writes in an email!
In order for the rep to be correct, there must be something about connecting a powered off battery to the drone and the hub that is telling the battery to bypass the discharge algorithm, and the 96% discharge after 24 hours must also not be working. The battery lights can also be very misleading. Check the battery percentage by booting up the battery in the drone. If the battery in the drone is at 96% after 24 hours (all mine always have been,) it is properly auto-discharging. I'm going to do further testing to see if I can get the batteries to not discharge, which is what I personally want! Not worried about battery swelling after a year, which was the issue with Mavic 2 batteries left fully charged for 10 days at a time. More concerned about flight time, and being able to fly spontaneously!

 

[GadgetGuy]

I do agree with you.. Although they should "know" when they are installed in the hub or drone, as there is a TINY amount of current draw.. There isn't a physical power switch on these devices, so they are always in "standby" taking some current.

The issue is that your experience differs from many (including myself).. So right now, there is confusion as DJI claim that they only way the discharge feature works is by removing the batteries so they are PHYSICALLY disconnected from any device.

I assume they are aware of this confusion and are working to clarify this, whethre in an update to the docs, or by a firmware change.

I wouldn't assume DJI is doing anything, or that they are even aware of what the rep is claiming is true. No FW change or document update will happen until a bug can universally be proven to exist. Right now, it's just a few anecdotes that may be attributed to user error, or a small bad batch of batteries. I can't confirm the bug. I also can't imagine why DJI would suddenly reverse course on their battery management and decide to deliberately stop auto discharge. The fact that the rep is making up a "thinking battery" justification for this apparent bug is a tribute to the rep's complete ignorance. Stay tuned.

 

[GTone]

It would appear my packs do drop down to 3 LEDs(75%) on the indicators after sitting in the hub after a couple weeks.
That seems correct.
The danger for lipo packs are draining them too far, killing the cell as that is usually not recoverable, or left fully charged and sitting doing nothing as the chems react still and it will over volt, swelling the cell.
I do not profess to know much about these dji packs, but after a few years of RC with lipos you learn really quick what lipo batteries like as it gets expensive to replace them often.

 

[GadgetGuy]

It would appear my packs do drop down to 3 LEDs(75%) on the indicators after sitting in the hub after a couple weeks.
That seems correct.
The danger for lipo packs are draining them too far, killing the cell as that is usually not recoverable, or left fully charged and sitting doing nothing as the chems react still and it will over volt, swelling the cell.
I do not profess to know much about these dji packs, but after a few years of RC with lipos you learn really quick what lipo batteries like as it gets expensive to replace them often.

They should auto-discharge to 72% after 5 days and should remain at that charge indefinitely, only losing a few percent a week thereafter, like all other Lipos.