Air 3 Combo Batteries Discharging from 100% to 58% in 30 Days?

[Meta4]

Can someone tell me if the auto discharge feature damages the batteries?

Leaving batteries fully charged for long periods damages them.
The auto discharge feature was introduced to reduce damage to batteries.

 

[Max Headroom]

Can someone tell me if the auto discharge feature damages the batteries?

It wouldn't do DJI's reputation any favours if they invented and sold a smart battery knowing it damages itself in the process of keeping itself safe.

 

[Felix le Chat]

Can someone tell me if the auto discharge feature damages the batteries?

On the contrary: auto discharge will keep the battery in a state where its long term performance is less likely to become degraded.

It can be annoying when you have stored your kit for a few days, decide to head out on the spur of the moment and find that all your IFB's are only showing 3 LED's... but I'd rather have that and face watching them charge for an hour than end up with a set of very expensive bloated (gassed) batteries that I daren't use.

Originally, DJI programmed the flight batteries to hold charge for 10 days before significant self-discharge (Mavic 2 batteries still have that option in the GO4 app), then the firmware updates altered that to a 2 day threshold.

 

[Max Headroom]

I noticed for the Air3 mentioned earlier in the thread the instructions say they drop to 60% after 9 days -



For mini 2 etc they drop to 72% after 9 days -

Smart batteries allow you to charge the batteries and store them safely so they are ready for your next outing if that is within 9 days you will not need to charge them again.

Read #2 below - they drop to 96% after one day then stay at 96% for a further 8 days when they discharge themselves to 72%.

 

[Droning on and on...]

Can someone tell me if the auto discharge feature damages the batteries?

No, it does not. In fact, it preserves them.

As others have pointed out, though, you can still engage a charging pattern that will reduce life.

Charging to 100%, allowing self-discharge, then charging up to 100% again when you actually fly is a wasted charge cycle. Charging stresses the battery. More than discharge per watt-hour. That's why charge and discharge current ratings are asymmetric.

 

[Cafguy]

Can someone tell me if the auto discharge feature damages the batteries?

No it will not BUT you not checking on the condition of your batteries for a few months- CAN. the Batteries still are using power even after they discharge to a certain amount. If you let this go for to long you will have a battery that wont charge.

 

[AroundTheWorld]

Thanks guys for all your answers.Glad to hear that I haven't damaged my batteries by letting them discharge automatically, as this has happened to me more than once.

 

[Cafguy]

The problem comes from those who charge and forget! not that the batteries discharge on their own. Just remember they will keep discharging until you use them. You will be fine doing it your way.

 

[Max Headroom]

Charging to 100%, allowing self-discharge, then charging up to 100% again when you actually fly is a wasted charge cycle

That is correct but as discussed several times if you know you are going to fly again in the next 9 days you won't need to charge again as the battery will be at 96%, if you are not going to fly in the next 9 days charge them to 75%.

 

[Erk1024]

If your batteries are very low when you have been out flying and you plan to fly in the next 9 days why not charge them fully then they are ready rather than wait until the day you plan to fly and you have to charge them from a very low charge state which can take quite a while if you have more than one, if you also keep them charged they are ready in case you decide to go out on an unplanned flying session.

The reason is that the degradation happens over time while they are at full charge. So if you charge them to 100% and then go fly, they aren't spending much time at 100%. But ... having said all this, if you cycle the three batteries in your fly-more combo 500 times each, then you've gotten your use out of the drone. At which point you're probably due for an upgrade, or you can always pick up fresh batteries. So feel free to ignore all this advice.

 

[Droning on and on...]

That is correct but as discussed several times if you know you are going to fly again in the next 9 days you won't need to charge again as the battery will be at 96%, if you are not going to fly in the next 9 days charge them to 75%.

That's not what I was talking about.

 

[riterb97]

Here are my concerns and questions:

1. Is this normal? I doubt it. If not, what could explain such a large discharge in relatively new batteries? During all my flights, I’ve only received low battery landing warnings 2-3 times. Airdata shows the battery health at 98-99%, which makes this steep drop puzzling.
2. What could be causing this discharge? Do others have similar experiences with their batteries?
3. Why is there such a big discrepancy between the "Times Charged" reported by Airdata and the Log Files?

@Max Headroom @Cafguy @Felix le Chat @Meta4

Hi everyone,
Thank you all for the valuable tips on charging and discharging. I found the information both educational and helpful.
Could someone please address my Point 3?
Thank you!

 

[Erk1024]

No it will not BUT you not checking on the condition of your batteries for a few months- CAN. the Batteries still are using power even after they discharge to a certain amount. If you let this go for to long you will have a battery that wont charge.

Yes! 100%. I killed two Mavic 2 Pro batteries this way.

 

[Paulomatic]

Why do this when the batteries are designed to do it automatically from 100% charge?


View attachment 178235

As someone who has been flying electric powered RC models since the late 70's I'll explain-

I assume they had the option to set the time to discharge to as many days as they felt necessary so i trust 9 is not going to do any harm.

As someone who has been flying electric powered RC aircraft since the late 70's I'll tell you- the DJI battery maintenance system is terrible. It waits much too long to discharge back to storage level causing long term damage to the battery. It's better than no discharge system at all, but it will absolutely do slight cumulative damage over time.
When I fly my planes, I charge the night before or the same morning, then return all batteries to storage level that evening. I have some 20 year old Lipo packs that still put out over 80% of capacity. My first three Air2s packs died of horrible swelling within two years (I fly a lot.)

 

[Paulomatic]

It wouldn't do DJI's reputation any favours if they invented and sold a smart battery knowing it damages itself in the process of keeping itself safe.

That is EXACTLY what DJI did. Their discharge system is slightly better than none at all, but only slightly.

 

[Max Headroom]

That is EXACTLY what DJI did. Their discharge system is slightly better than none at all, but only slightly.

Have you any evidence to back that claim up?

 

[Droning on and on...]

That is EXACTLY what DJI did. Their discharge system is slightly better than none at all, but only slightly.

I disagree very strongly.

I design and build power banks.

 

[Droning on and on...]

Can someone tell me if the auto discharge feature damages the batteries?

As a general answer, no.

More detailed, the most damage is done when using the battery – (relatively) high current charging and discharging.

Many think there is some sort of uniform issue with lithium ion batteries that results in damage while fully charged or discharged. While this is most often the case, it is not a general rule, it's a design parameter. There are lithium ion cells designed specifically for long term energy storage and can stay at 95% charge for years, with very little leakage losses.

I have no idea what cells are used in all these different battery modules, and DJI doesn't use the same cell type and spec in every drone.

I do, however, have a great deal of respect for DJI's engineers. If the power system is engineered with the same skill and excellence as everything else they make, I highly doubt it makes any meaningfull difference to discharge to storage in 3 days vs. 9. If it did, the BMS would discharge to 60% in 3 days.

 

[Droning on and on...]

Originally, DJI programmed the flight batteries to hold charge for 10 days before significant self-discharge (Mavic 2 batteries still have that option in the GO4 app), then the firmware updates altered that to a 2 day threshold.

It's a (better) two-stage process now... down to 93% after a few days, then down to 60% after 9.

 

[Max Headroom]

I disagree very strongly.

I design and build power banks.

Oh dear that's going to ruin his day