Hi,
I would to use powerbank as external power bank (and to discharge noused fully battery) with a charge connected.

Is there a protection in the battery to prevent overdischarge, did battery go to hibernation mode itself?
I dont want made the test to avoid a dammaged battery.

Olivier

I don't think the batteries are that intelligent, since they say in manual to"manually" discharge them while not in use.

I ran this exact test yesterday, with 3 full batteries in the Hub and using it as a power bank.  It drew down one pack then went on to a second one.  After this testing, the first pack recharged as normal, so I'd say it is safe to do this.

Thank a lot,
Minnesota, what's happen with just one battery? Delivery external stop when battery drew down??

Zolive Posted at 1-15 02:35
Thank a lot,
Minnesota, what's happen with just one battery? Delivery external stop when battery drew down??

YES.  I will post a video in a bit showing how one pack finishes and the next one starts up.

Thanks a lot for this Minnesota.

Questions.....

How far down does it discharge a battery, before moving to the next? A reference to what the lights indicated would be good.
Does it stop charging when all the batteries have reached a certain discharge level, or does it continue till the device being charged is fully charged.

Many thanks!

This answers the above questions.  

Every powerbank needs to have voltage cutoff protection, so it doesn't make sense if it's not present in DJI charging hub (as using intelligent flight battery as power bank is mentioned in users guide). But DJI representative should confirm that...

StubbornSwiss Posted at 1-15 04:42
Thanks a lot for this Minnesota.

Questions.....

If the capacity of charged device is higher than available capacity in DJI hub, it must stop charging at safe level. Othervise the flight battery can be demaged.

virtual Posted at 1-15 05:14
If the capacity of charged device is higher than available capacity in DJI hub, it must stop charging at safe level. Othervise the flight battery can be demaged.

Since the output port of the Hub is ~5V, it's hard to know precisely at what voltage and capacity level the "7.2V" battery packs go from 1 blinking LED to none.   

Thank a lot.
I fact i would discharge one fully not used battery without care while discharging.
I havent found to buy a  battery connector to plug with my special automatic lipo/lion discharger (it stop when voltage is above 7.6v (for 2 elements).
So i would discharge my not-used battery by the usb output  by using a charge as a resitor 3 ohm /10W  (or 50w12v car light).
But i wonder if the is a battery protection when the voltage of battery reach 2x3V (6v) and if the battery or hub disconnect the usb output.

Zolive Posted at 1-15 05:36
Thank a lot.
I fact i would discharge one fully not used battery without care while discharging.
I havent found to buy a  battery connector to plug with my special automatic lipo/lion discharger (it stop when voltage is above 7.6v (for 2 elements).

I ordered this unit for USB dummy load testing.  It comes today.

For your information this is the wiring of Battery on his connector
It not easy to check the voltage because pin are very small
Connector to the top pins from left to the right :
Pin1 ?      Pin2 Minus   Pin3 +output (typ7.2v) = Pin4+ Output (typ7.2v)    Pin5 Minus    Pin6?

Minnesota Posted at 1-15 05:35
Since the output port of the Hub is ~5V, it's hard to know precisely at what voltage and capacity level the "7.2V" battery packs go from 1 blinking LED to none.

Intelligent fly battery is Lion type, 2cell (3,6V per cell), with 2400 mAh capacity. Safety cutoff voltage for Lion cell is 2,8-3,0V, cell never should go below this level.
User guide sais one solid LED means 13-25% level, one blinkin LED 0-13% left in battery. So at 0% level there should be aprox. voltage 3V per cell (6V for the whole Intelligent fly battery)...

Zolive Posted at 1-15 06:02
For your information this is the wiring of Battery on his connector
It not easy to check the voltage because pin are very small
Connector to the top pins from left to the right :

The outside pins must be for data, for the battery firmware load.

Don't worry about the discharge!
This hub will work same as any other normal powerbank.
The flightbattery will be discharged untill it reaches the (save) discharge voltage and than switch to the next flightbattery (if installed).
When all leds are out doesn't mean the battery is dead. The battery is simply fully discharged.
The hub has internal charge and discharge managment.

Zolive Posted at 1-15 05:36
Thank a lot.
I fact i would discharge one fully not used battery without care while discharging.
I havent found to buy a  battery connector to plug with my special automatic lipo/lion discharger (it stop when voltage is above 7.6v (for 2 elements).

I suggest to store batteries half-charged (40-70%), easy way to discharge the fresh battery is hover with mavic mini 3-5 minutes...

Dirty Bird Posted at 1-15 10:12
The Mini uses Lithium-ion cells so they do not have the same requirements as Li-Po packs used in other DJI batteries.  This is why there is no auto-discharge for Mini packs.

Yes, but it is better store not fully charged batteries and charge them fresh for the flight (for the best discharge characteristics).

I agree, it is bad leaving batteries discharged, and li-ions do not suffer from selfdischarge. But the half-charged storage trick is used to get the best discharge characteristics (which means higher voltage under heavy load and less voltage drop at the end of discharge cycle) when storing batteries for weeks (not a few days). User guide for Mini sais "if not used for more than 10 days, it is recommended to discharge to 39-75% level". And that corresponds roughly with storage voltage on intelligent chargers.

Hi,
So i had made test yesterday.
With just one battery in the hub with a load on output usb (Light car 21w/12v) -->  @1.1A discharging
At the end just the last led blinking and time after no led on the usb.
At this time no voltage on usb out, no current, all is stopped.
Voltage on the direct output Battery connector 6.5v (3.25 per element if egual)

Hello and good day Olivier. Thank you for reaching out and for these information you have shared with us. The DJI Mavic Mini's intelligent flight battery's performance will be influenced if it is kept idle for a long time. To maintain the said battery's active state, it is recommended that users charge and discharge the battery every three months. Do not completely discharge the battery and then store it for a long time; otherwise, the battery will over-discharge and the battery cells will be damaged, which will make the battery unusable. Thank you.