Just a quick question, dji recommends storing batts at 50%.

As with the hub charger, how do you make it charge to 50%? When the lights blinks 3 you just unplug it?

Or charge to 100 and drain to 50%?

Either way. But you don't need to worry about this. After 10 days the batteries discharge themselves to a safe level for storage if they are not used. And DJI recommends to completely discharge and fully charge them thereafter every three months for maintenance.

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  Straight from DJI Spark's Manual. Hope it helps and good choice with storing them at around 50%