Two of my Phantom 4 intelligent batteries are dead and won't charge at all after a few months of storing those not being used at all.
What can I do to get these up again?

Hi yowich, we are sorry to hear the troubles with the batteries. An Intelligent Battery’s power will be consumed at a slow rate when it is being stored after being powered off. Also, the battery may become over-discharged if its power is critically low when being put into storage. Per your description, the batteries could be over-discharged. If they are still under warranty period, we recommend to send in, if not, we recommend to use a new battery.

To avoid this in the future, it is recommended that you discharge the battery to between 40% to 65% and store it in a cool, dry space (at an ambient temperature of 22°C to 28°C) when it is going to be idle for more than ten days. Check the battery’s power every three months and fully charge and discharge it at least once.

DJI Mindy Posted at 4-27 19:25
Hi yowich, we are sorry to hear the troubles with the batteries. An Intelligent Battery’s power will be consumed at a slow rate when it is being stored after being powered off. Also, the battery may become over-discharged if its power is critically low when being put into storage. Per your description, the batteries could be over-discharged. If they are still under warranty period, we recommend to send in, if not, we recommend to use a new battery.

To avoid this in the future, it is recommended that you discharge the battery to between 40% to 65% and store it in a cool, dry space (at an ambient temperature of 22°C to 28°C) when it is going to be idle for more than ten days. Check the battery’s power every three months and fully charge and discharge it at least once.

Thanks for the reply. Anyway, how can I find if my batteries are in warranty or not?

yowich Posted at 4-28 09:18
Thanks for the reply. Anyway, how can I find if my batteries are in warranty or not?

Please check your proof of purchase of the battery, the warranty period of the battery in your country is 6 months and charge cycle less than 200 times.