Dear: About what you comment, what I can tell you is that the batteries that are not charging is simply because they are damaged or blocked ... With any Lipo battery you have to take special care, you should not discharge it to the minimum because you can damage it, you should never let it discharge completely when they are stored, because if its voltage per cell that is 3.7 drops below 3.2 or 3.1 it is simply damaged. Most likely, that must have happened to the batteries that you mention that they do not charge or that when putting them in the charger a red light turns on on the charger, that indicates that the battery does not have the minimum voltage to be recharged. If you are using the original DJI charger for 3 batteries, you have the option to select the storage mode and the charger will charge them to 50% and so you can save them for a while, but you must, yes or yes, check the discharge level of ma battery and recharge it if necessary if the voltage drops below 15%. There are videos on YouTube that show you how to "recover" these batteries when they are blocked by a "very deep" discharge. Greetings.! ..

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