18650 Battery charger reverse polarity protection

Having many 18650 battery cells to charge, I bought a few dirt cheap TP4056 modules (0.22 EUR per piece) and discovered that they are “not designed for” reversed polarity cells. In other words, reversed battery = instant magic smoke.

As I know for sure I will insert more batteries in the wrong orientation again sooner or later, I wondered what the best reverse polarity protection would be.

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