Is it safe to use a smart phone charger to recharge a NiCad  battery? ?

I connected a nicad battery to a usb cable, then to a phone charger. It seems to have charged but it felt so hit at some poit so I disconnected from the charger...

Question is: is it safe to recharge a nicad battery in this way (i.e. Connecting the positive and negative ends to a usb cable then to the phone charger directly)? 

2 Answers

  • 1 month ago
    Favorite Answer

    You should use a resistor in series with the cell to limit the current, otherwise you are both overloading the charger and overcharging the cell.

    A 47 Ohm resistor would limit the current to around 75mA. 

    Divide the capacity of the cell by 75 to get the number of hours to leave it connected to fully charge from dead flat.

    Add about 20 to 40 percent to allow for cell efficiencies.

  • John P
    Lv 7
    1 month ago

    Are the voltages compatible?

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