Mixing Old and New Batteries

Many battery-powered electronic devices come with a warning like this:


Do not mix old and new batteries.  Do not mix alkaline, standard (carbon-zinc), or rechargeable (nickel-cadmium) batteries.

One device I noted this warning on was an automatic card-shuffling device. It seemed entirely out of place, since the machine only used ONE nine-volt battery.

Of course, the advice is sound and should generally be followed.  However, in this case I don’t think the warning necessary, as it would be practically impossible to use multiple batteries at once in this device.

According to Duracell, the reason to avoid mixing old and new batteries is that doing so will reduce overall performance and may cause battery leakage or rupture.  If you’re curious, for a more detailed explanation take a visit here.


  1. anthony faber says:

    Your link says …12/27/… and should be …12/28/… here and on Facebook. the short URL works, though.

  2. anthony faber says:

    My guesses are that the same battery compartment cover is used in different products, some of which use more than one battery, or the product was redesigned from multi battery to single 9v battery

  3. conalldempsey says:

    @ anthony faber

    Thanks for the tip on the link. I updated it now. As to the battery cover being used for other devices, that was my first thought as well, but I thought it was unlikely, as the cover has a 9V battery image printed right beneath the warning.

  4. Thank you for this wisdom. I am a service clerk at Walgreens, with very little knowledge of technical devices. The explanation was easy to understand with the car example and I have personally learned stuff to save me me money.

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