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How to Connect Two 12V Batteries in Series

12 volt batteries can be connected in two ways: in parallel or in sequence. Usually this will be dictated by the appliance they are to be used in: low-drain devices commonly use a parallel connection to preserve battery life while operating at a lower voltage, whereas devices with a higher power demand̵2;such as flashlights̵2; utilize a serial connection for a higher immediate voltage but faster drain.

Things You'll Need

Two or more 12v batteries
Copper wire

Instructions

- 1
  Assemble the batteries end to end. Ensure all batteries are the same type (Ni-Cad, Aluminum, etc.) and of equal charge. It is best to use batteries purchased at the same time, fresh from the box.
- 2
  Ensure the batteries are connected in a positive-to-negative chain. This means that the end of the battery with a (+) sign must be connected into the (-) end of the next battery. This is why the connection is called a "series," as opposed to "parallel," where the batteries are lined up side by side. You can also check the terminals themselves: positive terminals have a small protuberance, which fits into the indentation or onto the flat of the negative terminal.
- 3
  Connect the batteries to the appliance or circuit in which they are to be used. If the batteries are to be used in a store-bought device such as a flashlight or shotgun microphone, simple slide them into the battery compartment, making sure to maintain the serial order. If the batteries are to be used in a home-made circuit for hobby electronics or a DIY project, connect them into the circuit using copper wire. Make sure the positive terminal of the end battery is connected to the negative terminal within the appliance or circuit in which the batteries are to be used.

Insects & Science