Science project

Connecting Batteries in Series




Minimal, mostly the cost of batteries for the display

Safety Issues

Minor risk of too much voltage/amperage, which can make the wires hot enough to melt. Soldering connectors makes the display easier but presents the possibility of burns. Taking a dry cell battery apart means exposure to the caustic electrolyte inside.

Material Availability


Approximate Time 

1-2 hours, depending on complexity of the display


To demonstrate how battery packs work to bring higher voltage, higher amperage, or both.


  • Several batteries, to be connected in series, parallel, and series-parallel
  • Battery holders, or wire and soldering equipment
  • Voltmeter also capable of measuring amperage (Radio Shack)
  • Optional – a disassembled battery to label the parts


A single battery cell produces low voltage and low amperage. Combining cells in series increases the voltage. Combining them in parallel increases the amperage. Even a 9-volt battery is a “battery pack.” This project will explore how battery cells can be connected in many different configurations to do almost anything needed, depending on the voltage and amperage needed.  


Students can show diagrams of practical series/parallel circuits. In addition, devices that use multiple batteries can be displayed to demonstrate how, for example, 4 batteries are used to power a device that requires 6-volts.

Research Questions

  • What is a battery cell?
  • What is a series circuit?
  • What is a parallel circuit?
  • Is a 9-volt battery a battery cell, or a battery pack? How and why?
  • What is the difference between DC and AC?


  • Volt: the standard measure of electric pressure
  • Ampere: the standard measure of electric quantity
  • Series: one after another, like strings tied together
  • Parallel: in line, side-by-side, like railroad tracks


Electricity is the movement of electrons in a conductor. Voltage is the pressure, somewhat like the pounds per square inch of water flowing from a pipe. Amperage is the quantity of the electrons, somewhat like the number of gallons flowing from the pipe. Batteries generate electricity by a chemical reaction. They can be connected inline to provide greater voltage, in parallel to provide greater amperage, or in a combination to provide both greater voltage and greater amperage.

Connecting batteries in series involves creating a series circuit, which has the positive post connected to the negative post of another battery with each battery in line. Two 6-volt, 2 amp batteries connected this way will produce 12 volts, 2 amps.

A parallel circuit has the positive post connected to the positive post of another battery, and the negative post connected to the negative post. Two 6-volt, 2 amp batteries connected this way will produce 6 volts, 4 amps.

A series-parallel circuit combines both to produce whatever voltage and/or amperage is needed. For example, if 120 volts is needed, 20 6-volt batteries in series will provide the needed voltage. If each battery has a 1-amp capacity but 50 amps is required, 25 sets of those 20 batteries, the sets connected in parallel, will provide the end result of 120 volts at 50 amps.

Experimental Procedure

  1. Gather the materials.
  2. Decide if you will use battery holders or solder.
  3. Build a series circuit of batteries, and measure voltage and amperage.
  4. Build a parallel circuit of batteries and measure voltage and amperage.
  5. Build a battery pack to combine both and measure voltage and amperage.
  6. Measure and record voltage and amperage of each.
  7. Optional – disassemble a common battery to show the parts. (Adult supervision should be used because the electrolyte inside is caustic.)


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Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.

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