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Which Battery Lasts the Longest?

based on 289 ratings
Author: Mack Levine

Battery companies market their products by making impressive claims about how durable and reliable their batteries are. But which battery lasts the longest? Will a more expensive, brand name battery really last longer than a generic battery?

Before we make a hypothesis that addresses this question, let’s learn about the two most common types of batteries. Alkaline batteries are made with potassium hydroxide, which is a basic solution (meaning it can neutralize an acid). A non-alkaline battery is made with ammonium chloride and zinc. The ammonium chloride is acidic. Alkaline batteries tend to be more expensive than their non-alkaline counterparts, just like brand-name batteries are more expensive than generics. But in each case, what are people really paying for?

Problem

Which batteries last longer: brand-name or generic, alkaline or non-alkaline?

Materials

  • Several different brands of AA batteries. Try to purchase batteries that all have roughly the same expiration date (at least within the same year), and note the price you paid per battery. Here are some suggestions:
    • Brand-name batteries:
      • Rayovac
      • Energizer
      • Duracell
      • Eveready
      • Panasonic
    • Generic brands:
      • CVS
      • Walgreens
      • Rite Aid
      • Kirkland (Costco)
  • Several identical flashlights that take two AA batteries (get one flashlight for each type of battery you plan to test)
  • Notebook
  • Clock or watch  
  • Masking tape to act as labels

Procedure

  1. Choose a day where you’ll be able to monitor your experiment all day. Make sure to start your experiment in the morning!
  2. Label each flashlight with the model of battery you will use that flashlight to test.
  3. Load each flashlight with two of the appropriate model of battery.
  4. Turn all of the flashlights on at once. Note the time, and record it in your notebook.
  5. Monitor each flashlight until it dies. When one goes out, note and record the time in your notebook. Record your data in a chart like this:
Battery Brand Name or Generic? Cost Expiration Date Alkaline or Non-Alkaline? Time before Dying
           
           
           
           
           
           
           

Results

You may have found that name brand batteries don’t live up to the hype! In addition, there isn’t necessarily a correlation between how much a battery costs and how it performs. However, you may have found that alkaline batteries last longer than non-alkaline batteries.

Why?

A battery generates current through a chemical reaction, where new chemicals are formed on both sides of the battery. In general, the more chemicals a battery has that can change into other chemicals, the longer it lasts, and this is partly what explains why alkaline batteries have a slight chemical advantage over their non-alkaline counterparts.

Going Further

A great way to expand this experiment would be testing how a battery’s expiration date affects how long it lasts. Do older batteries perform more poorly? Test the same brand and type of battery, but test individual batteries with a range of expiration dates. You could even investigate which type of battery technology—alkaline or non-alkaline—will give a battery a longer shelf life!

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