How to Measure a Rechargeable Battery


Portable rechargeable batteries are dry cell batteries with a chemical composition of either nickel or lithium. Many manufacturers of battery operated electrical devices increasingly choose to power them using lithium cells; they are lighter, produce higher voltage and last considerably longer than nickel batteries. Items that have benefited from lithium technology include laptops, cell phones and power tools. If you want to know how charged your rechargeable battery is, then the best device to use to measure it is a multimeter.

Things You'll Need

  • Pen and paper
  • Multimeter
  • Use a pen and write down on a sheet of paper the output voltage and milliamp hour (mAh) rating of the rechargeable battery to want to measure. You can get this from the battery label. For example, a lithium battery is likely to have 3.6 volts and 2,400 mAh printed on it, whereas a nickel battery is likely to have 1.2 volts and 600 mAh.

  • Turn on your multimeter and set it to measure voltage. Refine the setting so the maximum voltage on the meter is about double the voltage from the battery. There is a dial or a selection of buttons on the meter so turn the dial, or press the appropriate button for voltage.

  • Place the metal contacts on the end of the wires from the meter onto the rechargeable battery terminals. The contact on the end of the red wire goes to the terminal labeled "+" and the contact on the end of the black wire goes to the terminal labeled "-."

  • Look at the meter display and compare the measurement to the voltage you wrote down from the rechargeable battery label. It reads the same, if your battery is charged above about 25 percent capacity. Rechargeable batteries maintain the labeled voltage until they are nearly discharged so if the voltage is less than the figure you wrote down, your battery needs recharging.

  • Keep the metal contacts from the meter on the battery terminals. Reset your meter to measure mAh set the maximum mAh to about 50 percent more than the reading you wrote down earlier. This is a more accurate method for finding out how charged your battery is as mAh gradually decreasing when you use the battery.

  • Read the meter again, but this time, write down the figure as you need to do a calculation. Remove the metal contacts from the multimeter and turn it off.

  • Divide the figure you just wrote down from the meter by the figure you wrote down from the battery label. Multiply the result by 100 to get the percentage charge in your battery. For example, if the meter reading is 1,200 mAh and the battery label says 2,400 mAh, then divide 1,200 by 2,400 to get 0.5. Multiply 0.5 by 100 to get 50. This means your battery is 50 percent charged.


  • Photo Credit Polka Dot Images/Polka Dot/Getty Images
Promoted By Zergnet


You May Also Like

Related Searches

Check It Out

How to Build and Grow a Salad Garden On Your Balcony

Is DIY in your DNA? Become part of our maker community.
Submit Your Work!