Multimeter measuring voltage

Voltage measurements are the most common measurement taken with a multimeter.

Measuring voltages of a simple circuit
Measuring voltages of a simple circuit

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How to take multimeter voltage measurements of a simple DIY electronics circuit demonstration

Battery state of charge voltage

Fully charged batteries are at their maximum safe voltage. As you use them, their voltage goes down until it is either unusable or at an almost unsafe voltage if it is rechargeable.

Multimeter measuring battery voltage to determine state of charge demonstration by electronzap

  • 1.6V is a common maximum alkaline single cell voltage that has a nominal voltage of 1.5V, such as AAA, AA, C, D. They are almost always connected in series for a larger voltage.
  • 4.2V is a common maximum lithium ion single cell that has a nominal voltage of 3.6V, such as most 18650s. Try to recharge when you get close to 3V. Never discharge below 2.5V. New batteries and long term storage batteries will probably be at 3.6V.
  • 9V alkaline battery is simply six 1.5V cells in series in one package. It is about 9.5V fully charged.
  • So called 9V lithium ion batteries are often two 4.2V max litium ion cells combined in series for an actual maximum voltage of 8.4V when fully charged. Try to recharge shortly after discharging to 6V. Definitely never let it drop below 5V under load. Looks like  there are some newer versions that have one 4.2V cell plus a small voltage booster in them to provide 9V.
Related topics:

555 timer is an integrated circuit (IC). Being an IC, it has complex circuitry combined in a single package with external pins/terminals to connect to other circuitry. You can easily make all kinds of fun circuits with just a 555 timer and the components covered above, so I think it’s a good component to learn next.

Transistors will probably be the most challenging components to learn. Understanding them will help you understand all of electronics much better, and help you the most in being creative while designing your own circuits.

Other topics:

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Circuits covered more quickly series: