Multimeters are a useful tool when it comes to testing or troubleshooting electronics. Most multimeters give access to a variety of features such as testing voltage, current, or resistance. For example, a multimeter can test if a battery is dead by checking if its voltage is usable. If a battery’s voltage, as measured by a multimeter, drops below 60% of its rated voltage, then it is unlikely to be usable in devices that require that voltage. LEDs, however, may still emit light if a connected battery is below 60%, increasing the longevity of our simpler projects.
Lithium batteries are an essential part of many electronic devices and contain a powerful, lithium based chemical reaction that generates electric current that can be drained from the battery. Some variants are rechargeable, meaning that they can be reused multiple times, while others are not, and must be disposed of properly. It is advised to keep a container for dead batteries which can be gotten rid of at a later date at one of many safe battery collection sites, which you can locate online.