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.