Testing Your NiMH Batteries
3. Methods for Accurate Voltage Assessment
Now that we know the critical "At what voltage is NiMH dead" threshold, how do we actually test our NiMH batteries to determine their health? There are several methods you can use, ranging from simple to more sophisticated. The best approach depends on the tools you have available and the level of accuracy you need.
The simplest method is to use a multimeter. A multimeter is an electronic measuring instrument that can measure voltage, current, and resistance. To test your NiMH battery's voltage, set the multimeter to DC voltage mode (usually denoted by "VDC" or "DCV"). Connect the red probe to the positive (+) terminal of the battery and the black probe to the negative (-) terminal. Make sure the battery is under a load. This can be achieved by leaving the battery in the device it powers, or connecting it to a resistor. The multimeter will display the battery's voltage.
For a more accurate assessment, consider using a battery analyzer or charger with built-in testing capabilities. These devices can typically measure the battery's internal resistance, capacity, and discharge curve. They often provide a more comprehensive picture of the battery's health than a simple voltage reading. Some advanced battery analyzers can even perform a "discharge test," which simulates real-world usage and provides a more accurate estimate of the battery's remaining capacity. The better ones even show you a lovely graph.
Finally, remember that temperature can affect battery voltage. Ideally, you should test your NiMH batteries at room temperature (around 20-25C or 68-77F) for the most accurate results. Extreme temperatures can skew the voltage readings and lead to inaccurate conclusions about the battery's health. So, if you've been storing your batteries in a hot car or a freezing garage, let them come to room temperature before testing them. Its like waiting for your coffee to cool down a bit before taking that first sip.
