Like humans, batteries function best at room temperature, and any deviation towards hot and cold changes the performance and/or longevity. Operating a battery at elevated temperatures momentarily improves performance by lowering the internal resistance and speeding up the chemical metabolism, but such a condition shortens service life if allowed to continue for a long period of time.

If the battery were a perfect power source and behaved linearly, the discharge time could be calculated according to the in-and-out current. “What has been put in can be taken out in the same form over time” is the argument, and in our example a one-hour charge at 5A should enable a one-hour discharge at 5A, or a 5-hour discharge at 1A. However,