The signs of that your Kia alternator is failing can be subtle - or can be easily missed all together. That's because a Kia alternator can fail slowly, so at first you might not be able to run some of the energy-sucking accessories that depend on an alternator. You might not notice any energy issues at first because the battery has reserve power stored in it, and can run for a while on those stored reserves. Often when an alternator is failing, simply turning off an accessory like the stereo or air-conditioning will preserve enough energy to keep the car running for a while. To determine if your Kia alternator is ailing, check if the alternator belts are tight and not slipping. If they are cracked or shiny on the side that faces the alternator pulley, then replace them. Check if the warning (also known as the 'idiot light') is on. Most car electrical systems have an electrical current passing through the filament of the warning light; this energizes a circuit in the alternator to start charging. Another diagnostic test requires using a cheap voltmeter to measure the voltage in the system. To do that, you must start the car, turn off any accessories and rev up your motor. With your voltmeter set to the DC scale, measure the voltage that comes across the battery terminals (both the positive and negative). In most systems, the voltage should read 14 volts; if it is less than 12 volts, then you may have a dying alternator.