The alternator is a generator that produces alternating current (ac), similar to the electrical current in your home. The wavy line after a v is ac (alternating current) voltage and is for checking the mains voltage in your house. How To Make A 12v Battery Charger Electronics Projects Diy Electronics Electronics Projects Diy If the peaks vary too much from the average dc, then the battery can be damaged. Does a car battery charger put out ac or dc . Most of the manual ranging meters have a 20v range, which is what you would need to test a car battery. Charging your auxiliary battery bank with the alternator is a simple, inexpensive and easy way of doing it. Ac chargers give an alternating current to the device meaning the current keeps switching back and forth whereas dc chargers can supply a constant voltage or current to the battery and it does not change its direction. Therefore, one cannot speak about ac charging. \$\begingroup\$ no, ac can't be used to charge a ba...