A fully charged 12 volt automobile battery will read 12.6 volts with a digital volt meter. It will read 12.4 at 75% charge, 12.2 volts at 50% charge and 12 volts at 25% charge.
get a multi meter that reads dc voltage & touch the black (negative -) wire to the negative battery post & the red (positive +) wire to the positive battery post with car running. car off is battery voltage, car on is alternator voltage.
when cranking the engine the battery voltage should not fall below 9.6volts if so replace battery
Yes, if your car battery is the same voltage as the ATV battery.
yes
Larger.
12.6 volts
Yes
12-14v
Sure, if the alternator voltage regulator is defective it can overcharge the battery.
Voltage is the same but amp hour capacity of the car battery is much higher.
Yes, IF the operating voltage of the stereo is the same as the battery output voltage of the vehicle.
Battery type: YB14L Initial Charging Rate: 1.4A 10 hours Specific Gravity: 1.280 Voltage should be at least 12V DC