Alternator or Battery?

370ZAWD · 04-27-2015, 01:30 PM

So I was driving home for lunch maybe 40 mph and then i notice the dash board cuts out and then comes back on. Immediately after that I notice my Voltmeter is bouncing around like crazy from 12 - 16 volts. I park and try to restart the car but its dead. What u guys think alternator or battery?

POS VETT · 04-27-2015, 03:40 PM

Got a voltmeter? No, not the one in the car.

370ZAWD · 04-27-2015, 03:43 PM

I have a hand held one recommendations?

POS VETT · 04-27-2015, 04:51 PM

Do this first - make sure the clamps on battery poles are tight. If they're, then proceed below.

Charge the battery using a battery charger for a couple hours, disconnect the charger, and measure the voltage. If voltage declined and fell below 12V, it's likely bad.

If the battery tested good, start the car, and measure voltage again while the engine is running. If it's less than 12.8V, the alternator may be bad.

nis350 · 04-28-2015, 12:17 AM

Probably both the alternator and battery. A good working alternator would provide all the juice needed while the engine is running. Another word, you can disconnect the battery and the car would keep running.

I would check for any loose connection, especially if you have installed any after market electronics. however, the oem battery only last about 3 to 4 yrs.

Quote:

Originally Posted by 370ZAWD

So I was driving home for lunch maybe 40 mph and then i notice the dash board cuts out and then comes back on. Immediately after that I notice my Voltmeter is bouncing around like crazy from 12 - 16 volts. I park and try to restart the car but its dead. What u guys think alternator or battery?

johnwiki · 04-28-2015, 01:09 AM

Sounds like the alternator went out and the car running drained the battery, thats why it wouldnt restart. A good test is get the car running and disconnecg the ground terminal from the battery. If the car dies your alternator is bad.

04-27-2015, 01:30 PM	#1 (permalink)
370ZAWD Base Member Join Date: Sep 2011 Location: Kansas Posts: 25 Drives: 2009 - Touring -Blue Rep Power: 14	Alternator or Battery? So I was driving home for lunch maybe 40 mph and then i notice the dash board cuts out and then comes back on. Immediately after that I notice my Voltmeter is bouncing around like crazy from 12 - 16 volts. I park and try to restart the car but its dead. What u guys think alternator or battery?

04-28-2015, 01:09 AM	#6 (permalink)
johnwiki Base Member Join Date: Oct 2013 Location: California Age: 33 Posts: 66 Drives: 2011 Gun Metallic Z Rep Power: 12	Sounds like the alternator went out and the car running drained the battery, thats why it wouldnt restart. A good test is get the car running and disconnecg the ground terminal from the battery. If the car dies your alternator is bad. __________________ Mods: Z1 CAI, Fast Intentions HFC + Cat Back, 4.08 Gears + VLSD Swap, Southbend DxD Clutch+lightweight flywheel = 310 HP 285 ft/lbs

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04-27-2015, 03:40 PM	#2 (permalink)
POS VETT Track Member Join Date: Apr 2015 Location: Columbus OH Posts: 612 Drives: Z34\|C4LT4\|C6Z06\|V25 Rep Power: 3366	Got a voltmeter? No, not the one in the car.

04-27-2015, 03:43 PM	#3 (permalink)
370ZAWD Base Member Join Date: Sep 2011 Location: Kansas Posts: 25 Drives: 2009 - Touring -Blue Rep Power: 14	I have a hand held one recommendations?

04-27-2015, 04:51 PM	#4 (permalink)
POS VETT Track Member Join Date: Apr 2015 Location: Columbus OH Posts: 612 Drives: Z34\|C4LT4\|C6Z06\|V25 Rep Power: 3366	Do this first - make sure the clamps on battery poles are tight. If they're, then proceed below. Charge the battery using a battery charger for a couple hours, disconnect the charger, and measure the voltage. If voltage declined and fell below 12V, it's likely bad. If the battery tested good, start the car, and measure voltage again while the engine is running. If it's less than 12.8V, the alternator may be bad.