voltage ,what does your car read?

havasuwiley · 11-12-2009, 04:20 PM

i havent been driv

ing my car much lately,but noticed my volt guage at 14.5 volts even after a hour or so of driving,my other cars charge at 13-13.5 most of the time.just wondering if this is high or normal for a z.

280z/300zx · 11-12-2009, 04:31 PM

Mine is always around 14.2-14.4.

ChrisSlicks · 11-12-2009, 04:34 PM

I noticed the in car gauge reading above 14V a lot more than it should as well. I'll have to throw a digital volt-meter across the terminals to see if it reports the same numbers. Could just be the gauge that's inaccurate.

speedoflife · 11-12-2009, 04:37 PM

There's absolutely nothing wrong with even 15 volts. Once you get up around 16 and above or lower than 11, you should probably start worrying.

ChrisSlicks · 11-12-2009, 04:44 PM

Just going by experience with previous models. 14V was common right after a start, obviously recharging the battery power drained doing the start itself. Typically this settled down to between 13V and 13.8V while running.

This car could just have a higher electrical drain, although I could have sworn 6 months ago when I got the car it was reading lower than it is now.

Modshack · 11-12-2009, 05:06 PM

I wrote this for another forum, but it might be handy for the group:

A fresh battery will have a resting voltage of around 12.7V. (measured at 65 degrees after sitting with no draw for 12 hours). The only way to measure this accurrately is with a digital voltmeter AT the battery terminals. Just switching on your car will skew the numbers as you're throwing a bunch of power draws into the equation which will lower the V. readout. When an alternator is running it will put out between 13.5 and 14.4 volts into the battery depending on the batteries state of charge. This voltage is regulated by (duh!) a regulator. A batteries ability to hold and accept this charge has nothing really to do with how much you're trying to stuff into it. A fully charged battery, that is well regulated will generally show an alternator supplied voltage of about 13.7 V depending on the voltage draw of the cars electrical systems. Voltages of higher than 14V into a fully charged battery may shorten the battery life if the amperage remains high, but it may also reflect the Running voltage needs of the car. Some tend to remain high no matter the battery state. My Corvette AND the 370Z seem to be in this category. A battery with a low charge will typically show 14V+ or so as the battery capacity is replenished by the alternator output. A totally bad battery may not accept a charge at all. A higher charge rate will show at the first start of the day as the battery recovers lost voltage from sitting and parasitic draws as well as needing to recover from a high load engine start. Batteries naturally age and over a period of time their ability to hold a charge and full voltage diminishes. At 4 years or so this usually drops to about 50% of the original capacity. A bad or shorted cell can also cause failure as all cells need to be fairly consistent...

Test a battery by either:
1)Taking a resting voltage reading
2)doing a load test

Test an alternator by:
1)measuring voltage while running. Anything over the batteries resting voltage means it's putting out. Voltages less than 13 or so means it's not putting out enough..Sometimes a bad or shorted battery will not accept any voltage even when the alternator is good.

shabarivas · 11-12-2009, 05:18 PM

on cold days closer to 15 but yea ... in the 14.5s

280z/300zx · 11-12-2009, 05:27 PM

A little off topic. Say you let your car sit too long because you were out of town and now the battery is too drained to start the car. It isn't totally dead and will let the radio or lights run but just not enough to start the car. So you jump it. How long will the car have to run to totally charge the battery so that it's "back to normal."

sometimes I don't drive my 280z or 300zx often enough and I will have to jump them. Usually I just take them for a 20-30min drive around town to charge the battery.

Modshack · 11-12-2009, 06:42 PM

Quote:

Originally Posted by 280z/300zx

A little off topic. Say you let your car sit too long because you were out of town and now the battery is too drained to start the car. It isn't totally dead and will let the radio or lights run but just not enough to start the car. So you jump it. How long will the car have to run to totally charge the battery so that it's "back to normal."

sometimes I don't drive my 280z or 300zx often enough and I will have to jump them. Usually I just take them for a 20-30min drive around town to charge the battery.

You really shouldn't do that...A battery's life is severely shortened if you allow it to drop to those levels. Do that more than a few times and you'll be lucky if your battery will hold 50% of its original charge. Do the resting voltage chec and see where you are. Driving around for a few hours, let alone 20 minutes doesn't really charge it correctly nor fully. YOur best bet is to put a battery tender on it when the car is not in use...

havasuwiley · 11-13-2009, 06:36 PM

thanks for the feedback,low 14s seems common enough

vipor · 11-14-2009, 12:24 PM

12.6 while off, 14.4 while running is normal. 14.4 was always the golden number for amplifier efficiency calculations.

CrownR426 · 11-14-2009, 12:26 PM

I hope you guys know that 12 isn't the actually standard and if it is charge your batteries! It's actually 12.6 Volts!

And remember, Red = Positive, Black = Negative

11-12-2009, 04:20 PM	#1 (permalink)
havasuwiley Base Member Join Date: Jul 2009 Location: lake havasu city az Posts: 131 Drives: 09 370z, 03 z06 etc Rep Power: 15	voltage ,what does your car read? i havent been driving my car much lately,but noticed my volt guage at 14.5 volts even after a hour or so of driving,my other cars charge at 13-13.5 most of the time.just wondering if this is high or normal for a z.

11-12-2009, 05:06 PM	#6 (permalink)
Modshack A True Z Fanatic Join Date: Mar 2009 Location: Greenville NC Posts: 2,883 Drives: 370Z Sport Rep Power: 976	I wrote this for another forum, but it might be handy for the group: A fresh battery will have a resting voltage of around 12.7V. (measured at 65 degrees after sitting with no draw for 12 hours). The only way to measure this accurrately is with a digital voltmeter AT the battery terminals. Just switching on your car will skew the numbers as you're throwing a bunch of power draws into the equation which will lower the V. readout. When an alternator is running it will put out between 13.5 and 14.4 volts into the battery depending on the batteries state of charge. This voltage is regulated by (duh!) a regulator. A batteries ability to hold and accept this charge has nothing really to do with how much you're trying to stuff into it. A fully charged battery, that is well regulated will generally show an alternator supplied voltage of about 13.7 V depending on the voltage draw of the cars electrical systems. Voltages of higher than 14V into a fully charged battery may shorten the battery life if the amperage remains high, but it may also reflect the Running voltage needs of the car. Some tend to remain high no matter the battery state. My Corvette AND the 370Z seem to be in this category. A battery with a low charge will typically show 14V+ or so as the battery capacity is replenished by the alternator output. A totally bad battery may not accept a charge at all. A higher charge rate will show at the first start of the day as the battery recovers lost voltage from sitting and parasitic draws as well as needing to recover from a high load engine start. Batteries naturally age and over a period of time their ability to hold a charge and full voltage diminishes. At 4 years or so this usually drops to about 50% of the original capacity. A bad or shorted cell can also cause failure as all cells need to be fairly consistent... Test a battery by either: 1)Taking a resting voltage reading 2)doing a load test Test an alternator by: 1)measuring voltage while running. Anything over the batteries resting voltage means it's putting out. Voltages less than 13 or so means it's not putting out enough..Sometimes a bad or shorted battery will not accept any voltage even when the alternator is good. __________________ Steal my car! (SOLD)...Now Porsche Cayman S Oil Cooler DIY: Here! Last edited by Modshack; 11-12-2009 at 05:15 PM.

11-14-2009, 12:24 PM	#11 (permalink)
vipor A True Z Fanatic Join Date: Aug 2009 Location: Euless, TX [ DFW ] Age: 41 Posts: 13,531 Drives: Nismo 09-0183 QAB Rep Power: 48	12.6 while off, 14.4 while running is normal. 14.4 was always the golden number for amplifier efficiency calculations. __________________ 2009 NISMO # 0193 \| QAB \| Albums! \| 05.04.10 (Dynojet) 291.94hp/248.28tq Oil Cooler (DIY) \| Custom Headlights \| GTSPEC Braces \| F.I. Long Tube Headers

11-14-2009, 12:26 PM	#12 (permalink)
CrownR426 A True Z Fanatic Join Date: Nov 2008 Location: South Korea Posts: 4,676 Drives: Manual Rep Power: 847	I hope you guys know that 12 isn't the actually standard and if it is charge your batteries! It's actually 12.6 Volts! And remember, Red = Positive, Black = Negative __________________ Love + Hardwork + Passion RIP SVTRacer

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11-12-2009, 04:31 PM	#2 (permalink)
280z/300zx Track Member Join Date: Feb 2009 Location: Nevada Posts: 689 Drives: 280z, 300zx, Vette Rep Power: 272	Mine is always around 14.2-14.4.

11-12-2009, 04:34 PM	#3 (permalink)
ChrisSlicks A True Z Fanatic Join Date: Mar 2009 Location: North East Posts: 6,203 Drives: 09 370Z Sport M6 Rep Power: 653	I noticed the in car gauge reading above 14V a lot more than it should as well. I'll have to throw a digital volt-meter across the terminals to see if it reports the same numbers. Could just be the gauge that's inaccurate.

11-12-2009, 04:37 PM	#4 (permalink)
speedoflife Enthusiast Member Join Date: Aug 2009 Location: MS/TX Posts: 268 Drives: '06 Pontiac G.P. Rep Power: 15	There's absolutely nothing wrong with even 15 volts. Once you get up around 16 and above or lower than 11, you should probably start worrying.

11-12-2009, 04:44 PM	#5 (permalink)
ChrisSlicks A True Z Fanatic Join Date: Mar 2009 Location: North East Posts: 6,203 Drives: 09 370Z Sport M6 Rep Power: 653	Just going by experience with previous models. 14V was common right after a start, obviously recharging the battery power drained doing the start itself. Typically this settled down to between 13V and 13.8V while running. This car could just have a higher electrical drain, although I could have sworn 6 months ago when I got the car it was reading lower than it is now.

11-12-2009, 05:18 PM	#7 (permalink)
shabarivas A True Z Fanatic Join Date: Apr 2009 Location: Sacramento, CA Posts: 2,188 Drives: 370z MB 6mt Rep Power: 914	on cold days closer to 15 but yea ... in the 14.5s

11-12-2009, 05:27 PM	#8 (permalink)
280z/300zx Track Member Join Date: Feb 2009 Location: Nevada Posts: 689 Drives: 280z, 300zx, Vette Rep Power: 272	A little off topic. Say you let your car sit too long because you were out of town and now the battery is too drained to start the car. It isn't totally dead and will let the radio or lights run but just not enough to start the car. So you jump it. How long will the car have to run to totally charge the battery so that it's "back to normal." sometimes I don't drive my 280z or 300zx often enough and I will have to jump them. Usually I just take them for a 20-30min drive around town to charge the battery.

11-13-2009, 06:36 PM	#10 (permalink)
havasuwiley Base Member Join Date: Jul 2009 Location: lake havasu city az Posts: 131 Drives: 09 370z, 03 z06 etc Rep Power: 15	thanks for the feedback,low 14s seems common enough