Battery voltage fluctuation

Rhythm Stick · January 8th, 2013, 08:05 PM

Last night I noticed that my voltage meter on my dash was fluctuating badly between normal and low. The car runs fine but my radio turned itself off and my headlights were flickering. This all started after my buddy welded up my exhaust.

Any ideas?

AnotherS197GT · January 8th, 2013, 08:07 PM

The voltage gauge is a dummy light. Doesn't actually do anything.

Was the battery disconnected during welding?

Rhythm Stick · January 8th, 2013, 08:08 PM

Originally Posted by AnotherS197GT

The voltage gauge is a dummy light. Doesn't actually do anything.

Was the battery disconnected during welding?

No.

Ponyryd · January 8th, 2013, 08:11 PM

Try disconnecting the battery and then touch the terminals together (NOT the posts, lol), reconnect and see if its better.

crackpotfox · January 8th, 2013, 08:29 PM

Originally Posted by AnotherS197GT

The voltage gauge is a dummy light. Doesn't actually do anything.

Was the battery disconnected during welding?

srsly?

AnotherS197GT · January 8th, 2013, 09:46 PM

Originally Posted by graystang01

No.

In the future, disconnect the battery first. You may have toasted something. It could also be pure coincidence. I would check the alternator since those are also shitty alternator signs.

Originally Posted by crackpotfox

srsly?

Yep. Same with the oil pressure gauge.

Ponyryd · January 8th, 2013, 09:51 PM

^Ya, notice how the gauge never actually moves?

07 Boss · January 8th, 2013, 10:02 PM

Battery gauge is not a dummy light like the oil pressure gauge. Trust me, I'm on my fifth alternator. I once drove 50+ miles on the battery and watched it slowly get lower and lower until the car died. It might not be that accurate but it will reflect the charge in your battery.

Aaron, you should have unhooked the battery before welding. From someone who is well versed on alternators, go change yours before you get stranded somewhere. It will go out at the most inconvenient time if you don't.

Edit: Saw on the news last night that there will be another season of Midnight Mayhem this year. First night of racing is the 25th of this month.

AnotherS197GT · January 8th, 2013, 10:12 PM

I've had my car dead in my driveway several times from a bum battery, and the gauge was still reading normal. Its about as precise as a butter knife for surgery.

07 Boss · January 8th, 2013, 10:19 PM

Originally Posted by AnotherS197GT

I've had my car dead in my driveway several times from a bum battery, and the gauge was still reading normal. Its about as precise as a butter knife for surgery.

Your gauge must be bad. If your battery was dead it should have reflected that. I've seen mine read from dead, to pegged, when it was over charging, and everywhere in between.

2006greyGT · January 9th, 2013, 12:09 AM

my gauge works.... bounces with the bass/subs when I crank it up...

Boss, they might have gone to dummy gauges after 07....IDK

Rhythm Stick · January 9th, 2013, 03:00 AM

Almost didn't make it home tonight. All of my lights shut off and the car sputtered a few times.

2006greyGT · January 9th, 2013, 06:28 AM

after you get it charged back up..check your ground connections.. and do the old school Alt test... pull the neg cable off the battery after you start the car... if it dies it is your Alt... most likely gonna be the Alt anyway... if it is the stock one then it is over due to die... I am on my third

Taxman · January 9th, 2013, 06:28 PM

I've gone through the same thing twice now. I'm on my third alternator. Last time I upgraded the wiring and got a high performance alternator. It's been good so far but I did have a battery issue and I'm working on tracking it down now. Most likely a common ground issue. I bet your alternator has that diode issue that Ford alternators have.

(Kohrs93) · January 9th, 2013, 06:59 PM

Originally Posted by AnotherS197GT

I've had my car dead in my driveway several times from a bum battery, and the gauge was still reading normal. Its about as precise as a butter knife for surgery.

A bad battery can still produce 12v and not be able to start a car. The CCA (cold cranking amps) are what determine the starting power of a battery.

Sent from my DROID RAZR HD using AutoGuide.Com Free App

2006greyGT · January 9th, 2013, 07:09 PM

me and Tax have the exact # of posts... what are the odds???? well this ruined it...lol

AnotherS197GT · January 9th, 2013, 07:10 PM

Originally Posted by (Kohrs93)

A bad battery can still produce 12v and not be able to start a car. The CCA (cold cranking amps) are what determine the starting power of a battery.

Sent from my DROID RAZR HD using AutoGuide.Com Free App

I'd venture to say it was voltage since I had left my interior lights on for a few hours each time lol

January 8th, 2013, 08:07 PM	#2
AnotherS197GT Eat Springs, Shit Valves 2008 Mustang GT Join Date: Jul 2010 Location: Dearborn, MI Posts: 8,450 iTrader: 11 reviews	The voltage gauge is a dummy light. Doesn't actually do anything. Was the battery disconnected during welding? __________________

January 8th, 2013, 10:02 PM	#8
07 Boss I Post Entirely Way Too Much 2007 Mustang GT Join Date: Nov 2008 Location: Las Vegas Posts: 6,623 iTrader: 3 reviews	Battery gauge is not a dummy light like the oil pressure gauge. Trust me, I'm on my fifth alternator. I once drove 50+ miles on the battery and watched it slowly get lower and lower until the car died. It might not be that accurate but it will reflect the charge in your battery. Aaron, you should have unhooked the battery before welding. From someone who is well versed on alternators, go change yours before you get stranded somewhere. It will go out at the most inconvenient time if you don't. Edit: Saw on the news last night that there will be another season of Midnight Mayhem this year. First night of racing is the 25th of this month. __________________ Whipple HO 3 1/8" pulley-Comp NSR's-Pacesetter L/T's and O/R H-pipe-4.10's-PH Driveshaft-Level 10 trans-PI triple disc 3000-elec H2O-Pro Kit-BMR billet LCA's w/brckts-BMR adj UCA & Panhard-BMR sway bars-Bilsteins-and a bunch of other really cool shit

January 8th, 2013, 10:12 PM	#9
AnotherS197GT Eat Springs, Shit Valves 2008 Mustang GT Join Date: Jul 2010 Location: Dearborn, MI Posts: 8,450 iTrader: 11 reviews	I've had my car dead in my driveway several times from a bum battery, and the gauge was still reading normal. Its about as precise as a butter knife for surgery. __________________

January 9th, 2013, 12:09 AM	#11
2006greyGT Premium Member 2006 Satin Silver GT 11.08@125.22 Join Date: Aug 2007 Location: KC Posts: 3,298 iTrader: 0 reviews	my gauge works.... bounces with the bass/subs when I crank it up... Boss, they might have gone to dummy gauges after 07....IDK __________________ 2.6l KB 298 Stroker, Ported heads Pro Motion Built 3650/McLeod RST/ MGW Short Throw LT/O/R X /Borla Touring 8 rib/65 lb injectors/GT500 twin fuel 3.73 gear Detroit Truetrac /CDC AGR Spoiler CHE K-member w/tq brace Che adj UCA

January 9th, 2013, 06:28 AM	#13
2006greyGT Premium Member 2006 Satin Silver GT 11.08@125.22 Join Date: Aug 2007 Location: KC Posts: 3,298 iTrader: 0 reviews	after you get it charged back up..check your ground connections.. and do the old school Alt test... pull the neg cable off the battery after you start the car... if it dies it is your Alt... most likely gonna be the Alt anyway... if it is the stock one then it is over due to die... I am on my third __________________ 2.6l KB 298 Stroker, Ported heads Pro Motion Built 3650/McLeod RST/ MGW Short Throw LT/O/R X /Borla Touring 8 rib/65 lb injectors/GT500 twin fuel 3.73 gear Detroit Truetrac /CDC AGR Spoiler CHE K-member w/tq brace Che adj UCA

January 8th, 2013, 08:11 PM	#4
Ponyryd Watch n learn Join Date: Jun 2007 Location: Canada Posts: 903 iTrader: 0 reviews	Try disconnecting the battery and then touch the terminals together (NOT the posts, lol), reconnect and see if its better.

January 8th, 2013, 09:51 PM	#7
Ponyryd Watch n learn Join Date: Jun 2007 Location: Canada Posts: 903 iTrader: 0 reviews	^Ya, notice how the gauge never actually moves?

January 9th, 2013, 06:28 PM	#14
Taxman Your new 5.0 is slow 2007 Mustang GT Conv. 12.8 @ 110 mph Join Date: Dec 2010 Location: North Texas Posts: 3,236 iTrader: 5 reviews	I've gone through the same thing twice now. I'm on my third alternator. Last time I upgraded the wiring and got a high performance alternator. It's been good so far but I did have a battery issue and I'm working on tracking it down now. Most likely a common ground issue. I bet your alternator has that diode issue that Ford alternators have. __________________ 2007 GT Convertible Build Thread Vortech V3 trim, FRPP Intake manifold, MAC LT's, Prochamber, Ford Racing 3:73 gears, FRPP springs, Hurst Billet shifter, Steeda CMDP's, FRPP 62mm Throttle body, tuned by True Street. 485 rwhp 429 lbft torque

January 9th, 2013, 07:09 PM	#16
2006greyGT Premium Member 2006 Satin Silver GT 11.08@125.22 Join Date: Aug 2007 Location: KC Posts: 3,298 iTrader: 0 reviews	me and Tax have the exact # of posts... what are the odds???? well this ruined it...lol __________________ 2.6l KB 298 Stroker, Ported heads Pro Motion Built 3650/McLeod RST/ MGW Short Throw LT/O/R X /Borla Touring 8 rib/65 lb injectors/GT500 twin fuel 3.73 gear Detroit Truetrac /CDC AGR Spoiler CHE K-member w/tq brace Che adj UCA

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