05’ GT new battery

[moooosestang]

my battery voltage at idle is always 14.3-14.5 volts. replaced my stock alternator with a PA performance way back in 2009 i think when the alternator problems were popping up on the forums. still have the stock alternator in a box. You should clean your two engine grounds for the hell of it, can't hurt. I added a beefy 3rd ground going from the motor mount to the frame rail when i did my trunk mounted battery. Same 1awg cable as the positive. I don't know my limits, i'm stupid like that. It has cost me a clutch and a lot of little things here and there. I've easily wasted $700 learning what not to do. Don't leave bearing grease inside the cavity of the crank behind the pilot bearing. it will leak out when it gets hot and ruin your clutch. Teaching myself to make battery cables was the most fun i think i've had working on my car. Something therapeutic about fusing copper together with a 5lb sledge.

 

[DieHarder]

Update.

I was doing my annual maintenance (oil, oil filter, fuel filter, lube etc) and cleaned up the terminals as best I could. Did another check and volts are doing slightly better. 14.1V at Idle and 13.9V at load (A/C, flashers, headlights on, etc.).

I am ok with this for now but will monitor as always.

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That isn't terrible but honestly your battery cables look like they've seen better days. You can still find OEM for ~$100 - $150. Sometimes less. I replaced mine and saw around 1.5v increase in output. Cost me ~$50 for the new cables. Not that bad replacing them either except for the ground cable that bolts to the underside of the passenger motor mount. That one's a bitch. Just replace one connection at a time and you'll be fine.

 

[DieHarder]

Update.

I was doing my annual maintenance (oil, oil filter, fuel filter, lube etc) and cleaned up the terminals as best I could. Did another check and volts are doing slightly better. 14.1V at Idle and 13.9V at load (A/C, flashers, headlights on, etc.).

I am ok with this for now but will monitor as always.

View attachment 93141

View attachment 93142

Replace the battery cables. Not that expensive and will likely "fix" the issue. Did on mine.

 

[JC SSP]

I have been researching since someone recommended it…

Found new for 2010 but need to cross reference parts numbers. I will replace soon. Thx

 

[moooosestang]

did you upgrade the cable from the alternator when you got the 200a? I think the stock wire is 6 or 8awg and 4awg is recommended for a 200a alternator. Just make your own out of 2awg cable for power and ground and be done with it. https://www.batterycablesusa.com/2-gauge-awg-battery-cable-red

 

[JC SSP]

Yes, 4-gauge power wire with in-line 250AMP fuse.

I will replace the cables and add an additional ground to the alternator.

THX for the help.