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The Pub For General Automotive Related Talk |
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#1 | ||
Banned
Join Date: Aug 2009
Posts: 382
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What should the voltage across the battery terminals read on a brand new battery installed into a car? Is it meant to begin at the battery's current off-the-shelf voltage (12.5) and as it charges, climb up until it matches the car's electrical system (13.8)? These measurements are made when engine is running btw.
I've just installed a new battery, and the voltage at the terminals with engine on, began at 12.5. After a short 5 minute drive, it was climbing towards 12.8. Shouldn't the voltage at terminals be already at around 14v, as soon as a new battery is installed and engine is turned on, or is everything ok? From inside the car (cig lighter socket), there's a healthy 13.8v however, regardless of what the battery terminals are at. Last edited by barra265t; 06-11-2009 at 12:23 AM. |
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#2 | ||
Now Fordless
Join Date: Aug 2005
Location: Fremantle, WA
Posts: 3,611
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Yep. Will be around 12.5 when car is not running. Around 14 when running.
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#3 | ||
Now Fordless
Join Date: Aug 2005
Location: Fremantle, WA
Posts: 3,611
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It should read 14 almost straight away. Try putting the lead of the multimeter on the positive on the back of the alternator and see whats coming out of there.
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#4 | |||
Banned
Join Date: Aug 2009
Posts: 382
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Quote:
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#5 | ||
FF.Com.Au Hardcore
Join Date: Jun 2007
Location: republic of wa
Posts: 869
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gday all . had this problem a few years back. turned out to be corroded connection on the alt. (main power feed to the battery). also the little wire going to the warning light was a bit loose. should read about 12.5 car off, 14.6 car running
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#6 | ||
Now Fordless
Join Date: Aug 2005
Location: Fremantle, WA
Posts: 3,611
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This pic is not of a Falcon its just an example.
![]() The positive going to the battery is a thickish wire usually held on by a nut as in photo and covered by a rubber boot. Will be on the back of the alternator. If its accessible,(im not sure I cant remember on these engines) you can put the positive side of the multimeter on this to check if the alternator is putting out any voltage. Warning - if this is attempted, make sure you dont touch any other metal and arc out the alterator. Will blow fuses |
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#7 | |||
FF.Com.Au Hardcore
Join Date: Jan 2005
Posts: 1,463
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Quote:
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