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Old 12-20-2017, 12:45 AM
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bennyb53 bennyb53 is offline
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2019 Sentra
2002 Altima
 
Join Date: Jan 2011
Location: Hawaii
Posts: 2,105
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1. Your number is flawed. From 12.74v to 12.59v is not 15 volts. It is 15 millivolts (15mV). A new battery is 12.6V so at 12.59v is just fine. At 12.74v is slightly overcharged that may indicate a problem with the Alternator's voltage regulator. A failing/or failed alternator will not charge the battery or may even overcharged the battery which is not safe

A load test is done to determine if alternator is working or has failed. It is not done to determine a Parasitic draw. If you have a parasitic draw, it means your battery is being drained over a 2 or 3 day period or if a massive draw the battery is drained overnight.

I suspect your issue is the alternator so you can do the load test. With a volt meter or digital multi meter take a battery voltage reading before starting the car. Start engine and after reaching normal operating temperature turn on your headlights, turn signals radio, fog lights if equipped, a/c or heater and fan on high. Then take battery voltage reading and you should get 14.5 to 14.7 volts. If you get less than 14V you need to replace your alternator.
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