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Battery voltage fluctuation and occasional no restart

8988 Views 7 Replies 4 Participants Last post by  repairman54
Hello all, I have a 2013 Malibu LT, I bought it of an auction and it appears to have a very irritating issue with the battery going dead. I am familiar with the charging system, but am hoping someone can give me a clue. Here is what happens. I start the car and the charging voltage starts at 14.4 then after 30 seconds starts dropping and ends at 12.5 volts. When this happens, if I stop the car it will not start, however, sometimes it stays at 14.2 and never have a problem starting. The car has never died while driving as it stays at 12.5 volts which is enough to keep it going, but not enough to recharge the battery. The battery holds a charge and I have watched the alternator charge at 14.2 and drop to 12.5 with a volt meter and the car's gauge. All connections are tight and clean, any thoughts? Diode in the alternator, voltage regulator??? Help!
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Get the battery load tested. Only way to confirm battery is indeed good and not having a weak cell only holding a ''surface'' charge. Confirmation of a good battery is step one and a load test will stress the battery bringing out any weakness in it.
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Yes voltage will drop as battery charges as a fully charged battery is 12.6 v . Good battery needs to be confirmed before any other diagnostics are done. Today's batteries may only last 3 to 4 yrs. .
OK, I understand. I have a Chevy Malibu 2013 LT 2.4 eco. The battery is brand new. Car starts and Voltage is 14.1 to 14.4 but will drop to 13.6 to 13.9. Then I will get a drop to 12.5 for a while then it kicks back up to the 13.6 to 13.9.
Normal readings.
Smart charging systems today will vary voltage as the battery needs it. In the 14's after a start is the system recharging the battery. As it takes a charge it will drop down, as it needs more it will charge more. New battery will ''bounce back'' faster than a older one. One short trips it may never get down into the 13's and also depends on what's running in the car like a/c , lights, heat, etc. . Longer drive times it will get down into the '12's with a good battery.
If alt. was bad it would never get into the '14's.
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