I had the alternator changed 1 yr ago. All the sudden my battery drains, battery is new. Just got it 4 days ago. But it drains. Even while driving. Alternator new had it tested 5 times. Tests come out good. What can it be?
It sounds like you have a parasitic draw. This is when a system in your vehicle remains powered up while the engine is not running. This will cause the battery voltage to drop and eventually cause a no start condition.
The best way to determine which system of the vehicle is causing the parasitic draw is to connect a digital multimeter to the battery with the engine off. You should see the voltage of the battery slowly dropping. Then, remove fuses one at a time and replace them until the voltage level stops dropping. Once the voltage level remains stable, you have found the system at fault.
I would then recommend having a certified professional, such as one from YourMechanic, check for shorts in that particular system and repair as necessary. If you cannot find the source of the draining, then have a professional perform an inspection to determine why the battery is not holding the charge correctly.
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