Start with the simple checks
Look for a glovebox, trunk, or vanity light left on, and unplug dash-cam or phone chargers that stay powered with the car off.
Parasitic draw
A healthy modern car draws under about 50 milliamps after modules sleep. A stuck relay or a failing module can draw several times that, killing a battery in a night.
Need this checked today?
Our mobile mechanics provide auto electrical repair at your location — call 469-421-7910.
Worn battery
Batteries over three years old in Texas often lose capacity. A load test shows whether it can still deliver its rated cranking amps.
Aftermarket accessories
Remote starters, stereos, and trackers wired to constant power are frequent culprits.
Frequently asked questions
How do mechanics find a parasitic drain?
With an ammeter in series with the battery, pulling fuses one by one to see which circuit drops the draw.
Can a bad alternator drain a battery with the car off?
Yes, a failed diode in the alternator can.
How long should a car sit before the battery dies?
A healthy car should sit 2–4 weeks without trouble.