What it usually is
- Parasitic drawmost common
A module, light, or aftermarket accessory stays on. Dead after a day or two of sitting.
Fix: Electrical Diagnostics & Repair → - Alternator underchargingcommon
Dies while driving or after short trips. Low charging voltage.
Fix: Alternator Replacement → - Bad battery (yes, even new ones)common
Fails a load test. Wrong type for the vehicle, or not registered on cars that require it.
Fix: Car Battery Replacement → - Corroded terminals or groundcommon
Charging looks fine but doesn't reach the battery.
Fix: Car Battery Replacement →
What to do right now
- Note whether it dies after sitting or while driving.
- Check for anything plugged into the 12V outlets or an aftermarket stereo.
- Book a parasitic draw test — we can leave it running overnight at your house.
How a mobile mechanic handles it
We come to where the car is — that's the whole point when it's a battery keeps dying situation. We diagnose with a professional scan tool and proper testing, tell you what's wrong and what it costs, and fix it on site when parts allow. Most of these are single-visit repairs in your driveway.
FAQ
Common questions
How much battery drain is normal?
Under about 50 milliamps once the car goes to sleep. Anything over that will kill a battery in days.