Battery keeps dying

A battery that is repeatedly flat after the car stands overnight is either worn out, not being charged, or being drained by something that stays on.

AreaStarting & electrical
UrgencyModerate

Can I keep driving? Drivable with care. Diagnose soon: performance, economy or other components can be affected.

Common causes

Old battery

Most car batteries last about 3–5 years, less in hot climates.

Charging system fault

A weak alternator or slipping belt never fully recharges the battery.

Parasitic drain

A module that does not go to sleep, a glovebox or boot light, or an aftermarket accessory.

Short trips only

Starting uses more energy than a few minutes of driving puts back.

Corroded terminals

Restrict charging current.

What to check

  1. Have the battery load-tested.
  2. Measure charging voltage with the engine running: typically about 13.5–14.7 V.
  3. Measure parasitic drain with an ammeter after the car's modules have gone to sleep.
  4. Clean terminals.

Related OBD2 codes

Repair guides

How to replace a car batteryHow to jump-start a car

Other starting & electrical problems

Car won't start, just clicksEngine cranks but won't start

General guidance only. A qualified technician can confirm the cause; brakes, steering and fuel leaks should be checked professionally if in doubt.