The Lemon IndexA battery that keeps going flat is either old, not being charged, or being drained while parked.
Get it checked. Have the battery and charging system tested. A shop can measure the drain while the car sleeps.
An old or failing battery. Then: a failing alternator; a parasitic drain (a module or light that stays on).
Owners describe this in 9,848 complaints to the U.S. government, most often on the Subaru Outback.
Cars owners report it on most
Complaints describing this symptom, by model, all years. Raw counts, not a failure rate: popular models get more complaints.
Model years that report it most
| Model year | Complaints | Share |
|---|---|---|
| 2017 Subaru Outback | 264 | 29% |
| 2019 Subaru Outback | 219 | 21% |
| 2016 Subaru Outback | 176 | 27% |
| 2020 Subaru Outback | 144 | 16% |
| 2018 Subaru Outback | 124 | 15% |
| 2019 Subaru Ascent | 111 | 25% |
| 2011 Ford Edge | 98 | 5% |
| 2013 Ford Edge | 96 | 4% |
| 2017 Honda CR-V | 77 | 4% |
| 2020 Subaru Ascent | 75 | 23% |
| 2015 Subaru Outback | 61 | 12% |
| 2012 Ford Edge | 59 | 5% |
Each row is that model year's record in NHTSA complaints, not the history of any one car. Share = complaints describing this symptom out of every complaint we hold for that model year (shown when the year has 50+ complaints).
Where it makes up the biggest share
2017 Subaru Outback · 29% 2016 Subaru Outback · 27% 2019 Subaru Ascent · 25% 2020 Subaru Ascent · 23% 2019 Subaru Outback · 21% 2020 Subaru Outback · 16% 2018 Subaru Outback · 15% 2002 Mercedes-Benz C-Class · 13%
Model years with 150+ complaints in our data and 10+ describing this symptom, ranked by share. A high share means owners of that year who complained often mentioned it.
The details
Common causes of car battery keeps dying
- An old or failing battery
- A failing alternator
- A parasitic drain (a module or light that stays on)
- Corroded or loose battery cables
- Lots of short trips that never recharge it
General causes, not a diagnosis. A shop should confirm the cause with tests before replacing parts.
Is it safe to drive if your car battery keeps dying?
Get it checked. Have the battery and charging system tested. A shop can measure the drain while the car sleeps.
Get help right away if the battery light comes on while driving.
Of the 9,848 complaints describing it, 1% mention a crash, 1% say the car was towed, 2% mention a fire and 0.9% report an injury.
What the complaints show
The parts owners filed these complaints under: electrical system (77%), engine (12%), power train (9%), exterior lighting (6%). A complaint can list more than one.
Median odometer reading when owners reported it: 50,000 miles.
Most reports by make: Subaru (1,669), Ford (1,216), Chevrolet (1,012), Honda (707), Dodge (581).
What owners say it cost to fix
Repair bills owners named in complaints that describe this symptom (electrical repairs): the middle half ran $267 to $1,100, typical $600, from 241 bills.
Each figure is one repair bill as an owner wrote it in a complaint, not a quote for your car. Prices vary with the part, the shop and the year.
Related symptoms
Car won't start Headlights not working All dashboard warning lights on Speedometer not working Power window not working Backup camera not working
Quick answers
What causes car battery keeps dying?
A battery that keeps going flat is either old, not being charged, or being drained while parked. Common causes: an old or failing battery; a failing alternator; a parasitic drain (a module or light that stays on); corroded or loose battery cables; lots of short trips that never recharge it.
Is it safe to drive if your car battery keeps dying?
Get it checked. Have the battery and charging system tested. A shop can measure the drain while the car sleeps.
Which cars have this problem most?
In complaints to NHTSA, owners describe it most on the Subaru Outback, Ford Edge and Honda CR-V. These are raw counts, so popular models rank higher; complaints are owner reports, not proof of a defect.
How much does it cost to fix?
In 241 repair bills owners named in complaints describing it, the middle half ran $267 to $1,100. The right repair depends on the cause.
Counts: NHTSA owner complaints whose text describes this symptom (we matched owners' own wording, then read samples to check the matches). A complaint is an owner's report, not a diagnosis or proof of a defect. Causes and advice are general information in our own words, not repair advice for your car. Every symptom · Engine code lookup