Q: Battery drain

asked by on

Car battery has been draining after running then shutoff sitting in driveway after a period of time. Charge battery with trickle charger then battery voltage is 12.5v car starts. Car dash reads 13.5-14v while running sometimes drops to 12.5 while idling in traffic There is an ignition interlock installed for past 2 months however this issue just started the past 3 days. Dies battery need to be replaced or is the alternator failing?

Thank you in advance

My car has 80000 miles.
My car has an automatic transmission.

It sounds like your alternator may not be charging quite as effectively as it should be. The drop in amperage at idle is not necessarily unheard of but could be the beginning of it starting to fail. The voltage when running seems to be normal as 13.5 to 14 is within normal range. The battery drain while sitting may suggest that the battery is slowly beginning to fail. I would recommend having an expert from YourMechanic come to your location to diagnose your charging system.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Battery drain

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: What should I replace before getting front end aligned? 2006 Toyota Corolla 140k miles.

Hi there. Before having an alignment performed on your car, check the ball joints, control arm bushings, and the tie rod ends. These items will cause the tires to wander around wearing out the tread fast. If your tires have...

Q: I'd like you recommend me about the usage of 'HHO Dry Cell Generator Kits' in Cars.

As long as you follow the directions exactly, you should have no problem installing the device. How efficient the system is varies by the design on the hydrogen generator and other component, including the engine itself. It can be argued...

Q: Mercury Mariner battery light

One hundred forty miles is too far if your alternator has failed, even if you depart with a fully charged battery. In your circumstance, what you want to determine is charging output at the battery posts. Charging output should be...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...