Skip the auto shop - Our mechanics make house calls

Q: Battery dies in 7 hours

asked by on

My car battery dies overnight

My car has 105000 miles.
My car has an automatic transmission.

A: First things first, Have the battery charge...

First things first, Have the battery charged and then load tested. If you have never put a new battery in your car it's probably about time. When you're satisfied that you have a good battery in the car, weather it's your current one or a replacement, the charging system needs to be load tested. It may be charging enough to keep the indicator out, but not all the way up to it's design capacity. Modern cars use a lot of electrical power, so the charging system has to be performing well. Then comes a test for off key draw. A low amp probe is placed on the battery cable and the car is allowed to shut down. This test takes some time because it takes about 20 minutes after you turn off your car for all the modules to "go to sleep." There will always be some off key draw, about 200 milliamps is common, to keep the modules alive, but a good battery should be able to keep the voltage up in spite of that for a few weeks at least. If the off key draw is in excess of 200 ma, then the source of the draw has to be foundand corrected. Most people don't have the time or the tools to perform these tests, but if you contact Your Mechanic they can send a technician to your home or office to check out you charging system and tell you what it's going to need.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 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!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Charging system failure.

This may be related to a faulty voltage regulator. The voltage regulator is a unit in your charging system that regulates the charging amperage that the alternator provides to the battery keeping it from under or over charging your battery....

Q: Car wont move

If the clutch has completely failed, it's definitely possible for it not to turn any wheels when in the air, just because the resistance in the drivetrain alone is enough to keep them from moving. With a working clutch, the...

Q: Which car is more expensive to maintain: the Audi Q5 2.0t or the BMW X5 35i?

Hello, thank you for your question. I'd be happy to provide my insight. The answer to this question isn't as simple as it may seem. The biggest factor is going to be the year of the two vehicles you are...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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 P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.