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・Fair and transparent pricing

Get a quote

What others are asking

Q: Battery light on while driving but then goes off?

The battery light indicates that your charging system has a flaw in it which may be a sign of a weak battery, a failing voltage regulator or failing alternator. As you may know, the alternator is responsible for charging the...

Q: I need to know if I am being ripped off

They sell a kit for $85 via Bonanza for your Audi A4. A timing chain solenoid replacement usually calls for about ~5.1 hours of labor which can average out to around $100 per hour. So I would expect around $800...

Q: Left indicator and windshield wipers work intermittently

If the fuse was blown on any of these circuits it would cause an open circuit. With an open circuit, whatever components that are controlled by that circuit will not function. The most likely cause would be an intermittent issue,...

Related articles

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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
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.