Q: Why won’t my battery hold a charge if it’s new?

asked by on

My 2009 Honda Pilot with 45,000 miles has a problem keeping the battery charged. The battery will just be dead some mornings. Other times, it is so weak that the motor barely starts. The alarm is sometimes involved. I have replaced the battery twice now and this problem is getting exhausting! What should I do?

The problem you are describing is what we call a parasitic draw on the battery, which is an excessive draw that prematurely kills the battery either over a certain amount of time or overnight. In order to test the system draw, an amp probe on a positive battery cable is used to see if more than 50 milliamps are being drawn.

There are two potential issues which may be killing your battery. The first, the A/C relay may stick closed after shutting off the engine, which would draw excessive amps and cause your battery to die in 8 or more hours. Replace the A/C relay to fix this. The second problem is that the sunroof module is causing excessive draw, killing the battery with in a week or two. Reprogram the roof module at the dealer to correct this. Another problem could be that the body control module is not going to sleep after shut down, which may be due to the door ajar switch or other issues. A thorough diagnostic would be needed to uncover what exactly is keeping the module awake. A trained mechanic, such as one from YourMechanic, can perform a battery inspection to determine why your battery is will not hold its charge at your home or office.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Why won’t my battery hold a charge if it’s new?

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: Q: What does the TPMS light mean?

The tire pressure monitoring system (TPMS) on your Accord does exactly what the name says – it monitors the air pressure in your tires. If the system detects a drop in pressure, it turns on the Low Tire Pressure light...

Q: My car pulls hard to the right during acceleration .

Hi there. Most of the time, when the car pulls to one side during acceleration, it is caused by either the suspension being out of alignment or what's referred to as a radial pull with the tire. Inside the tire...

Q: Battery keeps dying on my car

You have what is called a parasitic draw. The vehicle has a shutdown protocol it goes through to power all of the computer and accessories off. Something in the vehicle is failing to shutdown, which means they need to pull...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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...