Skip the auto shop - Our mechanics make house calls

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?

A: The problem you are describing is what we c...

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?

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

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: My car won't start.

It's not unheard of for a new battery to fail, but it seems likely that the car's charging system is not working. That should have lit up some warning lights long before it became enough of a problem to shut...

Q: Water in fuel tank

Hello! If there is water in the fuel tank, the only way to resolve it is to have the fuel tank drained and removed, so the fuel pump can be removed and the tank wiped down internally; you will want...

Q: Car not starting in temperatures over 80 degrees

Hi there. This can be a common issue that vehicles encounter when the temperature outside is warm or if there is a sticky starter solenoid. The solenoid will stick even if sufficient current is applied to its switch. I'd suggest...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
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.