Q: Q: Can a bad alternator drain a battery

asked by on

My car hasn't been driven in 2yrs. I bought a new battery and it was cranking. Two days later, I try to crank it and the battery is dead. Will a bad alternator drain a battery

My car has 150000 miles.
My car has an automatic transmission.

Hi there. Generally, a bad alternator will not drain a battery, but will not maintain the battery charge. It sounds like you have a parasitic draw on the electrical system; something is continuing to power on after the vehicle is turned off. Perform a quick check to see if the glove box light or the trunk light is staying on after closing; this is more common than most people realize. If these are operating ok, then there would need to be a parasitic draw test procedure performed that isolate the circuit, then the component or wire that is causing the draw. I suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a battery is dead inspection.

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. Q: Can a bad alternator drain a battery

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: Will bad brake calipers cause excessive vibrating in steering wheel while driving?

This may very well be caused by the uneven wear on the front tires. When uneven tread is subjected to various road conditions or braking power, this will definitely cause a vibrating or shaking feeling. This may also be caused...

Q: The engine coolant reservoir is bubbling over but will go down but the engine is not over heating wht could this be

Hi there. In many cases, when the coolant boils, it's due to the coolant being too thin in the mixture; meaning there is more water than coolant in the system. The mixture is supposed to be 50 % coolant to...

Q: Dealer told me to pull fuse to side mirrors as the motors will not stop even with car off. Drained the battery. After two hours I

It sounds like you may be having a problem with your power mirror switch. Most vehicles allow the power mirror switch to operate even with the engine off. A short in the power mirror switch would cause the system to...

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...
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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...