Skip the auto shop - Our mechanics make house calls

Q: Thought it was the battery but could possibly be the alternator

asked by on

For the past week when I'd go to get into my car I'd turn the key over and it would take a good two seconds before the car would start. When it would start, everything starts out dim then lights up and it's fine until the next day. Same thing would happen. Just the other day I had a friend look at it and the positive side on the battery was covered in corrosion. We cleaned off the corrosion, which reset everything in my car and now everything seems to be better. Went to auto zone and told the guy what it was doing before we cleaned it off and he said it's my alternator. Today I get in the car and there are no problems like there was before. Starts up fine and no dimming of lights. Any idea what it could be?

My car has 110000 miles.
My car has an automatic transmission.

Bad connection can be confusing. They are touching and the connection may even be tight, but electricity doesn’t care about what our eyes see. Electricity happens at the atomic level. A bad connection is a loose connection or a surface corrosion. A dirty surface can stop all electric current from flowing.

You stated you cleaned the corrosion off the battery terminal and you had positive results. This is a pretty good sign you are on the right track. My only suggestion is to do this again but buy a battery terminal cleaning tool, some battery cleaner and sealer. Once you see how the tool works, you will have a better idea of what electricity expects for it to do work for you.

Bad connections at the battery or anywhere along the connections from the alternator to the battery will result in a battery that isn’t fully charged. This will act like a bad battery and some will assume the alternator is bad. The fact is, neither of these can be accurately diagnosed without the proper conditions. Once things are as electricity expects, then accurate testing can occur.

I recommend having a certified technician, such as one from YourMechanic, service your battery cables to fix your issue.

Good luck!

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: With car off, exterior and interior lights start flashing

It sounds like somehow the anti theft system was activated and drained the battery. Try locking all of the doors from the inside and close them. Then lock, unlock, lock and unlock the doors to see if the problem persists....

Q: Have trouble code p2101. Cleaned the throttle body unit and still bad. Idle is always high surge like idle.

Hi, thanks for writing in. Code P2101 is titled Throttle Actuator Control Motor Circuit Performance. Instead of using a traditional throttle cable, your vehicle uses an electronic throttle control. In this system, the throttle control module receives input from sensors,...

Q: Front driver side wheel wants to lock up while driving it'll pull to the left and tries to stop.

There are a few possible causes for your brakes to engage. Caliper pistons can be seized, hoses can be pinched or closed off on the inside, or even electrical problems with the ABS. Have your vehicle scanned for ABS troubleshooting...

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...
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...
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.