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Battery or alternator issue?

dukebound85

dukebound85

macrumors Core
Original poster
Jul 17, 2005
19,218
4,342
5045 feet above sea level
Well my car didnt start last night....not cool at all

Car started up normal when left for night and then when i came back to it, wouldn't start

This same situation happened recently (a month and a half ago) and ended up being fixed by cleaning the terminals connections of the battery

However, what has me thinking it may be the alternator is the fact that while I was driving, when I started the heater, the car turned itself off for a microsecond (enough to yurn off my stereo) and turned back on. The car died when I was at a stop light, the rolled down the window and accidently held the switch down like a second after the window was down.

I then got jumpstarted and noticed that applying the brakes dimmed my headlights. This makes me think it is an alternator isssue right? As the car shouldnt be drawing any current from the batt while running

With that said, I replaced both my alternator and batt in June 2005 so over three years ago. I have put 25k miles on in that time


What are your thoughts? Anyone have a lot of experience with this?


I should mention that my car exhibited the same behavior last year and it turned out to be low water in batt and corroded connectors.

You think it is corroded connectors (doesnt look too bad but neither did last time) or do you think it is an alternator with how it died while running when i applied a load on it (aka power windows and heater)?
 
You could pull your battery out and take it to your local auto parts store (Canadian Tire in Canada) and they should do a free battery test for you.

One possible problem is that, if your battery is dead, a bad alternator could have killed it. Also, if you have a bad battery, you could end up damaging your alternator.

I had a similar problem. Turned out that I had a dead battery and I had the alternator checked and it wasn't charging properly (just slightly lower than expected). Luckily, they found a bad ground connection on the alternator and I didn't need to replace it. However, the main cause of my dimming lights etc. was the bad battery that was causing the alternator to work overtime trying to charge the battery while keeping the car running.

Cheers.
 
Get your car started, jump off ect, then remove the positive cable. If it dies, then its the alternator. If it doesn't take the battery in and have it checked. Could be a bad cell. Voltage regulator is a distant third.
 
Removing any cables while the car is running is not the smartest of things to do. If you get it jumped and the battery runs dead it is the alternator. if the car won't jump at all it is the battery.
 
well once again it turned out to be the connectors.

i first tried to start it and nothing happened (wanted to see if it was a temperature realted issues since it was like 40 last night and 80 now

I then took off the connectors and scraped them clean and then tried starting without jumping and it worked


with that said, is there a way to prevent/reduce corrosion on the terminals? i mean really, it didnt look like there was much at all on there yet it prevented my car from starting
 
They make a fiber washer to put on the terminal of the post types that slow or eliminate the build up on them. The alternative is to clean the terminals every 3 months, say when you get the oil changed.
 
Lithium grease can se used on battery terminals to help prevent corrosion.

My battery was doing the same thing as yours. I kept cleaning the terminals thinking that I was solving the problem. But my battery was weak and even slight corrosion on the terminals was enough to "mess things up". If you don't want to get stranded somewhere, it's worth having the battery tested. I went to the auto parts store, parked the car, yanked the battery, and took it in to be tested.

Cheers.
 
iMac-Knight said:
They make a fiber washer to put on the terminal of the post types that slow or eliminate the build up on them. The alternative is to clean the terminals every 3 months, say when you get the oil changed.
Click to expand...

In a pinch, a bottle of two of Coke or some other similar soda with phosphoric acid in it will do the trick. I don't recommend it as regular maintenance, but if you're in a bind it will help.
 
MacNut said:
Removing any cables while the car is running is not the smartest of things to do. If you get it jumped and the battery runs dead it is the alternator. if the car won't jump at all it is the battery.
Click to expand...

The suggested method was fine and specified the exact cable to remove. If you are scared of working on an engine then take it to a mechanic, but don't spread your fear to others.
 
at autoparts stores they sell some spray on stuff that reduces it.

I would recomend getting your altinator check. most autoparts stores have the tools to do it.

Things that tend to go back on alternator is the diodes. Those turn the AC current of the alternator to DC current. AC current will destroy you car's electrical
 
Here is one spray can version. I usually use a tube.

Cheers.
 

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