On Monday my discharge warning light came on while driving home from work. It seemed to be only when I hit the brake. I got home and checked the water in the battery. All 6 cylinders were about an inch from the top but it took a lot of water to fill them. The battery will actually only be a year old next month. The fan belt is relatively new, I got a new one on about a month or 2 ago. The connections on the battery seem nice and tight and everything is clean. I drove it around a bit again and the light only came on when I hit the brake and while sitting at a stop. It goes off if I accelerate or just coasting with no acceleration. I checked the fuse for the charging system last night and found that the prongs where a little discolored and brown so I went ahead and replaced it with a spare. The light still comes on. Ive only drove the car for maybe 20 miles since this happened. The car never seems to be losing power and it starts just fine.

Im going to see if Auto Zone can test my battery. Anyone have any ideas? Everyone is kinda wondering why it starts coming on when Im braking.

 

Do you have a multimeter?

 

I do have one laying around. Its just some cheap thing that came with a toolset and Ive never used it.

 

In that case, measure the battery's voltage in these scenarios:

1) At stop with the engine off
2) At idle with the engine running and gear lever in Drive.
3) At idle with the engine running, gear lever in Drive, and with the brakes depressed.

Now obviously you'll need a helping hand for number 2 and 3.

 

I will test this after work today. What #s will I need to be looking for? Or do you just want me to post them here after Im done. Either way, I'll be replying back tonight sometime with what it gave me.

 

usually with the engine off, the voltage should be around 12.5v. With the engine running, the voltage should be around 14.4v or so.

 

Well Ive never used the multimeter before, but I set the dial to 200 V, its the V with the solid line on top and the broken one below it. Here is what I got.

1)Engine Off
11.84

2) Idle, Engine On, in Park
11.1

3)Idle, Engine On, in Drive, Brakes depressed
10.5

So did I do it right? Should I go get a new battery?

 

get the charging system checked, perhaps your alternator

 

wow your electrical system is weak. First get your alternator tested. The voltage of a running car should ALWAYS be higher than the car off.

 

When you are braking your brake lights come on and the engine slows down. Your alternator puts out less at slower speeds and you are using a little more juice. Did you try with your rear defrost on and at idle? Do you have the stock audio system? Did you check the other end of your negative battery cable to see if it has a good ground?

 

sounds like the alt is bad.

 

Get a voltmeter and with the car running put the leads on the battery leads not the terminals and see how much voltage is coming back to the vehicle! If its not sufficient then replace the alternator!

Tucker
JP Importz

 

how many miles?

btw- even when I had a bad battery the discharge light never came on.

 

Sorry, I meant to post a reply the other day. I found that this issue is with my alternator being bad. I took the ground cable off the battery while it was running and the car died. This was a suggestion from my friend's father. Im gonna have to find a rebuilt one since for a new one Ive been pricing them over $500 including install. Thanks everyone for the help, i'll definetly be coming back here if/when I have anymore problems.

 

you should check with sewell for a price of a new oem.

just curious how many mile on that alt?