82SC Battery Dead (Again)

mtelliott · 11:25 AM

I've been using the search function to try and diagnose why my battery dies on occassion.

I have an 82SC. This morning, I go in to start her up and the battery is almost dead. This is the second time it's happened in three weeks. I drive it daily. I checked and I didn't leave light on or anything like that.

So, either my battery is dying or I have a electrical leakage.

So, how do I check for electrical leakage? I have a multimeter. I just need to know what to do. I read that you can take out all the fuses and then put them in one by one to see how it effects drain on the battery to see if a circuit is open that shouldn't be. Don't know how to use my multimeter to accomplish this though.

Any advice greatly apprecitated.

Michael

Jared at Pelican Parts · 05-17-2005, 06:22 AM

Check your ground straps first. Replacing them on my car solved a similar problem.

mtelliott · 05-17-2005, 06:40 AM

I'm familiar with the ground strap between the trans and the car. Are there others?

Jared at Pelican Parts · 05-17-2005, 06:46 AM

battery to the chassis...

Nitrometano · Nitrometano's Garage

Recently my brother 911 have this kind of problem. The first problem was the 12 volt cable that runs from the baterry to the starter. The second problem was the radio (cd receiver) is was leaking energy. The other problem was the 12 volt cable that runs from the baterry to the starter. The One year ago, I check a Mercedes with the same problem and was the radio. The problem was the radio output to the electric antenna.

One easy way to check if you have a energy leak is:
First disconect the hood light and music amplifiers. Then disconect the positive battery terminal and then touch the batterry pole. If you see a spark every time that you touch the pole. That is a leakage. Try to disconect the radio 12v of fuse and repeat again. If the problem persist, make the test every time that you remove one fuse. If you remove one fuse and ther is no spark on the test, you find the leakage and find were in the cable or accesory the energy leak occurs.

Good Luck!!!

mtelliott · 05-17-2005, 06:55 PM

These are the numbers I have for Voltage

After charging all day: 12.65 volts
After starting it up: 13.80 - 14.39 volts
15 minutes after shut down: 12.60

I'll read again in the A.M.

What do you think so far?

This weekend, I'll take the battery out and see how it does without being connected to anything.

Nitrometano · Nitrometano's Garage

With the engine running turn on the head lights high beam, a/c, radio, wipers, fog lights and check for a voltage drop. The drom can not be less than 12v. Turn off all the accesories and check the voltage. They will are between 13 and 14.5. Check the battery condition to know if are weak or bad. Then make the fuse removing test that I tell you.

mtelliott · 05-17-2005, 08:50 PM

I'll be trying the fuse removal test this weekend. It's a great suggestion and I thank you for pointing out how it's done.

It seems from my initial test that my charging system is OK and don't have a ground issue. Now it's down to either the battery or accessory leakage? Would you concur?

TerryH · TerryH's Garage

Checking for sparks repeatedly at the battery terminal sounds like a real bad idea. Instead hook up your volt meter, set on DC, inline between the neg battery terminal and neg cable. Unplug your hood light, make sure your doors are closed and get a reading. Hopefully, it should be somewhere below 100ma.

bigchillcar · bigchillcar's Garage

how old is your battery? many on this board, myself included, feel that replacing the battery every two years is pretty cheap insurance. if your battery is 3, 4 or more years old, it may very well have dead or dying cells...these aren't very big batteries. take the battery to a napa where they can not only check it's 'voltage', but see how it does under a load, which sound slike your issue. good luck.
ryan

Paulporsche · 05-18-2005, 04:06 AM

I second Big Chill. In the meantime, check to see that your light inside the front trunk goes off when the lid is down.

Ron.G · 05-18-2005, 04:06 AM

A word of caution on the "checking for spark" thing.
If you just charged your battery and the do this, It can cause a big explosion!

I've had this happen to me a long time ago and it was not good. Got covered in battery acid and never found the top to the battery. It went off like a bomb!

Sparks and batteries don't mix.

mtelliott · 05-18-2005, 06:09 AM

Battery was between 10.80 and 11.30 volts this A.M. Needless to say, she didn't start. Sounds to me like I have a battery going dead.

I'm going to disconnect the battery and see how it does with nothing on it? Then tomorrow, I'll take her to Napa to get a reading.

This weekend, I'm going to follow Nitro's advice and check each accessory for leaks.

Thanks for your help. I've learned a lot on diagnosing electrical gremlins.

Can anyone answer why my multimeter voltage doesn't stay constant when I take a reading? It always goes up and down. Does that have to do with how the probe connects with the terminal post. It's just a probe, not a clamp.

Nitrometano · Nitrometano's Garage

Maybe you can do this: Charge the battery and check the voltage. Leave the battery in some place and do not connect it to the car. Leave it alone. After a few days, check the voltage again to see if they drop.

mtelliott · 07:26 PM

What should the amperage register without having the ignition on? I have about a 2.6 amp register without the key in. Does that sound correct?

Update: No matter what fuse I pull, I get the same reading. I'm thinking I'm not using my meter correctly. Shouldn't I get a change in amp when I pull some of the fuses?

Paulporsche · 06:14 AM

I don't know what amperage you should be getting, although that seems high.

Maybe you have something that is unfused that is drawing. Besides the trunk light, some have mentioned alarms and ashtray lights. Maybe you have unfused audio equipment .

Maybe your battery has had it. How old is it?

mtelliott · 05-20-2005, 08:51 AM

Battery is at least 5 years old so I replaced it. There's no unfused audio equipment minus the connection to the battery for the cd player which only drawls enough to hold the settings. Light doesn't work in the trunk but I'll take a look at it. I'm missing something or not using my multimeter properly.

sammyg2 · 05-20-2005, 09:15 AM

My SC did the same thing when I bought it.
I did the voltage regulator trick, pulling fuses, checking. Everything looked fine, except the main power line going to the starter. It had a draw.
I got underneath and disconnected it and re-checked, it wasn't the starter. That meant it could only be one thing, the line going to the alternator. Checked it, bingo.
I had to get my alternator rebuilt, that took care of it. It had a small leak to ground.
Your problem may be completely different but my point is when dealing with sparktricity you need to follow a methodical, logical approach and not assume anything. if you do it logically you will be able to trace the source of the leak.
Electricity can be thought of as very similar to a hydraulic system, with invisible hydraulic fluid.
Of course I did all that after verifying that my battery was fine and everything else checked out.

oh, and whatever you do, don't let the magic smoke escape from the wires.

mtelliott · 05-20-2005, 09:40 AM

SammyG2:

How did you discover? I understand how to pull fuses and check for current flow. How do you check leakage on alternator and starter? What do you unplug. I guess on the starter, you pull the main power going to the starter and see if you have a leak. True? What about the alternator? How do you check that one?

bigchillcar · bigchillcar's Garage

5 years or more..wow..gotta be your issue.
ryan