Help with 87 Chevy Nova (electrical)

I have an 87 Chevy Nova. A month ago, the car died. It didn't make any sound when I went to turn it on. No idiot light came on. I had it jumped and I had
the battery checked and the alternator checked and the mechanic told me it was the battery (a bad cell) and the alternator was fine. That it wasn't crucial and I could possibly get away with the bad battery in the hot weather for a while. It worked for a few days, and then died again.
So I got a new battery at Walmart for less than $40.00. That was on the 10th. I've been driving the car fine for the last two weeks. This afternoon, after sitting for about 20 hours at the most, the car was dead. Again, no sound at all when I went to turn it on. I took it back to the first mechanic and he said this battery also had a bad cell, and that it was a cheap battery (walmart) and to buy a different one. He didn't recheck my alternator. I drove it around for 20 minutes to recharge the battery (or so I think......).
It started up again fine a few hours later, I drove it to Walmart (a 20 minute drive). They tested it and said the battery was fine, it had to be a short or the alternator. Still no idiot light came on.
Here's my question. How did the battery recharge itself on that 20 minute drive if the alternator is bad? Isn't it the alternator which would've recharged the battery? If the alternator was bad -wouldn't the battery's charge been even lower after the drive to Walmart (didn't use the a/c or the radio btw).
What's my next step? Could it be a short? Or could I have just gotten two bad batteries in a row? If it's a bad battery, would it have completely recharged itself? And why would it drive fine for 2 weeks and then just die overnight?
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This problem is most likely the battery cables. Known issue on all Toyota's from the 80's. You car is basically a Toyota Corolla.
Next time it dies, and will not restart: Try having someone turn the key, while your wiggle the terminal clamps at the battery. If needed, disconnect the terminals and reconnect them.
If it is the problem order new battery cables, and have them installed. The problem with the cables starts at the battery terminal. Cranking them down tight will not usually solve it. They will work them self's lose. The cables also corrode badly.Usually the positive at the fuse block on it. Charles
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Agree, also get yourself a multimeter. You can get one that is good enough for less than $10. Places like harbor freight have good selections.
http://www.harborfreight.com
Get one that can measure current up to 10 amperes too.
You can get a pretty good idea if the battery is in good shape with a couple quick measurements.
If you read about 14 volts on the battery when the car running it is probably OK.
If the starter doesn't turn as you experienced, have someone watch the battery voltage when trying to start. If the voltage drops way down then the battery is dead. If it stays up around 12 volts then the cables are bad.
How about your interior lights? Do they dim when trying to start? If not it is definitely the starter cable.
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It didn't read that when it was first jumped, but got to 12 after I had driven it for about 20 minutes.

Great tip! Fits in with the last poster's suggestion and a great (safe) way to test to see if it's the cables. Thanks.

I did a test after I read this. When I started the car this morning I didn't have anything on - just in case and it was hard enough getting it to start so I'm glad I didn't. But this last time, I went out and turned on the dome light first. It was pretty low. Then I started the car (again, barely turned over) and the dome light dimmed to almost being out. Once the car started though, it was bright as can be. And when I was done driving around to charge the battery, it was still very bright.
So - what does that mean?!?!?! Can you figure out from that scenario if it's the starter, battery or alternator that's the problem, or can you rule out one or the other as NOT being the problem?
Thanks again, CF
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I think you should be getting higher than that. I just don't know how long it takes to get up to near 14 volts using the alternator. Since the lights dim while trying to start I would guess that you have a very discharged battery. Still a question as to if it is really the battery or alternator. Right now I lean towards the alternator but I would like to see what the voltage might be when using a fully charged battery.
Next suggestion is to get a battery charger. It takes several hours to charge up a deeply discharged battery. A charger will also indicate if the battery can take a charge. Often with a bad battery the voltage will shoot way up but it will not take a charge current.

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Guessing on this issue is silly because it takes all of five minutes to do a proper load test and charging system test at a shop with the right equipment. A flakey alternator, crappy battery, and bad connections on cables and grounds are all quite possible. GW
nospam wrote:

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I know it's silly to all of you experts, but I'm trying to educate myself before I get to a mechanic so that when/if I get a third opinion from the third person to see the car (since the first two were different from each other), I can have some basic knowledge and understanding to contribute to the discussion instead of standing there like an idiot:) :) :)
That's why I am really appreciating all the input. I'm printing out all the messages to show the mechanic. (hope I don't insult him).
CF
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No, if he's a decent guy, you won't insult him. You now understand that there could be a dozen things wrong and you have to trust him to decide which the problem(s) is/are.
Two years ago, when I just read this stuff, and hadn't worked in the trade for a while, I'd have guessed hither and yon....but now that I'm doing it everyday again, my statement is "You need the battery load tested, the charging system tested under load, and a check for voltage drops and current draws." GW
crabbefan wrote:

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However, one warning I will have for you on this:
Sometimes batteries develop internal shorts that are quite capabable of discharging the battery overnight - but will not show up on a quick load test. The way you test for these is you charge the battery then disconnect it and let it sit overnight then load test it in the morning. It's not a common battery failure but it does happen.
Frankly with all of the ways that batteries can fail, and considering how much they cost, IMHO if you suspect a battery, and the battery is more than 5 years old, then just replace it. I can buy a brand new 100 month 850cca battery for about $70 here from a local parts store. It's been my experience with lead acid batteries that their lifespan is basically time-based. Vibration and temperature extremes shorten their lifespan, but in summary, there's no maintainence procedure that you can do that will extend their lifespan past roughly around 8 years. And every year they lose more and more capacity - a battery that will turn over a 4 banger to get it started, the same one may not manage to do it with a 6 cylinder.
Ted
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nospam wrote in alt.autos.gm

Since when the car runs the battery charges up, and the light get bright, the alternator seems to be working. When the car sits for a while the lights are dim and the car barely cranks, then the battery has lost part of its' charge. You did not say how the car cranks after driving it for a while, but I bet it will crank fine. What is happening is something is draining the charge off the battery. You need to check to see what it is. An easy way is to get a 12 volt lamp in a socket with wires off the ends. Called a test light. Remove the negative cable, and connect the light between the negative post and the negative cable. The light will burn. If there is no draw, then it will be very dim, as some things need to have battery power. But if it is even somewhat bright with all doors closed, and no light on under the hood, then start pulling fuses until the light goes dim. Start with the interior lights, simply so you can leave the door open while doing this. When you find the circuit that causes the light to go out, you just need to trace it out and find out what is shorted or closed. One of the more common places is the trunk light. These are often times controlled by a mercury switch, and it could be loose.
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wow...this was my first thought too, for no reason other than a gut reaction. I opened and slammed the trunk last night hoping that if some light was on, it would turn off.
Here's the latest "symptom" to help solve this problem.
Tonight, first time today when it was dark, when I went out for my "every six hours drive the car to keep it running" routine I noticed that the headlights dimmed when I was in idle, but got bright again if I just tapped on the gas pedal.
Does that sound more like a bad battery or the alternator? would an independent drain on the battery cause that, or is it just that the battery is so run down or the alternator is over worked?
And I do appreciate the input. I'll be taking the car to a mechanic on Monday, but I'd like to be educated when I get there and able to contribute to the discussion (not just told what it is and have to take it or leave it) :)
CF
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crabbefan wrote in alt.autos.gm

Neither. At worst, your belt might be loose. But that will not cause the battery to drain. If you can start the car fine after driving and letting it sit for a little while, then the alternator sounds like it is fine. You may have gotten a bad battery, after all, you didn't pay very muuch for it. But I would check for a short. And slamming the trunk will not help. At least remove the bulb and see if that helps.

Be careful. It is all too easy to tell the mechanic to do certain things, and not tell him to fix the problem. He will then do what you told him to do. Such as repair the trunk light, rather than to fix the problem. The problem may not be the trunk light so you get the car back with the light "repaired" but the battery still goes dead.
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This sounds a little frightening to me - is there any risk of electrical shock having your hands on the battery connections when you're starting the car? (serious question!).
I will definitely tell my mechanic to check out the cables when he checks the car this week.
So far, I've been starting the car at least once every 12 hours and driving it around for 10 minutes to hopefully keep the battery charged until I can get it to my mechanic. He wants to do some test to see if the battery is being drained by any shorts, but if it's the cables, that sounds a whole less complicated (and less expensive) to fix.
Thanks again for your suggestion.
CF
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nospam wrote:

Only if you have metal hands. lol Only touch one at a time if you are nervous. GW
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