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Unpredictable Battery

My 18 year old daughter inherited my 2001 Oldsmobile Alero. While this car has been reliable in most instances, it has a habit of not wanting to start every few months. The weather can be hot or cold, wet or dry, it doesn’t seem to make a difference. So she calls me, I look at it and when I try to start it, the engine tries to turn over, but there is not enough power. I get out the jumper cables, start the car and it is fine. On more than one occasion, I have taken the vehicle to a repair shop and ask them to check the battery. When they do, it comes back as OK. I have also had them check the alternator and it checks out OK as well. Any thoughts as to what could make the battery just not want to start from time to time. I asked my daughter if she was running a lot of accessories and she hasn’t been. She simply turns off the car, does some shopping and when she comes back it won’t start. I have asked several mechanics and none had a suggestion beyond changing the battery which I have done twice, but it continues to do it. I have ensure dthat the battery is firmly secured and not moving around, which I was told could cause problems. Your input would be appreciated. Thanks

Sounds like you have a parasitic drain. You need a good mechanic who will spend the time to find the problem. It takes time to do this because all the fuses have to be pulled one by one including circuit breakers. Read this web page for a further understanding of the problem: http://www.aa1car.com/library/battery_runs_down.htm

Buy her one of those portable starters to carry around in the trunk.

My suggestion will not cure whatever ails the car, but it will enable your daughter to always get the car going if it should act up. This item will cost less than a mechanic’s time, and he might not even be successful in solving the problem.

I Guess By Now That Somebody Has Disconnected The Battery Cables At The Battery, Thoroughly Cleaned The Cable Ends And Battery Terminals, And Then Reconnected Them. Is This Correct ?
I’d also check the other ends of the battery cables for corrosion or other problems. Also check the engine to body ground strap(s).

If you are called on to jump the car again try first connecting just one jumper cable to the Alero’s battery and then to a good ground on its engine and then try starting it. This will give you a temporary second ground wire in case the installed one is not doing its job.

CSA

Addition: I reread and see that the battery has been replaced with no solution to the problem, so I guess the battery to battery cable connections are pretty good, but maybe not the cables’ other ends.

A"portable starter" what is that? Now I know what you mean but the public reads this and thinks there is some kind of "portable starter " available. We have enough problems getting people to explain what they mean when they say “my car wont start”. We don’t need to add to the problem by using their poor communication skills.

OP, SteveF is talking about a portable battery pack or portable jump start pack.

I had a similar issue with a VW Jetta (1988). Dealer had no idea, an old school mechanic simply changed the ground strap (NOT CLEAN) and it was fine from then on.

There could be one or more of several conditions causing this problem. No way to diagnose over the net, but just to put things in perspective, there’s the starter, alternator, voltage regulator, & battery, & all the wires that connect them. You might go to a garage that specializes in automotive electrical systems. There seems to be one in every community. Since they specialize, they can pinpoint the culprit quicker, & since time means money, cheaper.

"She simply turns off the car, does some shopping and when she comes back it won't start."

I had this happen on an older Nova I had. The Battery Pos. cable was getting too hot being near the exhaust manifold, making the resistance too high to draw enough current to turn the starter properly. The problem I had was solved by moving the Pos. battery cable that goes to the starter away from anything that got hot (exhaust manifold, engine block). I had to get a longer cable and route it differently. Sometimes the cable actually originally had a tube that it went through or other insulation from heat that may have degraded over time.

This happened to me on my GM vehicle with side post tereminals. Try this: see if you can twist the battery cables and make them swivel around the post bolts. If you can, and you have already tightened them up as much as possible, the problem may be that the replacement battery bolt holes are not long enough for the battery bolts to be sufficiently tightened - they bottom out before they are tight. They should not swivel around the posts at all. It seems that some batteries have bolt holes that are too short.

The cure for this is to get a copper or brass washer and put it between the battery and the bolt. this will allow you to snug the battery bolts down long enough. This si not the only possible thing that could be wrong, but it is a quick and cheap place to check and fix.