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How to get my car started?
November 4, 2012 9:47 AM   Subscribe

I know very little about cars. So why won't mine start?

I have a 97 Honda Civic Del Sol Si. Last week, I replaced the battery. Several things are occurring, which make me think it's the alternator, or perhaps not:

With the keys in the ignition, the electrical system will turn on, the radio will play, the power windows work, etc. However, power will slowly get weaker (windows slow down, etc.)

If given a jump, the car will run fine. If I jump it, I can drive around no problem.

Once I turn the car off after the engine is running, it will not start. The car will attempt to turn over, but it will be extremely sluggish and not have enough juice to turnover.

When I jump the car and attempt to charge it for 40 or so minutes via a jump to another car, it does nothing to charge up the battery.

So, does this sound like an alternator issue? Relay? Something else?

Thank you MeFi!
posted by nurgle to Travel & Transportation (12 answers total)
 
Definitely sounds like your charging system isn't doing its job. The first culprit, as you suggest, is the alternator. Any competent garage will be able to check your charging system and make the suitable repair.
posted by Thorzdad at 9:53 AM on November 4, 2012


I agree. What i'm having trouble understand is why I can jump the car and drive it around for 40 minutes no problem. Seems like if the alternator wasn't working, the car would suddenly die , which hasn't happened. Am I missing something here, conceptually?
posted by nurgle at 10:00 AM on November 4, 2012


Yes, it does. Could just be the diodes, though. They convert the AC into DC, and are cheap to replace. The problem could also be the battery contacts. Make sure they are tight (do not over-tighten or you could break the battery). Also tighten the bolt or nut where the negative wire contacts the car body. If you have a multi-meter, put it on DC volts and place it across the battery when the car is running. It should read around 14 volts if the alternator is charging properly. If your alternator is not charging, you might damage the battery if it is fully discharged for long enough, even though it is new. Get several opinions from shops--some may want to replace the alternator when only the diodes need replacing.
posted by weapons-grade pandemonium at 10:01 AM on November 4, 2012 [1 favorite]


Yes. Alternators can go bad (become less effective) before they die.
posted by perspicio at 10:02 AM on November 4, 2012


Could be a loose alternator belt, also. Check it. It should be tight enough to not slide on the pulleys.
posted by weapons-grade pandemonium at 10:03 AM on November 4, 2012


The diodes... yep, they might be on the fritz, and they might be not too expensive to buy as replacement parts... but they are not easy or cheap to replace, unless you are a techie with the proper tools and knowledge. Usually, it is more cost effective to buy a rebuilt alternator.

I'm puzzled by this- "When I jump the car and attempt to charge it for 40 or so minutes via a jump to another car, it does nothing to charge up the battery."
That might point to a bad connection to one or both of the battery posts. 2nding what weapons-grade pandemonium said about that!
posted by drhydro at 10:27 AM on November 4, 2012 [1 favorite]


Depends on the car, drhydro. I have replaced diodes on several different cars, and it has been cheap and easy to do.

When I jump the car and attempt to charge it for 40 or so minutes via a jump to another car, it does nothing to charge up the battery.

It probably does charge up the battery a bit, but then as you drive you are draining the battery to run the car, the lights, radio, etc., instead of running the car on alternator current as is supposed to happen. So you're back to square one. But as I said, if you completely discharge a car battery, it might never charge properly again.
posted by weapons-grade pandemonium at 11:28 AM on November 4, 2012


I think your alternator is just fine. First thing, your alternator does nothing when your car is not running. It is a small AC electrical generator that is turned by a belt that is connected to the engines crankshaft. I think you either have bad battery (sometimes new ones are bad off the shelf-this is why they come with a warranty) or bad/poorly installed cables.

Your description of symptoms is consistent with a bad battery. If the battery doesn't have charge to crank the car, it wont have enough to run the car more than about 20 minutes at the most and most likely will not run at all once the outside jumper cables are removed. It is possible your alternator is making JUST enough power to keep your car running but not enough to charge the battery but seems unlikely.

The first thing to check is to see if you can physically move either battery cable (the positive and negative one) on or off the battery terminals. If you can grab and move the cables where they attach to the battery (the terminals) you have a connection problem and it will be obvious what bolts to tighten to fix this. Also if there is anykind of white powder or discoloration around the terminals/cables you probably need new cables as they have corroded to bady from the leaking acid from your old and/or current battery. This is very common in older cars as battery goes bad is just like brake pads-sooner or later you will need to replace the cables.

IF the cables are ok, you need to take the whole car in and have them run a whole test on the charging system (you can kinda do this with a multi meter at home but you need to know a fair amount about how to read multi meters and how much voltage you should be reading across the battery as the car runs-and from your description you don't).

My prediciton is your alternator is maybe going bad and you also got a bad battery. It is extremely common for both to go bad at the same time, they are linked closely and as one goes bad it places a lot of stress on the other and this will usually do in an old one. But if you karma is good you might get lucky and just have a bad connection on a cable.

here is some you tube clips
battery cables

diagnosis
alternator
testing

posted by bartonlong at 11:34 AM on November 4, 2012 [1 favorite]


Seems like if the alternator wasn't working, the car would suddenly die

Eventually yes. But unless you're using your headlights or the like, the rest of the car's electrical system puts a fairly light load on the battery, and it'll run for a good long while with a bad alternator (or bad/loose belt, as was the case in my car on a couple of occasions).
posted by hattifattener at 12:51 PM on November 4, 2012


I'd bet on the alternator. If it's 95% shot, you might still be able to drive the car on that 5%, as long as you're not using the lights or the wipers. (I once drove my 1990 CRX - the precursor to your car - for three days just by jumping it in the morning, driving to work, getting a jump at work to drive home, and parking on hills to pop-start it.) I would not be surprised if the dying alternator killed your already-weakened previous battery.
posted by notsnot at 2:51 PM on November 4, 2012


That might point to a bad connection to one or both of the battery posts. 2nding what weapons-grade pandemonium said about that!

I once had similar symptoms to what you describe due to a loose connection on the path to one of the poles - the battery wasn't charging due to the voltage drop from the extra resistance. One test for this kind of problem is to start the car, and measure the voltage accross the battery terminals: it should be measurablty higher than 12V, even with all electrical loads operating - something like 14V with nothing on, dropping to 12.5V with the headlights, radio etc running.
posted by Dr Dracator at 2:53 PM on November 4, 2012


When my alternator went bad, I couldn't start my car. I got a jump and things were going fine, when suddenly everything just died. The tape in the tape deck (this was several years back) got really slow and turned off. The windows stopped working. Then it just quit.

I was in a funeral procession at the time, so it was really embarrassing and the car behind me had someone get out and help push me out of the way.

If your car isn't dying while you are driving, my anecdote suggests it isn't the alternator.
posted by tacodave at 4:19 PM on November 5, 2012


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