Mechanics Advice Needed!

My 1997 Ford Taurus had been running just fine. Today when I got back from going to town the steering wheel locked up so I put the key back in the ignition to unlock it. The steering unlocked but I then realized it would not crank. I would turn the key into the start position and absolutely nothing would happen, panel lights or headlights wouldn’t come on and the doors wouldn’t lock. I went back out a few hours later and turned on the headlights, they were very dim. The panel lights came on but when I tried to start it, all I heard was one click. It did the same thing on the second attempt and on the third attempt the panel lights didn’t even come on and everything was dead, no click. Obviously, the battery is dead but it’s getting some small amount of power over time. Any ideas of what might be the problem? It cranked perfectly earlier in the day. Don’t think this matters but it has rained about 20 inches here in the last few days. Thanks in advance.

My first thought is that the alternator isn’t charging, either because the alternator itself has gone bad or there’s a bad connection due to a corroded wire or something similar.

If a car battery discharges too far it chemically self-destructs, so you might need a new battery now even though that may not have been the original problem. A cheapie battery charger from ye ol local auto parts store will charge the battery slowly, which is better for it when it is that far drained. After that, if you have a voltmeter, you can check the battery voltage. It should be around 12.6 volts when the battery is fully charged. If the alternator is working, the battery voltage should go up by a volt or two when the engine is running.

I would assume that the alternator is fine, since you drove all the way home, and the battery was stone dead when you got there. During normal operation, the alternator runs everything in your car while the engine is running, and has spare power to recharge the battery. The battery is only used to get the car started. What I would do is jump start the car, then run it with as much power usage as possible. Turn the radio on loud, turn the A/C on, turn on the brights, turn on the wipers. Your alternator should put out enough power to run everything. If that works, then you know that all you need to do is change the battery.

Not exactly.

What you posted was true back in the days of generators. Modern cars use alternators, which put out AC sine waves. While the alternator does have a voltage regulator built into it (some might have an external regulator, which was more common in older cars, but every one that I am familiar with has it built-in) the car relies on the battery to do a large bulk of the voltage regulation and smoothing of the AC waves into DC. When the alternating current dips low, the battery supplies the current, and when the alternating current is high, the alternator powers the entire load on the car, including charging the battery. On average, the alternator will put more energy into the battery during the high sides of the AC waves than the battery will put out during the low sides of the AC waves, so on average the battery will charge rather than discharge.

In the old days, you could disconnect the battery to test the generator. The generator’s output was constant enough that it would keep the engine running, and the car’s electrical system was pretty simple anyway.

If you disconnect the battery on a modern car that is running, the wild voltage swing that will result can easily damage a modern car’s complex and sensitive electronics and you could end up with an extremely expensive repair bill. Don’t try it.

Anyway, regardless of whether you have a generator or an alternator, if that fails, then the car’s battery will supply all of the electricity necessary to run the engine and the car’s electrical system. Everything will be fine at first, but then the headlights will start going dim (if you have them on) and things will start behaving erratically, and at some point the engine will stop running. In other words, it will behave very much like the OP described. The one click when trying to start the car is typical of a starter’s behavior when the battery is dead. The battery has enough energy to kick the starter solenoid out (that’s the click), but not enough energy to crank the engine, so nothing more happens. Sometimes you’ll hear multiple clicks if the battery is too weak to keep the starter solenoid fully engaged. The starter solenoid will click is it bangs out into position, but then it will fall back until it’s far enough back that the weak field from the solenoid coil and the weak battery can push it out again, and it repeats, just going click click click click etc.

The fact that the battery was weak enough that all it could do was click the starter solenoid makes me worry that the battery was damaged by being discharged too much.

Look for corrosion on your battery terminals. If they have corrosion you need to clean the terminals and terminal clamps to get a good connection. Also, check the date on the battery, it probably needs to be replaced.

Anytime you have a problem such as you described you need to go through a series of checks and verifications. No rreal shortcuts. You need to verify the state of charge on your battery. If the battery is low you need to test the condition of your battery, if the battery is good but discharged you need to check the alternator out put and lso check for draws on the system. Something may have been left on. The connections also need to be verified.

But the entire car will run just fine without the battery, (obviously can’t start itself though), and that means the word “Relies” is too strong.
That may be what happens when the battery is there but when its not there, the alternator is just fine for producing all the current for DC “12 volts” on its OWN ! The ripple might make the AM radio a bit noisy.
Batteries do tend to recover a little over time, on their own, so that suggests the battery is not the problem, the alternator (or its regulator) is its problem.

We’re talking about a 1997 Taurus, not some antique. Ford has been using alternators in all of its automobiles since the 1960’s.

My first run at the problem would be to check the battery cables for a good connection and/or corrosion. Once I knew those were tight and in good condition, I’d charge the battery with a battery charger. A cheap 1-2 amp charger can be had at Wal-Mart or other discount store for about $20. These are a good thing to have. Typically, they will have a display to let you know if the battery is charged and automatically switch from charging to a maintainer circuit to prevent overcharging the battery.

If the battery is fully charged and you still have problems, I would re-check the cables. I’ve had a corroded battery cable (on a Ford, incidentally, which is probably irrelevant) that looked good on the outside, but was corroded internally to the point it would not turn the starter–lights worked OK, just not the starter.

If the battery won’t hold a charge, or if the battery will start the car, but won’t again in a day or two, I’d replace the battery. While you may still have another problem, you will need a good battery to be able to find out. While a bad alternator will cause the battery to go dead, IME the majority of times it is caused by a bad battery and batteries are cheaper than alternators.

If you do have a fully charged battery and are having problems, it is time to take it to a repair shop. They will have the equipment to test the charging system and determine what the problem is (just make sure you tell them you just replaced the battery, as they will probably initially assume that that is your problem).

The battery may be 12 volts but the car runs on 14 volts. The alternator need to be putting out at least 14 volts.

As mentioned I’d check the terminal clamps first and correct when needed. Corroded terminals means it can’t be recharged.

Also there may be the time to replace the battery and/or the starter.

I have a 2003 Taurus and I’ve just replaced the battery and the starter. As a retired mechanic I can tell you it’s usually seasonal for breakdowns, at the end of the Summer and at the end of Winter where the temps were at the extreme.