Car won't charge battery when battery dead

I have an 88 Toyota Camry and when the battery runs down due to leaving a map light on, for instance, I can jump the battery with no problem but as soon as the cables are removed, the engine stops. I can take the battery and get it charged and then everything is fine.

One time we got it charged and it worked fine for a few days and then the engine kept wanting to stall. If it stalled, we would have to jump it and it would last awhile. So we took it to the shop and they said it was just loose cables. They checked everything out and it all looked good to them. So they tightened them up and it has been working perfectly for quite awhile now, probably 6 months.

But, whenever it gets drained all the way, as it just did when my son left the overhead light on, I can't just jump it and let the battery charge on its own, I have to take the battery and get it charge..
What could cause this? Would a bad alternator do this? Anything else? When they test the battery they say it is fine.

Any ideas?

I can't disagree more.

If the alternator is working correctly, it will have no problem charging the battery. It may take a hour but it will.

A dead battery will actually draw little current, since it's mostly water, not acid. Only after it charges a little will it start drawing more. Once it's charged and its voltage is up to 13.8 , it will again draw little. In short, a bell-curve.

Further, the alternator is designed to limit its output to safe levels, on any I have worked on. That's one reason the voltage regulator is internal; to provide temp. compensation.

The OP's symptoms point to an alternator that is not working at all, or is doing so partially/intermittently. You can load-test it yourself with an accurate voltmeter and ears.

Start the car. Measure the voltage at the bettery; it should be ~14.4v with the battery charged.

Turn on the headlights, heater fan, defroster, etc. The car should slow down slightly and you should hear a groan from the alternator and belt. The voltage may drop to ~13.8V or so.

Have someone rev the car up above idle -- not screaming, just oh 2500 RPM. The voltage should go back up to 14.4v.

If way off, OR if you can hear a loud whine in the radio at idle, chances are the alternator is ill. Seek help.

If all the above look good, it may be intermittent. Look for bad cables by wiggling the battery ground, hot and others -- please avoid getting your fingers in the moving parts as it makes a mess.

"Steve Cook" wrote

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Generally the alternator is designed to handle the typical accessory load during normal operation and to maintain the battery charge, not to recharge a dead one. If the battery has no charge, the alternator may not be able to produce enough output to operate the engine while charging the battery at the same time, especially at idle speeds where the alternator output is lowest. In some cases, the alternator can be overloaded and potentially damaged if forced to rapidly recharge a dead battery.

It's possible the alternator output is low, but this may also be entirely normal for this vehicle. My main suggestion would be to stop draining the battery

yeah yeah yeah a alt will charge a dead battery But it will not charge on with a bad cell dont be an idiot and use a voltmeter on your battery and have someone rev it up start your car and use the hot cable nutted to the back and ground the other lead somewhere 14.4v is great for an alternator as long as you have no less than 13.8v your alternator is charging fine check your battery to see if the plates in it are bad its not rocket science or if you dont have a voltometer take the alternator to your local parts store and have them test it while your testing the battery people try to act like they know more than others by using big or technical terms but its is basic stuff

I also recommend fixing the problem before you fry the battery and alternator. Also, how old is the battery and how long is it warrantied for and is it the largest CCA capacity battery that will fit into the car? You should have the largest capacity battery that you can fit in the car and clean your battery terminals. Sounds to me like you have a weak battery and possibly bad connections and maybe even loose alternator belt.

I'd posit that it's a bad idea to let the battery run down in the first place, not good for the battery, and not good for the alternator (unless you have an old American car with an incredibly overbuilt alternator.)
If you're really worried, have the alternator output tested, also check the voltage drop across the wiring between the alternator and the battery (should be minimal.

I agree that letting the battery run down completely is a bad idea.
But when you have a forgetful teenage son, it doesn't matter how often you tell him.

Thanks for the advice. I'll get the battery AND alternator checked.

Might I suggest a second battery?

Charge it up completely and set it aside. If he kills it, swap it out and charge out that one. Continue the cycle as necessary. In a bit over four years of driving, I only killed the battery once and that was when a rear door was ajar.

An alternator requires a certain minimum battery voltage just to energize the fields and start it charging. Some cars can run on less voltage than it takes to energize the starter. If you jump-start a dead battery you need to put a real charger on it at your first opportunity, or you will have starting problems again soon.
Rex in Fort Worth

It's generally not a good idea to rely on the alternator to charge a dead battery. Some older cars don't mind it, but many modern cars will fry an alternator if requested to charge a completely dead battery.

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Alternators are not self-exciting, they require an external voltage applied through the regulator. The dead battery is possibly loading the alternator enough that the voltage to the regulator is too low.

A friend bought a new alternator for his Jeep Cherokee and it point blank states the warranty will be void if this alternator is hooked up to a dead battery to try and charge it.

The battery needs some charge in it first, either a light charge from a booster cable to a running vehicle or a proper battery charge is needed.
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

I would say the alternator is bad, most auto parts stores such as Autozone will test the charging system for free so they can sell you the parts.
Take advantage of this and get it all checked out.

If possible, charge the battery to 12 volts before the test.

Good Luck

Battery will automatically gets charged when it is in running.Just you have to check for the water as or not when you open its caps. If water is not there you have to add the distilled water into that it will make the battery to live longer. And also keep your engine in a good condition by using a good fuel into that.


Here is a link that might be useful: clean diesel

Alternators are not battery chargers. An alternator maintains the charge of the battery and supplies power to all of the accessories on the car. The more accessories that are on the more strain there will be on the "charging system".

At idle the engine speed is between 650-1000 rpms. The alternators output is minimal (12.6 volts). At about 2500 rpms the alternator will put out its maximum voltage (up to 14.4 volts).

If you use an alternator to charge a dead battery you will eventually wear out the alternator because that is not it's intended purpose. I recommend using a battery charger set on the lowest setting (2 amp.) and slowly charge a dead battery for 8-12 hours or untill fully charged.

You can also install a solar panel (2-5 amp.) with suction cups on the inside of your windshield that you can either plug into your 12 volt "cigarette lighter" outlet or run wires out to the battery. They usually come with a diode so that the current generated by the solar panel goes to the battery and the battery doesn't discharge through the solar panel.