How long should a car run after being jump started?

[schwah]

I left my lights on the other day and killed my battery. Jump started it and drove around for approx 30 minute before turning the car off. When i tried to start it again, no go. The dash lights came on for a second but there wasn't enough juice to turn over the engine.

How long should you have to run a car to recharge a dead battery enough for it to start itself? I was under the impression that it should only take a few minutes, but I know next to nothing about cars so I might be wrong. Should I just jump it again and leave it running longer or is there probably a problem with something else? The battery is only a few weeks old.

[n.s.]

30 minutes should be plenty of time, especially if you were driving and not just idling the engine. My guess is that something else is wrong.

[Jameso]

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I left my lights on the other day and killed my battery. Jump started it and drove around for approx 30 minute before turning the car off. When i tried to start it again, no go. The dash lights came on for a second but there wasn't enough juice to turn over the engine.

How long should you have to run a car to recharge a dead battery enough for it to start itself? I was under the impression that it should only take a few minutes, but I know next to nothing about cars so I might be wrong. Should I just jump it again and leave it running longer or is there probably a problem with something else? The battery is only a few weeks old.

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30 minutes at better than idle RPM's should have been enough to recharge the battery. The most likely culprit is the alternator, but you should get it in to a shop and have them run a diagnostic on it. More info would help--year, make, model, etc. I would guess either worn brushes or a bad diode in the alternator, but either of these problems would most likely show up to you as a red light in the dash or a gauge that reads low. So get a diagnosis and get it fixed unless they quote you some ridiculous price. Again, year, make, model, is very helpful info.

[Ray Zee]

anyone with a ten dollar multi tester can tell you if your battery is good or where the trouble is. most times its the battery especially since you killed it. an older battery may not come back. if your battery is three years old you might as well get a new one anyway. they never fully recover from going dead.plus clean ther posts and cables.
it has to be the battery since it worked fine before you left the lights on. so just get a new one and dont fool around for a few dollars worth of life in an old one.

[JayTee]

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I left my lights on the other day and killed my battery. Jump started it and drove around for approx 30 minute before turning the car off. When i tried to start it again, no go. The dash lights came on for a second but there wasn't enough juice to turn over the engine.

How long should you have to run a car to recharge a dead battery enough for it to start itself? I was under the impression that it should only take a few minutes, but I know next to nothing about cars so I might be wrong. Should I just jump it again and leave it running longer or is there probably a problem with something else? The battery is only a few weeks old.

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30 minutes at better than idle RPM's should have been enough to recharge the battery. The most likely culprit is the alternator, but you should get it in to a shop and have them run a diagnostic on it. More info would help--year, make, model, etc. I would guess either worn brushes or a bad diode in the alternator, but either of these problems would most likely show up to you as a red light in the dash or a gauge that reads low. So get a diagnosis and get it fixed unless they quote you some ridiculous price. Again, year, make, model, is very helpful info.

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It wouldn't be the alternator if the car was running for 30 minutes after the jump. Stop by an AutoZone or maybe even a Wal-Mart garage and they should load test your battery free of charge.

[Jameso]

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I left my lights on the other day and killed my battery. Jump started it and drove around for approx 30 minute before turning the car off. When i tried to start it again, no go. The dash lights came on for a second but there wasn't enough juice to turn over the engine.

How long should you have to run a car to recharge a dead battery enough for it to start itself? I was under the impression that it should only take a few minutes, but I know next to nothing about cars so I might be wrong. Should I just jump it again and leave it running longer or is there probably a problem with something else? The battery is only a few weeks old.

[/ QUOTE ]

30 minutes at better than idle RPM's should have been enough to recharge the battery. The most likely culprit is the alternator, but you should get it in to a shop and have them run a diagnostic on it. More info would help--year, make, model, etc. I would guess either worn brushes or a bad diode in the alternator, but either of these problems would most likely show up to you as a red light in the dash or a gauge that reads low. So get a diagnosis and get it fixed unless they quote you some ridiculous price. Again, year, make, model, is very helpful info.

[/ QUOTE ]

It wouldn't be the alternator if the car was running for 30 minutes after the jump. Stop by an AutoZone or maybe even a Wal-Mart garage and they should load test your battery free of charge.

[/ QUOTE ]

It could very well be the alternator and I think it's pretty unlikely that the new battery is already toast. An alternator with a bad diode will run the vehicle and all of its accessories without recharging the battery. I would expect an alternator with worn brushes to trigger a red light or a low reading gauge. My best guess is that the output from the alternator is fine, but the diode issue is creating his problem.

[BiPolar_Nut]

What kind of car? My '95 'teg absolutely will not run on alternator alone...but most other (older and newer non-honda) vehicles I've owned will. 30 mins should be plenty to restart your car the next morning....unless the battery has a bad cell or you have something draining it while the key is out. Basically it's either a battery, alternator, or other wiring problem sucking rediculous juice after the key is out due to a (for example) miswired power amp or even an alarm wire that got caught in the door jam er sumfin. Batteries and alternators can be tested free as mentioned above if you're able to remove them (many parts stores will even test the battery w/o removal for free).

The chances are a competent shop could trace the cause very quickly if you don't feel comfy yanking out parts yourself. Then again, there is a slight chance it's some oddball electrical problem like a brake light wire on a car where they're always hot and grounded when you hit the pedal (honda loves to wire stuff always hot) and some part of the wiring pre-pedal switch is semi-grounding on a greasy ground (thereby not blowing the fuse and just putting a steady 10'ish amp drain on the batt).

Name your car and we could prolly give more specifics.

It will be something simple regardless....tho there's a chance it could take some hunting to find the cause.

[Jameso]

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Name your car and we could prolly give more specifics.

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The OP must have died or something, so I don't feel too bad about the hijack that I'm about to attempt:

If your car won't run on the alternator alone, how does the battery get charged? Is there some other component that assists in this department? Without doing a ton of electrical work I was able to pass the ASE test for electrical and I can't find a way to believe that this is a true statement. Not trying to be hostile here--there may be a logical explanation and I'd love to hear it.

[pig4bill]

You generally need about 2000 rpm to get full charge out of the alternator, so if your 30 minutes was in town, that's not enough. If it was on the highway it should have been enough. Try it again. If your lights were on or you have daytime running lights, maybe more time is needed. Buy a battery charger. It's cheaper than a new battery.

[CORed]

Thirty minutes won't fully charge a completely discharged battery, but nomally should charge it enough to start the engine. Most likely, either your battery or your alternator is dead. Completetly discharging a battery is not good for it. If it's an old battery, it can easily finish it off. OTOH, charging a fully discharged battery puts a heavy load on the alternator and can be enough to burn out an alternator that's on its last legs. The fact that the car ran after being jumped indicates that the alternator is not completely dead, but not necessarily that it's putting out enough voltage to properly recharge your battery. Also, corroded terminals and connectors can create enough resistance to keep the battery from charging properly.

My suggestion: Clean terminals and connectors, check water in cells if your battery isn't a "maintenance free" type and fill if necessary, and try giving it an hour or two to charge. This should be either driving around, or propping the throttle open somehow to run the engine at about 2000 RPM. Another option would be to buy a battery charger and use that to charge it. A charger is a useful thing to have, and it will cost you less to charge from the grid than by burning gasoline. If this doesn't work, have a garage or auto parts store test the battery and alternator. Most will do this for free. There's no sence to guessing which it is. It could be either, or, if you're really unlucky, both. If you guess wrong, you will waste $70 or $80, more if you pay somebody to replace the alternator. For most cars, the alternator is one of the easiest parts to replace yourself. If you want to do it the expnsive way, replace the battery first, especially if it's more than two years old.