How long should the engine idle to charge a dead battery?

[MacCassidy]

Charging time for a dead battery at idle speed: If the engine speed is 1500 rpm, charging for 20 minutes can provide enough power for the starter to start the engine once. Below is relevant information about car battery depletion: 1. Emergency measures: First, you need a set of jumper cables. Normally, such cables should be kept in the car for emergencies like this. Besides the cables, you'll also need assistance from another vehicle. Drive the other car over and park it facing your car. Open both hoods, then connect the positive terminals of both batteries with the jumper cable, and do the same for the negative terminals. 2. Knowledge introduction: Does the car come to a complete stop after turning off the engine? Traditionally, it's believed that once the car key is turned to the off position, all components stop working. However, when the engine temperature is too high, even if the car is turned off and the key is removed, the cooling system will automatically activate to cool down the engine. The cooling system will stop working automatically, usually within 3 to 5 minutes.

[AlexisFitz]

I've been dealing with this issue for a while – charging a depleted battery at idle does take quite some time. Generally, idling in place requires about 15 to 30 minutes, but this depends on the battery's discharge level and the vehicle model; older batteries may take even longer, possibly one to two hours. During charging, the engine speed maintains between 800-1000 RPM, and since the alternator output is relatively low, the efficiency isn't great. It's best to use a voltmeter for monitoring – if the voltage remains below 12V after 15 minutes, professional assistance is likely needed. Daily prevention is crucial, such as turning off headlights after engine shutdown to avoid excessive discharge. If this problem recurs frequently, it might indicate battery aging, and replacement shouldn't be delayed to prevent roadside breakdowns. Lastly, I'd suggest not just waiting idly – maybe tune into the radio to pass the time, but always prioritize safety first!

[MacVanessa]

As someone who has been driving for twenty years, I've encountered dead batteries multiple times. Once when my car wouldn't start, I idled it to recharge, which took about 20 minutes to restore roughly 70-80% of the charge. How long is appropriate? Having tested various models, compact cars might get by with 15 minutes, but SUVs or diesel vehicles often require half an hour or more. The key is patience—idling provides limited alternator output, so charging is naturally slow. Take the opportunity to check why the battery drained; in my case, it was due to leaving the AC on. If prolonged idling doesn't help, consider calling for assistance or replacing the battery. Developing good habits, like taking weekly short drives to fully charge the battery, can save a lot of hassle.

[Clyde]

When I first started driving, I also encountered this issue. Idling to charge a depleted battery usually takes 20 to 30 minutes, but the effect is mediocre. It really depends on the battery's condition—if it's completely dead, it might not charge at all, and you'd need professional help. It's better not to just wait; idling to charge is slow and wastes fuel, which isn't cost-effective. Instead, driving a short distance will increase engine RPM and charge the battery much faster. Always take preventive measures, like avoiding using car electronics after turning off the engine. If all else fails, replacing the battery is the safer option.