How long does it take to charge the battery by idling after a jump start?

[StAddyson]

The battery cannot be fully charged by idling. Starting from 20% remaining battery level, charge for over 60 minutes at 1500 RPM, then charge for another 60+ minutes at over 1900 RPM to reach approximately 90% charge. Below are some car battery maintenance tips: 1. Avoid using high-power electrical equipment during idling to prevent additional strain on the battery. 2. For vehicles parked long-term, charge the battery once a month for at least one hour each time. 3. Regularly clean accumulated dirt on the battery surface and oxides on the positive/negative terminals. Be careful not to short-circuit the positive terminal during cleaning. 4. Avoid frequent starting attempts as the starting current can reach hundreds of amps. After multiple unsuccessful starts, wait at least 5 minutes before trying again. If still unsuccessful, inspect or replace the battery.

[LunaDella]

After jump-starting my dead battery, I usually let the engine idle for 20-30 minutes to recharge it safely. The exact time depends on the situation: with a new battery and good alternator condition, 15 minutes might suffice, but for older vehicles or after cold starts in winter, it's better to wait longer, up to 40 minutes. I often check the headlight brightness - if the lights stay steadily bright without dimming, it means the battery is sufficiently charged. Never rush to drive on highways or turn on the AC immediately, as these will drain power and may lead to insufficient charge. Safety first - minimize electrical usage during idling to save fuel and charge efficiently. I make it a habit to test the battery voltage monthly, replacing it if below 12.5V to avoid jump-start hassles. Once my neighbor shut off after just 10 minutes and later found out it was an alternator failure costing 500 RMB to fix. The bottom line - allow extra charging time to prevent potentially serious breakdowns on the road.

[VanAnnie]

From a technical perspective, the required idling charging time after jump-starting depends on the battery capacity and alternator output. For a standard battery (48-72Ah) with an alternator output current of 50-100A, it takes approximately 20 minutes to reach a safe charge level after deep discharge. However, in practice, I recommend using a multimeter to measure voltage - it should stabilize above 13.5V during idling. Less than 15 minutes may be insufficient; I typically wait 30 minutes before driving. Factors affecting charging include battery age (older batteries charge slower and require more time). Avoid using audio systems or high-power devices as they slow down charging. Safety-wise, insufficient charging may lead to stalling. Regular battery health checks can prevent such situations.

[ODakota]

Last time my car battery died and I had to get a jump start, my friend told me to idle the car for about 25 minutes. While waiting in the car, I checked the brightness of the headlights and only felt safe to drive when they were bright. Don't rush to turn on the AC or navigation as they drain the battery quickly. If you don't wait at least 20 minutes, there might be issues, so it's safer to wait for 30 minutes. To avoid this situation, it's best to regularly maintain your battery. Just wait patiently, don't rush.