What could be the reason if the car still won't start after 15 minutes of jump-starting?

[MacGavin]

If the car still won't start after 15 minutes of jump-starting, this situation may be caused by a damaged battery or a circuit malfunction. In such cases, it is recommended to immediately go to a professional repair facility or a 4S shop for inspection and repair. The battery is an important component of a car and is also a wearable part that requires regular replacement. Introduction to car batteries: A car battery, also known as a storage battery, is a type of battery. Its working principle is to convert chemical energy into electrical energy. Typically, what people refer to as a car battery is a lead-acid battery, which is mainly composed of lead and its oxides, with sulfuric acid solution as the electrolyte. Working principle of car batteries: It uses lead plates filled with sponge-like lead as the negative electrode and lead plates filled with lead dioxide as the positive electrode. During charging, electrical energy is converted into chemical energy, and during discharging, chemical energy is converted back into electrical energy.

[EmeryLynn]

I've encountered this situation several times where the car still won't start after 15 minutes of jump-starting, and there are quite a few details to consider regarding possible causes. The most common issue is with the jump-start connection, such as reversed battery terminals, loose clamps, or aged cables resulting in insufficient current. If the battery itself is severely damaged or worn out, jump-starting might not be able to fully charge it, especially in cold weather when charging is slower. Additionally, starter problems are critical—if you only hear clicking sounds but the engine doesn't turn over, it could be due to burnt starter coils or relay failure. Fuel supply issues might also be at play, such as a non-functioning fuel pump, clogged filter, or an empty tank, all of which I've seen before. In such cases, it's best not to keep trying to avoid further damage. First, check if the jump-start connections are secure and use a voltmeter to test the battery. If it still doesn't work, consult a professional technician with a diagnostic tool. Safety comes first—don't force it to run to avoid stalling on the road.

[LaDonovan]

Last time my car broke down in the suburbs, I tried jump-starting it for a full 15 minutes but it just wouldn't start - it was absolutely nerve-wracking. Turned out to be a starting system issue - the jump could power the lights but the engine wouldn't crank, most likely due to a faulty starter motor or failed ignition coil. Also, if the jump-start connections are dirty or corroded, it affects conductivity; and if the battery has an internal short circuit, it's normal that it can't charge fully in a short time. My advice is not to panic when this happens - first ensure the connection points are clean and secure, then try pressing the accelerator to assist starting (sometimes the air-fuel mixture is too rich and needs assistance). If it still doesn't work, stop immediately to avoid over-draining the battery, and it's best to call for roadside assistance or a tow truck. Develop good driving habits - regular checks on battery health and starter motor condition can prevent most troubles. Never compromise on road safety.

[Verona]

I understand this situation. There could be several core reasons why jump-starting for 15 minutes doesn't work: the battery might be severely damaged and unable to hold a charge, poor connection in the jump-start cables, or issues with the starting system such as a failed relay. In vehicles, battery aging is common, especially if the car hasn't been driven for a long time. Additionally, engine ignition system failures, like carbon buildup on spark plugs, can also prevent the car from starting. At this point, don't keep trying; instead, check if the fuses are blown or if the battery terminals are corroded. Simple repairs might help, but if not, it's better to seek professional assistance quickly.