What are the reasons for being unable to jump-start a car battery?

[StGabriela]

The reasons for being unable to jump-start a car battery are: 1. Incorrect connection of positive and negative cables; 2. Battery malfunction. The functions of a car battery include: 1. Providing power to the starting system, ignition system, and electronic fuel injection system during engine startup; 2. Supplying power to vehicle electrical equipment when the engine is off or at low idle; 3. Acting as a voltage stabilizer for the vehicle's electrical system; 4. Storing excess electrical energy generated by the alternator. Battery maintenance methods are: 1. Clean the accumulated white acid corrosion powder on battery terminals to extend service life; 2. Add distilled water to the level between upper and lower markers; 3. Check whether the battery is charging normally.

[NorahFitz]

Last time my car wouldn't start with jumper cables, it was really frustrating. Turns out the issue was either the jumper cables not being clamped tightly enough, or the clamps being in the wrong position, or oxidized copper terminals affecting current transmission. It could also be that the battery itself was completely dead, with too high internal resistance after deep discharge to accept any charge. Additionally, if the starter is broken, jump-starting won't help; sometimes the vehicle's computer or security system locks out external current for starting. When jump-starting, it's recommended to first check cable quality and connections, ensuring red to red and black to body ground - don't reverse them. If the car cranks but won't start, it's likely a starter issue; if there's no response at all, the battery is probably dead. In such cases, don't persist - seek professional repair immediately. Otherwise, delaying could lead to complete battery failure, costing more for replacement. Safety first.

[LilyAnn]

Battery jump-start not working, as a DIY enthusiast, I often encounter this issue. Common causes include poor jumper cable connections, corroded battery terminals, or internal battery short circuits. When operating, ensure the positive clamp is securely attached to the battery's positive terminal post, and the negative clamp is grounded to a metal part of the car body; avoid directly clamping the negative terminal post to prevent sparks from igniting battery gases. If the cables are loose, current cannot flow; if the battery voltage is below 5 volts, it's completely dead. A blown starter or alternator fuse may also prevent starting—check the engine compartment's fuse box. If the car only cranks but doesn't start after a jump, it might be a faulty starter coil. It's recommended to clean battery terminals before each jump-start using baking soda to remove corrosion; if attempts fail after several tries, directly test battery health with a voltmeter—replace if below 10 volts, don't risk further attempts.

[VonTalia]

During my driving career, I've encountered situations where jump-starting a dead battery didn't work. This is mostly due to improperly connected cables or an aged/failed battery. For example, loose clamp connections, corroded terminals preventing current flow, or a frozen/short-circuited battery that won't accept a charge. Worn starters or blown fuses are also common culprits. Safety is paramount - if the vehicle shows no response at all, stop attempting to avoid damaging the electrical system. The wisest approach is seeking professional help at a repair shop, letting technicians diagnose the root cause, which saves both time and money in the long run.