Why Won't My Car Battery Jump-Start?

Suppose your vehicle fails to start when you turn on the ignition. In that case, you might be dealing with a dead battery due to cold weather, excessive heat, or leaving the lights, radio, or other electrical accessories on. A dead battery isn't necessarily damaged. All that's needed is to give the vehicle a jump start. At certain times, however, the jump-start will fail, and there can be multiple reasons for that.

Reasons Why A Car Won't Jump Start

Loose Or Corroded Battery Terminals

Loose or corroded battery terminals restrict electrical power from reaching the rest of the vehicle, making it difficult to start even with a jump. Remove the cables from the terminals and clean them with a wire brush, after which you should retighten them to the terminals. Doing this should restore the vehicle's electrical flow, and the car should start.

Faulty Alternator

The battery depends on the alternator as it cannot power all of the vehicle's electrical systems alone. When the engine runs, the alternator recharges the battery and supplies power to the vehicle's electrical accessories. A faulty alternator means the battery won't get enough charge. Always have a qualified mechanic check the condition of your alternator before considering a battery replacement.

Faulty Starter Motor

The starter motor spins to crank and start the engine any time you turn the ignition on. A faulty starter motor, even with full electrical power from the battery or a jump-start, cannot spin strongly enough for the engine to operate correctly. You'll hear a clicking or grinding sound as you try to start the vehicle. The ultimate solution is to have the starter motor replaced.

Faulty Jumper Cables

Long or light jumper cables need to carry sufficient current. Otherwise they cannot transfer the electrical power needed for the jump starts. Similarly, low-quality cables can get damaged, causing the jump start to fail. The same applies when the jumper cables are not correctly connected. During a jump start, always check the temperature of the rubber coating on the jumper cables. A warm cable means excessive resistance. Invest in new jumper cables when this happens.

Neutral Or Clutch Safety Switch

These safety switches allow a vehicle to start only under certain conditions. The gear lever must be in the park or neutral for automatic transmission cars, and the clutch pedal must be fully engaged for manual transmission cars. If the safety switch is faulty, the car won't be able to start even with a jump.

Damaged Battery

Every vehicle needs constant power from the batteries when running. Without it, the car wouldn't cooperate properly. Hence, it is impossible to jump-start a car with a dead battery. To ensure the battery isn't damaged, allow it to recharge when connected to the jumper cables, this should give the battery enough power to start the vehicle. No sign of power means the battery may be damaged and have to be replaced.

How To Properly Jump-Start A Vehicle

Not following the proper steps to jump-start a car is dangerous. It can cause the jump-start to fail and completely discharge or damage your battery. You can jump-start your vehicle successfully with a suitable jumper cable and another vehicle with a good battery. Here are the appropriate steps to follow:

• Park the vehicle with a good battery power close to yours. Ensure the hoods are facing each other and the parking brakes are engaged.
• Put both vehicles in the park or neutral and turn off the engines in both cars.
• Open the hoods of both vehicles and locate the batteries.
• Remove any plastic cover covering the batteries to access the terminals. Make sure the terminals are clean and not corroded.
• Connect one of the red clamps of the jumper cable to the dead battery's positive terminal and the other red clamp to the positive terminal of the good battery.
• Connect one of the black clamps to the negative terminal of the good battery and the other black clamp to an unpainted metal surface in the vehicle with a dead battery. Clamping it to the dead battery's negative terminal or close to it will result in sparks.
• Start the car with good battery power and leave it on for a few minutes. The dead battery should have enough charge to start.
• Start the car with the dead battery. If the jump is successful, remove the clamps in the reverse order.
• Drive your car around for at least 15 minutes to recharge your battery before turning it off.

Summary

Jump-starting your car can fail for several reasons. However, if you follow the proper steps, it will be easier to identify the exact cause. Safety should be your ultimate goal in such a situation since you are dealing with electrical power. Also, seek the assistance of a qualified mechanic if you need more clarification on anything, and follow good battery maintenance tips. 

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