Jump-Starting the vehicle

Jump-start is the process when a vehicle with a good battery is used to start the vehicle with a discharged or “dead” battery. Since starting the engine requires a large amount of electricity, the started vehicle can put a load on both vehicles. When the engine is started, the discharged battery has a low voltage. This causes the alternator on the utility vehicle to be under heavy load and to send maximum charging current. But as soon as the start is complete, the voltage spikes and is potentially high enough to damage electronic components in both vehicles. The same voltage spike can occur when jumper cables are disconnected.

Another risk is overheating and damaging the alternator on a started vehicle. Due to the increasing number of electrical devices on vehicles, today’s alternators are more powerful. However, a discharged battery can push the alternator into a dangerous operating zone. Due to the risk of damaging the electronics and alternator, many vehicle manufacturers do not allow jump-starting. They now recommend secondary charging the battery or replacing it with a charged one.

If you decide to jump-start the vehicle, always read the owner’s manual for both vehicles and follow their starting instructions. Never attempt to jump-start a frozen battery. It is usually best to allow 5 to 10 minutes for the frozen battery from the other vehicle to charge after connecting before attempting to start the vehicle. Once the dead vehicle’s engine starts, let both vehicles idle for a while. Do not switch off the vehicle with a discharged battery, as it takes a long time to recharge. Before removing the jumper cables, it is advisable to switch on additional consumers, for example, headlights, on both vehicles to protect the alternator. This allows any sudden increase in voltage due to a sudden decrease in alternator load to be absorbed. Another method to reduce the risk of damaging sensitive electronic devices is to use jumper cables with built-in surge protection.


Another less risky way does not to use another vehicle to start, but the starter. The starter does not involve the vehicle’s charging system and reduces the risk of voltage spikes. This device contains a relatively large capacity battery, short connection cables, and spring clamps for direct connection to a weak battery. It provides a significant additional increase in electrical energy to start the engine.

When connecting jumper cables, there is almost always a spark on the last connection you make. That’s why it’s to make the final connection on the engine block away from the battery and other flammable items. The spark also occurs when you disconnect the first connection, so it should be at the engine block. Also, do not connect the negative cable to the body or chassis because the ground wire from the body to the negative battery terminal is usually of small gauge and weak to carry the current needed to start the engine.

Alternators are generally not designed to charge a fully discharged battery while powering a few additional devices. It is preferable to refresh the battery a little with a charger before starting the engine. That way, the alternator won’t have to struggle as much. It takes only 15 minutes to burn up an alternator when charging a dead battery. And if you must drive the vehicle after starting it, turn off as many accessories as possible, which will lessen the load on the alternator.

To perform jump-start the vehicle, follow these steps:

Jump-Starting the battery

Place the starter or auxiliary vehicle battery as close as possible to the empty battery within reach of the jumper cables. Make sure that the vehicles do not touch each other. First, connect the short-circuit cable to the positive terminal of the discharged battery, and then the other end of the cable to the positive terminal of the auxiliary (starter or vehicle). Connect the second jumper cable to the minus terminal of the auxiliary battery (starter or vehicle), and the other end to the engine block as far as possible from the empty battery.

Engine start

Try starting the engine with an empty battery. If the full battery does not have enough power or the jumper cables are small, start the engine of the utility vehicle and let the discharged battery partially charge for a few minutes. Turn on the headlights on the support vehicle to reduce the voltage damaging the electronic equipment and try to restart the engine.

Disconnecting the auxiliary vehicle’s battery

When the engine has started, let both vehicles idle for a while. Disconnect the cables in the reverse order of connection. If the starting vehicle’s charging system is working properly and the battery is in good condition, the battery will recharge while the engine is running, otherwise, it may overheat and damage the alternator.

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