Many older motorcycles (and cars) have 6-volt systems and cannot be safely jump-started from a modern vehicle,[7]​ but other more recent designs with 12-volt systems can be jump-started with the help of a 12V car or truck as well. Unlike the process of jump-starting a car, when starting a motorcycle in this way, the car providing the electrical power must have its engine stopped to avoid overloading the motorcycle's electrical systems as blow fuses or damage the electronic system. In addition, car batteries usually provide enough power to start a motorcycle without the help of the alternator.[8]​ The alternative is to try to start the motorcycle by pushing it.[9]​.

lighter socket

An alternative to using traditional jump starter clips is to interconnect the 12 volt outputs of the cigarette lighter sockets of the two vehicles. While this eliminates the potential for erroneous interconnections and arcing near the battery terminals, the amount of current available through such a connection is small. This method works by recharging the spent battery slowly, not providing the current needed to start. You should not try to start the engine because the consumption of the starter motor would blow the fuse in the cigarette lighter socket. Many vehicles disconnect this terminal when turning off the ignition,[10]​ making this technique useless unless the key is turned to allow the accessories to operate or in position for the socket to be connected to the battery.

Battery booster

A portable battery, equipped with cables and its respective charger, can be used in a similar way to the battery installed in another vehicle.

These devices can also be equipped with a spent battery polarity detector; which comes into operation before sending power to the vehicle to start it, eliminating the risk of damage that may arise from reversing polarity.

Battery charger

Motorcyclists and workshops sometimes have a portable battery charger that runs on alternating current. There are also other small chargers whose intention is simply to maintain the charge in a parked vehicle, but a large one is capable of introducing enough charge into the accumulator to start in a few minutes. Chargers may be strictly manual, or may include controls to vary voltage and charging times. Some chargers are equipped with a setting that offers extra power capable of supplying enough power to the vehicle to start its engine. Chargers that apply excessive voltage, such as 16 V on a battery rated at 12 volts, will cause high emission of hydrogen gas from the battery and could damage the battery. A battery can be recharged without removing it from the vehicle, although in a typical situation on the road, there is usually no power outlet nearby.

Starting push

A vehicle with a manual transmission can be pushed started. This requires caution while pushing the vehicle and may require the assistance of several people. If the vehicle's battery cannot provide power to the ignition system, the initial push will be ineffective. Most vehicles with automatic transmissions cannot be started this way because the hydraulic torque converter in the transmission will not allow the engine to be driven to the wheels.

Future possibilities include caliper regenerative braking systems to embrace a jump start when necessary.

Previously, especially in cold climates, some jump starts were performed with two batteries connected in series to provide 24 volts to a 12 volt starter motor. However, such surges can cause serious and costly damage to the electronic systems of modern cars and should never be applied.

Heavy vehicles such as large trucks, excavation equipment, or vehicles with diesel engines can use 24-volt electrical systems. These cannot be powered from a 12 volt motor vehicle and should not be used to power a 12 volt motor vehicle.

Older cars may have 6-volt electrical systems, or may connect the positive terminal of the battery to the chassis. Methods intended to boost 12 volts, negative ground vehicles, cannot be used in such cases.

Passenger vehicles with 42 volt electrical systems should also never be used to "boost" other vehicles; professional assistance would be necessary to avoid serious damage to the vehicle and possible personal injury. Hybrid vehicles may have a very small 12-volt battery system inadequate for supplying the large amount of current required to power a conventional vehicle. [Citation Needed] However, as a hybrid vehicle's 12-volt system is only required to start the vehicle's control system, a small portable battery can successfully power a hybrid that has accidentally discharged its 12-volt system as well as the main propulsion battery. However, vehicles with hybrid voltage systems sometimes compensate for the voltage disparity in some vehicles (switched 12V/24V, although diesel trucks may lack this feature).

Known in military slang as a "slave start," the jump start procedure has been simplified for military vehicles. Tactical vehicles used by NATO militaries have electrical systems that operate at 24 volts and, in accordance with STANAG 4074, have standardized slave receptacles for quick and easy connection. A slave cable is plugged into the receptacle of both vehicles, and the inoperative vehicle is started with the other vehicle's engine running.

Operating a lead-acid battery can, if overcharged, produce flammable hydrogen gas due to the electrolysis of the water created inside it. The procedure for jump-starting a car is usually found in the vehicle's owner's manual.[2]​[3]​ The recommended sequence[4]​ of connections is intended to reduce the chances of accidentally shorting the charged battery or exploding the hydrogen gas surrounding it. The owner's manuals for each vehicle show the preferred places for connecting the cables, since, for example, some have the battery located under a seat or may have a terminal specially designed for this purpose built into the engine compartment.

Motorists can be seriously injured by an exploding battery. According to a 1994 study conducted in the United States of America by the National Highway Traffic Safety Association, it was estimated that about 442 people were injured by batteries that exploded while attempting a jump start.[5][6]​.

The current supplied by the support vehicle will charge the spent battery. It takes several minutes for the necessary energy to be transferred to allow the engine to start. If the connections are well made and the cables have a good section, the support vehicle will also supply some of the energy necessary to turn the starter motor. In an extreme case, it is possible to start a vehicle without a battery if the cables used have sufficient capacity. The current needed to do this is strong enough to damage low-quality cables by overheating; The electrical resistance of a thin wire is greater than that of a thick wire, and the resistance dissipates electrical energy into heat.

If the discharged battery case is cracked, or the battery has too low electrolyte level, or is frozen, a jump start will not return it to proper working order. A jump start is only effective in the case of a dead battery, and will not solve problems such as lack of fuel, a broken battery, or other mechanical problems. Even after a successful start, the vehicle may not be able to operate properly if the reason the battery is dead is because the charging system is damaged. Loss of car battery voltage has wide-ranging damaging effects, ranging from a trivial loss of radio preset stations to a significant loss of safety or engine control parameters.

Many older motorcycles (and cars) have 6-volt systems and cannot be safely jump-started from a modern vehicle,[7]​ but other more recent designs with 12-volt systems can be jump-started with the help of a 12V car or truck as well. Unlike the process of jump-starting a car, when starting a motorcycle in this way, the car providing the electrical power must have its engine stopped to avoid overloading the motorcycle's electrical systems as blow fuses or damage the electronic system. In addition, car batteries usually provide enough power to start a motorcycle without the help of the alternator.[8]​ The alternative is to try to start the motorcycle by pushing it.[9]​.

lighter socket

An alternative to using traditional jump starter clips is to interconnect the 12 volt outputs of the cigarette lighter sockets of the two vehicles. While this eliminates the potential for erroneous interconnections and arcing near the battery terminals, the amount of current available through such a connection is small. This method works by recharging the spent battery slowly, not providing the current needed to start. You should not try to start the engine because the consumption of the starter motor would blow the fuse in the cigarette lighter socket. Many vehicles disconnect this terminal when turning off the ignition,[10]​ making this technique useless unless the key is turned to allow the accessories to operate or in position for the socket to be connected to the battery.

Battery booster

A portable battery, equipped with cables and its respective charger, can be used in a similar way to the battery installed in another vehicle.

These devices can also be equipped with a spent battery polarity detector; which comes into operation before sending power to the vehicle to start it, eliminating the risk of damage that may arise from reversing polarity.

Battery charger

Motorcyclists and workshops sometimes have a portable battery charger that runs on alternating current. There are also other small chargers whose intention is simply to maintain the charge in a parked vehicle, but a large one is capable of introducing enough charge into the accumulator to start in a few minutes. Chargers may be strictly manual, or may include controls to vary voltage and charging times. Some chargers are equipped with a setting that offers extra power capable of supplying enough power to the vehicle to start its engine. Chargers that apply excessive voltage, such as 16 V on a battery rated at 12 volts, will cause high emission of hydrogen gas from the battery and could damage the battery. A battery can be recharged without removing it from the vehicle, although in a typical situation on the road, there is usually no power outlet nearby.

Starting push

A vehicle with a manual transmission can be pushed started. This requires caution while pushing the vehicle and may require the assistance of several people. If the vehicle's battery cannot provide power to the ignition system, the initial push will be ineffective. Most vehicles with automatic transmissions cannot be started this way because the hydraulic torque converter in the transmission will not allow the engine to be driven to the wheels.

Future possibilities include caliper regenerative braking systems to embrace a jump start when necessary.

Previously, especially in cold climates, some jump starts were performed with two batteries connected in series to provide 24 volts to a 12 volt starter motor. However, such surges can cause serious and costly damage to the electronic systems of modern cars and should never be applied.

Heavy vehicles such as large trucks, excavation equipment, or vehicles with diesel engines can use 24-volt electrical systems. These cannot be powered from a 12 volt motor vehicle and should not be used to power a 12 volt motor vehicle.

Older cars may have 6-volt electrical systems, or may connect the positive terminal of the battery to the chassis. Methods intended to boost 12 volts, negative ground vehicles, cannot be used in such cases.

Passenger vehicles with 42 volt electrical systems should also never be used to "boost" other vehicles; professional assistance would be necessary to avoid serious damage to the vehicle and possible personal injury. Hybrid vehicles may have a very small 12-volt battery system inadequate for supplying the large amount of current required to power a conventional vehicle. [Citation Needed] However, as a hybrid vehicle's 12-volt system is only required to start the vehicle's control system, a small portable battery can successfully power a hybrid that has accidentally discharged its 12-volt system as well as the main propulsion battery. However, vehicles with hybrid voltage systems sometimes compensate for the voltage disparity in some vehicles (switched 12V/24V, although diesel trucks may lack this feature).

Known in military slang as a "slave start," the jump start procedure has been simplified for military vehicles. Tactical vehicles used by NATO militaries have electrical systems that operate at 24 volts and, in accordance with STANAG 4074, have standardized slave receptacles for quick and easy connection. A slave cable is plugged into the receptacle of both vehicles, and the inoperative vehicle is started with the other vehicle's engine running.