Articles, on jump starting a vehicle, will normally include as many warnings as they do instructions. This is for a good reason. Jump-starting a vehicle can be dangerous. It is also potentially very damaging to both vehicles.
Dangers of jump-starting
Improperly connecting jumper cables can damage the electrical system of both vehicles. Gasses emitted from a battery can be explosive and when improperly making or removing connections, a spark can cause the battery to explode. It is always best to avoid jump-starting, except in an emergency.
Will jump-starting help the problem?
Jump starting can only help if the problem is a weak or dead battery. Many things can prevent a vehicle from cranking, other than just the battery. If the vehicle has a voltmeter, check to see if system voltage is less than twelve volts, when attempting to crank the vehicle. A volt meter showing less than twelve volts suggests a weak battery. We can also check without a volt meter by blowing the horn, while attempting to crank the engine. Turning the key to the crank position will load the electrical system and reveal a weak battery. Having enough power to blow the horn shows the battery is less likely a cause.
Check to see if any dash lights are flashing, especially those shaped like a padlock. This often shows a security system problem, which may prevent the vehicle from cranking. Finally, shift into neutral and see if the engine cranks. The manual lever position sensor can fail and not show that the shifter is in the park position. When this occurs, the vehicle will not crank. Attempting to jump-start a vehicle with other problems needlessly exposes us to risk and will not help.
A better plan
All automotive batteries have a life span. It is never a matter of if they will fail, only when. Realizing this helps prevent many problems with a failed battery and the need to jump-start a vehicle. The average life of a battery is around 38 months. This may be less in the South, where it is very hot and longer in the North, where it is cooler.
Replacing a battery, before it fails, may make a lot more sense to many people. One consideration is economics. If a battery cost $90.00 and gives three years of service, the cost is $30.00 per year. Push the battery to four years and the cost is $22.50 per year. This is not much of a savings considering the inconvenience of being stranded.
Other considerations may add even more weight to the argument. A weak battery will make the alternator work harder. Low system voltage affects the starter and can cause computer issues. When a battery dies, we lose the computer memory. Diagnostic trouble codes, shift patterns and even idle memory needs to relearn and will take time. The vehicle may shift erratically, stall or idle differently and may fail State inspection, until it learns the memory that is lost.
Why replace a battery before it dies?
We can plan a convenient time to replace a battery based on our schedule. This may not be possible when our vehicle suddenly leaves us stranded. A vehicle that will not start is inconvenient at best. With a dead battery, we may have few options. We must decide between jump-starting the vehicle and having it towed.
If a vehicle has to be jump-started, new technologies can greatly reduce the risk.
Polarity sensing jumper cables
Several companies manufacture jumper cables that can sense and correct reversed polarity. For example, mistakenly connecting the negative to the positive terminal could cause extreme damage. The polarity sensing cables will automatically correct this, no matter how we connect them. This is a great safety feature, but much like a bulletproof vest, one we hope to never need.
The advantages of these cables are light weight and easy storage. The drawback is, we need another vehicle as a donor, to supply power.
Another popular device is the auxiliary jumper battery. This is a self-contained battery with a charger, with short cables attached. More than enough power is available to start the vehicle, and when done, we can plug them in for charging. This saves potential damage to or the need for a donor vehicle. They are portable and work in many applications.
An advantage is, jumper batteries do not require a donor vehicle and one person can easily use them. Disadvantages are, we must recharge them and they do have a life span.
Best is to only jump-start a vehicle when it is absolutely necessary and always follow instructions. If in doubt, check the owner’s manual of the vehicle for the recommended procedure.