by Jim Kerr
With the latest cold snap, the number of vehicles seen on the back of a tow truck has been astounding. Talk with the tow truck drivers and you will find that many of these vehicles needed a tow to a repair shop because they wouldn’t start. Usually the problem is related to the starting or charging system, and the result is a dead battery.
Loose or dirty connections at the battery, starter or alternator can prevent the battery from getting a full charge. The battery slowly becomes discharged. In cold weather, vehicles are driven short trips and spend a lot of time idling so they can warm up. All the accessories such as headlights, heater, rear defogger and seat heaters can use more power than the charging system is producing at an idle. Again, the result is a discharged battery.
The daylight hours are also getting longer. This means that we start our drive to work in the dark but often arrive when it is light out. Guess what happens? We accidentally leave the headlights on and the battery goes dead.
Regardless of the reason for a battery becoming discharged, a boost is usually the first thing attempted. Getting a boost means using heavy cables to supply battery power from one vehicle to another. Some car manufacturers do not recommend boosting a vehicle, They state that damage to electronic controls can occur if voltage surges flow through the electrical system during boosting. Instead of boosting, the auto manufacturers prefer that a fully charged battery be installed in place of the dead one or that the dead battery be charged. This is often impractical because of where the vehicle is sitting so most people with a dead battery boost their vehicle – but several important steps must be followed to prevent damage.
First of all, to prevent damage, turn off all electrical accessories on both the vehicle being boosted and the one providing the boost. If there is an electrical surge, this will prevent damage to those accessories.
Many people leave the engine running on the vehicle providing the boost, but as soon as the starter is cranked on the vehicle with the dead battery, the alternator on the running vehicle produces maximum electrical output. If the cranking takes too long before the dead vehicle starts, the alternator can be damaged on the running vehicle. To prevent this, connect the booster cables and let the running vehicle charge the dead battery for several minutes. Then turn off the running vehicle before cranking the other vehicle.
When connecting the booster cables, the red cable ends should be connected to the + or positive posts on the batteries of both vehicles. On many new vehicles, the battery is concealed under the rear seat, in the trunk or beneath plastic covers in the engine compartment. Fortunately, the manufacturers usually provide a positive connector under the hood to provide a connection point for boosting. Look for it under a bright red plastic cap marked ” battery” or with a + sign.
The black booster cables should be connected to a metal bracket or mount directly on the engine. Do not connect the ends to the battery negative posts or a spark can occur. Hydrogen gas generated in the battery could be ignited by the spark created when connecting the cables and the resulting explosion could spray battery acid on the operator. Be careful to keep sparks and flames away from batteries.
Don’t be surprised if the horn starts honking on the vehicle being boosted. Many newer vehicles have security systems activated when the car is locked. Because the battery was dead, the system did not disarm when the car was unlocked but now there is power supplied by the other vehicle and the alarm triggers. Simply unlock the vehicle again using the key fob or the key in the driver’s door to deactivate the alarm.
With the cables connected, the dead vehicle’s engine can now cranked. Don’t crank the starter for longer than 15 seconds or the starter motor may overheat. Allow the starter to cool at least one minute between each 15 second crank attempt. With the engine started, remove the booster cables carefully so that none of the ends touch each other or the vehicle until all the cables are disconnected.
Hopefully, you will never need a boost but if you do, following the procedure carefully will help prevent harm to yourself and your vehicle.