1993 BMW 740i Battery Test Cost

The battery in all passenger vehicle's serves the same function. They allow storage of electrical power to start the engine, and allow electronic components to function when the alternator cannot produce enough power. The latter is the case with many vehicles that use a secondary battery.

As the engine is running, the alternator is constantly recharging the battery, and providing electrical power to the vehicle simultaneously. The battery stores this electrical power and, when requested by turning the key, uses the stored power to start the engine. When additional batteries are stored on a vehicle, they may assist in starting the engine, or they can send power to additional components that were not included with the vehicle when manufactured. Some vehicle's use up to four batteries, such as the original HUMMER, but for the overwhelming majority of vehicle's, one battery is sufficient for all standard operations.

The battery is considered “dead” when there is insufficient charge to start the engine, or run electrical components. Normally, the first sign is dim lighting in the interior of the vehicle, and when attempting to start, the engine may crank extremely slowly, or not at all. A very rapid clicking noise is normally heard if there is any charge left in the battery, but in many cases the vehicle will be completely unresponsive to any input. If the battery is losing charge while driving the vehicle, the battery warning light will illuminate, and the engine may stall from lack of electrical power needed to run.

Vehicles with manual transmissions can be manually started by pushing the vehicle to considerable speed, and releasing the clutch quickly. If the battery is faulty, this will allow the vehicle to start using power from the alternator This method is commonly called push-starting, and is an effective method of manually starting the engine using the vehicle's transmission to turn the flywheel. The vehicle may be able to start using jumper-cables, but if the battery is faulty, the jumper-cable wire thickness must be sufficient to allow the engine to start using power exclusively from the second vehicle’s battery. Keep in mind, many newer vehicles require a threshold voltage and amperage to be achieved before starting the vehicle and operating many systems, even if the battery has enough power to turn the starter. For these vehicles, even with manual transmissions, the battery must be fully charged before starting. Testing the battery may also determine the battery must be replaced.

Batteries fail at no specific mileage interval or age. The older a battery however, the more typical it is to experience failure. Proper maintenance of the starting and charging system can prolong the life of the battery, as well as other starting and charging components. A good rule of thumb is to purchase a battery with the longest available warranty, and expect it to last around that amount of time.

We have all heard of the term “dead battery”, or experienced this issue ourselves. But it is important to note that a “dead battery” does not necessarily mean the battery is at fault. vehicle's exhibiting the symptoms noted above will be connected to a starting and charging system test machine. This is an advanced device that will test every part of the starting and charging system automatically by following onscreen instructions. The machine will display results, and indicate the possibility of battery failure, but may also require the servicing technician to complete visual inspections while testing is in progress. If the battery is found to be discharged below the required voltage, it will be recharged, retested, and possibly replaced. It is also possible to use the service of a battery tester at many auto parts suppliers. This requires the battery to be removed, connected to a charger, and tested under a set of load ranges after the battery is charged. If the battery fails at these load ranges or fails to charge, it will be considered faulty.

Battery replacement, for most vehicles, is typically fast and easy. The battery cables should be removed, any battery insulation material will be removed, and the battery retaining bracket will be loosened or removed. The battery will then be free to remove. The new battery will be installed in the reverse order of operations. Note that some vehicle's place the battery in the trunk, the front or rear wheel well, or under the seats. In these instances, accessibility of the battery may dictate dismantling several components before replacement can being.

We recommend using a battery rated identically to the original battery. Using too small or too large of a battery will result in overcharging or undercharging, and will lead to repeated failure. This may also result in damage to electronic components around the vehicle, or the battery could fail catastrophically.

A dead battery can be caused by several components. Most commonly, the issues causing battery power depletion are battery cables, failed connections due to corrosion, an electrical system malfunction causing battery drain while the vehicle is off, and long periods without using a vehicle. That being said, the battery must be tested prior to replacement, as the battery very often replaced needlessly. If ever a hissing sound is heard from a battery, the hood should be closed, and the vehicle left off for several hours before removing the battery or towing to a repair facility. This noise indicates a heavily overcharged state.

Replacing the battery, or batteries, is a great DIY project that can be completed in short order for most vehicle's. However, there is a risk of electrical shock and other electrical component failure if arcing occurs at the battery terminals. Prior to performing this maintenance, the vehicle's battery location should be noted and if the location requires much disassembly, either a very experienced DIYer, or a trained technician should be trusted with the repair.