How Your Auto Battery Works

Here’s a simple guide to understanding how car batteries work, from the alternator to cold cranking amps to different types of car batteries. Find out:

• How a battery starts your car
• How the battery provides power
• What cold cranking amps are
• How the battery recharges
• Why car batteries die
• What the different types of auto batteries are

How a Car Battery Starts a Car

The first purpose of an auto battery is to provide power for starting your vehicle. It also acts as a surge protector for the car's computer and provides power for short-term use of things like lights, stereo, GPS or wipers when the engine is off.

The car battery is part of the starting system. There are three main components in this system:

1. The ignition switch is either the starter button you press or where you insert your key.


2. The switch controls the starter relay (also called a solenoid). When you turn the ignition, it sends a small electrical current to the starter relay. This causes a pair of contacts to close.


3. When those contacts close, the battery sends voltage to the starter motor, which turns some gears to start the car.

How the Battery Provides Power

The two types of auto batteries — flooded and AGM batteries — use lead-acid technology. A typical lead-acid car battery contains plates of lead alternating with plates made up of other materials, all immersed in an electrolyte solution of about one-third sulfuric acid and two-thirds water.

Turning the ignition triggers the acid in the liquid electrolyte solution to react with the active material on the plates (active material refers to any substance in the battery that reacts with the solution to discharge or recharge the battery). This generates a bigger electrical current. The current travels through the starting system in a chain of reactions that cues the engine to start.

What Are Cold Cranking Amps?

Cold cranking amps (CCA) refers to the amount of power a battery can supply for 30 seconds even at low temperatures. Larger engines require more power to start, as does starting the car for the first time on a cold day.

A high CCA rating is important for standard auto batteries in areas with subzero temperatures, since deeply discharged wet cell batteries can freeze solid in such weather.

How the Car Battery Recharges

The alternator is responsible for recharging your car battery as you drive. This part also supplies power for your car’s electronics when you're underway. It is driven by the alternator belt from the engine. As the belt goes around, it generates electrical current to run your vehicle's electronics. It also sends some current back to the battery to recharge it.

A voltage regulator controls this flow of electricity to keep it even and deliver the right amount of charge to meet needs like running the AC or heater. It also protects the battery from overcharging, which can damage it.

Why Does My Battery Die?

Over the life of a battery, discharge-recharge reactions happen thousands of times. Each cycle wears out the plates a bit, and over time the lead deteriorates. As your car battery loses capacity, cold cranking amps decrease.

Deep discharging, which happens when you use the battery to run the stereo, lights or other electrical systems in your car when the engine is off, is responsible for a good portion of battery failures. Discharging most of your battery's capacity by using it in this manner for too long and then recharging it through driving can cause the sulfur in the electrolyte solution to stick to the lead and create other damage to the plates in the battery.

What Are the Different Types of Auto Battery?

The two most common auto batteries for sale today are standard wet cell batteries and absorbed glass mat (AGM) batteries. Both use lead-acid technology. The differences are in the needs of the car.

Standard Wet Cell Batteries

These are also called flooded, conventional or SLI (starting, lights, ignition) batteries. Some standard batteries have vents that allow for airing out corrosive gases, steam, and condensation (these may be called vented batteries). They have removable caps for adding fluid. Other wet cell batteries are closed systems, with no removable caps.

• Service needs: Occasional simple maintenance including cleaning off corrosion on terminals and topping off the fluid with distilled water if the battery has removable caps. The battery should be visually checked every year. Battery charge should be checked before road trips and after summer before temperatures fall.

Absorbed Glass Mat (AGM) Batteries

These are a type of VRLA battery, which stands for valve-regulated lead-acid. They’re sometimes called regulated valve, dry cell, non-spillable or sealed batteries. They are called sealed because they have no removable caps, don’t vent gases and can’t leak any acid. They do have pressure-activated relief valves that open only if the battery overheats during recharging.

Some newer cars, such as those with start-stop technology, require AGM batteries. These batteries will continue to deliver power to a car’s computer and electronics even when the engine isn’t running.

AGM batteries hold a charge longer than standard wet cell batteries. They can tolerate periods of disuse and repeated deep discharging and recharging cycles better than flooded batteries. They have a short recharge period but they can be easily damaged by overcharging. They also perform well in harsh climates with extreme heat or cold.

• Service needs: Charge should be checked before road trips and after summer before temperatures fall.

Wet cell batteries and AGM batteries are not interchangeable — your car requires one or the other.

Lowering Suspension: Pros and Cons

Lowering your car or truck so it’s closer to the ground is a popular way to customize your ride. Done right, it’s a great look that also boosts handling performance. Done wrong, it could compromise handling, drivability and traction, reduce tire tread life and even damage parts.

Pluses and Minuses of Lowering Suspension

Benefits

More Road Feel
A lowered suspension helps a driver be highly attuned to how their vehicle acts on different pavement as more of the vibrations from imperfections in the road surface come through the steering wheel.

Stiffer Ride
With this setup, you have to have more rigid springs so the front or back of your vehicle won’t bottom out over bumps or depressions. This is the driving experience many prefer, versus a cushier ride from, say, a luxury sedan.

Less Lean in Corners
The lean of a vehicle around a sharp turn is greatly reduced because the shift of weight is less due to the lower center of gravity. The part of the vehicle on the outside of a turn stays more level with the inside. This lets a car settle more quickly into a turn and act more responsively.

Better Handling
Another effect of being closer to the ground is improved responsiveness, more stability, and grip at speed. Because lowering means getting stiffer springs, there is less weight transfer when you hit the gas or brake hard. This means you’ll enjoy faster acceleration and quicker stops.

Less Air Drag
Lowered vehicles are more aerodynamic. There’s less air hitting the wheels and tires (that are not streamlined shapes). This makes these cars faster. Some owners of low-stance vehicles also notice improved gas mileage. BUT, lowering a car too much will actually increase wind drag.

Less Rollover Risk
Lowered vehicles have a lower center of gravity, which decreases rollover risk when cornering.

Improved Traction
Lowering generally means you’ll put a plus-sized tire and wheel package on the vehicle. Such tires have shorter sidewalls, a larger contact patch (that keeps more rubber in contact with the road) and less roll around corners.

Good Looks
Cars and trucks that have been lowered with custom wheels are attention-getters. It’s a more aggressive and performance-oriented look that stands out in a crowd.

Drawbacks

Less Ride Comfort
If you and your passengers are accustomed to a softer suspension that cushions impacts like bumps and potholes, you may think less of the ride comfort of a lower suspension. You may also notice increased road noise since you’re closer to the pavement.

No Go on Rough Roads
The lower clearance will not be your friend on rutted, rocky, washboard and potholed roads.

Uneven or Accelerated Tire Wear
Lowering changes the geometry of your wheel-tire fitment. If it’s done improperly, your car may have an alignment problem that results in premature or extreme wear patterns.

Bottoming Out
Even an inch-and-a-half lower suspension can cause problems around corners, with slight potholes or on speed bumps. Traveling over the lip of a parking garage or starting up a driveway or ramp could cause the front of your vehicle to hit the pavement. Contact with the ground can cause serious damage to components underneath the car, like the exhaust system and oil pan.

If you ever need a tow truck, you may require a flat bed. Otherwise, there could be a problem with the back body of the vehicle dragging on the ground.

Potential Rubbing on Parts or Tires
Poorly done or extreme lowering can cause suspension and steering parts to contact each other, the wheels or the tires. It could also cause tires to rub the body during turns or going over bumps.

Can’t Use a Standard Jack
If you get a flat tire, you may find out at an inconvenient time that there’s not enough clearance to get the unit under the vehicle’s frame.

Cost
Quality components and keeping correct alignment can get pricey. The lower you go, the more chance you’ll need additional parts. For example, if coilovers (meaning coil spring over shock) are part of your new setup, you’re likely looking at an outlay of $1,000 or more.

Warranty Issues
You should check both your owner’s manual and any manufacturer’s or aftermarket warranty to determine if 1) the manufacturer advises against lowering your car, or 2) if lowering your car will void or adversely affect any warranty coverage you currently have.

Know This Before You Modify Your Suspension

Here’s what to know before you go low.

1. If it’s higher performance you’re after, you may need to lower a lot less than you think. It’s easy to miss the mark and actually make your suspension worse. To be sure that components like struts and springs can do the work of keeping tires at the right angles, get expert help.


2. Don’t cut corners when it comes to shocks, struts or other components. You’re making changes to the structure and balance of your vehicle. You don’t want to risk failing parts.


3. If you modify your vehicle in ways that aren’t road legal, your insurer may not pay a claim for damage. Talk to your agent before you customize your ride and ask if your premiums will go up or policy terms change.


4. Installing extreme aftermarket wheel-tire setups or suspension changes can result in steering, suspension or drivetrain problems that won’t be covered by your vehicle warranty. Check to see if the modifications you’re planning will result in denied warranty claims BEFORE installation.


5. Get an alignment after you lower to ensure the best handling and tire life.


6. Take care while you get accustomed to how your new setup performs. With the much stiffer suspension, your vehicle may steer a little differently and won’t absorb road shocks as well. A sudden hard brake or tight turn on a bumpy road could cause a loss of traction.

Any time you change your vehicle’s OE (original equipment) suspension, you should be sure that you’re not creating a setup that is either unsafe or is going to cause problems with other car functions. Like with many aftermarket customizations, it’s about finding the right balance of safety, performance, looks, cost, and drivability. Stop by your local Les Schwab for help.