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Car Batteries – What Do I Need To Know?


At Midwest Performance Cars we receive a lot of vehicles that are towed in as they suddenly will not start. This is often due to a failed battery and is very prevalent during the winter months.

However, your battery is just one part of your vehicle’s complex electrical system. A dead battery may be a result of another problem. Often a faulty alternator is not charging the battery properly and causing it to fail. You may also have a “parasitic draw” which means some component of your car is putting an undue draw on the battery when the car is parked. Remember, vehicles these days often have more CPUs than your home and office combined. Many of these electrical systems require a small drain on the battery all the time. However, if something is amiss, then they can drain the battery dead.

Why do car batteries fail in the cold weather? There are a number of reasons:

1. A battery produces less power or energy as the temperature drops. In fact batteries are measured using Cold Cranking Amps (CCA). A CCA rating is the number of amps a battery can deliver at 0 ° F for 30 seconds and not drop below 7.2 volts. According to Interstate Battery’s website:  “Your vehicle’s battery loses 33 percent of its power when the temperature dips below freezing, and over 50 percent of its power when the temperature falls below zero.”

2. At the same time it takes more current to turn over a car’s engine when it is cold outside. The oil gets thick and there is more resistance that the starter has to deal with.

3. Cars are often “short-tripped” more in the winter. Short tripping is when a car is started and driven for a short period of time which does not allow the alternator to fully recharge the battery.

4. Vehicles are often driven less frequently in the winter. Periods on non-use can negatively affect the health of your battery – particularly if it is older.

Getting into your car and having it not start due to a dead battery is one of the most frustrating and disruptive aspects of car ownership (along with flat tires, running out of gas, and shoveling). Since you are in your car, you need to go somewhere – to work, to take your kids to school (in which case they are in the car), wherever. And there is no easy fix – you usually have to wait for the tow truck.

How Can I Prevent A Dead Battery?

Fortunately, your car will give you some early warning signs that your battery is at the end of its life.
• Age – most batteries today last an average of 3-5 years – less in harsher climates. In Chicago, if your battery is more than three years old you should have it tested periodically.
• Slow Engine Crank – when your car is harder to start than normal and slow to turn over, your battery is weak. The dreaded “rur, rur, rur” noise. If it does fire for you, don’t put it off too long.
• Check Engine Light/Battery Light/Strange Lights – some vehicles these days have a low battery light, others may throw a check engine light, or you may see weird lights that come on and off seemingly randomly. These are due to low voltage faults – one of the computers in the system is not getting enough power.
• Corrosion – look at the top of your battery and at your cables. Are your cables tight? Do you have something green that looks like it is growing off your battery or cables?

Let Midwest Performance Cars Check Your Charging System:

At Midwest Performance Cars we have diagnostic equipment specifically designed to check your entire charging system. This test will check the following:
1. The condition of your battery
2. The condition of your alternator
3. Your starter’s amp draw
4. If you have any parasitic draws
This test usually takes approximately one hour on most vehicle depending on where your battery or batteries are located.