How Batteries Work

Understanding Care And Maintenance Will Extend Your 12-Volt Electrics

Robert Eckhardt Jan 1, 2001 0 Comment(s)

Step By Step

Modern batteries are getting stronger. New technology involving the construction, materials, and chemicals provides more power for a longer period of time. A 72-month battery will never see 40 months unless it’s maintained properly.

A single cycle consists of discharging and recharging a battery one time. It can be to any depth of discharge and for any length of time. What’s critical in choosing a battery is the amount of discharge it can withstand and the time it’s in that discharged state.

This chart shows the relationship between the amount of discharge and the number of times that a deep-cycle battery can be recycled. If the battery routinely uses only the top 25 percent of its capacity, it can be recharged around 2,200 times. Drawing the battery down to 50 percent of its power cuts the life of the battery in half. This explains two things. First, do not allow the battery to discharge any deeper than necessary if you want long battery life. Second, abusing the battery by not keeping it fully charged cuts battery life, and that’s expensive.

One way to test the charge of the battery is with a hydrometer. The other is with a voltmeter. A hydrometer shows the specific gravity of the electrolyte inside the battery. The advantage to a hydrometer is it allows you to determine if one of the cells is weaker than the other cells. With a voltmeter, a battery can show that it has enough voltage, but one cell may be weak and not able to hold a charge. In this case, the battery will leave the shop with a full charge but let you down later in the day. A graduated float-style hydrometer will give the most accurate readings.

The type of cycle is important in choosing a battery because it will tell you what Cold Cranking Amperage (CCA) and Reserve Capacity (RC) is best for your application. A battery that’s used only to start the vehicle will only cause a shallow (10 percent) draw on the charge of the battery. In this case, a battery with fewer CCA will be sufficient. On the other hand, if the battery is constantly cycled deeply into the 60-percent and 70-percent range, a deep-cycle battery is required.

Our own Hot Rod magazine teamed up with Interstate to offer this specialized battery that features Pinnacle Plus Technology which is said to offer 22 percent more battery life.

If the engine is considered the heart of your Corvette, the battery is certainly the pacemaker. The car will not run if the engine won't start, and the power to get everything moving comes from the battery. The battery is one of those parts that you seldom consider when it's working, and think a lot about when it's not.

Many Corvettes sit in the garage for extended periods of time awaiting the next sunny day. This is hard on a battery. A battery will discharge even if it's disconnected and just sitting in the car. If the car is equipped with a computerized ignition, a clock, or an alarm system, there's a constant drain on the battery. The longer a battery sits idle, the more it will discharge.

When a car sits idle and the temperature rises above 80 degrees F, a battery will start losing around five percent of its charge, and the longer it's exposed to heat, the more it will discharge. Batteries are unforgiving if not properly maintained. Choosing the right battery and its proper maintenance will lessen the likelihood of inconvenience and expensive towing bills.

Two Types

There are two basic types of batteries. A starting battery is designed for one purpose--to start the engine. It is not designed to go through a deep discharge and recharge cycle more than 50 times. The more it's discharged, the shorter its life span. When a starting battery is allowed to discharge to half its power, it will lose half of its overall life.

A deep-cycle battery is designed for hundreds of deep discharging and recharging cycles. You can use a deep-cycle battery for starting a vehicle, but it's not recommended unless it has a high cold-cranking amperage rating. There is a difference in the construction and materials inside each type of battery. A deep-cycle battery will have thicker plate materials and a different chemical electrolyte mixture.

If your vehicle sits for extended periods even with the battery disconnected, it's wise to install a heavy-duty starter battery that has higher cold-cranking amperage (CCA) and reserve capacity (RC) ratings than a standard OEM battery. A starting battery with higher CCA and RC should offer good performance and lasting power. If you leave the battery connected and it's powering the accessories, installing a deep-cycle battery with higher CCA and RC is advisable.

As with most items in our market-driven society, bigger may not always be better. Battery manufacturers will tout a battery's high CCA numbers, but that comes at a price. Generally, as the CCA goes up, the RC goes down. This is due to the internal construction of the battery. So the question is, how much CCA is enough? A rule of thumb is, you need at least the same number of CCA as the cubic-inch displacement of your engine.

Another consideration is the temperature in your region of the country. It's unlikely, but if you fire up your Corvette in the middle of a North Dakota winter, you'll need a battery with a massive CCA number. In most cases, look for a battery with a respectable CCA number and a corresponding high RC. That way, you'll get the best of both worlds.

Maintenance

Properly maintaining a battery will add to its life span. The Corvette owner should periodically charge their battery to peak capacity, and make sure battery connections are tight. A loose battery connection leads to poor performance and acid buildup on the posts. Another tip is to keep the top of the battery clean. Dirt and acid can be electrically conductive and cause self-discharging of any battery. Use an old toothbrush to scrub the top of the battery and the posts with a solution of water and baking soda.

Check the battery's fluid level every time you change the motor oil. Most maintenance-free batteries are, in reality, low-maintenance batteries. If you can remove the top vent caps, the battery water needs checking. Add enough distilled or top-quality drinking water to bring the electrolyte to the bottom of the fill hole. Do not overfill the battery--that can cause acid to boil out of the battery while you're driving.

Battery Chargers

Battery chargers come in different power ranges and with different functions. One of the largest manufacturers of battery chargers is Schumacher. They make over 40 different models to meet your specific charging need. Two units of interest to the home mechanic would be models SE-60 and SE-5212A. Both are 50-amp/10-amp/2-amp chargers.

You run out to the garage late for your local Corvette show and when you hit the key, nothing happens. The 50-amp mode on the charger is used to start a car whose battery is dead. This is for emergency starting. It will not charge the battery.

It's early that morning and you're making final preparations for the car show; you discover the battery is dead. By using the 10-amp mode, you can completely charge the battery in three to five hours. This way, you won't need a jump-start at the show to return home.

The best approach is to use the 2-amp mode the night before and trickle-charge the battery to maximum voltage in 2 to 12 hours. This way, the battery is ready to start the car the next morning. Model SE-5212A is fully automatic. You can set it and forget it, and it won't overcharge the battery. The SE-60 has a timer, but it's not fully automatic. Therefore, you must watch the charger so it doesn't overcharge the battery.

Model SE-60 has a couple of other features worth mentioning. It has a 300-milliamp maintenance mode. It will keep the battery at full power when the car is in storage. It also has a built-in multifunction-test voltmeter to test the battery's condition before and after charging.

Another approach to battery maintenance comes from Auto Meter Competition Instruments. Its Battery Extender monitors the power of stored batteries. With sophisticated electronic circuitry, it delivers a one-amp charge with 250 milliamps of maintenance current to keep the battery at peak efficiency. By continuously charging and monitoring the battery, it will not allow the battery to be overcharged and boil the water out of the battery. This unit can also detect bad cells or warn of a sulfated battery.

The Battery Extender will work on deep-cycle and gel-cell batteries in addition to normal starter batteries. The advantage beyond extending battery life is the constant power to maintain any accessories and alarms that are battery-powered. You won't have to reprogram your favorite radio stations because your battery went dead when your Corvette was in storage. This small (4x4-inch) box can be permanently mounted next to the battery, making it easy to plug in when the car is in the garage.

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