Our Generation Florida

Automotive Batteries in Florida

By Jason Gaschel

What you need to know to keep your car running in Florida.

It is one of the most popular topics we teach here at SCC. Every year students want to know why batteries don’t last too long in our hot climate. They also ask about myths they have always heard about batteries. Being a native of New York, I can attest that batteries react differently in Florida than they do up north. The average lifespan for a car battery here seems to be around three years, whereas I have personally had batteries last over eight years in the colder northern climate. I will give you my take on this, but first let’s take a quick look at the job of the car battery and what is going on inside of it.

An automotive battery performs four vital functions:
1. Supplies electrical energy for the accessories when the engine is not running.
2. Supplies energy to the car’s starter and ignition system or glow plugs as the engine is started.
3. Intermittently supplies current for lights, radio, heater, and other accessories when the electrical demands of those devices exceed the output of the generator.
4. Acts as a voltage stabilizer in the electrical system.

Battery Composition and Maintenance:

Given this vital role in the overall health of your vehicle, batteries should not be ignored. Some batteries are labeled “maintenance free” and do not require anything more than cleaning the top of the battery, but most are not. So how do you know what you have under your hood?

If there are removable caps on the top of the battery, then your battery is not “maintenance free”, even if the label states that it is. Under the caps is a liquid substance called electrolyte. Over time and normal use, the battery gets hot and this electrolyte will vent from the battery causing a low level in each cell. You should use only distilled water to refill these cells, as contaminants in tap water will reduce the overall life of the battery. A 12-volt battery contains 6 cells, which consist of a positive and negative plate. Each cell produces 2.1 volts. A fully charged battery has a voltage level of 12.6 volts when checked with a digital voltmeter.

Inside an automotive battery, there are positive and negative plates that have different properties to create electron flow. These plates are surrounded by a liquid electrolyte. The reddish brown colored positive plate contains lead dioxide (PbO2), which consists of lead (Pb) and oxygen (0). The light gray colored negative plate contains sponge lead (Pb). The electrolyte consists of water (H20) and sulfuric acid (H2SO4,). The electrolyte solution is approximately 64% water and 36% sulfuric acid and has a specific gravity of 1.265 at 80ºF. As a battery discharges, the electrolyte becomes more like water, and the properties of both plates become similar. To create electricity, the battery depends on the difference in the composition of the positive and negative plates. As the battery discharges, the lead dioxide (PbO2) in the positive plate reacts with a sulfate radical (SO,) from the electrolyte to form lead sulfate (PbSO4). The lead (Pb) in the negative plate reacts with a sulfate radical (SO4,) from the electrolyte to also form lead sulfate (PBSO4) without these sulfate radicals, the electrolyte becomes more like water (H20). When recharged, the plates return to their normal composition, and the electrolyte returns to normal.

At 80ºF, the battery has 100% cranking power and the engine starts with 100% efficiency. At 32ºF, the battery has only 65% cranking power and the engine requires 250% more power than at 80ºF. At 0ºF, the battery has only 45% cranking power and the engine requires 350% more power than at 80ºF. In cold weather the molecules move slowly and can’t rapidly discharge the battery. That’s why when a car sits for several weeks in cold weather it might not start. Starting problems in cold weather get worse when electrolyte freezes. As mentioned earlier, as the battery becomes discharged, the electrolyte loses acidity and becomes almost like water. The electrolyte in a discharged battery can freeze and ruin the battery in temperatures around 32ºF. To prevent permanent damage due to freezing, keep batteries in a charged condition so that the electrolyte maintains a high specific gravity. Since the temperature here rarely gets to that point, freezing does not seem to be much of a problem.

So what does this all mean to you? Living here in Florida, the heat will create a condition known as self-discharge. Temperatures above 80ºF have an adverse effect on batteries. As ambient air temperature rises, the normal chemical reactions speed up and the battery self-discharges. This means that a battery can lose power while a car is sitting and not being used. A common observation on battery life states that you remove about six months of life every time your battery goes dead. Just like the human body, the temperature of a battery needs to be regulated to stay healthy. Is there anything you can do to prolong battery life? Yes, by keeping your battery properly maintained with the correct electrolyte level, you can get the most from your current battery. It should also be noted that vehicles that go off road are more likely to have a battery failure due to excessive vibrations. Consider a gel-cell battery that does not contain liquid electrolyte for these applications. Vehicles are now incorporating smart technology to help you get the most of your battery. The new Chevrolet Corvette has advanced battery circuitry that keeps tabs on battery condition by monitoring the voltage and current. It also prohibits jump-starting the vehicle, as sensitive electronic components could be damaged.

Many of the hybrid vehicles you see on the streets today rely on batteries to help power the electric motors onboard. This takes some of the burden of powering the vehicle from the internal combustion engine. Although the components are very different than the typical car battery discussed above, they still perform the same basic function of storing energy to be used by the vehicle. Look for batteries to have an increased role in the vehicles of tomorrow. As the price of gasoline increases, manufacturers are looking to produce more battery-powered plug in hybrid vehicles. This all depends on the advanced development of battery types, such as lithium-ion.

I welcome any questions concerning automotive topics for my article, so please feel free to drop me a line.
Send your automotive questions to: editor@ourgenerationflorida.com

Looking for a career as an automotive technician?
Visit www.scc-fl.edu/automotive for more information.