Car Battery, How To Charge & What The Numbers Mean

When will I need to replace my battery?

Battery replacement will be required if one or all of the following symptoms develop.
1. Loss of power in cold or extended starts.
2. Slow or interrupted turnover of the starting motor
3. Battery discharge light on the vehicle instrument panel is lit.

If you are experiencing any of the above symptoms then you should have your car battery and the electrical system checked, a lot of places now will do this check for free so you can easily find out what is causing your problems

What can cause your battery to fail?

Heat and vibrations are the most harmful elements to a car battery and unfortunately it is difficult to protect from as most car batteries are in the engine bay which is a hot environment prone to shakes and rattles. There are many other factors that can cause battery failure and these stem from poor maintenance (out of site out of mind). These include things like corroded cables and terminals, low levels of electrolyte, plates sulfating, alternator/regulator malfunction, and short circuits. Most of these problems can be avoided but remember batteries do not last forever and most have a 3 or 4 year warranty.

How do you charge a car battery correctly?

If a battery was discharged quickly then it should be recharged quickly, and a slowly discharged battery should be recharged slowly. The main concern is to not overheat nor overcharge the battery. All batteries contain sulfuric acid and can generate explosive gases. Read and follow all warning labels before charging a battery. Be sure to charge in a well-ventilated area. It is important to follow the charging instructions to ensure that the battery is returned to a full charge as battery chargers vary by manufacturer. For best results, charge the battery as soon as you know it is discharged. For charging an average fully discharged car battery using a 10-amp automotive charger, it will take approximately 8-10 hours at 25 degrees C temperature to reach full charge. Take Note, Once a battery has been fully charged, it should be disconnected from the charger immediately. Continuing to charge a fully charged battery will severely damage the internal plates and shorten battery life although you can get chargers that automatically change to float charge once the full charging cycle is complete. This is useful for classic cars that are layed up over the winter, with one of these chargers fitted it will monitor the charge state of the battery and charge as necessary so when you come to start your car in the spring it is ready to go.

How do you maintain your Car battery?

Many car batteries come with 2 removable vent caps at the top of the battery. These caps can be removed to check the electrolyte level in the battery. If the level appears low, add distilled water to the cells. DO NOT OVERFILL! Overfilling can cause acid to be discharged from the battery during operation. The fluid level should be checked at least once a year in cold or mild climates and more often in hot climates. While checking the electrolyte, you should also check the battery terminals for signs of corrosion. Clean the terminals and attached cables of any dirt and corrosion to ensure a good connection and proper starting. By removing any oil and dirt from the battery's casing, you will reduce the risk of short circuiting.

How does heat and excessive cold affect my battery?

Heat increases the rate of evaporation, which causes a loss of water from the electrolyte. Extreme heat also increases the rate of self-discharge and promotes the corrosion of the positive plate grids. Extreme cold dramatically reduces the speed at which chemical reaction can occur, while increasing electrolyte resistance. It is important to keep batteries at a full charge during periods of extreme cold. Batteries in a discharged state are susceptible to freezing, which can cause damage to the plates and battery container. Cars demand more from a battery in freezing temperatures as the engine oil thickens and makes the engine harder to crank and turn over.
Heat is the number one killer of a battery; although it increases the performance of the battery short-term, its life is drastically reduced over time.

AH (Amp Hours) CA's (Cranking Amps) & CCA's(Cold Cranking Amps)

Amp Hours is the claimed charge held withing the battery and a 50 AH battery should deliver 1 Amp for 50 hours.
Cranking amps are the numbers of amperes a lead-acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery). In other words, CA/cranking amps determine how much power you have to start your car in most climates. The basic job of a battery is to start an engine; it must crank, or rotate the crankshaft while at the same time maintain sufficient voltage to activate the ignition system until the engine fires and maintains rotation. This requirement involves a high discharge rate in amperes for a short period of time. Since it is more difficult for a battery to deliver power when it is cold, and since the engine requires more power to turn over when it is cold, the Cold Cranking rating is defined as: The number of amperes a lead-acid battery at 0 degrees F (-17.8 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). In other words, CCA/cold cranking amps determine how much power you have to start your car on cold winter mornings.


Reserve Capacity

Reserve capacity is the time in minutes that a new, fully charged battery will deliver 25 amperes at 25 degrees C and maintain a terminal voltage equal to, or greater than, 1.75 volts per cell. This rating represents the time the battery will continue to operate essential accessories if the alternator or generator of a vehicle fails. Put another way, reserve capacity is a battery's ability to sustain a minimum vehicle electrical load in the event of a charging system failure. Under the worst conditions (winter driving at night), this minimum could require current for ignition, low beam head lamps, windshield wipers, and defroster while driving at low speeds.

Can different size batteries have the same capacity?

Batteries come in many different group sizes. A battery's group size simply determines it's length, width, height, and terminal configuration; this has nothing to do with a battery's capacity. Regardless of the group size, two batteries are equal in power if the CCA ratings are the same. New technology enables a great deal of power to be put into smaller cases with today's new high capacity output design.


How do I store my automobile battery? Is concrete O.K.?

When storing an automobile battery, it is important to make sure it is at a full charge and the electrolyte level is full. A battery stored in a discharged state is susceptible to freezing sulfation and an increased rate of further discharge. The battery should be placed in a cool dry area, the cooler the better without going below 32°F, that is well ventilated and out of reach of children and pets.
A battery will not lose its state-of-charge strictly from placing it on a concrete surface, but will discharge it over a period of time, due simply to neglect.


If you found this page useful why not donate a little bit of cash to help with site costs. Its the online version of buying me a pint!

| Contact us |
Copyright Classic-Car-Magazine 2013
| Updated 03-May-2008 |