Besides writing tech articles for our own customers, we have written several for other trade papers and automotive magazines. Here is a series of articles written about batteries.

Battery Article-A

   This will be the first in a series of articles about batteries, yes good old boring batteries. I started my research for these articles by contacting Jim DeCoste of East Penn/Power Battery. I was quick to learn that I had several misconceptions about batteries. Many of the things my father taught me about them are no longer relevant. This month we will start with the very basics, what do those abbreviations mean? Battery testing was standardized by the Battery Council International (B.C.I.) and the following explanations are derived from literature provided by East Penn/Power Battery.

Cold Cranking Amps (CCA): This is one of the more important ratings found on the battery, as providing power to your starter is one of the primary functions of your battery. Your battery has to provide a lot of amperage in a short period of time. So your CCA rating is actually the cranking performance rating and is defined as follows: The discharge load in amperes which a new fully charged battery, at 0F (-17.8C), can deliver for a period of 30 seconds and still maintain a voltage of 1.2 volts per cell or higher. That would be a minimum of 7.2 volts for a 12 volt battery. An example of this would be a battery with a CCA rating of 800 amps would be able to provide 800 amps for 30 seconds without the voltage dropping below 7.2 volts. This would be at 0ºF (-17.8ºC), as you go up in temperature the amount of available amps significantly increases as well.

   You have to be aware of the difference between the CCA rating and the CA (Cranking Amps) rating. The CA rating is the same as the CCA rating except that the test is done at 32F (0ºC). A CA rating will always be significantly higher than a CCA rating. There is also a Marine Cranking Amps (MCA) rating. It is the same as the CA rating. So when comparing batteries make sure you are comparing the same rating, the old adage of making sure you are comparing apples to apples and oranges to oranges really applies here. There is usually 200 to 300 amps difference in the CCA and CA rating for the same battery. To be more specific you use this formula, CA= CCA X 1.22 or CCA= CA X .82 .

   We will discuss selecting the proper CCA rating for your application in a future issue. For now you cannot go wrong by going with an equal to or slightly higher CCA rating than OEM battery. But biggest is not always the best either. As to obtain a higher rating more plates need to be used, which can reduce the service life of the battery significantly. An example: On average a set of 4 group 31-750CCA batteries in a diesel truck will last 1 to 2 years longer than a set of 4 1000CCA batteries.

Reserve Capacity (RC): This is the second most important rating on the battery. It represents the number of minutes a new fully charged battery will deliver 25 amps at 80ºF (27ºC). The 25 amps represents a full electrical load in the average car with no accessories, such as the AC or heater, turned on. The BCI figures this represents the number of minutes a driver has to find help after the vehicle’s charging system fails. We on the other hand know it is a representation of approximately double the length of time you can play your stereo at the beach and still have hope of starting your car. The reserve capacity is the most important figure on any battery that is being used in deep cycle applications. Which is when you are using a battery when it is not being recharged right away.

Cell: Cells are the basic current producing parts of a battery. There are six cells in a 12 volt battery. Each cell will have a positive and negative set of plates, electrolyte, and separators all in its own individual casing.

Direct Current (DC): This type of current flows in one direction only. All automobiles use this form of electricity almost exclusively (some use AC to heat windshields). It should be noted that we can only produce AC current, which then has to be rectified to DC current. This is done because we can only store DC current.

Cycle: A cycle in a battery is when it completes one discharge plus one recharge.

Electrolyte: Electrolyte is sulfuric acid diluted with water. In a lead acid battery it is the conductor that supplies both the water and sulfate that make for the electrochemical reaction.

   A battery has three main purposes in automotive applications. The first is to supply power to your starter and ignition systems. The second is to supply extra or back-up power when the demand you place on your electrical system is higher than your alternator produces. This occurs frequently when you are driving in the city, i.e. start and stop. Your vehicle may be equipped with a high output alternator, but it must see higher than idle engine RPMS in order to produce any significant power. The last purpose is likely the most over looked of all. Your electrical system produces some ultra high voltage spikes during normal operation. These spikes are absorbed by your battery, making your supply of voltage very smooth. These spikes would destroy your vehicle’s computer equipment, your alternator’s diodes, and any other sensitive equipment. In 2005 Original Equipment vehicle manufacturers spent on average, $1000 per vehicle to suppress voltage spikes. Note: This is why removing a battery cable while the engine is running is a major no-no. Doing this is almost always a guarantee that you blow the diodes in your alternator at minimum. We still see this in our shop on a regular basis, even from Class A mechanics. We keep warning you and you keep ignoring us. Oh well, it is good for business.

   It would probably wise to briefly describe how a battery works before we go too far. When two unlike materials such as the positive plates (coated in lead dioxide) and negative plates (coated in sponge lead) are immersed in electrolyte (sulfuric acid) a battery is created and a voltage is developed. It is possible to vary the voltage of a battery by changing the materials used to make up the positive and negative plates or in the electrolyte. A typical12 volt lead acid battery is made of 6 cells, each producing approximately 2.1 volts. Whenever a circuit is made between the positive and negative terminals, you turn on something, a chemical reaction happens inside the battery. The electrical current flows as electrons through the outside circuit and as charged ions between the positive and negative plates inside the battery.

   Next month we will look at the different kinds of batteries that are available for automotive use.Battery Article B

   For an awesome source of battery information we suggest you visit the East Penn Deka website. The have hundreds of pages devoted to battery technical information on all the products they sell, which we distribute as well. There tech documents have to be some of the best we have ever seen.