What Do All The Letters Mean: CCH, AH, And RC

What Do All The Letters Mean: CCH, AH, And RC

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  1. Auto mechanic, like most complex subjects, has a language all its own. Along with that esoteric speak, comes a plethora of acronyms and abbreviations. If you were to set down with a glossary of those words, acronyms, and abbreviations and tried to memorize them all in order that they appear in, you would soon give up in despair. You want to learn them in the context of their application. This time out we are going to take a closer look at three common ones, CCH, AH, and RC.

    This Is For The New DIY Mechanic
    These abbreviations are familiar to the veteran auto mechanic, but I am writing this for those of you who are just starting out as a do-it-yourself auto mechanic. You need to have a clear understanding of this material because being able to select the right replacement battery for your vehicle will depend on it. The automotive electrical system is probably the hardest system, for the DIY mechanic to understand and repair, because you are working with something you cannot see, electricity. Many people shy away from automotive electrical work and leave it for the professional because electricity seems so mysterious to them. Many professional mechanics feel the same way, which is why automotive electrical, has become a specialty service. A big part of the reason it scares people off is the language; it is like a foreign language. The happy news is that you can learn the language if you have the desire.

    Selecting The Right Battery For Your Car Or Truck
    Selecting the right battery depends on more than selecting one with the right physical dimensions to fit the battery box. Just because, a battery fits in the battery box does not mean that it is the right battery for your car or truck. The battery has to fit the carrier, but there are other more significant considerations to consider when buying a new battery. Those considerations all consider the battery’s electrical ratings. Their Cold Cranking Amperes (CCA) rating, their Ampere-Hour (AH) rating, their Reserved Capacity (RC) rating, and their Power rate car batteries in Watts (W) rating.

    Cold Cranking Amperes (CCA)
    One of the hardest jobs that every automotive battery has to perform is starting the internal- combustion engine. Cranking the engine requires a considerable deal of electric current. The actual number of amperes that the starter motor pulls will vary with the size of the engine it is cranking. For a compact car, the starter may require as little as 150 amperes. A truck with a V8 engine may require 350 amperes or more. The CCA rating of a battery is the maximum number of amperes that a fully charged battery can discharge for a period of 30 seconds at a temperature of 0º F while maintaining a cell voltage of not less than 1.2 Volts (V) per cell or 7.2V for a 12V battery. The CCA rating is marked on the old battery. The required CCA rating can also be found in your owner’s manual or the service manual for your car or truck.

    Reserved Capacity (RC)
    The RC of a battery is a vital consideration because it is an indication of how long you can drive your vehicle after the vehicle alternator or generator fails. The RC rating of a battery is its ability to provide emergency power for the ignition system, lights, and other electrical accessories after the charging system quits working. The RC rating specifies how long a fully charged battery can provide 25A at 80º F while maintaining a minimum cell voltage of 1.75 V or a battery voltage of 10.5 V for a 12 V battery. Most batteries used with compact vehicle have a RC rating of 55 to 115 minutes.

    Ampere-Hour (AH) Rating
    The Ampere-Hour (AH) Rating is also known as the battery’s 20-Hour Rating. In simple language, the AH rating is the amount of current a battery can provide under light load for 20 hours at a temperature of 80º F while maintaining a minimum cell voltage of 1.75 V. A battery that can provide 20 amperes per hour for 20 hours has an AH rating of 80 AH (4 X 20 = 80).

    Power In Watts (W)
    Watts is an alternative way of rating a battery’s cranking power but you are more likely to encounter CCA when reading service manuals and specification sheets for car batteries.

    Armed with this information, you are ready to buy the right battery for your vehicle. Even if you are not going to buy and install the battery yourself, you are now able to understand what your mechanic is talking about when he or she starts tossing that alphabet soup around.

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