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Cold-cranking amperes or CCA is unit of measurement that generally determines a battery's ability to start your engine. CCA is a measurement of worst conditions under which a battery can be expected to deliver current, and it tests how much current in amperes a battery can deliver under extreme cold. According to American SAE standard, CCA is determined by measuring how much current can be delivered in amperes for 30 seconds at -18 degrees C with a final voltage of 7.2 volts per cell or higher.
Reserve capacity is an important measurement for total capacity of battery and shows how long a battery can keep engine running if alternator/generator fails. Reserve capacity of a battery is measured in minutes at room temperature (approximately 70 degrees F). During this test, 25 amperes is drawn from battery for as long as voltage does not drop below 10.5 volts. For off-road use, it's a good idea to make sure any battery you purchase has a reserve capacity of at least 120 minutes.
Reserve capacity is also important for those times when you need to run a radio, spotlight, winch, or other electrical accessory without running engine.
A Batteries Two Enemies
Although just about all modem batteries are pretty reliable, there are two enemies that can grind even a brand-new battery to a halt - extreme cold and extreme heat. Batteries are at their best with internal temperatures (not ambient) above 50 degrees F and below 105 degrees F. Below and above this range, problems can develop, and a dead, damaged, or . useless battery can be result.
We've all noticed that under extremely cold conditions (below freezing), battery will turn over starter motor slowly, if at all. This is because when internal temperature of battery gets below optimum range, chemical reaction inside battery happens more slowly, and for every 10-degree drop below freezing, time that chemical reaction takes doubles. Because of this increased resistance, voltage in battery drops and cannot turn over engine.
Heat can also have an adverse effect on your battery's overall health. Battery power is reduced when it's subjected to excessive temperatures, but problem may not be immediately noticed until temperature drops. At higher temperatures, chemical reaction within battery is more rapid. The battery can produce more energy more quickly. This is good, right? Wrong. The higher rate of energy production results in an increase in off gassing; water in battery is vented out as hydrogen and oxygen molecules and rate of internal corrosion, or sloughing, increases. This can result in a short in one or more cells that is not noticed until cold weather diminishes overall ability of battery.
What to Buy
When it comes to batteries for automotive use, there is no such thing as a perfect battery. Any battery can fail if it is neglected, constantly overloaded, or overcharged. The important thing to remember is to get right battery for your needs, one that is rated for your vehicle and all accessories you use. Generally, this means a high Ah, high CCA, and high reserve capacity. Also, make sure you buy a quality unit. Don't be fooled by low price of budget shops. Batteries sold in no-name-battery discount stores often are poorly assembled and use inferior materials in plates and separators. Name-brand batteries, such as AC-Delco, Sears DieHard, Exide, Interstate, Optima, and others, are manufactured to highest standards, delivering high reliability combined with long life.
For off-road use, however, we feel that recombination battery is best overall, since it delivers high output, needs no maintenance, holds up well to rigors of off-road driving, and has a quick recharge rate, as well as a long life span. It is a particularly useful battery for off-roader because it has no liquid to leak out and can be mounted in any position (even upside down). Because of this, it won't corrode battery trays or cables and is safe in a collision. You can actually shoot a 45-caliber bullet through battery casing and it will still crank at full power. Try that with a conventional battery, and you have a leaking mess that will at best produce minimal voltage.
Although recombination batteries are sold under various brand names, Optima's 800U is original and also only battery available with both top posts and side terminals, a feature that makes it especially well suited for specialized installations and powering accessories and where there is installation room for only one battery Since we also run a winch and driving lights from starting battery, it has to be a powerful one. The 800 CCA and 120 minutes of reserve capacity Optima offers means we can rely on unit as a power source for lights and winch use when engine is down, without sacrificing starting ability. Additionally, side terminals make it easy to power winch and other accessories directly off battery without disconnecting main power cables and disabling vehicle's computer. This makes for a clean installation without a lot of cable clutter at main battery posts, which is especially important when there's limited space around battery top.
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