The 7 Best Car Batteries
We spent 43 hours on research, videography, and editing, to review the top choices for this wiki. You never think about your car battery until it fails to start your vehicle. Then it becomes an emergency that usually results in arriving late to wherever you were heading or not getting there at all. So give yourself some peace of mind by investing in one of these reliable and high performance units. We've included models suitable for every type of vehicle, from small cars to large trucks. When users buy our independently chosen editorial picks, we may earn commissions to support our work. Skip to the best car battery on Amazon.
History Of The Car Battery
The original starting and charging systems installed in cars were positive-ground, 6 V systems.
These properties later made them ideally suited to use in motor vehicles, which require a high current to power the electric starter.
The French physicist Gaston Planté invented the lead-acid battery in 1859. It was the first ever rechargeable battery and had the ability to supply high surge currents despite having low-energy-to-weight and energy-to-volume ratios. These properties later made them ideally suited to use in motor vehicles, which require a high current to power the electric starter.
Though the lead-acid battery was created in 1859 and the birth of the modern car occurred in 1886, early car models didn't use lead-acid batteries. In fact, they didn't use any batteries at all as they had very limited electrical systems. They used a hand powered bell for the horn, the engine was crank-started, and the headlights were gas-powered. It wasn't until the 1920s, as they started installing electric starters, that car batteries became widely used.
The original starting and charging systems installed in cars were positive-ground, 6 V systems. They had a direct connection between the vehicle's chassis and the positive battery terminal as opposed to today's car battery systems, which are negative-ground, 12 V systems.
Until the mid-1950's, all cars used the 6 V system, but as they started installing larger engines with higher compression ratios, more power was needed to start the engine and the switch to a 12 V system began. Except for smaller cars like the Volkswagen Beetle, nearly all cars had switched to a 12 V system by the late 1950s, with the Beetle following suit in the mid-1960s.
Early lead-acid batteries used a liquid electrolyte and actually required periodic refilling. They could also only be mounted in one position, as side-mounting them could cause leakage. In 1971, the first sealed lead-acid battery or valve-regulated lead-acid battery (VRLA) was invented. These were designed to never be refilled and were also available in models with a gel electrolyte, which could be mounted in any orientation without worry of leakage. Now, both sealed and unsealed car batteries are available and with either a gel or liquid electrolyte.
How A Car Battery Works
When it comes to explaining how a car battery works, there is a long version and a short version. Since you probably aren't here to learn about the exact sciences behind the chemical reactions that take place in your battery, we will focus on the short version.
When you crank your engine, the voltage can dip as low as 8 volts.
A car battery provides a surge of electricity that your car's electrical components require to function. When you turn the key, your battery takes chemical energy stored in the electrolyte substance and turns it into electrical energy that the starter and accessories can use. In addition to providing the initial power surge, the battery also helps to regulate the voltage output from the alternator and safeguards against AC spikes.
A car can technically continue to run once started, even if the battery cables are removed, as the alternator is supplying power, but since it is helping to regulate the 14 volts your alternator is cranking out, one should never do this as you can fry all of your electronics.
While a car battery is referred to as a 12 volt battery, this is more of an average than anything else. A standard automotive battery is comprised of 6 cells, each capable of holding 2.1 volts when fully charged. This means your car battery is storing 12.6 volts, and sometimes slightly higher, at a full charge. When you crank your engine, the voltage can dip as low as 8 volts. A car battery is considered fully charged at 12.4 volts and discharged at anything less.
Types Of Car Batteries
There are basically two main types of car batteries; starting and deep cycle. These types of batteries can be further broken down into three sub-categories; wet cell, gel cell, and absorbed glass mat (AGM).
Gel cell batteries use a gelified electrolyte substance that allows for mounting in any position.
A starting battery is capable of delivering quick bursts of high energy. A deep cycle battery on the other hand, has greater long-term power delivery, but less instant surge energy. Generally deep cycle batteries are best used in marine applications or for electric vehicles like golf carts, which need a constant supply of low power over a longer period of time. Deep cycle batteries can also be good for people with competition speaker systems in their car who plan on running the speakers for long periods while their engine is off. There are also dual-purpose batteries, but these don't excel in either area and it is best to avoid them if possible.
Nearly every factory-installed battery is a sealed, maintenance-free battery, but wet cell batteries are available in unsealed models as well. Sealed batteries are known as maintenance-free while unsealed batteries are considered serviceable. They are serviceable because they allow, and often need, the addition of water, as some will evaporate over time. They also allow for one to check the specific gravity of the electrolytes, which can help you determine the charge level.
Gel cell and AGM batteries cost more than wet cell, but they hold their charge better through long periods of inactivity. Gel cell batteries use a gelified electrolyte substance that allows for mounting in any position. They are also more resistant to physical shock, hot temperatures, and electrolyte evaporation. AGM batteries have similar characteristics to gel cell batteries, but use glass mats made into very thin fibers that are meshed together to store power instead of a gel substance.
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