The word “battery” comes from the Old French word baterie, meaning “action of beating,” relating to a group of cannons in battle. In the endeavour to find an energy storage device, scientists in the 1700s adopted the term “battery” to represent multiple electrochemical cells connected together. The battery consists of two electrodes that are isolated by a separator and soaked in electrolyte to promote the movement of ions. New active materials are being tried, each offering unique attributes but none delivering an ultimate solution.
A car battery supplies power to the starter and ignition system to start the engine. They also supply the extra power necessary when the vehicle's electrical load exceeds the supply from the charging system. A car battery acts as a voltage stabilizer in the electrical system. The battery evens out voltage spikes and prevents them from damaging other components in the electrical system.
The commercial use of the lead acid battery is over 100 years old. The same chemical principal is being used to create energy that our Great, Great, Grandparents may have used.
If you can grasp the basics you will have fewer battery problems and will gain greater battery performance, reliability, and longevity. I suggest you read the entire tutorial, however I have indexed all the information for a quick read and easy reference.
Present day chassis battery power requirements are huge. Look at today’s vehicle and all the electrical devices that must be supplied. Electronics require a source of reliable power. Poor battery condition can cause expensive electronic component failure. Did you know that the average vehicle has 11 pounds of wire in the electrical system? Look at RVs and boats with all the electrical gadgets that require power. I can remember when a trailer or motor home had a single 12-volt house battery. Today it is standard to have 2 or more house batteries powering inverters up to 4000 watts.
Average battery life has become shorter as energy requirements have increased. Life span depends on usage; 6 months to 48 months, yet only 30% of all batteries actually reach the 48-month mark. A Few BasicsThe Lead Acid battery is made up of plates, lead, and lead oxide (various other elements are used to change density, hardness, porosity, etc., like Calcium/Calcium plates) with a 35% sulfuric acid and 65% water solution. This solution is called electrolyte which causes a chemical reaction that produces electrons. When you test a battery with a hydrometer you are measuring the amount of sulfuric acid in the electrolyte. If your reading is low, that means the chemistry that makes electrons is lacking. So where did the sulfur go? It is attached to the battery plates, and when you recharge the battery the sulfur returns to the electrolyte.These topics are covered below in more detail:
We must think safety when we are working around and with batteries. Remove all jewellery. After all you don't want to melt your watchstrap while you are wearing the watch. The hydrogen gas that batteries make when charging is very explosive. I have had 2 batteries blow up and drench me in sulfuric acid. That is no fun. This is a good time to use those safety goggles that are hanging on the wall. Sulfuric Acid eats up clothing and you may want to select Polyester clothing to wear, as it is naturally acid resistant. I just wear older clothes, after all Polyester is so out of style. When doing electrical work on vehicles it is best to disconnect the ground cable from the battery. Just remember you are messing with corrosive acid, explosive gases and 100's amps of electrical current.
Basically there are two types of batteries; starting (cranking), and deep cycle (RV/marine/golf cart). The starting battery (SLI starting lights ignition) is designed to deliver quick bursts of energy (such as starting engines) and have a greater plate count. The plates will also be thinner and have somewhat different material composition. The deep cycle battery generally has less instant energy but greater long-term energy delivery. Deep cycle batteries have thicker plates and can survive a number of discharge cycles. Starting batteries should not be used for deep cycle applications. The so-called Dual Purpose Battery is only a compromise between the 2 types of batteries, although this is changing as technology makes advances. (There are now newer technology batteries available in New Zealand, so shop around and ask questions)
Wet Cell (flooded), Gel Cell, and Absorbed Glass Mat (AGM) are various versions of the lead acid battery. The wet cell comes in 2 styles; serviceable, and maintenance free. Both are filled with electrolyte and for deep cycle use, I prefer one that I can add water to and check the specific gravity of the electrolyte with a hydrometer. The Gel Cell and the AGMbatteries are specialty batteries that typically cost twice as much as a premium wet cell. However they store very well and do not tend to sulfate or degrade as easily as wet cell. There is little chance of a hydrogen gas explosion or corrosion when using these batteries; these are the safest lead acid batteries you can use. Gel Cell and some AGM batteries may require a special charging rate. I personally feel that careful consideration should be given to the AGM battery technology for applications such as Marine, RV, Solar, Audio, Power Sports and Stand-By Power just to name a few. If you don't use or operate your equipment daily; this can lead to premature battery failure; or if you depend on top-notch battery performance, then spend the extra money. Gel Cell batteries are still being sold, but AGM batteries are replacing them in most applications where they have been used in the past. There is some confusion about AGM batteries because different manufacturers call them different names; some of the popular ones are sealed regulated valve, dry cell, non-spillable, and sealed lead acid batteries. In most cases AGM batteries will give greater life span and greater cycle life than a wet cell battery, although with modern technological advances, this is becoming less so, so consider both when making your decision.
Special Note About Gel Batteries: It is very common for individuals to use the term GEL CELL when referring to sealed, maintenance-free batteries, much like one would use Kleenex when referring to facial tissue or "Xerox machine" when referring to a copy machine. Be very careful when specifying a battery charger, many times we are told by customers they are requiring a charger for a Gel Cell battery when in fact the battery is not a Gel Cell.
AGM: The Absorbed Glass Matt construction allows the electrolyte to be suspended in close proximity with the plate’s active material. In theory, this enhances both the discharge and recharge efficiency. Actually, AGM batteries are a variant of Sealed VRLA batteries. Popular usage; high performance engine starting, power sports, deep cycle, solar and storage battery. AGM batteries are typically good deep cycle batteries and they will deliver their best life performance if recharged before the battery drops below the 50 percent discharge rate. If these AGM batteries are discharged to a rate of 100 percent the cycle life will be 300 plus cycles and this is true of most AGM batteries which are rated as deep cycle batteries.
GEL: The gel cell is similar to the AGM style because the electrolyte is suspended, but different because technically the AGM battery is still considered to be a wet cell. The electrolyte in a GEL cell has a silica additive that causes it to set up or stiffen. The recharge voltages on this type of cell are lower than the other styles of lead acid battery. This is probably the most sensitive cell in terms of adverse reactions to over-voltage charging. Gel Batteries are best used in VERY DEEP cycle application and may last a bit longer in hot weather applications. If the incorrect battery charger is used on a Gel Cell battery poor performance and premature failure is certain.