Battery Basics: A Layman's Guide to Batteries
If you have done any research on how batteries work or what you should look for when selecting the best high performance battery, you're probably buried in information, some of which is conflicting. At BatteryStuff, we aim to clear that up a bit.
You've most likely heard the term KISS (Keep It Simple, Stupid). I'm going to attempt to explain how lead acid batteries work and what they need, without burying you with a bunch of needless technical data. I have found that battery data will vary somewhat from manufacturer to manufacturer, so I will do my best to boil that data down. This means I may generalize a bit, while staying true to purpose.
The lead acid battery has been used commercially for over 100 years. The same chemical principle that's being used to store energy is basically the same as our great grandparents used.
A battery is like a piggy bank. If you keep taking out and putting nothing back, you'll have nothing left. Present day vehicle or powersport vehicle battery power requirements are huge considering all the stock electrical devices that must be supplied with power. All these electronics require a reliable source power, and poor battery condition can cause expensive electronic component failure. Did you know that the average auto has 11 pounds of wire in the electrical system? Look at RVs and boats with all the electrical gadgets that require power. It wasn't long ago when trailers or motor homes had only a single 12-volt house battery. Today recreation vehicles use their rv batteries to power inverters up to 4000 watts.
Average battery life has become shorter as energy requirements have increased. Life span depends on usage and depth of discharge—usually 6 to 48 months—yet only 30% of all batteries actually reach the 48-month mark. If your unable to maintain the battery with an battery charger you can extend your battery life by hooking it up to a solar charger during the off months.
If you can grasp the basics, you'll have fewer battery problems and will gain greater battery performance, reliability and longevity. I suggest you read the entire tutorial; however, I've indexed all the information for easy reference.
A Few Basics
The lead acid battery is made up of plates, lead, and lead oxide (various other elements are used to change density, hardness, porosity, etc.), 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's resting on the battery plates so that when you recharge the battery, the sulfur returns to the electrolyte.
- Battery types, Deep Cycle and Starting
- Wet Cell, Gel-Cell and Absorbed Glass Mat (AGM)
- CCA, CA, AH and RC; what's that all about?
- Battery Maintenance
- Battery Testing
- Selecting and Buying a New Battery
- Battery Life and Performance
- Battery Charging
- Battery Do's
- Battery Don'ts
1. You must think safety when you're working around, and with, batteries. Remove all jewelry. (After all, you wouldn't want to melt your watchband while you're wearing it!) The hydrogen gas that batteries make when charging is very explosive. We have seen several instances of batteries blowing up and drenching everything in sulfuric acid. That was no fun, and would have been a good time to use those safety goggles hanging on the wall. Heck, you could even break out your disco outfit. Polyester isn't affected by sulfuric acid, but anything with cotton will be eaten up. If you don't feel the need to make a fashion statement, just wear junk clothes—after all, polyester is still out of style.
When doing electrical work on vehicles, it's best to disconnect the ground cable. Just remember that you're messing with corrosive acid, explosive gases and hundreds of amps of electrical current.
2. Basically, there are two types of lead acid batteries (along with three sub categories). The two main types are starting (cranking), and deep cycle (marine/golf cart). The starting battery (SLI starting lights ignition) is designed to deliver quick bursts of energy (such as starting engines) and therefore has a greater plate count. The plates are thinner and have somewhat different material composition.
What is a deep cycle battery? The deep cycle battery has less instant energy, but greater long-term energy delivery. Deep cycle batteries have thicker plates and can survive a lot of discharge cycles. Starting batteries should not be used for deep cycle applications because the thinner plates are more prone to warping and pitting when discharged. The so-called Dual Purpose Battery is a compromise between the two types of batteries, though it is better to be more specific if possible.
3. Wet cell (flooded), gel cell, and absorbed glass mat (AGM) are various versions of the lead acid battery. The wet cell comes in two styles; serviceable and maintenance free. Both are filled with electrolyte and are basically the same. 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 AGM batteries are specialty batteries that typically cost twice as much as a premium wet cell battery. However, they store very well and do not tend to sulfate or degrade as easily as wet cell. Although not impossible there is little chance of a hydrogen gas explosion or corrosion when using these batteries; they are the safest lead acid batteries you can use. Gel cell and some AGM batteries may require a special charging rate. If you want the best and most versatile battery, then consideration should be given to the AGM battery type. AGM batteries are great 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, AGM batteries will hold their charge better than other types. If you must depend on top-notch battery performance, spend the extra money. Gel Cell batteries still are being sold, but AGM batteries are replacing them in most applications.
There is common confusion regarding AGM batteries because different manufactures call them by different names. Some of the more common names are "sealed regulated valve," "dry cell," "non-spillable," and "valve-regulated lead acid" batteries. In most cases, AGM batteries will give greater life span and greater cycle life than a wet cell battery.
SPECIAL NOTE: It's common for individuals to use the term "gel cell" as a generic term when referring to sealed, maintenance-free batteries, much like one would use Kleenex when referring to facial tissue. As a result, we get lots of requests for a gel replacement battery or gel battery charger when in fact the battery is an AGM. For this reason, we always recommend verifying the battery type when purchasing a replacement or looking for a charger to maintain the battery.
AGM: The Absorbed Glass Mat construction allows the liquid electrolyte to be suspended in a fiberglass matting. This matting surrounds the plate’s active material and in theory this enhances both the discharge and recharge efficiency. AGMs are commonly manufactured for applications that include high-performance engine starting, power sports equipment, deep cycle, solar and storage battery. The larger Deep Cycle AGM Batteries we sell typically offer great cycle life if recharged before they drop below the 50% discharge rate. When deep cycle AGM batteries are discharged to a rate of no less than 60%, the cycle life will generally increase by 300 plus cycles.
The Scorpion motorcycle batteries we carry are a meet or exceed the specification for the OEM battery. We also carry the Motocross branded batteries for those that have brand loyalty to the OEM battery as they are Yuasa’s aftermarket battery.
GEL: The gel cell battery is like the AGM battery in the fact that it is considered non-spillable, but the electrolyte is not a wet liquid. The electrolyte in a gel cell has a silica additive that causes it to set up or stiffen. In most cases the recharge voltage on gel battery is typically lower than a standard flooded wet cell battery or AGM battery, apart from those made by MK Battery where their 12-volt batteries can accept up to 14.6 volts. Most gel batteries can only be charged as high as 14.2 volts per 12-volt battery and are probably the most sensitive battery 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 or application where the battery gets excessively discharged. If the incorrect battery charger is used on a gel cell battery, poor performance and premature failure is certain.
4. CCA, CA, AH and RC. These are the standards that most battery companies use to rate the output and capacity of a battery.
CCA: Cold cranking amps is a measurement of the number of amps a battery can deliver at 0°F for 30 seconds and not drop below 7.2 volts. So a high CCA battery rating is especially important in starting battery applications, and in cold weather. This measurement is not particularly important in deep cycle batteries, though it is the most commonly "known" battery measurement.
CA: Cranking Amps are measured at 32°F. This rating is also called marine cranking amps (MCA). Hot cranking amps (HCA) is seldom used any longer but is measured at 80°F.
RC: Reserve Capacity is a very important battery rating. This is the number of minutes a fully charged battery at 80°F will discharge under a 25 amp load until the battery drops below 10.5 volts.
AH: An Amp/Hour is a rating usually found on deep cycle batteries and is a capacity rating. The standard rating is a based on how many amps you can pull out of the battery over a 20-hour period. For a 100 AH rated battery this means you can draw from the battery for 20 hours, and it will provide a total of 100-amp hours. That translates to about 5 amps an hour (5 x 20 = 100). However, it's very important to know that the total time of discharge and load applied is not a linear relationship. As your load increases, your realized capacity decreases. This means if you discharged that same 100 AH battery by a 100-amp load, it would not give you one hour of runtime. On the contrary, the perceived capacity of the battery will be that of 64-amp hours.
5. Battery Maintenance: A properly maintained battery is important for the ultimate in service life. Consider these points on a regular basis:
- The battery should be cleaned using a baking soda and water solution; a couple of tablespoons to a pint of water.
- Cable connections need to be cleaned and tightened as battery problems are often caused by dirty and loose connections.
- A serviceable battery needs to have the fluid level checked. Use only mineral-free water; distilled is best as all impurities have been removed and there is nothing left that could contaminate your cells.
- Don't overfill battery cells, especially in warmer weather because the natural fluid expansion in hot weather can push excess electrolytes from the battery.
- To prevent corrosion of cables on top-post batteries, use a small bead of silicone sealer at the base of the post and place a felt battery washer over it. Coat the washer with high temperature grease or petroleum jelly (Vaseline), then place cable on the post and tighten. Coat the exposed cable end with the grease. The gases from the battery condensing on metal parts causes most corrosion.
6. Battery Testing: This can be done in more than one way. The most accurate method is measurement of specific gravity and battery voltage. To measure specific gravity, buy a temperature-compensating hydrometer. To measure voltage, use a digital D.C. Voltmeter. A quality load tester may be a good purchase if you need to test sealed batteries.
For any of these methods, you must first fully charge the battery and then remove the surface charge. We recommend letting the battery sit for several hours to remove the surface charge (I prefer at least 12 hours). Letting the battery sit gives you the most accurate result on how the battery will normally act. However, if you need to remove the surface charge faster it is possible to discharge the battery for several minutes. For deep cycle batteries you could simply power the device that uses the battery for several minutes. For starting batteries simply powering the headlight using the high beam can work as well. Once the surface charge has been removed you can begin testing.
|State of Charge||Specific Gravity||Voltage|
Load testing is yet another way of testing a battery. A load tester removes amps from a battery much like starting an engine would. Some battery companies label their battery with the amp load for testing. This number is usually half of the CCA rating. For instance, a 500 CCA battery would load test at 250 amps for 15 seconds. However, most load testers will either allow you to input the CCA or in the case of an analog tester it will show you a graph the battery should test at.
A load test should only be performed when the battery is at near or full charge. If you don't own or want to buy a load tester, then simply charge the battery, wait 12 hours, and then take it to an automotive shop for testing. Avoid taking a discharged battery to an automotive shop for testing as the test will only indicate something you already know.
The results of your testing should be as follows:
- Hydrometer readings should not vary more than .05 differences between cells.
- Digital volt meters should read as the voltage as shown in this document. The sealed AGM and gel cell battery voltage (fully charged) will be slightly higher in the 12.8 to 12.9 range. If you have voltage readings in the 10.5 volt range on a charged battery, that typically indicates a shorted cell.
- If you have a maintenance-free wet cell, the only ways to test are volt meter and load test. Any of the maintenance-free batteries that have a built in hydrometer (black/green window) will tell you the condition of 1 cell of 6. You may get a good reading from 1 cell but have a problem with other cells in the battery.
- When in doubt about battery testing, call the battery manufacturer. Many batteries sold today have a toll-free number to call for help.
7. Selecting a Battery: When buying a new battery, I suggest you purchase a battery with the greatest reserve capacity or AH rating as possible. Of course, the physical size and terminal type must be a consideration. You may want to consider a gel cell or an absorbed glass mat (AGM) rather than a wet cell if the application is in a harsher environment, or the battery is not going to receive regular maintenance and charging. AGM and Gel cell batteries typically have a lower self-discharge rate so they can last longer when not being maintained.
Be sure to purchase the correct type of battery for the job it must do. Remember that engine starting batteries and deep cycle batteries are different. Freshness of a new battery is very important. The longer a battery sits the more damaging sulfation build up there may be on the plates. Most batteries have a date of manufacture code on them. While the date code isn’t always apparent many manufacturers or dealers will indicate the month with a letter, such as the letter with "A" being January. The letter is then followed by a number such as “4” corresponding with the year 2021. C4 would tell us the battery was manufactured in March 2021. Remember the fresher the better. The letter "I" is not used because it can be confused with the number 1.
Battery Warranties are figured in the favor of battery manufacturers. Let's say you buy a 60-month warranty battery, and it lives 41 months. The warranty is pro-rated, so when taking the months used against the full retail price of the battery you end up paying about the same money as if you purchased the battery at the sale price. This makes the manufacturer happy. What makes me happy is to exceed the warranty. Let me assure you it can be done.
8. Battery Life and Performance: Average battery life has become shorter as energy requirements have increased. Two phrases I hear most often are "my battery won't take a charge," and "my battery won't hold a charge." Only 30% of batteries sold today reach the 48-month mark. In fact 80% of all battery failure is related to sulfation build-up. This build-up occurs when the sulfur molecules in the electrolyte (battery acid) become so deeply discharged that they begin to coat the battery's lead plates. Before long the plates become so coated that the battery dies. The causes of sulfation are numerous:
- Batteries sit too long between charges. There are two states when it comes to batteries: They are either being charged or they are self-discharging.
- Battery is stored without some type of energy input. Even if you disconnect the battery it will still self-discharge.
- "Deep cycling" an engine-starting battery. Remember these batteries can't stand deep discharge.
- Not completing the charge cycle. Undercharging a battery will allow the sulfation buildup that occurred during discharge to harden. When this happens, it reduces the area on the lead plates for the chemical reaction to occur thereby reduces the capacity of the battery.
- Heat of over 100°F increases internal discharge. As temperatures increase so does internal discharge. A new fully charged battery left sitting 24 hours a day at 110°F for 30 days would most likely not start an engine.
- Low electrolyte level. Battery plates exposed to air will immediately sulfate.
- Incorrect charging levels and settings. Most cheap battery chargers can do more harm than good. See the section on battery charging.
- Cold weather is also hard on the battery. The chemistry does not make the same amount of energy as a warm battery. Also a deeply discharged battery can freeze solid in sub zero weather. We recommend gel batteries by MK Battery for subzero weather as some of their batteries are rated down to -76°F.
- Parasitic drain is a load put on a battery with the key off. Depending on the parasitic load we have seen batteries discharged in a few days to a few months. We recommend testing your parasitic load so you know what to expect.
There are ways to greatly increase battery life and performance. All the products we sell are targeted to improve performance and battery life.
An example: Let's say you have "toys" such as an ATV, classic car, antique car, boat, Harley, etc. You most likely don't use these toys 365 days a year as you do your car. Many of these toys are seasonal, so they are stored. What happens to the batteries? Most batteries that supply energy to power our toys only last 2 seasons. You must keep these batteries from sulfating or buy new ones. We sell products to prevent and reverse sulfar buildup on batteries. The BatteryMINDer products are patented electronic devices that reverse and prevent sulfation. Also Battery Equaliser, a chemical battery additive, has proven itself very effective in improving battery life and performance. Other devices such as solar trickle chargers are a great option for battery maintenance.
Parasitic drain: Most vehicles have clocks, engine management computers, alarm systems, etc. In the case of a boat, you may have an automatic bilge pump, radio, GPS, etc. These devices may all be operating without the engine running. You may have parasitic loads caused by a short in the electrical system. If you are always having dead battery problems, most likely the parasitic drain is excessive. The constant low or dead battery caused by excessive parasitic energy drain will dramatically shorten battery life. If this is a problem you are having, check out PriorityStart! battery switches to prevent dead batteries before they happen. This special computer switch will turn off your engine start battery before all the starting energy is drained. This technology will prevent you from deep cycling your starting battery.
Remember, for proper battery maintenance you must put back the energy you use immediately. If you don't, the battery sulfates, which will affect performance and longevity. The alternator is a battery charger. It works well if the battery is not deeply discharged. The alternator tends to overcharge batteries that are very low and the overcharge can damage batteries. In fact, an engine-starting battery on average has only about 10 deep cycles available when recharged by an alternator. Batteries like to be charged in a certain way, especially when they have been deeply discharged. This type of charging is called 3-step regulated charging. Please note that only special smart battery chargers using computer technology can perform 3-step charging techniques. You don't find these types of chargers in parts stores or big box stores.
- The first step is bulk charging, where up to 80% of the battery energy capacity is replaced by the charger at the maximum voltage and current amp rating of the charger.
- When the battery voltage reaches 14.4 volts this begins the absorption charge step. This is where the voltage is held at a constant 14.4 volts and the current (amps) declines until the battery is 98% charged.
- Next comes the Float Step. This is a regulated voltage of not more than 13.4 volts and usually less than 1 amp of current. This in time will bring the battery to 100% charged or close to it. The float charge will not boil or heat batteries, but it will maintain the batteries at 100% readiness and prevent cycling during long term inactivity. Note: Some gel cell and AGM batteries may require special settings or chargers.
10. Battery Dos
- Think Safety First.
- Do read entire tutorial.
- Do regular inspection and maintenance, especially in hot weather.
- Do recharge batteries immediately after discharge.
- Do buy the highest RC reserve capacity or AH amp hour battery that will fit your configuration.
11. Battery Don'ts
- Don't forget safety first.
- Don't add new electrolyte (acid).
- Don't use unregulated, high-output battery chargers to charge batteries.
- Don't place your equipment and toys into storage without some type of device to keep the battery charged.
- Don't disconnect battery cables while the engine is running (your battery acts as a filter).
- Don't put off recharging batteries.
- Don't add tap water as it may contain minerals that will contaminate the electrolyte.
- Don't discharge a battery any deeper than you possibly have to.
- Don't let a battery get hot to the touch and boil violently when charging.
- Don't mix size and types of batteries.
While that was a detailed look at battery types and how to maintain them, there's always more to learn. Check out this additional battery tutorial, and find out more battery basics.