VIEWS: 814 PAGES: 6 POSTED ON: 10/23/2010
Battery Electrochemistry 1. A battery is an electrochemical device, using chemical reactions between two different substances to create electric current. Basic battery design calls for two electrodes: an anode (negative terminal) and a cathode (positive terminal). These are never allowed to have direct contact, since that would create a short circuit. They are instead connected indirectly by an electrolyte. Using the electrolyte as a bridge, the anode and cathode react so that positively charged electrons travel to the cathode and negatively charged electrons travel to the anode. Left alone, this operates as a circuit for electric current. When a device is connected to the battery, it forms a larger circuit, with power flowing out of the cathode and then back into the anode, minus much of the charge. How Lead-Acid Batteries Work 2. In a lead-acid battery, the anode and cathode are made of lead and lead dioxide respectively. The electrolyte is a solution made with one-third sulfuric acid. As power is discharged from the battery, both the anode and cathode undergo a chemical reaction that progressively changes them into lead sulfate. Recharging 3. When electric current is applied to a lead-acid battery, the electrochemical reaction is reversed. When current flows into the battery through the anode, it causes the conversion of the anode and cathode into lead sulfate to partially reverse. This partial reversal to their original states "recharges" them. Practical Function 4. Lead-acid batteries are a 19th century invention. While they have seen much improvement, they are still relatively primitive. They have extremely poor overall power-to-weight ratio and stamina issues. However, what they can do is deliver a big, sudden charge of electricity. This potential to put out a big jolt of power makes them ideal for use as car batteries, where there is a need for a big, short charge to power the engine's starter. VRLA Batteries 1. A gel battery is classified as a VRLA, valve regulated lead-acid battery, which is a category of low maintenance lead-acid battery. These types of batteries are pre-sealed; the owner does not need to maintain them by checking their water levels. A gel battery contains far less acid than a traditional battery. In fact, they are filled with a gel substance, referred to as a gel electrolyte, that replaces what some of us know as battery acid. Gel Batteries 2. The gel electrolyte is sulfuric acid combined with silica. The gel is immobile, like gelatin. Traditional batteries, however, are liquid or wet-cell batteries. A gel battery is referred to as a sealed battery, but this isn't completely true. A truly sealed gel battery would create gas build up, and dangerous levels of pressure. Gel batteries regulate their gas build up through openings in the seal. Gel Electrolyte 3. Battery electrolyte is generally a solution of 35 percent sulfuric acid and 65 percent water. The solution produces electrons through a chemical reaction, which creates the "juice" that makes a battery work. Adding fumed silica to the sulfuric acid adds a thickening effect to the electrolyte, and suspends the acid. Fumed silica is quartz sand that has been cooked in a 3000 degree electric arc. By thickening the electrolyte, the battery does not require the monitoring that traditional batteries require. The electrolyte gel does not need to be replenished, because it does not evaporate. Relieving Gel Battery Pressure 4. Gel batteries contain a valve regulating system. This system allows gas to be released or expelled when needed. Along with the gas being expelled, the gel substance contains calcium, instead of the antimony that is found in traditional batteries. The calcium keeps the gel from gassing in the same way a traditional battery might. Charging A Gel Battery 5. Overcharging a gel battery will dry out the gel electrolyte, causing holes in the gel that don't fill back up (heal). Undercharging can be just as harmful. If undercharging becomes a habit, the positive plate of the battery will form a layer of sulfate. Over time, the sulfate build-up prevents the ability to recharge the battery. Over- or undercharging can be prevented by using a temperature-compensated and voltage-regulated charger. Constant current chargers are not to be used on a gel battery. Advantages Of Gel Batteries 6. Gel batteries have a few strong advantages that keep them on the market. They don't typically leak, or produce spills or corrosion. Even if they are cut open, the gel does not flow out of the battery. The batteries are not known to evaporate, which is a constant issue with traditional wet batteries. They have a better resistance to extreme temperature changes, and are more vibration-resistant and shock-resistant than other types of batteries. How to Charge Gel Cell Batteries Gel cell batteries are often used in wheelchairs, motorcycles and radio communications. They are known to hold up in extreme heat and cold. The batteries never spill, so they are often called dry cell batteries, non-spillable batteries and maintenance free batteries. The batteries are considered deep cycle batteries because they contain a suspended electrolyte between the lead battery plates. You will need a gel cell battery charger to recharge a gel cell battery. One of the best charging methods is constant voltage charging, which you can accomplish in two different ways. Things You'll Need: Gel cell battery charger Fast Charging (Cyclic Charging) 1. Step 1 Insert your battery into the gel cell battery charger. Follow the manufacturer's instructions for correct insertion. 2. Step 2 Turn the charger on, and charge your battery until the terminal voltage reaches 2.40 to 2.45 volts per cell (14.4 to 14.7 volts on a 12-volt battery) at 20 degrees Celsius (58 degrees Fahrenheit). 3. Step 3 Leave the battery on this voltage until the charge current lowers to 0.01 x C amps (considering C to be the battery's amp-hour rating). 4. Step 4 Stop the battery charger in the cyclic charging mode, or change over to the float charging mode. Float Charging (Standby Service) 5. Step 1 Put your battery in the gel cell battery charger by following the manufacturer's instructions for use of the charger. 6. Step 2 Turn the charger on, and charge your battery at a continuous voltage of 2.25 to 2.30 volts per cell (13.5 to 13.8 volts on a 12-volt battery at 20 degrees Celsius (58 degrees Fahrenheit). The battery should regulate its own level of current at this voltage. 7. Step 3 Stop charging your battery when it is completely charged. Remove it from the battery charger. Tips & Warnings Avoid under-charging or over-charging your battery. Don't use an automobile battery charger on your battery because the charger may not be properly voltage-regulated for gel cell batteries. Don't charge your battery near flames or sparks. Continually charging your gel cell battery in the fast charge mode can overheat the battery and cause damage to it. How to Recondition a Car Battery at Home If your car's battery isn't holding a charge or otherwise is not up to par, you may be able to fix it yourself. The most common cause of degraded battery performance in lead acid batteries is sulfation. Sulfation occurs when sulfur collects on the lead plates in the battery, blocking the electric current. It's not hard to recondition a car battery at home. You need Epsom salts, distilled water and a few tools. Sulfation does cause irreversible corrosion of the lead plates so this process will only work three to five times, but it can still be a great money saver. Things You'll Need: Epsom salts (magnesium sulfate) Distilled water Plastic funnel Safety goggles Rubber gloves Voltmeter Battery charger For sealed batteries: Drill Plastic plugs 1. Step 1 Put safety first. Car batteries contain sulfuric acid, which is among the most powerful of acid compounds. Work only in a well-ventilated area and don't have open flames nearby. Wear safety goggles and rubber gloves. If you do get acid on your skin, irrigate it with plenty of water immediately. 2. Step 2 Test the battery to see if it is likely to respond to reconditioning. In order to recondition a car battery at home, it needs to register 12 volts on a voltmeter. If it's between 10 and 12 volts, you may be able to restore the battery to full function, but if it tests at less than 10 volts, you're probably wasting your time. 3. Step 3 Measure out 250 grams (about 7 to 8 ounces) of Epsom salts (magnesium sulfate). Heat 500 ml of distilled water (1/2 quart) to 65-degrees Celsius (150-degrees Fahrenheit). Dissolve the Epsom salts in the water. Avoid using tap water because it contains chemicals that will damage a battery. 4. Step 4 Remove the battery cell caps. If you have a sealed battery, find the "shadow plugs" that cover openings to the battery cells. You'll need to drill through these. Drain any fluid out of the battery and then use a plastic funnel to pour enough of the Epsom salt solution in to fill each cell of the battery properly. Insert plastic plugs in the drill holes or replace the battery caps and then shake the battery to make sure the Epsom salt solution is well distributed. 5. Step 5 Recharge the battery on a slow charge for 24 hours and then re-install it in your car. It should function properly. However, it's wise to put it on the battery charger each night for 3 to 4 days to restore it fully to the maximum possible capacity. How to Recondition Automotive Lead/acid Battery As your battery age, it may need to get reconditioned. Reconditioning restores a battery like if its new. So let's get started, just follow the steps below to begin. Instructions 1. Step 1 Items needed to recondition a battery include safety glasses, plastic funnel, battery hydrometer, battery post cleaner, a screwdriver, a volt meter, battery load tester, and battery reconditioning chemicals. 2. Step 2 First, let's clean the battery posts. Use the battery post cleaner to clean out both posts on each side. 3. Step 3 Check the voltage of the battery. Use your volt meter and connect the leads to the posts. Your battery should read at least 12 volts. If not at least 12 volts, you may want to check the cells in your battery. 4. Step 4 To test your cells, use a screwdriver to pry open the battery caps. Once the caps come off, use leads and hook them up to your volt meter. Do not use the leads on your volt meter because they can get ruin as acid is stored in the battery cells. Make some leads out of wire and hook it up to the leads on your volt meter. 5. Step 5 First start off by putting the positive lead on the positive post of the battery. Put the negative lead on the first cell of the battery. It should read two volts. Now put the positive lead into the first cell of the battery and the negative lead into the second cell of the battery. Continue this pattern until you have reached the last cells. If you get less then two volts, you may have a weak or bad cell. 6. Step 6 Now we are going to do a battery load test. Hook up the positive lead first on the battery. Then hook up the negative lead. The battery load tester should read at least 12 volts. Turn on the switch that's on the load tester. Hold the switch and count for about ten seconds. Then let go of the switch. The needle should read no less then at least 9-10 volts when a load was on the battery. Now remove the negative lead first this time then the positive. 7. Step 7 Now we are going to do a hydrometer test. Place the end of the hydrometer into the first cell. Squeeze the top of the hydrometer, then let go. The float inside the glass tube should begin to float. The fluid level should be in the green area. If fluid has passed the green area, then you need to charge the battery. If below the green area, your battery is in good condition and charging is not necessary. Do the same for each cell. 8. Step 8 Last thing left to do is add the chemicals to the battery. Get your plastic funnel. Put the funnel over the battery cell and pour a table spoon of chemicals into each cell of the battery. Put the battery to charge for about 24 hours. That's it, you are done. If you're like most of us, you know how much of an expense and inconvenience a dead battery can be. By the time you pay for a tow truck to come and boost or replace your battery, plus any lost earnings that you may have incurred, you can see that the costs quickly add up. And while being able to recondition a dead battery may not solve your immediate problems, it can definitely eliminate the expense of buying a new battery. Plus, if you're so inclined, you can turn it into a very profitable business. And the best part is that it's very easy and inexpensive. Automotive lead-acid batteries generate electricity by using lead plates surrounded by sulfuric acid. Along with electricity, this double sulfate reaction also produces lead sulfate. Normally in a healthy battery, the lead sulfate is converted back to lead and sulfuric acid when it is recharged. But in an older battery, or one that's been discharged for a long period of time, the lead sulfate changes to a crystalline form. It then coats the lead plates of the battery and reduces the capacity of the battery. This process is known as sulfation, and is a normal occurrence in lead-acid batteries. It's also one of the most common reasons that these batteries fail. When sulfation happens, it causes a host of problems within the battery. It's responsible for lowered capacity, longer recharge times, higher working temperatures, and increased corrosion. The good news is that sulfation can often times be reversed. A specialized battery charger that pulses a high current through the battery is often used. This allows the crystalline lead sulfate to be broken down and turned back into lead and sulfuric acid, thus cleaning the lead plates and regaining charge capacity. So before you throw that battery away, you should look into battery reconditioning as a way to save it. And if you're interested, you can also earn a substantial amount of money by reconditioning free dead batteries, and then reselling them. A very small investment for a very large return! The Battery Reconditioning Guide will show you everything you need to know about repairing and rejuvenating dead batteries. Whether they're lead-acid, nicad, or nimh batteries, they can most likely be repaired. Not only can you save money doing this, you can easily Make Money by reconditioning batteries for others. And the best part is that it's inexpensive to do. How to Promote Sulfation in a Lead Acid Battery Lead-acid batteries make use of a chemical reaction to provide electrical energy and produce a voltage differential between the positive and negative terminals on the battery. The chemical reaction produced by exposure of lead (the positively charged cell electrodes) and lead oxide (negatively charged cell electrodes) to a sulfuric acid electrolyte produces a voltage; but over time, it also produces lead sulfate crystals. These crystals build up on the electrodes, and reduce the battery voltage. To promote sulfation (the growth of lead sulfate crystals), the battery must be discharged slowly, and not recharged. Things You'll Need: Lead-acid battery, 12-volt 2 battery cables 12 Ω, 50W resistor Soldering iron and solder Slip-joint pliers Adjustable wrench 1. Step 1 Hold the negative (black) battery cable terminal connector retaining bolt with the slip-joint pliers, and loosen the retaining nut with the adjustable wrench. Loosen the positive (red) battery cable terminal connector retaining bolt with the slip-joint pliers, and loosen the retaining nut with the adjustable wrench. 2. Step 2 Attach the positive battery terminal connector to the positive battery post. Tighten the terminal connector retaining nut until the terminal connector is snug. Connect the other end of the positive battery cable to one of the resistor leads, and solder the connection. 3. Step 3 Connect the non-battery terminal end of the negative battery cable to the free resistor lead, and solder the connection. Connect the negative battery cable terminal connector to the battery post, and tighten the retaining nut so that the connector is snug. Discharging a lead-acid battery from 12 volt to 7.2 volt at a rate of 1 A per hour will take approximately seven hours for a battery rated at 860 CA. To determine amp-hour rating, use the following formula: [(CA value)/120] = Battery Amp-hours. To determine discharge time use the following formula: (Amp-hours)/(current draw in Amps) How to Charge Deep Cycle Batteries Deep cycle batteries are specifically designed to be able to transmit a constant and steady electrical charge. Deep cycle batteries are often found in low power vehicles, such as golf carts. Just as deep cycle batteries function differently from more common forms of batteries, the way that deep cycle batteries recharge is also unique. Knowing how to charge deep cycle batteries is important to know, especially for those who operate vehicles and other devices that utilize these batteries. Things You'll Need: Protective eye wear Fan Regulated, deep-cycle charger 1. Step 1 Understand the three stages of deep cycle charging. The first stage is called the "bulk charge." During this stage, deep cycle batteries are charged until they are approximately 90 percent charged. As more electricity is channeled to the battery, the battery enters the absorption stage in which the charging current slowly decreases. The final stage is called the "float stage." During this stage, the deep cycle charger maintains the battery's state by sending a very low level of electricity to the battery cells. 2. Step 2 Turn off the device or vehicle connected to the deep cycle battery. 3. Step 3 Disconnect the deep cycle battery. Remove the vent caps and check the battery's electrolyte levels (follow the instructions in the battery manual as testing methods may differ depending on the battery manufacturer). 4. Step 4 Replace the vent caps. 5. Step 5 Wear protective eye wear and move the battery to a well ventilated, open area. The recharge process can release fumes which, if concentrated in a small area, can be toxic. 6. Step 6 Connect the deep cycle battery to a deep cycle recharger. The recharger should be turned off prior to being connected to the battery. Follow the battery charger's instructions as different chargers work differently. The process may take up to 20 hours to recharge. How to Equalize Deep Cycle Batteries Deep cycle batteries should be equalized every month or so, along with their regular charging. Equalizing refers to a steady, controlled overcharge of the battery that causes the electrolyte inside to bubble and remove the lead sulfate that builds up on the plates. The buildup occurs gradually with each charge and reduces the battery's ability to store a full charge. Equalizing your deep cycle batteries will keep them operation longer. Things You'll Need: Battery charger/generator Voltmeter Clean distilled water Baking soda 1. Step 1 Make sure the battery is fully charged, testing it with a voltmeter or multimeter. A fully charged 12- volt battery reads at around 12.7 volts or greater. The charge current will slowly decrease after the battery reaches its bulk voltage. 2. Step 2 Set the charger's voltage to 7.8 volts for each cell the battery has (a cell containing 6 volts). In other words, set the voltage to15.6 volts if working with a 12-volt battery. Charge the battery at this level for at least 2 hours. 3. Step 3 Top off the battery's electrolyte during the second hour, using clean distilled water and a clean funnel in one of the fill holes under the caps. Make sure no debris gets into the battery while filling. 4. Step 4 Wipe away any mist on the battery tops after equalizing, using a disposable cloth. Keep the cloth away from any clothes or other objects that can be ruined by battery acid. Dispose of the cloth. 5. Step 5 Continue equalizing each day until you get a full equalization charge. An equalized 12-volt battery can give a temporary charge of up to 14.4 volts. Tips & Warnings Neutralize any spills on the ground or clothes with baking soda, but make sure no soda gets into the battery. It can take multiple attempts to obtain a proper equalization charge if the battery hasn't been equalized in some time or has been greatly discharged and left uncharged for a long time. Always wear goggles and rubber gloves when working on batteries.
Pages to are hidden for
"Battery Electrochemistry"Please download to view full document