Useful materials (9)
Installation of battery
GENERAL PRECAUTIONS
• Wear appropriate protective clothing and safety glasses.
• Before removing an old battery, make sure the engine, lights and all accessories are turned off.
• Check if vehicle has a computerized electrical system. If so, an alternative power source to maintain electronic memory when battery is disconnected may be required (to avoid damage to the main computer or other segments of the vehicle’s electronically controlled equipment).
• Check if vehicle has air bags fitted. If so, see following...
SAFETY PRECAUTIONS FOR VEHICLES FITTED WITH AN AIR BAG
• Always check to ensure that the ignition is off before removing either of the battery terminals.
• Don’t sit behind the steering wheel or in other seats with an air bag while any electrical service work is carried out on the vehicle.
• Removing or replacing battery terminals will not unintentionally trigger an air bag system, however removal of battery terminals with the ignition on can cause damage to electronic components, including the air bags - so don’t do it.
• If you need to work on the electrical system beyond replacing the battery, you must electrically disable the air bag system first.
• Never indiscriminately probe the electrical wiring / connectors in or near the steering column.
• Most air bag systems use bright yellow wiring and harness connectors - do not interfere with any harness of this colour.
REMOVAL OF OLD BATTERY
• Note location of positive (+) terminal and mark polarity on positive cable.
• Remove the negative or earth (-) terminal first to avoid damaging the wiring or battery by accidentally grounding tools.
• Remove positive (+) terminal.
• Undo the hold-down clamp and remove old battery, noting position of terminal posts.
NEW BATTERY INSTALLATION
• Inspect tray and area for corrosion and replace or repair as necessary.
• To clean tray, scrub the area with water and baking soda (sodium bicarbonate), then rinse with water.
• Dry and paint corroded steel parts with acid proof paint.
• Clean and brush terminalls.
• Check cable and starter motor connections tighten if necessary.
• Replace terminal clamps and / or cables if badly corroded.
• Sit the new battery in the tray ensuring it’s level and that the terminal posts are correctly positioned.
• Secure battery with hold-downs, tightened to ensure battery can’t move in the tray.
• Apply a thin coating of high temperature grease to the posts and cable connections.
• Replace cables ensuring that the earth (-) terminal is connected last.
• Tighten connections but don’t over tighten.
• Never hammer cable connections onto battery posts as this can damage your battery.
DISPOSE OF OLD BATTERY
Contact your nearest office of Imahiju Ltd for safe disposal and recycling of the old battery.
WHY IS BATTERY CHARGING NECESSARY?
It is not just important having a battery charger, but it is even more important to have the right battery charger. Most of us are not engineers or mechanics – but we still want to be able to fix and prevent battery problems in a simple way. The battery charger must be guaranteed to be free from problems and safe for all users and as regards the vehicle or machine, be simple to operate so that anyone can use it and be flexible enough to satisfy the many different needs.
In fact, why is it necessary to charge the batteries?
The answer is short, but very important:
• Lead acid batteries need maintaining charging, to ensure achievement of their expected life.
• It is a good investment. In the long term it is cheaper to buy a charger, than to replace the batteries.
• Vehicles are expected to be reliable and to start when needed. The answer is in regular charging.
• Good for the environment. Buying unnecessary batteries increases the use of lead, transport and waste collection.
• Modern vehicles with extensive electronics are discharging battery even when parked.
These instructions are designed to minimize the explosion hazard. Keep sparks, flames and cigarettes away from batteries at all times.
Both batteries should be of the same voltage (6, 12, etc.).
• When jump starting, always wear proper eye protection and never lean over the battery.
• Do not jump start a damaged battery; inspect both batteries before connecting booster cables.
• Be sure vent caps are tight and level.
• Be sure that the vehicles are not touching and that both ignition switches are in the “OFF” position.
• Turn off all electrical equipment (radio, defroster, windshield wipers, lights, etc.).
The following steps should be followed exactly!
1. Connect positive (+) booster cable to positive (+) terminal of discharged battery.
2. Connect other end of positive (+) cable to positive (+) terminal of assisting battery.
3. Connect negative (-) cable to negative (-) terminal of assisting battery.
4. MAKE FINAL CONNECTION OF NEGATIVE (-) CABLE TO ENGINE BLOCK OF STALLED VEHICLE, AWAY FROM BATTERY AND CARBURETOR.
5. Be sure that cables are clear of fan blades, belts and other moving parts of both engines.
6. Start vehicle and remove cables in REVERSE order of connections.
How to choose the right battery?
The car battery is the power underneath the hood of your car. It provides electricity needed to start the car, for door locks, power windows, lights, audio and other car accessories. You must discard the old battery properly:
• Sell it to Scrap Metal buyers ; and,
• Automotive battery supply stores, they will buy off your battery with certain price value according to market.
Five important factors in choosing a car battery:
• Size
• Capacity
• Cold-cranking amps
• Age
• Brand
Size
Size refers to the height, width and length of the battery. They come in different group sizes to fit most cars’ battery tray. It is important that the battery fit securely. Always refer to your car manufacturer's manual to know your car's specific battery group size. You may also consult the reference guides, which battery retailers provide, find out the appropriate battery size for your car. Buying a wrong-sized battery will just be a waste of money and might just set off more damage to your car.
Capacity
The longer the operating time of the battery' reserve capacity, the better; because this is the one quality of the battery that could save you from getting stranded. Consider the RC rating as your car's emergency kit. In times of unexpected trouble, you can still run to safety instead of getting stuck somewhere.
Cold-Cranking Amps
Cold-cranking amps (CCA) measure the battery's ability to start your car even on an extremely cold weather. Your car will be hard to start (or to ignite) because the car's engine oil thickens and chemical reactions, in turn, slow down.
Choosing a battery with a high number of CCA is better; particularly to those vehicles being driven in a cold climate. A higher cold- cramping amps assure that your car's engine will start obediently even on snowy mornings.
Age
The age of the battery gives you an idea on how long it should be able to perform. A battery is considered ‘fresh' if it is less than 6 months old.
Brand
Brand refers to the trademark given to a certain product. Buying the battery brand specified in your owner's manual is the best way. But if that particular brand is too expensive and you want to do some cost-cutting, follow the specification requirement also found in the owner's manual.
Problems and solutions
Problem: Acid flood from the lid
Possible Cause: Battery is overfull
Solution: Decrease the liquid level in the battery. Comply with the warning and instructions
Problem: Acid level is deficient
Possible Cause: There may be a leak from the covering box or gas outflow because of overcharging.
Solution: Check your charger or buy a new battery
Problem: Low acid density (<1.240 kg/dm3) and difficulty on starting
Possible Cause: Inadequate charging, a hardware draining the electricity, short circuit
Solution: Charge your battery again, get your cars charging system checked (regulator, alternator, electric system)
Problem: High acid density (>1.240 kg/dm3)
Possible Cause: Battery has been added acid instead of pure water
Solution: Acid level should be decreased and replaced with pure water (shall be repeated if needed)
Problem: Difficulty on march starting, low voltage
Possible Cause: Battery is discharged, dead (loss on positive plates), problem in one of the cells or sulphation
Solution: If it is discharged battery can be charged again otherwise a new battery should be purchased.
Problem: Excessive wear and tear on terminal and connections
Possible Cause: Faulty electric system or terminal connection
Solution: Tighten the connections or renew cleats if needed
Problem: Boiling in one or more cell during start
Possible Cause: Failure in cells or loosened, gapped polar connection
Solution: Tighten the connections or renew cleats if needed, purchase a battery if the problem continues
Problem: Easily and often discharged battery
Possible Cause: Charge level of the battery may be low, there may be a short circuit or sulphation (plates in the battery goes stiffen and turn to white)
Solution: Check the charging level of the battery or purchase a new battery
Problem: Short life time
Possible Cause: Wrong battery selection, too much exposure to deep discharge or leaving the battery for too long in deep discharge mode.
Solution: Replace the battery with a higher capacity one, if this is not possible check periodically and charge when needed.
Problem: Battery getting hotter than normal during operation and excessive water loss
Possible Cause: Your car might be charging on a high voltage
Solution: Get your cars electrical system, alternator checked
Problem: Explosion of the battery
Possible Cause: After charging gasses flared up because of static electric or short circuit causing explosion
Solution: Purchase a new battery
Problem: Battery not working
Possible Cause: Failure in the internal system of the battery or deep discharge
Solution: Purchase a new battery
Lead acid batteries - types and characteristics ...
Sealed Lead Acid
The first sealed, or maintenance-free, lead acid emerge in the mid-1970s. The engineers argued that the term “sealed lead acid” is a misnomer because no lead acid battery can be totally sealed. This is true and battery designers added a valve to control venting of gases during stressful charge and rapid discharge. Rather than submerging the plates in a liquid, the electrolyte is impregnated into a moistened separator, a design that resembles nickel- and lithium-bases system. This enables to operate the battery in any physical orientation without leakage.
The sealed battery contains less electrolyte than the flooded type, hence the term “acid-starved.” Perhaps the most significant advantage of the sealed lead acid is the ability to combine oxygen and hydrogen to create water and prevent water loss. The recombination occurs at a moderate pressure of 0.14 bar (2psi). The valve serves as safety vent if gases build-up during over-overcharge or stressful discharge. Repeated venting would lead to an eventual dry out.
Driven by these advantages, several types of sealed lead acid have emerged and the most common are gel, also known as valve-regulated lead acid (VRLA), and absorbent glass mat (AGM). The gel cell contains a silica type gel that suspends the electrolyte in a paste. Smaller packs with capacities of up to 30A are called SLA (sealed lead acid). Packaged in a plastic container, these batteries are used for small UPS, emergency lighting, ventilators for healthcare and wheelchairs. Because of economical price, dependable service and low maintenance, the SLA remains the preferred choice for biomedical and healthcare in hospitals and retirement homes. The VRLA is the larger gel variant used as power backup for cellular repeater towers, Internet hubs, banks, hospitals, airports and other sites.
The AGM is a newer design and suspends the electrolyte in a specially designed glass mat. This offers several advantages to lead acid systems, including faster charging and instant high load currents on demand. AGM works best as a mid-range battery with capacities of 30 to 100Ah and is less suited for large systems, such as UPS. Typical uses are starter batter for motorcycles, start-stop function for micro-hybrid cars, as well as marine and RV that need some cycling.
With cycling and age, the capacity of AGM fades gradually; gel, on the other hand, has a dome shaped performance curve and stays in the high performance range longer but then drops suddenly towards the end of life. AGM is more expensive than flooded, but is cheaper than gel.(Gel would be too expensive for start/stop use in cars.)
Unlike the flooded, the sealed lead acid battery is designed with a low over-voltage potential to prohibit the battery from reaching its gas-generating potential during charge. Excess charging causes gassing, venting and subsequent water depletion and dry out. Consequently, gel, and in part also AGM, cannot be charged to their full potential and the charge voltage limit must be set lower than that of a flooded. The float charge on full charge must also be lowered. In respect to charging, the gel and AGM are no direct replacements to the flooded type. If no designated charger is available with lower voltage settings, disconnect the charger after 24 hours of charge. This prevents gassing due to a float voltage that is set too high.
The optimum operating temperature for a VRLA battery is 25°C (77°F); every 8°C (15°F) rise above this temperature threshold cuts battery life in half. Lead acid batteries are rated at a 5-hour (0.2C) and 20-hour (0.05C) discharge. The battery performs best when discharged slowly and the capacity readings are notably higher at a slow discharge rate. Lead acid can, however, deliver high pulse currents of several C if done for only a few seconds. This makes the lead acid well suited as a starter battery, also known as starter-light-ignition (SLI). The high lead content and the sulphuric acid make lead acid environmentally unfriendly.
The following paragraphs look at the different architectures within the lead acid family and explain why one battery type does not fit all.
Starter and Deep-cycle Batteries
The starter battery is designed to crank an engine with a momentary high power burst; the deep-cycle battery, on the other hand, is built to provide continuous power for a wheelchair or golf car. From the outside, both batteries look alike; however, there are fundamental differences in design. While the starter battery is made for high peak power and does not like deep cycling, the deep-cycle battery has a moderate power output but permits cycling. Let’s examine the architectural difference between these batteries further.
Starter batteries have a CCA rating imprinted in amperes; CCA refers to cold cranking amps, which represents the amount of current a battery can deliver at cold temperature. SAE J537 specifies 30 seconds of discharge at –18°C (0°F) at the rated CCA ampere without dropping below 7.2 volts. (SAE stands for Society of Automotive Engineers.)
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Starter batteries have a very low internal resistance, and the manufacturer achieves this by adding extra plates for maximum surface area (Figure 1). The plates are thin and the lead is applied in a sponge-like form that has the appearance of fine foam. This method extends the surface area of the plates to achieve low resistance and maximum power. Plate thickness is less important here because the discharge is short and the battery is recharged while driving; the emphasis is on power rather than capacity. |
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Figure 1: Starter battery |
Figure 2: Deep-cycle battery |
Table 3: Cycle performance of starter and deep-cycle batteries. A discharge of 100% refers to a full discharge; 50% is half and 30% is a moderate discharge with 70% remaining.
A starter battery cannot be swapped with a deep-cycle battery and vice versa. While an inventive senior may be tempted to install a starter battery instead of the more expensive deep-cycle on his wheelchair to save money, the starter battery won’t last because the thin sponge-like plates would quickly dissolve with repeated deep cycling. There are combination starter/deep-cycle batteries available for trucks, buses, public safety and military vehicles, but these units are big and heavy. As a simple guideline, the heavier the battery is, the more lead it contains, and the longer it will last. Table 3 compares the typical life of starter and deep-cycle batteries when deep-cycled.
Advantages and limitations of common lead acid batteries in use today.
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Advantages: Inexpensive and simple to manufacture; low cost per watt-hour |
Limitations: Low specific energy; poor weight-to-energy ratio
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A battery is a device for storing electrical energy in a chemical form, and then releasing it as direct current in a controlled way. All types of batteries contain a positive and a negative electrode immersed in an electrolyte, the whole assembly being within a container. All Electra are lead-acid batteries, which mean that they have positive and negative electrodes made of lead compounds in a dilute sulphuric acid electrolyte. Lead-acid batteries are secondary batteries, which mean that they can be recharged after they have been discharged. Primary batteries can be discharged only once and then have to be thrown away; examples are some types of torch and radio batteries.
What is a Battery Made of?
Grids
As the positive and negative electrodes are made of weak materials, they need a mechanical support which is provided by a grid made from a lead alloy; lead on its own would be too soft. In addition to providing a support for the electrodes (the active material), the grid also conducts electricity from the electrodes to the outside load.
Electrodes
The electrodes are initially made from a mixture of lead oxide and lead sulphate. This is converted into lead dioxide in the positive plate and porous lead in the negative plate when the battery is initially charged. The negative electrode also contains small amounts of additives to give the battery a good discharge performance at low temperatures to improve starting. The combination of grid and electrode is normally called a plate.
Electrolyte
The electrolyte is dilute sulphuric acid. This acts as a conductor to transport electrical ions between the positive and negative plates when the battery is being charged or discharged. The acid also takes part in the discharge as the sulphate ions react chemically at the electrodes to produce lead sulphate.
Separator
The separator is an insulator placed between the positive and negative plates to prevent them shorting together. The separator needs to be microporous with very small holes to allow the ions to flow through the separator from one plate to another. It also needs to be able to resist the high temperatures and strongly acidic oxidising conditions that occur in a battery. Most modern separators are made of microporous polyethylene, which has the right properties to meet the demanding conditions within the battery.
Container and Lid
These are normally made of polypropylene, which is a light but strong plastic. Unlike some plastics, it does not become brittle when it is cold, and so can resist knocks during handling. It is not attacked by acid and it can also withstand the fluids (petrol, diesel, brake-fluid, antifreeze) normally found on a vehicle.
How do Battery Work?
The positive electrode is made of lead dioxide and the negative electrode is made of porous lead. When an electrical load (for example lights or a starter-motor) is connected across the battery, a current flows through the electrolyte in the battery and through the external load. This causes the battery to discharge, which results in the chemical composition of both the electrodes changing to lead sulphate. A battery can be charged by putting a current through the battery from an outside source of electricity such as an alternator, dynamo or charging unit. This converts the lead sulphate back to the original materials of lead dioxide and porous lead. As the battery becomes charged, the electricity begins to decompose (hydrolyse) the water in the electrolyte into its constituent elements of hydrogen and oxygen, which are released as gas. This is why a battery gases when it is charged.
Charging of lead-acid batteries
Lead acid charging uses a voltage-based algorithm that is similar to lithium-ion. The charge time of a sealed lead acid battery is 12–16 hours, up to 36–48 hours for large stationary batteries. With higher charge currents and multi-stage charge methods, the charge time can be reduced to 10 hours or less; however, the topping charge may not be complete. Lead acid is sluggish and cannot be charged as quickly as other battery systems.
Lead acid batteries should be charged in three stages, which are [1] constant-current charge, [2] topping charge and [3] float charge. The constant-current chargeapplies the bulk of the charge and takes up roughly half of the required charge time; the topping charge continues at a lower charge current and provides saturation, and the float charge compensates for the loss caused by self-discharge. Figure 4-4 illustrates these three stages.
During the constant-current charge, the battery charges to 70 percent in 5–8 hours; the remaining 30 percent is filled with the slower topping charge that lasts another 7–10 hours. The topping charge is essential for the well-being of the battery and can be compared to a little rest after a good meal. If deprived, the battery will eventually lose the ability to accept a full charge and the performance will decrease due to sulfation. The float charge in the third stage maintains the battery at full charge.
The switch from Stage 1 to 2 occurs seamlessly and happens when the battery reaches the set voltage limit. The current begins to drop as the battery starts to saturate, and full charge is reached when the current decreases to the three percent level of the rated current. A battery with high leakage may never attain this low saturation current, and a plateau timer takes over to initialize the charge termination.
The correct setting of the charge voltage is critical and ranges from 2.30 to 2.45V per cell. Setting the voltage threshold is a compromise, and battery experts refer to this as “dancing on the head of a needle.” On one hand, the battery wants to be fully charged to get maximum capacity and avoid sulfation on the negative plate; on the other hand, an over-saturated condition causes grid corrosion on the positive plate and induces gassing.
To make “dancing on the head of a needle” more difficult, the battery voltage shifts with temperature. Warmer surroundings require slightly lower voltage thresholds and a cold ambient prefers a higher level. Chargers exposed to temperature fluctuations should include temperature sensors to adjust the charge voltage for optimum charge efficiency. If this is not possible, it is better to choose a lower voltage for safety reasons. Table 4-5 compares the advantages and limitations of various peak voltage settings.
Table 4-5: Effects of charge voltage on a small lead acid battery
Cylindrical lead acid cells have higher voltage settings than VRLA and starter batteries.
Once fully charged through saturation, the battery should not dwell at the topping voltage for more than 48 hours and must be reduced to the float voltage level. This is especially critical for sealed systems because these systems are less able to tolerate overcharge than the flooded type. Charging beyond what the battery can take turns the redundant energy into heat and the battery begins to gas. The recommended float voltage of most low-pressure lead acid batteries is 2.25 to 2.27V/cell. (Large stationary batteries float at 2.25V at 25°C (77°F.) Manufacturers recommend lowering the float charge at ambient temperatures above 29°C (85°F).
Not all chargers feature float charge. If your charger stays on topping charge and does not drop below 2.30V/cell, remove the charge after 48 hours of charge.
Aging batteries pose a challenge when setting the optimal float charge voltage because each cell has its own age-related condition. Weak cells may go into hydrogen evolution as part of overcharge early on, while the stronger ones undergo oxygen recombination in an almost starved state. Connected in a string, all cells receive the same charge current and controlling individual cell voltages is almost impossible. A float current that is too high for the faded cell might starve the strong neighbor and cause sulfation due to undercharge. Companies have developed cell-balancing devices, which are placed on the battery and compensate the differences in cell voltages that occur as a result of cell
Much has been said about pulse charging of lead acid batteries. There are apparent advantages in reducing sulfation; however, manufacturers and service technicians are divided on the benefits, and the results are inconclusive. If sulfation could be measured with accuracy and the pulses applied as a corrective service, then the remedy could be beneficial. Assumptions without knowing the underlying results can be harmful.
Lead acid batteries must always be stored in a charged state. A topping charge should be applied every six months to prevent the voltage from dropping below 2.10V/cell. With AGM, these requirements can be somewhat relaxed.
Measuring the open circuit voltage (OCV) while in storage provides a reliable indication as to the state-of-charge of the battery. A voltage of 2.10V at room temperature reveals a charge of about 90 percent. Such a battery is in good condition and needs only a brief full charge prior to use. If the voltage drops below 2.10V, the battery must be charged to prevent sulfation. Observe the storage temperature when measuring the open circuit voltage. A cool battery lowers the voltage slightly and a warm one increases it. Using OCV to estimate state-of-charge works best when the battery has rested for a few hours, because a charge or discharge agitates the battery and distorts the voltage.
Some buyers do not accept shipments of new batteries if the OCV at incoming inspection is below 2.10V per cell. A low voltage suggests partial charge due to long storage or a high self-discharge induced by a possible micro-short. Battery users have indeed found that a pack arriving at a lower than specified voltage has a higher failure rate than the others. Although in-house service can often bring such batteries to full performance, the time and equipment required adds to operational costs. (Please note that the 2.10V/cell acceptance threshold does not apply to all lead acid types.)
Simple Guidelines for Charging Lead Acid Batteries
• Charge in a well-ventilated area. Hydrogen gas generated during charging is explosive.
• Choose the appropriate charge program for flooded, gel and AGM batteries. Check manufacturer’s specifications on recommended voltage thresholds.
• Charge lead acid batteries after each use to prevent sulfation. Do not store on low charge.
• The plates of flooded batteries must always be fully submerged in electrolyte. Fill battery with distilled or de-ionized water to cover the plates if low. Tap water may be acceptable in some regions. Never add electrolyte.
• Fill water level to designated level after charging. Overfilling when the battery is empty can cause acid spillage.
• Formation of gas bubbles in a flooded lead acid indicates that the battery is reaching full state-of-charge (hydrogen on negative plate and oxygen on positive plate).
• Reduce float charge if the ambient temperature is higher than 29°C (85°F).
• Do not allow a lead acid to freeze. An empty battery freezes sooner than one that is fully charged. Never charge a frozen battery.
• Do not charge at temperatures above 49°C (120°F).
Definitions in batteries
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