How Lead Acid Batteries Work

Here is a short run-through of how lead-acid batteries work. I’ll start with some basics and work my way up – hence the absence of an alphabetical order. Depending on your familiarity with the subject, you may want to scroll down more or less. hp compaq PA-1900-18H2 Adapter dell M70 Adapter

Voltage Voltage is an electrical measure which describes the potential to do work. The higher the voltage the greater its risk to you and your health. Systems that use voltages below 50V are considered low-voltage and are not governed by an as strict (some might say arcane) set of rules as high-voltage systems. Current Current is a measure of how many electrons are flowing through a conductor. Current is usually measured in amperes (A). Current flow over time is defined as ampere-hours (a.k.a. amp-hours or Ah), a product of the average current and the amount of time it flowed. Power Power is the product of voltage and current and is measured in Watts. Power over time is usually defined in Watt-hours (Wh), the product of the average number of watts and time. Your energy utility usually bills you per kiloWatt-hour (kWh), which is 1,000 watt-hours. What is a Lead-Acid Battery? A lead-acid battery is a electrical storage device that uses a reversible chemical reaction to store energy. It uses a combination of lead plates or grids and an electrolyte consisting of a diluted sulphuric acid to convert electrical energy into potential chemical energy and back again. The electrolyte of lead-acid batteries is hazardous to your health and may produce burns and other permanent damage if you come into contact with it. Thus, when dealing with electrolyte protect yourself appropriately! Deep Cycle vs. Starter Batteries Batteries are typically built for specific purposes and they differ in construction accordingly. Broadly speaking, there are two applications that manufacturers build their batteries for: Starting and Deep Cycle. As the name implies, Starter Batteries are meant to get combustion engines going. They have many thin lead plates which allow them to discharge a lot of energy very quickly for a short amount of time. However, they do not tolerate being discharged deeply, as the thin lead plates needed for starter currents degrade quickly under deep discharge and re-charging cycles. Most starter batteries will only tolerate being completely discharged a few times before being irreversibly damaged. Deep Cycle batteries have thicker lead plates that make them tolerate deep discharges better. They cannot dispense charge as quickly as a starter battery but can also be used to start combustion engines. You would simply need a bigger deep-cycle battery than if you had used a dedicated starter type battery instead. The thicker the lead plates, the longer the life span, all things being equal. Battery weight is a simple indicator for the thickness of the lead plates used in a battery. The heavier a battery for a given group size, the thicker the plates, and the better the battery will tolerate deep discharges. Some “Marine” batteries are sold as dual-purpose batteries for starter and deep cycle applications. However, the thin plates required for starting purposes inherently compromise deep-cycle performance. acer PA-1750-04 Adapter Compaq Presario V2000 Adapter Thus, such batteries should not be cycled deeply and should be avoided for deep-cycle applications unless space/weight constraints dictate otherwise. Regular versus Valve-Regulated Lead Acid (VRLA) Batteries Battery Containers come in several different configurations. Flooded Batteries can be either the sealed or open variety. Sealed Flooded Cells are frequently found as starter batteries in cars. Their electrolyte cannot be replenished. When enough electrolyte has evaporated due to charging, age, or just ambient heat, the battery has to be replaced. Deep-Cycle Flooded cells usually have removable caps that allow you to replace any electrolyte that has evaporated over time. Take care not to contaminate the electrolyte – wipe the exterior container while rinsing the towel frequently. VRLA batteries remain under constant pressure of 1-4 psi. This pressure helps the recombination process under which 99+% of the Hydrogen and Oxygen generated during charging are turned back into water. The two most common VRLA batteries used today are the Gel and Absorbed Glass Mat (AGM) variety. Gel batteries feature an electrolyte that has been immobilized using a gelling agent like fumed silica. AGM batteries feature a thin fiberglass felt that holds the electrolyte in place like a sponge. Neither AGM or Gel cells will leak if inverted, pierced, etc. and will continue to operate even under water. Battery Cells Battery Cells are the most basic individual component of a battery. They consist of a container in which the electrolyte and the lead plates can interact. Each lead-acid cell fluctuates in voltage from about 2.12 Volts when full to about 1.75 volts when empty. Note the small voltage difference between a full and an empty cell (another advantage of lead-acid batteries over rival chemistries). Battery Voltage The nominal voltage of a lead-acid battery depends on the number of cells that have been wired in series. As mentioned above, each battery cell contributes a nominal voltage of 2 Volts, so a 12 Volt battery usually consists of 6 cells wired in series. State of Charge The State of Charge describes how full a battery is. The exact voltage to battery charge correlation is dependent on the temperature of the battery. Cold batteries will show a lower voltage when full than hot batteries. This is one of the reasons why quality alternator regulators or high-powered charging systems use temperature probes on batteries. hp 239427-003 Adapter HP Pavilion dv6700 Adapter Depth of Discharge (DOD) The Depth of Discharge (DOD) is a measure of how deeply a battery is discharged. When a battery is 100% full, then the DOD is 0%. Conversely, when a battery is 100% empty, the DOD is 100%. The deeper batteries are discharged on average, the shorter their so-called cycle life.

Most new batteries go through a formatting process during which

the capacity gradually increases and reaches optimal performance

at 100–200 cycles. After this mid-life point, the capacity Dell Inspiron 8200 Adapter

gradually

begins decreasing and the depth of discharge, operating temperatures

and charging method govern the speed of capacity loss. The deeper

the batteries are discharged and the warmer the ambient temperature

is, the shorter the service life. The effect of temperature on the battery

can be compared with a jug of milk, which Dell XPS M140 Adapter

stays fresh longer when refrigerated. Most portable batteries deliver
between 300 and 500 full discharge/charge cycles. Fleet batteries in
portable devices normally work well during the first year; however, the confidence

in the portable equipment begins to fade after the second and

third year, when some batteries begin to lose capacity. New

packs are added and in time the battery fleet becomes a jumble

of good and failing batteries. That’s when the headaches begin.Dell Inspiron 1300 Adapter

Unless date stamps or other quality controls are in place,

the user has no way of knowing the history of the battery, much

less the performance. The green light on the charger does not reveal

the performance of a battery. The charger simply fills the available

space to store energy, and “ready” indicates that the battery is full.

With age, the available space gradually decreases and the charge

time becomes shorter. This can be compared to filling a jug with

water. An empty jug takes longer because it can accept more water

than one with rocks. Figure 2 shows the “ready” light that often lies.

The “ready” light lies Figure 2: The “ready” light lies The “ready”

light on a charger only reveals that the battery is fully charged; Dell PA-12 Adapter

there is no relationship to performance. A faded battery charges

faster than a good one. Bad batteries gravitate to the top. Courtesy

of Cadex Many battery users are unaware that weak batteries charge

faster than good ones. Low performers gravitate to the top and

become available by going to “ready” first. They form a disguised

trap when unsuspecting users require a fully charged battery in

a hurry. This plays havoc in emergency situations when freshly charged

batteries are needed. The operators naturally grab batteries dell Inspiron 1520 Adapter
that show ready,

presuming they carry the full capacity. Poor battery management is the

common cause of system failure, especially during emergencies. Failures

are not foreign in our lives and to reduce breakdowns, regulatory

authorities have introduced strict maintenance and calibration guidelines

for important machinery and instruments. Although the battery can be

an integral part of such equipment, it often escapes scrutiny. The battery as

power source is seen as a black box, and for some inspectors correct

size, weight and color satisfies the requirements. For the users, however,

state-of-function stands above regulatory discipline and arguments arise

over what’s more important, performance or satisfying a dogmatic

mandate. Ignoring the performance criteria of a battery nullifies the

very reason why quality control is put in place. In defense of the

quality auditor, batteries are difficult to check, and to this day there are

only a few reliable devices that can check  dell Inspiron E1705 Adapter
batteries with certainty.

Line art drawing of a dry cell:
1. brass cap, 2. plastic seal, 3. expansion space, 4. porous cardboard, 5. zinc can,

6. carbon rod, 7. chemical mixture.

An electrical battery is one or more electrochemical cellsDell Inspiron 910 Battery

that convert stored chemical energy into electrical energy.[1] Since the

invention of the first battery (or ”voltaic pile”) in 1800 by Alessandro

Volta, batteries have become a common power source for many

household and industrial applications. According to a 2005 estimate,

the worldwide battery industry generates US$48 billion in sales each year,

[2] with 6% annual growth.[3] DELL Inspiron Mini 9 Battery There are

two types of batteries: primary batteries (disposable batteries), which are

designed to be used once and discarded, and secondary batteries (rechargeable

batteries), which are designed to be recharged and used multiple times.

Batteries come in many sizes, from miniature cells used to power hearing

aids and wristwatches to battery banks the size of rooms that provide standby

power for telephone exchanges and computer data centers.

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1 History 2 Principle of operation 3 Categories and types of batteries 3.1

Primary batteries 3.2 Secondary batteries 3.3 Battery cell types 3.3.1 Wet cell

3.3.2 Dry cell 3.3.3 Molten salt 3.3.4 Reserve 3.4 Battery cell performance 4

Battery capacity and discharging 4.1 Fastest charging, largest, and lightest

batteries 5 Battery lifetime 5.1 Life of primary batteries 5.1.1 Battery

Dell NC929 keyboard sizes 5.2 Lifespan of rechargeable batteries 5.3

Extending battery life 5.4 Prolonging life in multiple cells through cell

balancing 6 Hazards 6.1 Explosion 6.2 Leakage 6.3 Environmental c

oncerns 6.4 Ingestion 7 Battery chemistry 7.1 Primary battery

chemistries 7.2 Rechargeable battery chemistries 8 Homemade cells 9 See

also 10 References 11 Further reading 12 External links History

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As we examine the characteristics of battery systems and compare alternative power

sources, such as the fuel cell and the internal combustion (IC) engine,

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dell PA-21 Adapter we realize that the battery is best suited for portable

and stationary systems. For motive applications such as trains, ocean

going ships and aircraft, the battery lacks capacity, endurance and reliability.

The dividing line, in my opinion, lies with the electric vehicle. We now

compare the battery as a power source and begin with the positive traits,

and then look at the limitations.toshiba PA3469U-1ACA Adapter

Energy storage
Batteries store energy well and for a gateway ADP-65HB BB Adapter

considerable length of time. Primary batteries (non-rechargeable) hold

more energy than secondary (rechargeable), and the self-discharge is

lower. Alkaline cells are good for 10 years with minimal losses. Lead-,

nickel- and lithium-based batteries need periodic recharges to

compensate for lost power.hp Pavilion DV7 Adapter

Specific energy (Capacity)
A battery may hold adequate energy for portable use, but this does not
transfer equally well for large mobile and stationary systems. For example
a 100kg (220lb) battery produces about 10kWh of energy — an IC
engine of the same weight generates 100kW.hp Pavilion DV6500 Adapter

Responsiveness
Batteries have a huge advantage over other power sources in being ready to
deliver on short notice — think of the quick action of the camera flash! There
is no warm-up, as is the case with the internal combustion (IC) engine; the
power from the battery flows within a fraction of a second. In
comparison, a jet engine takes several seconds to gain power, a fuel cell
requires a few minutes, and the cold steam engine of a locomotive needs hours to build up steam.

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