how to recondition batteries

Lead–acid battery

Lead–acid car battery
Specific energy	35-40 Wh/kg[1]
Energy density	80-90 Wh/L[1]
Specific power	180 W/kg[2]
Charge/discharge efficiency	50–95%[3]
Energy/consumer-price	7 (sld) to 18 (fld) Wh/US$[4]
Self-discharge rate	3–20%/month[5]
Cycle durability	<350 cycles[6]
Nominal cell voltage	2.1 V[7]
Charge temperature interval	Min. −35 °C, max. 45 °C

The lead–acid battery was invented in 1859 by French physicist Gaston Planté and is the earliest type of rechargeable battery. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, its ability to supply high surge currents means that the cells have a relatively large power-to-weight ratio. These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required by starter motors.

As they are inexpensive compared to newer technologies, lead–acid batteries are widely used even when surge current is not important and other designs could provide higher energy densities. In 1999 lead–acid battery sales accounted for 40–45% of the value from batteries sold worldwide (excluding China and Russia), equivalent to a manufacturing market value of about $15 billion.^[8] Large-format lead–acid designs are widely used for storage in backup power supplies in cell phone towers, high-availability settings like hospitals, and stand-alone power systems. For these roles, modified versions of the standard cell may be used to improve storage times and reduce maintenance requirements. Gel-cells and absorbed glass-mat batteries are common in these roles, collectively known as VRLA (valve-regulated lead–acid) batteries.

In the charged state, the chemical energy of the battery is stored in the potential difference between the pure lead at the negative side and the PbO₂ on the positive side, plus the aqueous sulphuric acid. The electrical energy produced by a discharging lead–acid battery can be attributed to the energy released when the strong chemical bonds of water (H₂O) molecules are formed from H⁺ ions of the acid and O²⁻ ions of PbO₂.^[9] Conversely, during charging the battery acts as a water–splitting device.

History[edit]

The French scientist Nicolas Gautherot observed in 1801 for 1 last update 2020/04/01 that wires that had been used for electrolysis experiments would themselves provide a small amount of "" current after the main battery had been disconnected.^[10] In 1859, Gaston Planté''s first model consisted of two lead sheets separated by rubber strips and rolled into a spiral.^[11] His batteries were first used to power the lights in train carriages while stopped at a station. In 1881, Camille Alphonse Faure invented an improved version that consisted of a lead grid lattice, into which a lead oxide paste was pressed, forming a plate. This design was easier to mass-produce. An early manufacturer (from 1886) of lead–acid batteries was Henri Tudor.^{[citation needed]} The French scientist Nicolas Gautherot observed in 1801 that wires that had been used for electrolysis experiments would themselves provide a small amount of "" current after the main battery had been disconnected.^[10] In 1859, Gaston Planté''s first model consisted of two lead sheets separated by rubber strips and rolled into a spiral.^[11] His batteries were first used to power the lights in train carriages while stopped at a station. In 1881, Camille Alphonse Faure invented an improved version that consisted of a lead grid lattice, into which a lead oxide paste was pressed, forming a plate. This design was easier to mass-produce. An early manufacturer (from 1886) of lead–acid batteries was Henri Tudor.^{[citation needed]}

This battery uses a gel electrolyte instead of a liquid allowing the battery to be used in different positions without leaking. Gel electrolyte batteries for any position were first used the 1930s, and in the late 1920s, portable suitcase radio sets allowed the cell vertical or horizontal (but not inverted) due to valve design.^[12] In the 1970s, the valve-regulated lead–acid battery (VRLA, or "") was developed, including modern absorbed glass mat types, allowing operation in any position.

It was discovered early in 2011 that lead–acid batteries did in fact use some aspects of relativity to function, and to a lesser degree liquid metal/molten salt batteries such as the Ca/Sb and Sn-Bi also use this effect.^[13][14]

Electrochemistry[edit]

Discharge[edithow to recondition batteries 🔴how to how to recondition batteries for for 1 last update 2020/04/01 ]]

Fully discharged: two identical lead sulfate plates and diluted sulfuric acid solution

In the discharged state both the positive and negative plates become lead(II) sulfate (how to recondition batteries ☑how to how to recondition batteries for PbSO
₄), and the electrolyte loses much of its dissolved sulfuric acid and becomes primarily water. The discharge process is driven by the pronounced reduction in energy when 2 H⁺(aq) (hydrated protons) of the acid react with O²⁻ ions of PbO₂ to form the strong O-H bonds in H₂O (ca. −880 kJ per 18 g of water).^[9] This highly exergonic process also compensates for the energetically unfavorable formation of Pb²⁺(aq) ions or lead sulfate (PbSO
₄(s)).^[9]

Negative plate reaction

Pb(s) + HSO⁻
₄(aq) → PbSO
_4
4(s) + H⁺
(aq) + 2e⁻

The release of two conducting electrons gives the lead electrode a negative charge.

As electrons accumulate they create an electric field which attracts hydrogen ions and repels sulfate ions, leading to a double-layer near the surface. The hydrogen ions screen the charged electrode from the solution which limits further reaction unless charge is allowed to flow out of electrode.

Positive plate reaction

PbO
₂(s) + HSO⁻
₄(aq) + 3H^+
+
(aq) + 2e⁻ → PbSO
₄(s) + 2Hhow to recondition batteries ⭐️how to how to recondition batteries for
₂O(l)

taking advantage of the metallic conductivity of PbO
_2
2.

The total reaction can be written as

Pb(s) + PbO
₂(s) + 2H
₂SOhow to recondition batteries 🔥how to how to recondition batteries for
₄(aq) → 2PbSO
₄(s) + 2H
₂O(l) E c e l l ∘<!-- ∘ --> = 2.05 V {\displaystyle E_{cell}^{\circ }=2.05{\text{ V}}}

The net energy released per mol (207 g) of Pb(s) converted to PbSO
₄PbSO
₄(s), is ca. 400 kJ, corresponding to the formation of 36 g of water. The sum of the molecular masses of the reactants is 642.6 g/mol, so theoretically a cell can produce two faradays of charge (192,971 coulombs) from 642.6 g of reactants, or 83.4 ampere-hours per kilogram (or 13.9 ampere-hours per kilogram for a 12-volt battery). For a 2-volt cell, this comes to 167 watt-hours per kilogram of reactants, but in practice a lead–acid cell gives only 30–40 watt-hours per kilogram of battery, due to the mass of the water and other constituent parts.

the 1 last update 2020/04/01 ChargingCharging[edithow to recondition batteries 👍how to how to recondition batteries for ]

Fully recharged: Lead dioxide positive plate, Lead negative plate, and concentrated, aqueous sulfuric acid solution

In the fully charged state, the negative plate consists of lead, and the positive plate is lead dioxide. The electrolyte solution has a higher concentration of aqueous sulfuric acid, which stores most of the chemical energy.

Overcharging with high charging voltages generates oxygen and hydrogen gas by electrolysis of water, which bubbles out and is lost. The design of some types of lead-acid battery allows the electrolyte level to be inspected and topped up with pure water to replace any that has been lost this way.

Effect of the 1 last update 2020/04/01 charge level on freezing pointEffect of charge level on freezing point[edit]

how to recondition batteries 👍how to how to recondition batteries for Because of freezing-point depression, the electrolyte is more likely to freeze in a cold environment when the battery has a low charge and correspondingly low sulfuric acid concentration.

Ion motion[edit]

During discharge, H⁺
produced at the negative plates moves into the electrolyte solution and is then consumed at the positive plates, while HSO⁻
₄ is consumed at both plates. The reverse occurs during charge. This motion can be electrically driven proton flow or Grotthuss mechanism, or by diffusion through the medium, or by flow of a liquid electrolyte medium. Since the electrolyte density is greater when the sulfuric acid concentration is higher, the liquid will tend to circulate by convection. Therefore, a liquid-medium cell tends to rapidly discharge and rapidly charge more efficiently than an otherwise similar gel cell.

Measuring the charge level[edithow to recondition batteries 👍how to how to recondition batteries for ]

A hydrometer can be used to test the specific gravity of each cell as a measure of its state of charge.

Because the electrolyte takes part in the charge-discharge reaction, this battery has one major advantage over other chemistries: It is relatively simple to determine the state of charge by merely measuring the specific gravity of the electrolyte; the specific gravity falls as the battery discharges. Some battery designs include a simple hydrometer using colored floating balls of differing density. When used in diesel-electric submarines, the specific gravity was regularly measured and written on a blackboard in the control room to indicate how much longer the boat could remain submerged.^[15]

The battery''s nominal voltage is 2 V for each cell. For a single cell, the voltage can range from 1.8 V loaded at full discharge, to 2.10 V in an open circuit at full charge.

Float voltage varies depending on battery type (i.e. flooded cells, gelled electrolyte, absorbed glass mat), and ranges from 1.8 V to 2.27 V. Equalization voltage, and charging voltage for sulfated cells, can range from 2.67 V to almost 3 V.^[17] (only until a charge current is flowing)^[18][19] Specific values for a given battery depend on the design and manufacturer recommendations, and are usually given at a baseline temperature of 20 °C (68 °F), requiring adjustment for ambient conditions.

Construction[edit]

Plates[edit]

Internal view of a small lead-acid battery from an electric-start equipped motorcycle

The lead–acid cell can be demonstrated using sheet lead plates for the two electrodes. However, such a construction produces only around one ampere for roughly postcard-sized plates, and for only a few minutes.

how to recondition batteries 🔴how to how to recondition batteries for Gaston Planté found a way to provide a much larger effective surface area. In Planté''s initial charge (called "") the cured paste on the plates was converted into electrochemically active material (the ""). Faure''s battery.^[20] Faure''s operating temperature range.

how to recondition batteries ☑how to how to recondition batteries for Absorbed glass mat (AGM)[edit][edit]

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In the absorbed glass mat design, or AGM for short, the separators between the plates are replaced by a glass fibre mat soaked in electrolyte. There is only enough electrolyte in the mat to keep it wet, and if the battery is punctured the electrolyte will not flow out of the mats. Principally the purpose of replacing liquid electrolyte in a flooded battery with a semi-saturated fiberglass mat is to substantially increase the gas transport through the separator; hydrogen or oxygen gas produced during overcharge or charge (if the charge current is excessive) is able to freely pass through the glass mat and reduce or oxidize the opposing plate respectively. In a flooded cell the bubbles of gas float to the top of the battery and are lost to the atmosphere. This mechanism for the gas produced to recombine and the additional benefit of a semi-saturated cell providing no substantial leakage of electrolyte upon physical puncture of the battery case allows the battery to be completely sealed, which makes them useful in portable devices and similar roles. Additionally the battery can be installed in any orientation, though if it is installed upside down then acid may be blown out through the over pressure vent.

To reduce the water loss rate calcium is alloyed with the plates, however gas build-up remains a problem when the battery is deeply or rapidly charged or discharged. To prevent over-pressurization of the battery casing, AGM batteries include a one-way blow-off valve, and are often known as "", or VRLA, designs.

Another advantage to the AGM design is that the electrolyte becomes the separator material, and mechanically strong. This allows the plate stack to be compressed together in the battery shell, slightly increasing energy density compared to liquid or gel versions. AGM batteries often show a characteristic "" in their shells when built in common rectangular shapes, due to the expansion of the positive plates.

The mat also prevents the vertical motion of the electrolyte within the battery. When a normal wet cell is stored in a discharged state, the heavier acid molecules tend to settle to the bottom of the battery, causing the electrolyte to stratify. When the battery is then used, the majority of the current flows only in this area, and the bottom of the plates tend to wear out rapidly. This is one of the reasons a conventional car battery can be ruined by leaving it stored for a long period and then used and recharged. The mat significantly prevents this stratification, eliminating the need to periodically shake the batteries, boil them, or run an "" through them to mix the electrolyte. Stratification also causes the upper layers of the battery to become almost completely water, which can freeze in cold weather, AGMs are significantly less susceptible to damage due to low-temperature use.

how to recondition batteries 🔴how to how to recondition batteries for While AGM cells do not permit watering (typically it is impossible to add water without drilling a hole in the battery), their recombination process is fundamentally limited by the usual chemical processes. Hydrogen gas will even diffuse right through the plastic case itself. Some have found that it is profitable to add water to an AGM battery, but this must be done slowly to allow for the water to mix via diffusion throughout the battery. When a lead-acid battery loses water, its acid concentration increases, increasing the corrosion rate of the plates significantly. AGM cells already have a high acid content in an attempt to lower the water loss rate and increase standby voltage, and this brings about shorter life compared to a lead-antimony flooded battery. If the open circuit voltage of AGM cells is significantly higher than 2.093 volts, or 12.56 V for a 12 V battery, then it has a higher acid content than a flooded cell; while this is normal for an AGM battery, it is not desirable for long life.

AGM cells that are intentionally or accidentally overcharged will show a higher open circuit voltage according to the water lost (and acid concentration increased). One amp-hour of overcharge will liberate 0.335 grams of water; some of this liberated hydrogen and oxygen will recombine, but not all of it.

Gelled electrolytes[edit]

During the 1970s, researchers developed the sealed version or gel battery, which mixes a silica gelling agent into the electrolyte (silica-gel based lead-acid batteries used in portable radios from the early 1930s were not fully sealed). This converts the formerly liquid interior of the cells into a semi-stiff paste, providing many of the same advantages of the AGM. Such designs are even less susceptible to evaporation and are often used in situations where little or no periodic maintenance is possible. Gel cells also have lower freezing and higher boiling points than the liquid electrolytes used in conventional wet cells and AGMs, which makes them suitable for use in extreme conditions.

The only downside to the gel design is that the gel prevents rapid motion of the ions in the electrolyte, which reduces carrier mobility and thus surge current capability. For this reason, gel cells are most commonly found in energy storage applications like off-grid systems.

"", "" and ""[edithow to recondition batteries 🔴how to how to recondition batteries for ]

Both gel and AGM designs are sealed, do not require watering, can be used in any orientation, and use a valve for gas blowoff. For this reason, both designs can be called maintenance free, sealed and VRLA. However, it is quite common to find resources stating that these terms refer to one or another of these designs, specifically.

Applications[edit]

Most of the world'' cap lamps headlamps typically have two or three cells.^[24]

Cycles[edit]

Starting batteries[edit]

Lead–acid batteries designed for starting automotive engines are not designed for deep discharge. They have a large number of thin plates designed for maximum surface area, and therefore maximum current output, which can easily be damaged by deep discharge. Repeated deep discharges will result in capacity loss and ultimately in premature failure, as the electrodes disintegrate due to mechanical stresses that arise from cycling. Starting batteries kept on a continuous float charge will suffer corrosion of the electrodes which will also result in premature failure. Starting batteries should therefore be kept open circuit but charged regularly (at least once every two weeks) to prevent sulfation.

Starting batteries are of lighter weight than deep cycle batteries of the same size, because the thinner and lighter cell plates do not extend all the way to the bottom of the battery case. This allows loose disintegrated material to fall off the plates and collect at the bottom of the cell, prolonging the service life of the battery. If this loose debris rises enough it may touch the bottom of the plates and cause failure of a cell, resulting in loss of battery voltage and capacity.

Deep-cycle batteries[edithow to recondition batteries 👍how to how to recondition batteries for ]

Specially designed deep-cycle cells are much less susceptible to degradation due to cycling, and are required for applications where the batteries are regularly discharged, such as photovoltaic systems, electric vehicles (forklift, golf cart, electric cars and other) and uninterruptible power supplies. These batteries have thicker plates that can deliver less peak current, but for 1 last update 2020/04/01 can withstand frequent discharging.^[25] Specially designed deep-cycle cells are much less susceptible to degradation due to cycling, and are required for applications where the batteries are regularly discharged, such as photovoltaic systems, electric vehicles (forklift, golf cart, electric cars and other) and uninterruptible power supplies. These batteries have thicker plates that can deliver less peak current, but can withstand frequent discharging.^[25]

Some batteries are designed as a compromise between starter (high-current) and deep cycle. They are able to be discharged to a greater degree than automotive for 1 last update 2020/04/01 batteries, but less so than deep cycle batteries. They may be referred to as "" batteries, or "". Some batteries are designed as a compromise between starter (high-current) and deep cycle. They are able to be discharged to a greater degree than automotive batteries, but less so than deep cycle batteries. They may be referred to as "" batteries, or "".

Fast and slow charge and discharge[edit]

Charge current needs to match the ability of the battery to absorb the energy. Using too large a charge current on a small battery can lead to boiling and venting of the electrolyte. In this image a VRLA battery case has ballooned due to the high gas pressure developed during overcharge.

The capacity of a lead–acid battery is not a fixed quantity but varies according to how quickly it is discharged. The empirical relationship between discharge rate and capacity is known as Peukert''s plates, react with sulfuric acid in the electrolyte to form lead sulfate. The lead sulfate first forms in a finely divided, amorphous state and easily reverts to lead, lead dioxide, and sulfuric acid when the battery recharges. As batteries cycle through numerous discharges and charges, some lead sulfate is not recombined into electrolyte and slowly converts to a stable crystalline form that no longer dissolves on recharging. Thus, not all the lead is returned to the battery plates, and the amount of usable active material necessary for electricity generation declines over time.

Sulfation occurs in lead–acid batteries when they are subjected to insufficient charging during normal operation. It impedes recharging; sulfate deposits ultimately expand, cracking the plates and destroying the battery. Eventually, so much of the battery plate area is unable to supply current that the battery capacity is greatly reduced. In addition, the sulfate portion (of the lead sulfate) is not returned to the electrolyte as sulfuric acid. It is believed that large crystals physically block the electrolyte from entering the pores of the plates. A white coating on the plates may be visible in batteries with clear cases or after dismantling the battery. Batteries that are sulfated show a high internal resistance and can deliver only a small fraction of normal discharge current. Sulfation also affects the charging cycle, resulting in longer charging times, less efficient and incomplete charging, and higher battery temperatures.

SLI batteries (starting, lighting, ignition; e.g., car batteries) suffer the most deterioration because vehicles normally stand unused for relatively long periods of time. Deep cycle and motive power for 1 last update 2020/04/01 batteries are subjected to regular controlled overcharging, eventually failing due to corrosion of the positive plate grids rather than sulfation. SLI batteries (starting, lighting, ignition; e.g., car batteries) suffer the most deterioration because vehicles normally stand unused for relatively long periods of time. Deep cycle and motive power batteries are subjected to regular controlled overcharging, eventually failing due to corrosion of the positive plate grids rather than sulfation.

Sulfation can be avoided if the battery is fully recharged immediately after a discharge cycle.^[31] There are no known independently verified ways to reverse sulfation. ^[8][32] There are commercial products claiming to achieve desulfation through various techniques such as pulse charging, but there are no peer-reviewed publications verifying their claims. Sulfation prevention remains the best course of action, by periodically fully charging the lead-acid batteries.

Stratification[edit]

A typical lead–acid battery contains a mixture with varying concentrations of water and acid. Sulfuric acid has a higher density than water, which causes the acid formed at the plates during charging to flow downward and collect at the bottom of the battery. Eventually the mixture will again reach uniform composition by diffusion, but this is a very slow process. Repeated cycles of partial charging and discharging will increase stratification of the electrolyte, reducing the capacity and performance of the battery because the lack of for 1 last update 2020/04/01 acid on top limits plate activation. The stratification also promotes corrosion on the upper half of the plates and sulfation at the bottom.^[33] A typical lead–acid battery contains a mixture with varying concentrations of water and acid. Sulfuric acid has a higher density than water, which causes the acid formed at the plates during charging to flow downward and collect at the bottom of the battery. Eventually the mixture will again reach uniform composition by diffusion, but this is a very slow process. Repeated cycles of partial charging and discharging will increase stratification of the electrolyte, reducing the capacity and performance of the battery because the lack of acid on top limits plate activation. The stratification also promotes corrosion on the upper half of the plates and sulfation at the bottom.^[33]

Periodic overcharging creates gaseous reaction products at the plate, causing convection currents which mix the electrolyte and resolve the stratification. Mechanical stirring of the electrolyte would have the same effect. Batteries in moving vehicles are also subject to sloshing and splashing in the cells, as the vehicle accelerates, brakes, and turns.

Risk of explosionRisk of explosion[edit]

Car lead-acid battery after explosion showing brittle cracking in casing ends

Excessive charging causes electrolysis, emitting hydrogen and oxygen. This process is known as "". Wet cells have open vents to release any gas produced, and VRLA batteries rely on valves fitted to each cell. Catalytic caps are available for flooded cells to recombine hydrogen and oxygen. A VRLA cell normally recombines any hydrogen and oxygen produced inside the cell, but malfunction or overheating may cause gas to build up. If this happens (for example, on overcharging) the valve vents the gas and normalizes the pressure, producing a characteristic acid smell. However, valves can fail, such as if dirt and debris accumulate, allowing pressure to build up.

how to recondition batteries 🔥how to how to recondition batteries for Accumulated hydrogen and oxygen sometimes ignite in an internal explosion. The force of the explosion can cause the battery''s terminals can be reduced by coating the terminals with petroleum jelly or a commercially available product made for the purpose.^[38]

how to recondition batteries ⭐️how to how to recondition batteries for If the battery is over-filled with water and electrolyte, thermal expansion can force some of the liquid out of the battery vents onto the top of the battery. This solution can then react with the lead and other metals in the battery connector and cause corrosion.

The electrolyte can seep from the plastic-to-lead seal where the battery terminals penetrate the plastic case.

Acid fumes that vaporize through the vent caps, often caused by overcharging, and insufficient battery box ventilation can allow the sulfuric acid fumes to build up and react with the exposed metals.

See also[edit]

Referenceshow to recondition batteries 🔴how to how to recondition batteries for for 1 last update 2020/04/01 [[edithow to recondition batteries 🔴how to how to recondition batteries for ]