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Lead-Acid Battery
Introduction
Lead-acid batteries are the most efficient rechargeable type, with up to 95% conversion efficiency. However, commercial lead-acid battery fabrication and recycling are energy-intensive and the lead powder and alloys used are especially hazardous. Long-lasting commercial batteries are very expensive. Batteries are expensive to ship due to their weight. Because the lead-acid battery is a fairly simple technology, local fabrication using a simple process might be a realistic alternative to commercial batteries.
The solar thermal energy application calls for efficiency, fast charging, long lifespan, and minimum hazard in a battery. The stationary, sheltered application reduces or eliminates temperature extremes, inertial forces, vibration and size/weight restrictions of automotive applications. Solid lead sheet is a simple and relatively safe alternative to the lead paste/grids used in most commercial batteries. Solid lead's low resistance increases battery efficiency, enables faster charging, and is much less hazardous than lead powder. Solid lead plates have much less discharge sulfation problem than pasted plates. If high purity lead sheet and plate separator material are available at a reasonable cost, it's probably feasible to build a battery that could last for two decades in a stationary, sheltered day-cycle application such as residential solar thermal.
Electrochemistry
A lead-acid battery is composed of two lead plates and a porous separator submerged in a sulfuric acid/water mixture (electrolyte). The plates undergo an initial forming process in which a sequence of discharge/charge cycles forms a porous layer of lead dioxide on the positive plate and a porous layer of lead on the negative plate. The volume of the porous layers determines the charge capacity. Charge/discharge rates are limited by molecular diffusion (electrolyte equalization) rates and electrical resistance in the plates. The essential electrochemical process is shown below in chemistry notation.
On discharge, the positive plate's lead dioxide is reduced to lead sulfate and the negative plate's porous lead is oxidized to lead sulfate. The positive plate accepts electrons from the circuit, while the negative plate gives up electrons to the circuit. The positive plate gives up oxygen, which combines with hydrogen ions in the electrolyte to form water.
On charge, the positive plate's lead sulfate is oxidized to lead dioxide and the negative plate's lead sulfate is reduced to porous lead. The positive plate gives up hydrogen ions to the electrolyte, and gives up electrons to the circuit, while the negative plate accepts electrons from the circuit.
Positive plate: PbO2 + 2e- + SO42- + 4H+ < charge/discharge > PbSO4 + 2H2O
Negative plate: Pb + SO42- < charge/discharge > PbSO4 + 2e-
Overall: Pb + PbO2 + 2H2SO4 < charge/discharge > 2PbSO4 + 2H2O
Pb = lead (s) H2O = water (l)
PbO2 = lead dioxide (s) H+ = hydrogen ion
PbSO4 = lead sulfate (s) e- = electron
H2SO4 = sulfuric acid (aq) SO42- = sulfate ion (aq)
(s) = solid, (l) = liquid, (aq) = aqueous solution
Battery History
The lead-acid battery has been around since the mid-1800s. The first lead-acid batteries were cylindrical and spiral-wound to maximize plate area using thin sheets of lead. But batteries are sensitive to a number of factors and undergo a variety of abuses in automotive applications so the flat plate design emerged to enable rebuilding damaged batteries at local shops. To tolerate handling, the plates were made thicker, adding to the cost, weight, and size. Solid lead plates are still made for stationary applications without space and cost restrictions but something different was needed for automotive applications.
Commercial Batteries
Most commercial batteries are for automotive applications that require a short intense current burst for engine starting and a reserve supply for emergencies. Automotive battery plates have porous lead paste and lead dioxide paste on alloy grids which increases the plate surface area and charge capacity for the battery size and weight compared to solid lead plates. But automotive batteries suffer high internal resistance from reduced lead content in the grid and thus quickly overheat. They suffer high self-discharge rates, grid corrosion, water loss and capacity loss from grid alloys, resulting in decreased efficiency and capacity with age. They also suffer more severe sulfation. Resistance is an acceptable trade-off for a burst application and grid alloys are required for strength in automotive applications. Sulfation isn't a problem because car batteries are normally recharged immediately.
Compared to automotive batteries, deep-cycle batteries used in golf carts, fork-lifts, and similar applications are designed to discharge more slowly and over longer intervals, typically one day. Deep cycle battery plates are also generally made with paste on alloy grids. But the paste has larger granularity and the plates are thicker and fewer. The thicker plates provide strength to tolerate the mechanical and thermal stresses of deep discharge. Thicker plates limit electrolyte access to the interior of the plates, compensated somewhat by the larger paste granularity, but which still limits the discharge rate. The application typically allows for increasing capacity by adding more batteries.
Solar Power Application
Residential solar power often requires only 24 hours of reserve capacity. But a higher reserve capacity is needed for extended overcast periods. A practical reserve capacity would cover a five-day overcast period. The number of these five day overcast periods per year depends on climate and may range from two to twelve with six as average. A good capacity allows the daily discharge of the battery bank to reach 70% capacity and the five-day deep discharge to reach 30% (see Charging Strategy and Charge/Discharge Rates). A backup charger should be used after five days of discharge to protect the batteries.
Commercial automotive batteries can only tolerate six deep discharges per year for two or three years. Commercial deep-cycle batteries might tolerate this number for seven to twelve years. Solid lead plate batteries might tolerate this number for two to three decades *. The difference is in the battery design's resistance to sulfation during extended periods of discharge.
Local climate averages should be consulted in selecting a reserve capacity to meet expected overcast periods for the number of years that the budget will allow. The simplest would be to select the reserve capacity to align the battery lifespan with the service intervals of other system components or preferably the system lifespan. Check here for historic solar irradiation data to characterize a location's overcast periods.
An alternative is to employ a backup charger that operates on all overcast days, reducing the battery capacity requirement to 24 hours, with an average daily discharge to 50% to preserve the target battery lifespan.
Solid Lead Plates
A stationary application does not require compact size or alloy strength but does require low internal resistance for fast recharge, long lifespan and economy. Solid lead plates offer lower electrical resistance, thus reduced heat stress, because the plate is solid and less is porous. Solid lead plates may have lesser sulfation problems (chemical resistance, etc) due to thinner porous layers, and lack of alloy problems (antimony migration, etc). Commercial solid plate batteries are available for industrial applications but they are expensive due to smaller markets and higher profit margins. Solid plate batteries generally have double to triple the lifespan of pasted plate batteries in stationary applications. They may also be recycled with a much simpler/inexpensive process.
The major disadvantage of solid lead plates is that more lead (expense) is needed to get the same plate surface area (charge capacity) as in lead paste attached to lead alloy grids. But lead sheet is generally available in a range of thicknesses, and stationary applications don't need mechanical strength like motive applications, so the penalty might be reduced to zero. The plate's solid layer must withstand mechanical stress created by the expanding and contracting porous layers in order to maintain good electric conduction to the battery terminals. Another disadvantage of solid lead plates is that a relatively long initial forming process is required.
Plate Thickness
The strength of solid lead plates depends on the thickness of the solid layer. In the early days of farm lighting applications (see Witte), thick plates enabled inspecting and replacing individual plates. Thick plates also offered more tolerance to abusive charge/discharge conditions. But thinner plates offer greater charge capacity, faster charge/discharge rates, and greater tolerance to sulfation, for the same amount of lead. And since lead is expensive and hazardous, it's better to avoid rebuilding, but instead maximize the battery lifespan through proper management. So the plate thickness should be determined only by the electrical and mechanical requirements of the sheltered, stationary application. Stationary batteries don't require the mechanical strength of motive batteries, and thinner plates can hold up well under moderate temperatures, moderate charge/discharge rates/ranges, and proper electrolyte maintenance.
Thinner porous layers, compensated with more plate area, enable a higher charging rate, without increased stresses. This is important in a solar application with short winter daylight periods. Thinner porous layers achieve a higher charging rate through greater access to the electrolyte pool, i.e. more efficient electrolyte equalization.
Thinner porous layers are less constricted by sulfation because of the smaller volume of electrolyte needed per unit area and time. This is important in a solar application because sulfation is inevitable with extended battery discharge during periods of cloudy weather.
Plate Geometry
Possible geometries include a two-plate spiral-wound cylinder, a thin stack of long flat plates, and a thick stack of square flat plates. The cylinder geometry affords the greatest strength via partial conversion of shear to compressive force, and may enable greater plate area to thickness ratios. The spiral-wound reduces chopping/handling of lead to a minimum but may require longer sheets. Cylinder strength increases with height. Bending effects become relevant at smaller cylinder diameter to plate thickness ratios. Commercial spiral wound cylinders are claimed to tolerate ten or more times the charge rate, which is of great value in a solar application.
Compared to spiral-wound cylinders, flat plates require more chopping/handling of lead, are more vulnerable to shear stress, but are easier to assemble and without bending effects. A thick stack of square flat plates requires maximum chopping/handling but provides maximum electrolyte access. A thin stack of longer flat plates reduces chopping/handling but is more vulnerable to shear stress.
Plates should be mounted vertically so gases easily bubble to the top , and for equal wear among the plates. Less plate height increases electrolyte access to the inner plate surface and decreases electrolyte stratification, minimizing mechanical stress at higher charge/discharge rates.
Plate Separators
Plate separators prevent electrical contact between the battery plates. Their porosity enables diffusion of electrolyte components at the plate surface. Separators also provide mechanical support to prevent excess plate stress while the porous layers expand/contract during the discharge/charge cycle. Over time this ensures uniform plate wear, helping to extend battery lifespan.
Separators should have good electrical resistance, oxidation resistance, porosity, wettability and electrolyte diffusion. Pore size is important. Too small pores restrict diffusion. Too large pores enable lead dendrite formation at deep discharge when the lead sulfate is soluble enough to diffuse through the pores. Lead dendrites create short circuits between the plates. Separators should be tested for large pores and those rejected. An effective technique to protect against large pores is to use multiple layers of separator material. Separator edges should extend past plate edges to prevent dendrites from forming around the separator.
Separators have been made from wood, paper, rubber and polymers. Wood separators must be boiled to neutralize the acids (see Witte). According to Amerace, rubber separators show the best performance * (pdf) by producing fewer impurities which can lead to several problems such as dendrite growth and high end of charge current.
Separators usually have ribs that face the positive plate and make contact with the solid plate material to minimize contact with the mechanically weak lead dioxide. To allow space for the porous material's expansion/contraction during discharge/charge, the rib depth should equal the maximum thickness of the porous layer (at about 80% discharge). The ribs also provide channels for electrolyte to flow more freely from the top/botom edges to the center of the plate. This raises the electro-chemical process rate at the positive plate to better match the negative plate's. The positive plate's process rate is inhibited during discharge by water production which dilutes the acid. The channels also reduce shedding of lead dioxide when gassing occurs by providing the gas easier access out of the plates and to the air above, the ribs being vertical for this purpose.
The separator's negative plate side should have ribs, probably with a lesser depth. The negative plate's porous lead is much stronger and does not expand/contract as much as the positive plate's lead dioxide. But the negative plate still benefits for the same reasons, especially during the forming process.
Electrolyte
Electrolyte is a mixture of sulfuric acid and pure water that fills the battery cells. The electrolyte should contain enough sulfuric acid to supply the conversion of the plate porous layers into lead sulfate. Too little acid reduces the battery capacity and too much acid corrodes the plates. A motive battery is compact so it needs a higher concentration of acid. A stationary battery can hold a larger volume of electrolyte that is more dilute, reducing plate corrosion. The battery case should be 10% larger in volume than the plate assembly and the initial electrolyte mix should be about 30% sulfuric acid and 70% pure water, corresponding to a specific gravity of 1.2.
The sulfuric acid should be obtained from reliable sources and be very pure. Use 98% concentrated sulfuric acid to extend the lifespan of the battery. Water must not be poured into a container of acid. Acid should be poured into a container of water, very slowly while stirring to minimize heat generated. Acid burns skin and eyes. Use skin and eye protection. Mix outdoors for ventilation. Avoid breathing the vapors. Avoid spilling the acid. Use the actual battery case as the mixing container to avoid contaminating the electrolyte with a dirty container. The battery case must be very clean. Unused acid should be returned to the source.
Cell Connections
Each cell has about 2.1 volts potential. Cells may be connected in parallel to increase current and in series to increase voltage. Higher voltage / lower current allows economies in distribution lines and appliances by lowering resistive heat loss.
Cells have slight variations in internal resistance. Cells with lower resistance work harder when cells are connected in parallel. Cells with higher resistance work harder when cells are connected in series. The harder-working cells weaken faster over time, resulting in a battery of cells that are increasingly mismatched and limited by the weaker cells. In parallel connections, the longer cables may be assigned to lower the current to the harder-working cells. One way to improve the match in series connections is to make each node in the series a parallel pair of half capacity cells. Each pair is assigned a high-resistance cell and a low-resistance cell connected with a cable length matching the average resistance of the high-resistance cells. This cuts the resistance error distribution in half. Throughout the battery's lifespan the resistances should be re-checked and better compensation provided to the weaker cells as their deterioration advances.
Batteries degrade in two other ways: sulfation, which degrades battery capacity by reducing plate area, and plate shorting, which degrades battery capacity by leaking battery charge. When a set of 2V batteries are connected in series, for example to achieve a 12V batter bank, a battery weakened by either sulfation or shorting is worked harder than the other batteries because it discharges faster. So at the bank's end-of-life, the other batteries' unused capacity is wasted, unless a replacement can be found for the remainder of the bank life. The tendency of the weak battery to isolate its problem to itself enables battery vendors to offer battery warranties for series-connected batteries, it seems.
When a set of 12V batteries are connected in parallel instead, a battery weakened by either sulfation or shorting works the whole bank harder, so at the bank's end-of-life there tends to be less unused capacity, and the overall bank life should be longer than for the series 2V bank. But in the case of a catastrophic short in a battery, the whole bank can be severely damaged. But catastrophic shorts tend to be rare in stationary applications, so the parallel bank is probably better than the series bank, even if the series batteries have a better warranty.
6V batteries connected in series pairs, then connected in parallel, offers the possibility of switching batteries around to mitigate the series connection issues that affect the battery pairs.
Battery Case
The battery case may be made from whatever material can contain the electrolyte, tolerate the dilute sulfuric acid and introduces no contaminants of its own. Wood may be used with a layer of acid-resistant material, e.g. rubber, on the inside to seal in the electrolyte. The plates should be elevated so that plate shedding can accumulate on the bottom without reaching the plates. The electrolyte reservoir should be 10% greater in volume than the plate assembly. The case should be leak-proof, and vent at the top but prevent debris and creatures from entering. The top should open for inspection and to add water. The top should not accumulate debris that will fall into the electrolyte when it's opened.
Battery Construction
important: read handling lead
A spiral-wound battery can be made with long rolls of lead sheet and suitable plate separator material. There are four layers to be rolled up: a lead sheet for the positive plate, a separator sheet, a lead sheet for the negative plate, and a separator sheet. A number of narrow strips can be cut from one lead sheet edge leaving lugs to which the strips are soldiered before rolling. The separators must extend past the plate edges to prevent short circuits, especially at the lugs. The four sheets are rolled up together with an initial radius not excessively small and a length that makes it manageable. The winding tension should not compress the separator ribs. Temporary supports between the ribs may be needed to prevent this. After fitting the cylinder in the container, the strips are soldered together to form the terminals, electrolyte is added to the container and its level marked, then the plate active layers are formed.
Over time, relatively minor imperfections can develop into battery failures, so the lead sheets should be as pure and uniform as possible. They should be inspected before accepting delivery and any imperfections including dents, creases, holes, corrosions, stains, or contaminations rejected. Same goes for the separators. Same goes during construction. No mechanical damage. Precision alignment. No uneven mechanical stresses. No contaminants on any surfaces. Wear clean gloves and keep the work area clean.
The finished plates should be uniform, with smooth, clean edges. Sawing the lead sheet and the separator materials should be avoided. Lead dust contaminates the battery and is dangerous to people. Cut instead of saw. Use damp clean cloths to remove dust from material surfaces.
The separators should be composed of multiple layers. This prevents a defect in a single layer from causing battery failure. Extra separator margin around plate edges is required to prevent shorts. All components must be very clean before final assembly. The electrolyte must be pure and remain pure through the battery's lifespan.
Battery Construction - Europulse
Battery Room / Maintenance
The battery room should be ventilated to prevent the accumulation of hydrogen gas produced in the event of overcharging. The vent outlet must be at the highest point in the room and vent to the atmosphere. The vent inlet, placed near the floor must also vent to the atmosphere facing prevailing winds to ensure a consistent airflow to the upper outlet vent. Ventilation is precautionary as gassing should be minimized with the charging strategy. The battery room should not share any airflow with the residential space. Sparks and flames should be avoided as hydrogen gas is highly flammable. The optimum temperature for a lead-acid battery is 25°C (77°F). Every 8°C (15°F) sustained rise in temperature cuts the battery lifespan in half. High temperature also compromises battery performance as does low temperature. If the battery room is within the residential walls the battery temperature is easily kept close to the optimum. If the battery room is outside residential walls the batteries might be placed at ground level or below to exploit the ground's moderating effect. Lacking adequate temperature regulation, the charge voltage should be temperature-compensated to maintain optimum charge parameters and limit heat/gas production.
Water is lost to gassing, so the electrolyte level should be checked and pure water added to match the original level. Any plate area exposed to air will permanently sulfate. More water is lost under fast/high charge and/or high ambient temperature. The acid does not gas, but droplets may be carried out with the gas. In the event of heavy gassing, surfaces outside the battery should be cleaned of acid and the specific gravity checked/adjusted by adding acid very slowly while stirring. The surface of the battery case between the terminals should be kept free of dust and moisture to prevent conduction between the terminals. Terminal connections may be protected from corrosion, caused by gassing and moisture, with a thin layer of grease.
Forming
Forming is a sequence of charging cycles that forms the porous lead dioxide layer on the positive plates and the porous lead layer on the negative plates in a newly-constructed battery. The cycle is initially very short in duration and as the porous layers grow in thickness the charging cycle lengthens *. The commercial pasted plates are formed in as little as one day but solid plates can take many weeks with one charge cycle per day. This might be cut down to a couple of weeks or less for a thin plate design. Other approaches to expediting the forming process include roughening up the lead surfaces mechanically and/or dipping the plates in a 50% nitric acid bath which may reduce forming time by a factor of five *.
The polarity of charging must be reversed after each discharge. Each porous layer alternates between lead and lead dioxide on each charge reversal. If both sides of the separators have the same depth ribs there will be no excessive pressure on the porous layers. A charge controller that lets two banks charge-discharge each other would greatly reduce the energy required in the forming process.
Testing
The lifespan of the battery may be estimated by placing small prototypes under various high levels of stress, e.g. charge rate, and measuring their lifespans. This data may be extrapolated to estimate lifespan at the normal stress levels. Also, the battery voltages and currents may be monitored while in service and data extrapolated to estimate lifespan. As the battery ages its capacity will drop and this can be observed in the data.
Electrolyte specific gravity is measured with a hydrometer, and may reliably indicate state of charge if temperature compensated and surface charge is removed through a 6 hour rest period. The specific gravity should be measured and recorded on battery construction. A programmable charge controller more conveniently monitors state of charge through voltages and currents.
Charging Strategy
Strict limits should always be maintained on the battery's state-of-charge to maximize battery lifespan. The battery should not be discharged below about 20% capacity because the resulting high density of the lead sulfate greatly accelerates sulfation. A failure to daily charge the battery to 90% capacity also leaves the battery vulnerable to sulfation.
The battery should not often be charged to more than 90% capacity
due to
the inefficiency and stress caused by excess heat and gassing. A
good charging strategy for a solar application is to normally discharge
to around 70% of capacity and
allow
discharge to around 30% of capacity during extended periods of overcast
weather, while
strictly maintaining limits of 20% and 90%.
See also: Charge Controller: Battery Charging Cycle
Charge/Discharge Rates
To maximize the lifespan of a battery, the charge/discharge rates must be held to practical limits. Too fast a charge/discharge rate can cause uneven rates of chemical change across the plate area, resulting in uneven plate thickness, creating a mechanical stress (warping or bowing) that weakens the plate. This happens because sulfate increases porous layer volume, especially on the positive plate. Also, too fast a charge/discharge rate can surpass the electrolyte equalization rate, causing excessive gassing, water loss, and porous layer shedding. And it can cause excessive heat, due to electrical resistance in the plates, which wastes power and weakens the plates. The charge rate has a much lower practical limit than the discharge rate. Given the limited charge period in a solar application, the charge rate is prioritized in the design with more porous layer area, less porous layer thickness, and shorter distance from plate edge to center.
Gassing
Gassing is the production of hydrogen and oxygen when the charge rate exceeds the electrochemical process limit. This limit decreases as the battery charges, making the battery more prone to gassing near full charge. Gassing causes lead dioxide to shed from the positive plate. Lead dioxide is more delicate and vulnerable to shedding than the porous lead on the negative plate. Gassing also depletes the water in the electrolyte.
Both the battery case and the battery room should be vented to allow the gases to escape to the atmosphere, because hydrogen gas is highly flammable. During gassing, tiny electrolyte droplets are suspended in the gas which carries them out of the battery case. Some of this acid mist settle on and corrodes materials near the batteries, metals and organics being most vulnerable. Gassing is also accompanied to some extent by heating. For all of these reasons the charge rate should be well-regulated to minimize gassing.
Shedding
Shedding is the loss of porous material from the plates. It falls to the bottom of the battery case and piles up and if it reaches the plates it can cause electrical short-circuit. Shedding is caused by expansion/contraction of the plates during discharge/charge. Shedding is also caused by gassing which exerts pressure on the porous material. Shedding also results from jolts and vibration but these occur rarely in a stationary application. Lead dioxide on positive plates is much more prone to shedding because it is much weaker mechanically. Ribbed plate separators reduce shedding by reducing pressure on the porous material during expansion/contraction and gassing.
Sulfation
Lead sulfate normally forms with a very fine granularity on the battery plates during discharge. This fine granularity provides the electrolyte the necessary access to reach the lead sulfate for conversion back to porous lead/lead dioxide on subsequent charge. Sulfation is a solidifying of the lead sulfate into large crystals before it can be converted back. This loss of granularity greatly reduces electrolyte access and battery capacity. Sulfation progresses by the hour so the key to minimizing sulfation is to promptly recharge the battery. A discharged battery is a distressed battery, even at small amounts and for short periods. Excess sulfation is the most common cause of premature battery failure.
Obtaining Lead
important: read handling lead
Recycled and virgin lead (99.9% pure?) sold for an average of 48 cents per pound in the U.S. in 1998 while old batteries sold for 6 cents and other sources of lead scrap sold for 19 cents. The prices can vary widely over time. Spent commercial batteries are by far the most plentiful source of lead. First obtain effective sealable storage containers. Separate out the lead paste while avoiding skin contact, inhalation, and spillage. Remove the slough from the lead paste which includes sulfate, oxide, antimony and possibly other materials that are hard to identify (see smelting links below). Store the various materials including the acid, case, plate separators and plate grids in the storage containers (see Safety / Environmental).
Other sources of lead scrap that require less complex processing include battery terminals, auto wheel balancing weights, fishing weights, and bullets. Some of these will probably contain 2% to 5% impurities including about .25% antimony and the rest tin and other metals and minerals. Clip-on wheel weights seem to have more antimony than adhesive types and other scrap lead (see smelting links below).
The 5 to 10% antimony content in commercial battery grids leak antimony ions, shortening battery lifespan. 2 to 5% impurities will also shorten lifespan. A battery made from 99.9% pure lead might last 60% longer than one made from 95% pure lead, all else equal. To make lead sheet create a mold in the shape of a pan using a level and pour lead in to a depth of about 1/4". Use a cold rolling mill to roll the resulting thick sheet into a thin, smooth sheet.
Lead and Zinc Smelting (pdf)
Handling Lead
Handle lead with strict care. Read lead poisoning and lead: health effects. Among other things, lead damages biological systems by stealing the place of beneficial metals and failing to exhibit the properties of those metals. Most species haven't adequately adapted to the presence of lead. Wear gloves & mask, and avoid creating lead dust, vapors or compounds that cannot be fully contained. Lead should not be discarded in the environment. Contain all lead safely, including contaminated gloves & masks. All unused lead should be stored responsibly or delivered to a responsible handler, such as your local government's household hazardous waste program. For general information see the USEPA HHW page.
Additional lead safety information.
References
Submarine Batteries Report (pdf)
US DOE Handbook1084 - Lead-Acid Batteries
Accumulator - 1911 Encyclopedia Britannica
The Automotive Storage Battery - 1922 - 0. A. Witte
A Study of Lead-Acid Battery Efficiency Near Top-of-Charge (pdf)
Deep Cycle Battery FAQ, including AGM and gelled batteries.
Plate Thickness:
typical
automotive: 0.040"
typical golfcart: 0.070" to 0.110"
Trojan L-16 and US Battery L-16: 0.090"
Trojan T-105: 0.090"
Concorde AGM: 0.115"
Rolls CH-375: 0.150"
Rolls 6 CS-25 P (forklift): 0.265"
------
Rich Sheet Metal Works
(310) 829-2478 1725 Colorado Ave
Santa Monica, CA 90404
8-4:30 M-F
2.5 lb/sqft sheet lead will cut to any size $2.30/lb
4 lb/sqft is about 1/16" so 2.5 lb/sqft is about 0.039" thick.
Your Reference E-mail via
Web-site
Dated April 01 2005
Our Reference 148348//A F Scott
Date April 06 2005
For the attention of: Mr. Robert T. Drury
Our quotation reference : Q296354
Thank you for your inquiry referenced as above. We have pleasure in offering
subject to our standard conditions of sale as follows:
1. PB000411 Lead
Foil Thickness : 1.0mm
Purity : 99.95% Temper : As rolled
300 mm x 0.5 m $ 217.00 Lot
300 mm x 1 m $ 312.00 Lot
300 mm x 2 m $ 529.00 Lot
2. PB000401 Lead
Foil Thickness : 0.5mm
Purity : 99.95% Temper : As rolled
300 mm x 0.5 m $ 234.00 Lot
300 mm x 1 m $ 291.00 Lot
300 mm x 2 m $ 441.00 Lot
3. PB000450 Lead
Foil Thickness : 2.0mm
Purity : 99.95% Temper : As rolled
300 mm x 1 m $ 563.00 Lot
We offer our standard width coil (300mm) in standard lengths, longer lengths
can be offered if required.
Supplied for Research & Development purposes only.
I certify that all the chemical substances in this shipment are
not subject to the TSCA.
Signed ................... G. Few (Shipping Manager)
Goodfellow Corporation is classified by U.S. Government regulations as a accumulates
Small Business for purposes of Federal procurement.
Tolerances
Unless specified above our standard tolerances are :
Thickness: <0.010mm ±25%
0.010 - 0.050mm±15%
>0.050mm ±10%
Size (linear dimension):<100mm ±1mm
>=100mm +2% / -1%
Terms of payment To be agreed at the time you place an order.
Normal terms for established accounts : Nett 30 days
Shipment forecast 24 hours
after receipt of order.
Terms of shipment: Shipping costs included in our prices
We hope this quotation is of interest and look forward to hearing from you.
Goodfellow Corporation
(US representative of Goodfellow Cambridge Ltd, Huntingdon PE29 6WR, England)
EIN: 23-2557381
Goodfellow Corporation
237 Lancaster Avenue, Suite 252, DEVON, PA 19333-1594
Tel: 1-800-821-2870
Fax 1-800-283-2020
Updated: FILEDATE
Copyright (c) 2005-2013 Robert Drury
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
See "GNU Free Documentation License".
Disclaimer: This information may contain inaccuracies and is provided
without warranty. Safety first when working with high temperatures,
pressures, potentials, speeds, energies, various tools and materials.