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Lead Acid Batteries

Simple PbA cell made with plates of Lead & Lead Oxide in a waterproof container filled with sulfuric acid or battery acid. Before plastic, waxed wood boxes were used. In 1859 Frenchman Gaston Planté invented the first lead acid battery, a low energy density rechargeable battery technology that continues to be used today in automobiles worldwide as of 2024.

Watch this YouTube video https://youtu.be/FN1FUmyJpVE?si=VqlLjVYar-kXYmgF


Even our 2022 Toyota Corolla Hybrid with its 2ZR-FXE engine has a 45AH 12vdc SLI battery to the front drivers side of the engine bay. See images below. This car went without being driven for 10+ days because I was sick with a flu & cold virus back to back. The voltage was 11.8vdc when I measured it, so I used a cheap $27 fully automatic battery charger shipped same day from Amazon Prime to fully charge it, since keeping lead acid batteries fully charged makes them last longer.

In the Operating Manual of the SC1304 Schumacher Charger it says 12.8v + fully charge, 12.2-12.7v needs charging, less than 12.2v discharged- charge immediately!

Longer lasting when fully charge one the reasons the world's automakers continue using lead acid batteries, among other rechargeable battery types, lead acid works best when kept fully charged, accomplished in traditional gas powdered cars by the engines alternator once the engine is on & vehicle being operated. If the alternator works correctly, it takes about 2 hours of steady state highway driving to fully charge the vehicles battery. 

The SLI starting lighting & ignition battery provides energy for the keyless entry system, then to power the vehicles electrical loads so the engine can start when the ignition key is turned or the start button is depressed to turn the vehicle on.

2022 Toyota Corolla Hybrid Under the Hood
2ZR-FXE Engine + HSD Full Hybrid System
Net System Power 121-hp, 105-lb-ft

GS YUASA 345LN1-MF 45Ah @20HR Rate : CCA 295A
Made in Japan 12vdc SLI WET Flooded PbA Battery
This Battery Weighs 11.5kg or 25.35 lb
Dimensions in millimeters : W207xD175xH190
In inches thats W8.14"xD6.89"xH7.48" 
H4 LN1 also called Group 140R in USA

Not Always Engine Starting

In our 2022 Toyota Corolla Hybrid the PbA battery does not crank the engine, so its Ah or amp hours of energy storage are more important to enable the smart key systems to lock & unlock the vehicle, and to energize all the other electrical loads so that the vehicle can be started, where the start button effectively closed high current relays that use the traction battery & MG1 or the HSD system accomplish engine cranking nearly instantly. Our 2013 Honda PCX has a similar ACG system that instantly starts the engine, as the alternator combined as the starter motor directly on the engine crankshaft, as a 350W unit that easily cranks the single 153cc liquid cooled fuel injected engine in under 900 milliseconds when the starter button pressed, the engine instantly roars to life!

Terminal Corrosion Fix 

Once your car battery installed, your might notice corrosion near the positive terminal, as blue or white or green crystals. That's because the incompetent manufacture of the battery did not seal the top correctly, such that acid wicks up between the post terminal and the case, where dissimilar metals in cable connectors attacked to the terminal posts undergoes redox & oxidation reactions with sulfuric acid water & oxygen to form colorful blue, green or white crystals. These crystals are water soluble & contain lead which is a brain toxin, so wear nitrile gloves & rinse this off with distilled water, using a brass or copper or steel brush to clean the terminals, a post cleaner to clean the battery posts, then once everything clean & dry, attache the positive terminal connector first, then attach the negative terminal. Smear a nice thin layer of petroleum jelly over the connector & post to reduce corrosion. 

When the terminal connectors are disconnected from the battery, I recommend a nice bead of petroleum jelly applied where the terminal post  exits the battery case, at this interface is where acid vapor typically exist onto the terminals causing corrosion, so that layer of jelly applied blocks the vapors & prevents corrosive acid gas from corroding your terminals or connectors. Some enthusiasts use gold plated battery connectors. Once the battery hooked up and working, it's wise to put a thin layer of insulating jelly or paint over the parts prone to corrosion. 

These coatings to protect the terminal can produce an insulator that requires a clean wiping down in order to attach a battery charging clamp to get a good connection. You might have to use some IPA on microfiber to clean it up nicely. 

Another option are what are called terminal rings or battery terminal protection kit. These are colored red for the positive terminal and black for negative terminal, felt rings that are impregnated with an acid neutralizer to minimize terminal corrosion. These terminal cleaner and protection kits often contain a terminal cleaner with terminal connector cleaning brush, and battery terminal cleaner spray & terminal protector spray, and can be obtained from an automotive store for under $20. Wear eye protection & gloves when dealing with the battery terminals, since the lead & lead salts are toxic to your brain. 

Lithium Iron Phosphate 12V SLI Alternatives 

There are LiFePo4 or LFP or lithium iron phosphate batteries that replace SLI batteries, and I installed one of those in our 2013 Honda PCX150 scooter about 8 years ago & it still works, even though we rarely fire it up. I never actually have to charge the battery. Every month or so I turn the scooter on & ride it, even if its cold & rainy, just to keep the fluids moving, top it off with fresh ethanol free gasoline with fuel stabilizer added, and to pump up the tires. Vehicles that sit for long time have to be refurbished if you do not regularly use them. 

These LFP cost a lot more than AGM or SLI or PbA batteries, but weigh about 5X less or are about 1/5th the mass of a similar PbA battery with the same cranking amps or cold cranking amps or CCA rating. Typically LFP starting batteries do not have a lot of energy, such that they cannot run loads for as long as the same size format lead acid battery, in terms of Ah or amp hours of energy storage, and are typically tuned higher current LFP cells designed to send out a large amount of current to spin the starter motor when engages the flywheel or crank of the engine to start the engine, while other DC diverted to the ECU for spark plug ignition control & other functions to enable the engine to start while the dash lights & other accessories are also energized. 

One trick if you use and LFP in a motorsport vehicle, when you first turn it on after its been in storage for a long time, make sure to leave it on for at least 10 seconds before starting the engine, since it needs to be warmed up by the other electrical loads in order to achieve peak current for engine starting. If you charge the LFP you have to use a lithium specific 12v charger, as a normal car battery charger cannot charge lithium ion batteries. 

Lead Acid Batteries Are Economic Barometers

A societies net economic activity can actually be tracked by how much lead & sulfuric acid are consumed. I learned about this in the CIA Facebook about the world. Because 12v batteries are used in so many kinds of vehicles, cars, trucks, SUV, buses, RV's, boats, airplanes, motorcycles, scooters, literally there are millions of different vehicles that use lead acid starting batteries because they can provide high surge currents needed to spin the engine starting motor to crank the engine during engine cold start. The worldwide market for lead acid batteries worth more than $20 billion, and this kind of battery often used because of its low cost & widespread availability even where a newer battery technology offers better energy density. 

Lead Acid Failure Explored

The sulfuric acid electrolyte will sulfate the anode & cathode, lead & lead oxide plates respectively, especially as the voltage of the battery declines as it self discharges. Some power sport batteries are shipped with a dry PbA battery & a plastic cartridge with the battery acid that is pushed into the top of dry cell to wet the cells with acid, then the battery rests until the bubbling subsides & is charged up all the way using a WET Lead Acid battery charger with a amp or so current for small 6V and small 12v SLI batteries, perhaps 4-8amps for typical car batteries like 24F or 34, and 10amps + for larger AGM batteries or large capacity marine or truck batteries like 4D or 8D or 31MDC size respectively.

When fully charged the lead acid battery cells contains a cathode plate made of lead alloy (calcium, antimony), and an anode made of Lead Dioxide. In the fully charged state the watery sulfuric acid most concentrated. As the cell is discharged the sulfuric acid produces lead sulfate at the anode & cathode, reducing lead dioxide to lead sulfate & sulfating lead alloy to lead sulfate. Charging the lead acid cell forces reverse reactions restoring the cathode to lead alloy & anode to lead dioxide.


 

Overcharging Can Causes An Explosion

If a charger or alternator malfunctions & overcharges a lead acid battery, the plates start gasifying the water electrolyte into oxygen & hydrogen gas by virtues of the water undergoing high voltage electrolysis. In some wet cells, like a GC6 golf cart battery, distilled water must be added to replace any water lost from high heat evaporation or electrolytic decomposition. This is known as topping up the water in a battery, sometimes called topping up the acid, never add acid, only add distilled water. 

When a battery explosion occurs, the result typically means the plastic case rupture spilling battery acid, often spraying it in, near, and around where the battery installed, which can and often does cause corrosion of metals parts nearby in the engine bay or compartment where the battery stored. Rinsing this area with a weak baking soda solution then distilled water, then blowing the areas dry with a hair dryer or heat gun until no moisture remains a great way to neutral the acid & stop corrosion. 


Peak crank amps achieved near STP or standard temperature & pressure, namely room temperature, such that CCA are measure at freezing temperatures to judge how well the battery will send out engine cranking amps when the battery frozen cold. Since the electrolyte a solution of sulfuric acid & water colder temperatures reduce the performance, such that at 0F or -10C, a PbA can only discharge about 40% of its rated CCA. This means that vehicles operated in the arctic have to have battery heaters, engine bay heat blankets, block heaters, or have to be heated up by other means before they can be started in very cold conditions. Many vehicles operated in the arctic or extreme conditions have 2 large batteries, as do some diesel light duty trucks.

Cell shedding of the plates means that vibrations causes some of the plate materials of the anode and cathode to fall off the plates & accumulate at the bottom of the cells.

Gravity also causes some vertical stratification of the water acid concentration, such that the acid stronger at the the bottom than the top of the battery cell. AGM means absorbed glass mat, effectively like wrapping the anode & cathode in acid soaked fiberglass that holds everything in place longer. In practice AGM batteries last twice as long as flood types, are 10X more durable under deep discharge conditions, and tolerate higher heat, more vibration & harsh conditions better. Fumed silica added to GEL cells to improve the battery life in power chairs & hospital equipment, telecom batteries, or backup batteries, on ships & in other applications with lots of NVH or noise vibration and harshness.


Lead A Recycling Victory

Over 98% of lead acid batteries are recycled in the USA due to a core rebate program where people get $20 for turning in their old car batteries, boat batteries, or RV batteries, or Golf Batteries or Truck batteries etc. Lead bullets shot into nature are one major way lead enters environments. Lead wheel weights that fling off & some lead fishing lures are other routes of lead entering the environment. In the past lead oxide a white pigment, was used in leaded paint, though titanium dioxide replaced lead oxide as the white pigment in lead free paint sold today.


Lead is Toxic

Lead is very poisonous because it blocks the citric acid cycle, accumulates in the brain, kidneys & bones, and has a valence electron configuration that enables it to break cells like a catalysts, causing brain damage, kidney damage & bone damage respectively. The brain damaging effect of lead reason that almost all modern gasoline unleaded as TEL or tetraethyl lead was added as an anti-knock & engine lubricant in leaded gasoline sold many decades ago. 100LL or low lead gasoline still sold at airports for some piston powered helicopters.


Measuring Voltage or State of Charge 

The specific gravity of battery acid can be used to determine the state of charge, usually done with a ball float tool with a rubber bulb that sucks battery acid into the tool, made of clear plastic demarcated with information, such that the ball of a specific density will float to a specific indicated level, showing the state of charge.

Lead Acid battery cathodes of lead dioxide produce hydrogen + ions that move into the aqueous sulfuric acid electrolyte while sulfate ions are consumed at the anode & cathode. This process entirely reverses upon charging, and convective forces churn the liquid electrolyte around such that WET batteries tend to have faster charging & more rapid discharging, where AGM & GEL cells inhibit electrolyte circulation, which means they have to be charged at higher voltage also.
Open circuit voltage is what you measure in a car turned off thats been parked, when you pop the hood & hit the battery terminals with a volt meter to measure the floating voltage. This floating voltage should be above 10.5v which is fully discharged. 12.8vdc means fully charged. 11.3vdc about 1/2 or 50% charged. 14.2vdc a full charge when charging, though the charger will probably use 15.1vdc to accomplish the required delta or voltage differential to accomplish charging with enough electron pressure.

The nominal voltage for a lead acid cell 2.2V or 13.2vdc for a 12V battery. Fully discharge lead acid cells are 1.8vdc or 10.8vdc for 12v automotive battery. Aim to keep your vehicle battery above 12.5vdc, as close to 12.8v as possible with periodic battery charging using a 12v car battery charger, or by driving your vehicle at least 2 hours so the alternator or DC to DC converter can fully charge the battery.

Advance 7 Stage Automatic Battery Chargers

Many modern PbA chargers use a pulsing de-sulfate mode at 2.67v or even 3V, 16v to 18v for a 12 V battery to under Sulfation of the anode & cathode that happens during deep discharged states if a car has been sitting for a long time without use. The voltage drops to a lower charging voltage once current starts flowing. Sometimes a dead car battery below 4vdc requires a special charging mode to reform the plates & effectively charge the battery back up. AGM are much more fault tolerating to deep discharge than wet flooded batteries.

The charging stages are optimized to enhance the charge effectively, power efficiency of charging, and to prolong the life of the battery. Many people use battery maintainers on the starting batteries of seasonal use vehicles, like a law mower with electric start. Our 2020 Yamaha MT-03 has a small AGM battery, but I only use it during dry weather when it's above 50F outside, so it sits around without being used much. I hook a battery charger in AGM mode to top off the battery every few weeks to keep the battery fully charged, which makes lead acid batteries last a lot longer. We only drive our 01 Audi once per week, so mid week I throw a battery charger on that large 48AGM in AGM mode & top charge it.

Construction of a Modern Lead-Acid Battery

Making Modern PbA Batteries an Industrial Art

The plate in a modern battery are actually a screen grid made of lead selenium or lead calcium antimony thats much stronger than pure lead. These screen grid plates are then coated with lead paste & lead dioxide paste in a high humidity steam environment to form the cells. Newer battery paste made with carbon black, barium sulfate, and lignosufonate mixes that act as nucleation points for seed crystal formation to start the long dendrite high surface area formation of needle like structures the enable massive electron flow for high current cold cranking of engines. These long crystals are easily converted back to chemical intermediates upon charging. A dispersant additive made of sulfonated naphthalene improves barium sulfate mobility in the paste, enabling more rapid steam vapor setting of new cell paste, making the plate more break resistant, reducing fine lead particles, improving the handling and pasting properties, thereby increasing the battery life by increasing end of charge voltage and making the cells more stabile in higher temperatures in the engine bay when the engine fully hot or during hot summer weather operation, when racing & similar. 

PbA in Modern EV's 

Even modern EV's typically have a 12v lead acid battery that acts to enable electronic locking & access, when the vehicle turned off. Almost all automotive electronics are 12vdc as they were designed when LEAD ACID batteries were the only practical SLI battery, and that creates a lot of inertial for low voltage systems, even though 24 and 48v automotive voltage systems are proposed, it takes a long time to overcome technological lock-in effective of 12v being so common in so many components made by so many different venders & OEM's. This creates a lot of global market inertia to keep using 12v even though higher voltages would enable smaller lower mass lighter wires to carry more power. Most hybrid & EV's use 300-800 V between the battery pack and traction motors, so that smaller wires can move hundreds of KW of power for acceleration or brake regeneration charging. 

Heavy LEAD Acid Benefit

In hospitals carts, wheel chairs, fork lifts, and submarines, the heavy mass of lead acid batteries acts as counter balance or ballast weight such that he higher mass actually a benefit for stabilization. In an electric power chair for example, it's safer for the system to have a lower center of gravity, so the heavy lead batteries below help to lower the center of gravity, making the chair bottom heavy or resistant to tipping over. Diesel-electric locomotives and even nuclear submarines use lead acid batteries for similar reasons. Sealed valve regulated AGM batteries are used in common computer UPS systems, in data center power backup systems, in alarm systems as power backup, in some electric scooters, and were used in early vacuum tube electric radio receives and mining lamps. 

Lead Metal

Lead Pb82 

One of the most interesting metals, lead the highest atomic element number of any stabile element and the end decay product of the natural decay of radioactive isotopes in natures, but is toxic even in tiny amounts, and children are especially sensitive to its toxic effects. Children eating paint chips made of leaded paint an issue because lead oxide has a sweet taste, so in older buildings where the paint flaking away, sometimes small children are prone to eating pieces of it because they put random stuff in their mouth as part of their early development. This is why lead oxide was phased out of lead and nearly all modern paints use titanium dioxide or zinc oxide as the white pigment.

Freshly cut metallic lead a soft malleable metal and was used to make early pipes in antiquity. Metallic lead has a shiny grey metallic with a slight blue tinge, but oxidizes in moist air to a dull grey oxide. It resists corrosion due to the formation of passivation oxides on surface, like chromium or aluminum.

The low melting point of lead combined with its high density makes it easy to cast into weights, bullets, & other dense items with low heat, even used in stained glass to bind the parts together, in solder to joint metallic parts in plumbing and electrical.

In early human history lead ore could be rendered easily with crude fire due to its low density and propensity to accrete to other lead molecules in polyhedral bonding structures, similar to other lighter elements in the same grouping of the periodic table of the elements. In Ancient Rome the silver bearing ore Gelena contains lead sulfide, a crystal used to make early crystal radios, but the interest in silver gave rise to widespread use of lead, which decline after the collapse of the Roman Empire.

In Europe the low melting point of lead made it possible to cast movable type font printing plate letters which were able to be assembled into words, then sentences, and paragraphs, in printing racks to hold all the cast lead letter parts in place for inking, after which the printing plate inked pressed into paper, which started the modern printing revolution or what eventually fueled the high renaissance by making information access less expensive and printed materials more widely available, eventually adopted into high volume offset printing press technology to mass produce newspapers, though still done in small artisan book printing applications as of 2024 in San Diego for example. Millions of tons of lead are mined annually since lead so useful in construction, plumbing, batteries, bullets, shots, weights, solders, pewter, fusible alloys, paint, gasoline with TEL, and even as radiation shielding. As a heavy metal neurotoxin lead bioaccumulates in soft tissue & bones, first noted as lead poisoning or the toxicity of lead by Ancient Greek & Ancient Roman writers who noticed the symptoms of lead poisoning.

With a high density of 11.34 grams per cubic centimeter, it compares against copper at 8.93 or iron at 7.87. The close face centered cubic structure gives it high volumetric density. The idiom "This or that will go over like a lead ballon" references the high mass density of lead. Gold and tungsten are 19.3 grams per cubic centimeter, and osmium 22.59 the most dense. With a Mohs hardness of only 1.5 lead can be scratched with a fingernail, also very malleable and ductile. Bulk modulus is a measure of how much something can be compressed, where lead scores 45.8 gigapascal, compared with 75.2 for aluminum or 169 for mild steel. Tensile strength measure strength under tension like pulling on a wire, and lead has very low tensity strength, 10x less than copper, 15X less that mild steel, though alloying lead with copper or antinomy improves its tensity strength. Lead melts at only 621.5 F or 327.5 C and boils at 3180 F or 1749 C. Lead has poor electrical conductivity of only 192 nano ohm per meter, copper 15.43, gold 20.51, aluminum 24.15, though at 7.19 degrees Kelvin, lead becomes a superconductor.

Lead rod heat on a bunsen burner

The passivation layer on the surface of lead varies depending on what reacted with it, though typically lead carbonate, though the sulfate of lead or lead chloride are common in urban environments due to air pollutants. Finely powdered lead readily spontaneously combusts in air as a pyrophoric and burns with a blue white flame.

Lead fluoride forms at room temperature, but readily combines with chlorine if heated, but can also react with oxygen, sulfur and other halogens to produce lead chalcogenides. Its lead's ability to resist reacting with sulfuric acid that enabled the Lead Acid battery to be made as the first rechargeable battery type 1859. Lead also incredibly resistant to phosphoric acid, though nitric and hydrochloric acid can attack lead. Even vinegar can dissolve lead if oxygen present.

Sulfuric Acid Battery Electrolyte
Pack to Fill 4L-BS Power-sports Battery
Which are Stored dry for long shelf life.
Acid pack pushed into top of battery
filling battery with acid, then capped.
Once bubbles subside, its charged up!

Oil of Vitriol or Sulfuric Acid a viscous liquid that readily reacts with water, its colorless and odorless, but a strong acid that easily corrodes rocks & metals and has powder dehydrating properties to flesh where it can cause serious chemical burns. If concentrated sulfuric acid added to water it produces so much heat upon dissolving that it boils and spatters through acid mist fumes off which can cause thermal burns & chemical burns, so gloves and eye protection important when working with battery acid. Water is always added to the acid slowly to minimize the thermal spiking that causes the problem when acid is added to water. In lead acid batteries the sulfuric acid typically 15 to 35 % concentration, but can be as high as 50%, the remainder being water. The industrial strength of an economy can be determine by measuring how much suffering acid is produced as a commodity chemical, in the wet sulfuric acid profess, lead chamber process, in fertilizer manufacturing synthesis, acid drain cleaners, cleaning agents, you can make sulfuring acid by dissolving sulfur trioxide in water. Sulfuric acid (H2S04) is a corrosive substance, destructive to the skin, eyes, teeth, and lungs.







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