The Magic of Lead-Acid Batteries: A Comprehensive Guide

Lead-acid batteries are a crucial component in most vehicles, providing the power needed to start the engine and run various accessories. But have you ever wondered what makes these batteries tick? In this article, we'll delve into the inner workings of lead-acid batteries, exploring their structure, operation, and limitations.

A 12-volt, lead-acid car battery consists of six cells, each producing two volts. These cells are connected in series, with a positive terminal on one end and a negative terminal on the other. The plates hanging out in an electrolyte bath of about 65 percent water and 35 percent sulfuric acid play a crucial role in the battery's operation.

When the acid is in solution, hydrogen ions and sulfate ions are free to interact with the lead and lead dioxide plates. The hydrogen ions bond with the lead dioxide, yielding a lead oxide and H2O, effectively giving the terminal a positive charge. At the same time, sulfate ions bond with the lead surface, forming lead sulfate and giving the terminal a negative charge.

As the battery isn't being used, electrons gather around the negative terminal, not super happy about it, as they are negatively charged. They'd rather head over to balance things out on the positive side of the battery. However, they can't move through the sulfuric acid bath to get there. A circuit, a conductive loop through which electricity can travel, provides an alternative path for the electrons.

When you switch on the ignition, those stored-up electrons are released, racing out through the negative terminal, through the wiring harness, and powering your dash light, stereo, and everything else that runs off electricity. The chemical reactions in the flow of electricity can keep going until there's nothing left with which to free electrons.

However, if your battery loses all its juice, well, those lead plates are coated with so much sulfate that the reaction won't reverse. Some battery chargers have a descaling or reconditioning mode, using a different kind of current to try to break up the sulfate scaling, getting the battery to accept a charge.

But there are concerns with traditional lead-acid batteries when this reaction is happening. Sometimes we're producing a lot of gas, and if the battery isn't properly vented, KAPOW! Now that we've got a properly vented battery, unfortunately, sometimes the H2O evaporates, throwing off the balance of acid and water.

To ensure your battery doesn't just run out of juice when you're driving around, there's an alternator. The alternator gets its name from the fact that it produces electricity in an alternating current (AC). But to get that into the battery, it needs to change it into a direct current (DC).

The alternator converts some of the mechanical energy from your engine into electricity, which is really only there to fire the engine up and run some accessories when the engine is off. The alternator produces AC power, but this needs to be converted to DC so that the car's electrical bits are powered.

So how does it convert mechanical power to electric current? It's not magic, but a series of magnets with alternating north-south pole directions placed around a rotor inside the alternator. These magnets make an electric current when they interact with a coil, which is then converted into DC power by diodes and a voltage regulator.

A voltage regulator stands between the diodes and the battery to determine how much electricity passes by, ensuring that the electrons now flowing into the battery break down lead sulfate and start the process all over again. With this comprehensive understanding of lead-acid batteries and alternators, you'll be better equipped to appreciate the intricacies of vehicle maintenance and repair.

Batteries! This episode of Science Garage is brought to you by Yourselves! Guys, thanks for watching. We couldn't do all this cool stuff without you, tune in every Wednesday. Click this subscribe button so you never miss an episode. Check out the up-to-speed on NISMO. Check out Nolan's wheelhouse on how to import foreign cars. Check out shop.donut.media. Follow me on instagram at BIDSBARTO, follow Donut at DONUTMEDIA. Don't tell my wife I left the dome light on. I'm gonna blame it on her!

WEBVTTKind: captionsLanguage: enLeadAcidIt can burn your face off.It can blow up.But you know what else?It can start your car.We're talking about lead-acid batteries.So, lead, and acid.I already said that.A 12-volt, lead-acid car battery consists of six cells.That each produce two volts.Each cell holds two thin plates.One is lead, and the other is lead-dioxide.The plates hang out in an electrolyte bath of about 65 percent water, and 35 percent sulfuric acid.The cells are connected in series.And there's a positive terminal on one end, and a negative terminal on the other.When the acid's in solution, the hydrogen ions and the sulfate ions are free.To interact with the lead and the lead dioxide plates, the hydrogen's bond with the lead dioxide yielding a lead oxide and H2O.It effectively gives the terminal a positive charge.While this is happening on the lead dioxide plate,sulfate ions are busy bonding with the lead surface forming lead sulfate.and giving that terminal a negative charge.So when the battery isn't being used the electrons gather around the negative terminal and they're not super happy about it either.After all they areNegative. They'd rather head over and balance things out over on the positive side on the battery.But they can't move through the sulfuric acid bath to get there. They need a different paththat'll let them travel around to the positive side.That would be a circuit, which is a conductive loop through which electricity can travel all of your car'selectric bits are connected to the battery terminals by the wiring harness and that makes one complete electrical circuitwhen you switch on the ignitions all thoseelectrons stored up in the battery get released.They race out through the negative terminal, through the wiring harness to power your dash light. stereo and everything else that runs off electricity.And then they get over to the positive side of the battery.Ah home at last, the chemical reactions in the flow of electricity can keep going until there's nothing left with which to free upelectrons. When the lead plates get completely coated in lead sulfate and the sulfuric acid is diluted with waterWell you got a depleted batteryBut one of the cool things about a lead acidbattery, is that those chemical reactions can be reversed, And that allows you to repeat the process overAnd over and over again and over and over and over and over againover and over and over and overBut, if your battery loses all its juice,well those lead plates are coated with so much sulfate,that the reaction won't reverse.Some battery chargers have what's called a descaling or reconditioning mode.And that uses, a different sneaky pulsating kind of current to try to break up all thatsulfate scaling trying to get the battery to accept a charge, but when the battery's doneIt's done, but there's some other concerns with traditional lead acid batteries when this reaction is happeningSometimes we're producing a lot of gas. If the battery isn't properly vented well,KAPOW!And now that we've got a properly vented batteryWell, unfortunatelySometimes that H2O is gonna evaporate, then it throws off the balance of acid and water.Sometimes you got to recharge it which is different than recharging it. You know what I mean.So how do you make sure that your battery doesn't just run out of juice when you're driving around?The alternator.The alternator gets its name from the fact that it produces electricity in analternating currentthat's called AC,but to get that into the battery it's to change it into a direct current or DCAC/DCAn alternator converts some of the mechanical energy from your engine into electricitythe battery is really only there to fire the engine up and run some of theaccessories when the engines off. When the engines on the alternator produces all the electricity that your car needs while alsocontinuously recharging the battery. An alternator is a little AC power generator that's bolted to your car's engine.So how does it convert mechanical power to electric current?MagicOh, yeah, okayHere's what really happens the alternators driven off the crankshaft by a belt that spins a rotor inside the alternatorThere's a series of magnets with alternatingnorth-south poll directions that are placed around the rotor the whole thing is surrounded by aStationary set of copper wires now. I know this sounds crazyBut when you pass a magnet over a conductive wireIt makes an electric current with several magnets beingcontinuously moved over a crap-ton of wires inside an alternator you get quite a bit of electricity.In fact, it makes a lot more electricity than a typicaldirect current generator does.At idle cars need more than a DC generatorcan make and so that's why we use alternatorslook a bunch of Voodoo hocus pocus goes on in there that has to do withelectromagnetic fieldsalternating currentsAll we really need to know is that a lot of electricitycomes shooting out of there and it's in the wrong format and it needs to get converted to the right formatso they you can operate your power windows to accomplish that theAC power is routed to the diodes that stop the current from alternating effectively forcing it in one direction.The alternator typically makes more voltage than a battery can handle 13 and a half to 15 volts.Compared to the 12 that your battery likes to hold on to pumping in too much power can fry that thingSo after the AC/DCconversion, a voltage regulator stands between the diodes and the battery to determine how much electricitypasses by. With the electrons now flowing into the battery, lead sulfate gets broken back down and the wholeprocess can start all over again.BATTERIES!This episode of science garage is brought to you byYourselves! Guys, thanks for watching. We couldn't do all this cool stuff without you, tune in every WednesdayClick this subscribe button so you never miss an episodeCheck out the up to speed on NISMO. Check out Nolan's wheelhouse on how to import foreign cars.Check out shop.donut.media. Follow me on instagram at BIDSBARTO, follow Donut at DONUTMEDIA. Don't tell my wifeI left the dome light on. I'm gonna blame it on her