Lead
Acid
It 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 are
Negative. 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 path
that'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's
electric bits are connected to the battery terminals by the wiring harness and that makes one complete electrical circuit
when you switch on the ignitions all those
electrons 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 up
electrons. When the lead plates get completely coated in lead sulfate and the sulfuric acid is diluted with water
Well you got a depleted battery
But one of the cool things about a lead acid
battery, is that those chemical reactions can be reversed, And that allows you to repeat the process over
And over and over again and over and over and over and over again
over and over and over and over
But, 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 that
sulfate scaling trying to get the battery to accept a charge, but when the battery's done
It's done, but there's some other concerns with traditional lead acid batteries when this reaction is happening
Sometimes 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 battery
Well, unfortunately
Sometimes 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 an
alternating current
that's called AC,
but to get that into the battery it's to change it into a direct current or DC
AC/DC
An alternator converts some of the mechanical energy from your engine into electricity
the battery is really only there to fire the engine up and run some of the
accessories when the engines off. When the engines on the alternator produces all the electricity that your car needs while also
continuously 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?
Magic
Oh, yeah, okay
Here's what really happens the alternators driven off the crankshaft by a belt that spins a rotor inside the alternator
There's a series of magnets with alternating
north-south poll directions that are placed around the rotor the whole thing is surrounded by a
Stationary set of copper wires now. I know this sounds crazy
But when you pass a magnet over a conductive wire
It makes an electric current with several magnets being
continuously 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 typical
direct current generator does.
At idle cars need more than a DC generator
can make and so that's why we use alternators
look a bunch of Voodoo hocus pocus goes on in there that has to do with
electromagnetic fields
alternating currents
All we really need to know is that a lot of electricity
comes shooting out of there and it's in the wrong format and it needs to get converted to the right format
so they you can operate your power windows to accomplish that the
AC 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 thing
So after the AC/DC
conversion, a voltage regulator stands between the diodes and the battery to determine how much electricity
passes by. With the electrons now flowing into the battery, lead sulfate gets broken back down and the whole
process can start all over again.
BATTERIES!
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