The Secret Life Inside Lead-Acid Batteries

Did you ever wonder what happens inside the sturdy cases of our sealed lead-acid batteries? Well the truth of the matter is chemicals are whizzing around creating energy. We decided to disclose the secret life inside lead-acid batteries in a series of short posts. So relax, pull up a chair and discover what few other people may know.

How Do Lead Plates Generate Electricity in Sulfuric Acid?

Lead-acid batteries contain a number of cells. Each or these has a pair of plates. One of these is a positive electrode, while the other is a negative one. The two plates are physically separated by diluted sulfuric acid solution called electrolyte.

Each cell comprising two plates is capable of delivering around 2.1 volts when holding full charge. So if you need 6 volts you need a battery comprising three cells. Whereas if you need 12 volts you need 6. Dead simple so far!

Yes it is, although there is a bit more about this to know. First the lead plates on each cell are actually grids with slightly different chemical compositions. And secondly they have different active materials bonded to their surfaces.

And Now for the Secret Life Inside Lead-Acid Batteries

Every kid at school should know what we told you so far. But how many understand what happens when you connect a lead battery to a device? When you use the battery it discharges by giving up some of its stored energy. Chemically speaking, this consumes some of the sulfuric acid in the water solution.

The secret life inside lead-acid batteries unfolds further as sulfate from the acid gradually coats the plates. This reduces the surface available for the chemical reaction to continue. When the plates are fully covered over, the reaction stops and the battery is flat.

That could be the end of the road for single-use batteries. However, we can renew the lives of lead-acid batteries by recharging them. Because recharging returns the sulfate to the acid, so the process can begin over again. Well, almost all of the sulfate that is, because some of it remains on the plates each time. Not even solid lead-acid batteries last forever. But that’s life!