- by Bryan Veldboom - updated on 2/24/2022
Rechargeable batteries are all around us, in our cars, phones and laptops. Chances are pretty good you've already used one thing that's powered by a rechargeable battery today. While the batteries themselves may vary, the one thing they all have in common is their reliance on battery chargers. Battery chargers help recharge batteries by reversing the chemical processes that enable them to provide power in the first place. Today we'll take a close look at the science behind battery recharging. We'll explain the dangers posed by under and overcharging your battery, discuss different charging methods and review the different types of battery chargers available.
Obviously, there are too many different types of batteries to discuss in one place, so for our purposes here we'll be focusing on lead acid batteries. Lead acid batteries are used in a variety of applications, however, they are most commonly used as starting batteries in cars, trucks, boats and other vehicles.
Before we get into recharging though, we need to walk through the basics of how a lead acid battery works. The interior of a 12 volt lead acid battery is divided into 6 separate cells. Each cell contains a series of rectangular grids holding a number of lead plates. The grids are arranged in an alternating series of positively and negatively charged grids, each of which is divided by a separator. The battery also contains a sulphuric acid solution called an electrolyte which reacts with the material on the positively and negatively charged grids.
When the battery is connected to a load and switched on, it causes a series of chemical reactions inside which convert lead, lead oxides and acid from the electrolyte into free electrons, water and lead sulfates. For a more in-depth look at this process, check out our blog entitled "How Does a Car Battery Work?" When the battery's voltage drops to the point where it can no longer deliver electricity, it has been discharged.
Battery chargers work by reversing the chemical processes that allowed the battery to provide electricity in the first place, restoring the components to their original state. During the recharging process, the sulfate in both the positive and negative plates are split back into their original lead and sulfate. The water left over from the electrolyte is divided into hydrogen and oxygen. The sulfate in the plates combines with the hydrogen in the water, restoring the electrolyte to its original state as sulfuric acid is formed. While this is happening, the oxygen in the water will also combine with lead on the positive plates to form lead dioxide. When this process is complete, the battery has been recharged and can be used once again.
When charging a battery, it's important to avoid both under and overcharging it. If you apply too little current, the battery will remain undercharged. When a battery is undercharged, the chemical processes aren't allowed to complete and lead sulfate remains on the battery's plates. Sulfation has a negative impact on your battery's performance, leading to longer charging times, shorter run times between charges and a shorter overall lifespan.
Overcharging can be equally damaging. Applying too much current cooks the components inside your battery. This can cause the water in the electrolyte to break into oxygen and hydrogen, creating a buildup of flammable gasses that need to be vented. This loss of hydrogen and oxygen throws off the chemical composition of the electrolyte, making it far too acidic. Overcharging can also cause the battery's plates to corrode, harming the battery's performance and shortening its lifespan. If you overcharge a battery too much, you can kill it completely.
Battery chargers are designed to work with a particular battery chemistry at a particular voltage in order to apply the correct amount of electrical current. That's why it's important to use a charger that matches your battery's chemistry and voltage. Keeping that in mind, there are essentially three basic types of battery chargers available for lead acid batteries: standard chargers, trickle chargers and battery maintainers.
Visit Batteries Plus online or in-store for all of your charging needs. We carry battery chargers for cars and trucks, motorcycles, boats and so much more. If you want to know more about this topic, we have plenty of helpful articles in our online blog. Some related articles include "How Far Do I Need to Drive to Charge My Car Battery?" and "How Do Battery Charging Cycles Work?"