Cars+Group+6

Group 6 - Julie, Sarah, and Cindy

=BATTERIES!= The chemistry determines the voltage of a cell and the number of cells determines the voltage of the battery. A standard car battery is six lead/acid cells in series.

Batteries contain sulfuric acid. That's one of the six strong acids! Sulfuric acid is used because it combines with water to produce electrolytes. A car battery can deliver up to 300 amps if short circuited! This is very dangerous. Extreme heating can result, lots of outgassing, the plates will overheat and warp and the battery will be destroyed, often dramatically. However, this is exactly what happens when you crank a starter motor. The battery survives because these large cranking loads are very short lived. Be very careful when transporting charged batteries and hooking them up. **Shorting the terminals of a large battery can be quite dangerous.**

When a load completes the circuit between the two terminals, the battery produces electricity through a series of electromagnetic reactions between the anode, cathode and electrolyte. The anode experiences an **oxidation reaction** in which two or more **ions** (electrically charged atoms or molecules) from the electrolyte combine with the anode, producing a compound and releasing one or more electrons. At the same time, the cathode goes through a **reduction reaction** in which the cathode substance, ions and free electrons also combine to form compounds. While this action may sound complicated, it's actually very simple: The reaction in the anode creates electrons, and the reaction in the cathode absorbs them. The net product is electricity. The battery will continue to produce electricity until one or both of the electrodes run out of the substance necessary for the reactions to occur.

Most car batteries are lead-acid batteries. The lead acid battery is made up of plates, lead, and lead oxide (various other elements are used to change density, hardness, porosity, etc.) with a 35% sulfuric acid and 65% water solution. This solution is called electrolyte which causes a **chemical reaction** **that produce electrons**. When you test a battery with a hydrometer you are measuring the amount of sulfuric acid in the electrolyte. If your reading is low, that means the chemistry that makes electrons is lacking. So where did the sulfur go? It is stuck to the battery plates and when you recharge the battery the sulfur returns to the electrolyte. Basically there are **two types of batteries**; starting (cranking), and deep cycle( marine/golf cart). The **starting battery** is designed to deliver quick bursts of energy (such as starting engines) and have a greater plate count. The plates will also be thinner and have somewhat different material composition. The **deep cycle battery** has less instant energy but greater long-term energy delivery. Deep cycle batteries have thicker plates and can survive a number of discharge cycles. Starting batteries should not be used for deep cycle applications. The so-called Dual Purpose Battery is only a compromise between the 2 types of batteries.

http://chemistry.about.com/od/howthingsworkfaqs/f/coldbattery.htm

Video Ideas: Changing a car battery Jumping a car battery Talk about how a car battery works Discuss the chemistry behind a car battery

**__ List your suggestions below: __**
Amanda and Emily- common disfunctions of batteries Hanna & Kayla: What causes a car battery to go bad? Kayla K & Sienna G- Brands of batteries and cost Dylan and Paul- Show how cold weather effects a battery Norbert and Ethan - Show the dangers of battery acid. Katelynn and Amanda- explain how to safely change a car battery. Alex - Explain how jump starting a car works.