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What Does The Battery Do?
The battery's main function is supplying power to the starter motor of the vehicle, which is what allows the vehicle to crank over to start. The battery also provides electrical power for the vehicle when the alternator doesn't provide enough and it smooths out current ripples (like a capacitor) to protect more sensitive electronics.
Different Types of Batteries:
Flooded Lead Acid Batter (Wet Cell)
Oldest and most common that consists of a liquid electrolyte solution that supplies 12.6V at full charge
Reliable but it needs the solution to be topped off to avoid reduction in battery life (occurs at 50% depth-of discharge (DoD)* and has to be vertical to avoid spillage
2. Silver Calcium Battery
Improvement of the Wet Cell that has lead-calcium-silver plates instead of the lead-alimony plates and is usually sealed/maintenance free
More resistant to corrosion and high temps, but requires higher charging voltage and deteriorates if battery plates are damaged (Sulfation)
3. Enhanced Flooded Battery (EFB)
Optimized version of Wet Cell that is designed to take twice the cycling endurance
Sealed battery that can provide approx. 85,000 cranks to the 30,000 of the conventional battery and a lower-tier version of the AGM
4. Gel Cell Battery (Dry Cell)
Non-spill version of Flooded Battery and is a type of VRLA
Uses calcium instead of antimony in the lead plates and has silica added to the solution to make it a gel
Increased cycle and resistance to vibrations, but advances with AGM batteries has limited the application of them
*Depth-of-Discharge: Percentage that battery can be drained to without damaging it
5. Absorbent Glass Mat Battery (AGM)
VRLA battery to support electricity in modern vehicles that has a fiberglass separator ("glass mat") that absorbs the electrolytes and keeps them in place
Charges 5 times faster, has 3 times more life cycle and can cycle down to 80% DoD
Ideal for vehicles that have automatic start-stop, but can cost 40-100% more than conventional batteries
6. Deep Cycle Battery
Can either be flooded or sealed and has thicker battery plates along with
denser active material
Designed for lower current draws for longer periods of time
Recreational vehicles, golf carts, marine vehicles ("Marine Battery")
7. Lithium Ion (Li-Ion) Battery
For hybrid or electric vehicles, stores more energy, and has less charging time
Lighter than regular batteries, but also costs more
Lasts longer than lead acid batteries and are recyclable
8. Nickle Metal Hydride (NiMH) Battery
Longer life cycle than both Li-Ion and Lead Acid, but very expensive and a short shelf life
Mainly used in hybrid vehicles due to heat generated at high levels, which isn't effective for recharging
Related Parts:
Alternator
Generator for electric power to charge batter and power the electrical system
Converts rotational energy into electrical energy
Capacitor
Stores energy to be discharged instantly when audio system requires more energy
EX. lights don't dim when audio needs more power
Mainly found in higher end audio systems that have enhanced aspects like bass or larger speakers
Major Car Battery Designs:
Flooded Battery
Wet cell battery that requires to be regularly topped off with distilled water
Valve Regulated Lead Acid (VRLA) Battery
Low-maintenance, sealed, and won't spill
Also known as a Sealed Lead Acid (SLA) Battery
Lithium Ion Battery
Mainly used in hybrid or electric cars
What Makes Up A Battery?
Plate Block
Acid
What is Battery Acid?
Diluted sulfuric acid solution
Facilitates the flow of electrical currents between plates and is a conductive medium to allow for storage and discharge of energy
What is a Plate Block:
A plate block is the battery cell that is made up of negative and positive plate sets.
The items within the plate sets are described as the electrodes of the respective charges.
The items within an electrode are as follows:
Positive electrode:
Positive Plate-
Positively charged plate that consists of lead oxide (lead-oxygen mixture) that is immersed in an electrolyte
Positive Grid-
Positive grid consisting of a lead alloy to hold the active material and acts as a current collector
Negative Electrode:
Negative Plate-
Negatively charged plate that consists of pure lead and is also immersed in an electrolyte
Negative Grid-
Negative grid that has a lead alloy and serves the same purpose as the positive grid
The electrodes are separated by a separator bag if the charges are different.
The electrolyte is a mix of sulfuric acid and distilled water that is either in a liquid form, a gel form, or bound in a glass mat.
Reaction Occurring Within The Battery
The battery has energy stores in a chemical form and converts it into electrical energy. The main elements that are interacting are Hydrogen, Oxygen, Lead, and Sulfur.
The process goes as follows:
The electrolyte decomposes into positively charged hydrogen ions and negatively charged sulfate ions
Electrons travel from the negative to the positive electrode through an external consumer at the same time as the prior step
Sulfate ions travel to the negative electrode where they react with the lead to make lead sulfate
Lead oxide bond is broken by transfer of electrons and oxygen passing into the electrode, remaining lead bonds with sulfate from electrolyte
Oxygen bonds with hydrogen to make water and the sulfuric acid is used by the formation of lead sulfate—which reduces the amount of the electrolyte solution
When the level of sulfuric acid falls below a certain level, the battery had to be recharged
Charging the battery causes the process to take place in reverse order and the original elements are found once more.
The conversion process does have losses, so the battery can only do a limited number of recharges.
Problems With Lead Acid Batteries
Acid Layering
If the battery is charged with a voltage too low or operates at a voltage too low, stratification will occur.
Stratification is the dividing of layers due to varying densities of the liquids.
When stratification occurs, only the middle section of the electrolyte can be used
Can be caused when short journeys with high use of electrical consumers happen frequently.
Sulfation
A result of acid layering and occurs if the lead sulfate crystallizes on the electrodes to form a crystalized structure.
The crystallization prevents reconversion between lead sulfate and lead/lead oxygen.
Can be prevented by making sure the battery is never at a low charge for a long time.
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