Aux 1 Unit 16 Q4

Storage batteries, also known as secondary batteries or rechargeable batteries, are electrochemical devices that can store electrical energy in the form of chemical energy and then release it on demand as electrical energy. They are composed of one or more electrochemical cells, where chemical reactions occur to convert between electrical and chemical energy.  

1. DOE Explains…Batteries – Department of Energy

2. Batteries: Electricity though chemical reactions – Chemistry LibreTexts

Key Features:

• Rechargeability: The primary characteristic of storage batteries is their ability to be recharged multiple times. This is achieved by reversing the chemical reactions that occur during discharge, effectively replenishing the stored energy.   1. Storage battery Definition & Meaning – Merriam-Webster www.merriam-webster.com
• Energy Storage: They store electrical energy generated by sources like generators, solar panels, or shore power for later use.   1. Battery Storage vs. Generator, What’s Best for You? | Briggs & Stratton energy.briggsandstratton.com
• DC Power: Storage batteries typically store and supply direct current (DC) electricity.   1. Battery Energy Storage System (BESS) | The Ultimate Guide – Edina.eu www.edina.eu
• Various Chemistries: Several different chemistries are used for storage batteries, each with its own advantages and disadvantages, including:
  • Lead-acid: Common and affordable, but have a lower energy density and shorter lifespan compared to some newer technologies.   1. Lead-acid battery – Wikipedia en.wikipedia.org
  • Lithium-ion: Higher energy density, longer lifespan, and faster charging, but more expensive.
  • Nickel-cadmium (NiCd) and Nickel-metal hydride (NiMH): Less common, often used in specific applications.

Applications on a Vessel:

• Emergency Power: Provide backup power to essential systems during main power failures.
• Engine Starting: Deliver the high current needed to crank and start the main engines and generators.
• Load Leveling: Smooth out power fluctuations and supplement the main power supply during peak demand periods.
• Uninterruptible Power Supply (UPS): Provide continuous power to critical equipment like navigation systems or communication devices during power interruptions.
• Renewable Energy Storage: Store energy generated from renewable sources like solar panels or wind turbines for later use.   1. Wind and Solar Energy Storage | Battery Council International batterycouncil.org

Importance:

• Essential for Safety and Operation: Storage batteries are vital for ensuring the safety and continued operation of a vessel, especially during emergencies or when the main power source is unavailable.
• Versatile Power Source: They offer a portable and flexible source of DC power for various onboard applications.

Maintenance:

• Regular Inspection and Testing: Check electrolyte levels (for flooded lead-acid batteries), terminal connections, and overall battery health.
• Charging: Ensure proper charging using appropriate charging profiles to avoid overcharging or undercharging, which can damage the batteries.
• Ventilation: Maintain adequate ventilation in battery compartments to prevent the buildup of flammable gases.

In conclusion:

Storage batteries are indispensable components of a vessel’s electrical system, providing backup power, facilitating engine starting, and supporting various other critical functions. Proper selection, installation, and maintenance of these batteries are vital for their longevity, reliability, and safety.

There are a couple of primary methods to determine the level of charge in lead-acid batteries:

1. Voltage Measurement

• Open Circuit Voltage (OCV):
  • This is the battery’s voltage when it’s not connected to any load or charging source.   1. Open Circuit Voltage Test – Master Instruments www.master-instruments.com.au
  • It provides a good estimation of the state of charge, especially when the battery has been resting for a few hours.
  • A fully charged 12V lead-acid battery typically has an OCV of around 12.6-12.8 volts. As the battery discharges, the voltage drops.   1. Battery Testing Basics – A Few Tips Can Get You a Long Way – Clore Automotive cloreautomotive.com2. BU-501: Basics about Discharging – Battery University batteryuniversity.com
  • Limitations: OCV can be influenced by temperature and battery age, so it’s not always a perfectly accurate indicator.   1. Impact of temperature and aging on OCV behavior of the battery, a.1)… – ResearchGate www.researchgate.net
• Voltage Under Load:
  • Measuring the voltage while the battery is supplying current to a load gives a more realistic picture of its state of charge under working conditions.
  • However, the voltage drop under load depends on the load current and the battery’s internal resistance, so it’s not a straightforward measurement for determining the exact state of charge.

2. Specific Gravity Measurement (Flooded Lead-Acid Batteries Only)  

1. State of Charge – Flooded Lead-Acid Batteries

• Hydrometer: A hydrometer is used to measure the specific gravity (density) of the electrolyte (sulfuric acid solution) in each cell of a flooded lead-acid battery.   1. Measuring the density and specific gravity of battery acid in lead acid batteries – Anton Paar wiki.anton-paar.com
• Direct Correlation: The specific gravity of the electrolyte is directly related to the battery’s state of charge.
  • Fully charged: Specific gravity is typically around 1.265 – 1.280.   1. What is the specific gravity of a fully charged lead acid battery? – Testbook testbook.com
  • Discharged: Specific gravity drops, reaching around 1.120 when fully discharged.
    1. Measuring Specific Gravity – Rolls Battery Technical Support support.rollsbattery.com
• Accurate Indication: This method provides a more accurate indication of the state of charge compared to voltage measurement alone.
• Limitations:
  • Only for Flooded Batteries: This method is not applicable to sealed lead-acid batteries (SLA) or AGM (Absorbed Glass Mat) batteries, as their electrolyte is not accessible.
  • Requires Access to Cells: You need to open the battery caps to access the electrolyte, which might not be possible or recommended in some sealed maintenance-free batteries.
  • Safety Precautions: Handle the electrolyte with care, as it’s corrosive.

Other Methods:

• Load Testing: Applying a controlled load to the battery and measuring the voltage drop over time can give an indication of its capacity and health.
• Internal Resistance Measurement: Specialized equipment can measure the battery’s internal resistance, which increases as the battery ages or deteriorates. This can indirectly indicate the battery’s health and remaining capacity.   1. Why does internal resistance of a battery increase over time? Impedance? – PowerStream Technology www.powerstream.com
• Battery Monitoring Systems: Some advanced systems use sophisticated algorithms and sensors to estimate the battery’s state of charge based on various parameters like voltage, current, and temperature.

In Summary:

• Voltage measurement: Provides a quick and easy estimate of the state of charge, but it’s not always completely accurate.
• Specific gravity measurement: More accurate for flooded lead-acid batteries, but requires access to the electrolyte and careful handling.
• Other methods: Load testing, internal resistance measurement, and battery monitoring systems can provide additional information about the battery’s health and capacity.

Choosing the method depends on the battery type, accessibility, and the desired level of accuracy.

Determining the level of charge in alkaline batteries, unlike lead-acid batteries, is not as straightforward due to their relatively flat discharge curve. However, there are a few methods you can use to get an estimate:

1. Voltage Measurement:

• Open Circuit Voltage (OCV):
  • This is the simplest method, involving measuring the battery’s voltage using a multimeter when it’s not connected to any load.   1. Open Circuit Voltage,What Is An Open Circuit? – BLUETTI www.bluettipower.com
  • A fresh alkaline battery typically has an OCV of around 1.5-1.6 volts.   1. Alkaline battery – Wikipedia en.wikipedia.org
  • As the battery discharges, the voltage gradually decreases. However, the voltage drop is not linear, and it can be challenging to accurately correlate voltage to the remaining capacity.   1. Battery – 5 – What Takes Place During Discharge – PowerStream Technology www.powerstream.com
  • Generally, a voltage below 1.3 volts indicates a significantly discharged battery that should be replaced.   1. The voltage in an aaa battery – how does it work – Tycorun www.tycorun.com
• Voltage Under Load:
  • Measuring the voltage while the battery is powering a load can give a more realistic indication of its remaining capacity. However, this method is less practical for routine checks and requires specialized equipment to apply a controlled load.

2. Battery Testers:

• Dedicated Devices: Battery testers are available that apply a load to the battery and provide a visual indication of its remaining capacity, often using a simple scale or LED lights.
• Accuracy Varies: The accuracy of these testers can vary depending on their quality and the specific battery type.   1. Battery Testers – A Complete Guide – RS Components uk.rs-online.com

3. Bounce Test (Informal Method):

• Drop and Observe: This is a simple but less reliable method where you drop the battery from a short height onto a hard surface. A fully charged battery will typically produce a dull thud and not bounce much, while a discharged battery will bounce more due to changes in its internal chemistry.   1. Battery bounce test often bounces off target – Princeton University www.princeton.edu
• Not Precise: This method is not very accurate and provides only a rough estimation of the charge level.

4. Internal Resistance Measurement (Advanced):

• Specialized Equipment: This method involves measuring the battery’s internal resistance using specialized equipment. As the battery discharges, its internal resistance increases.   1. Measuring the Internal Resistance of a Battery: An In-Depth Look bansheebatteries.com
• More Accurate: This can provide a more accurate estimation of remaining capacity compared to voltage alone, but it requires specialized tools and knowledge.

Important Considerations:

• Alkaline Batteries are Primary Cells: Remember that alkaline batteries are primary cells, meaning they are not designed to be recharged. Once discharged, they should be replaced.   1. You Can Recharge Alkaline Batteries But Should You? – Pale Blue Earth paleblueearth.com
• No Specific Gravity Measurement: Unlike lead-acid batteries, alkaline batteries do not have a liquid electrolyte whose specific gravity can be measured to determine the state of charge.
• Limited Accuracy: Most methods for estimating the charge level of alkaline batteries are not as precise as those for rechargeable batteries.

In Summary:

While measuring open-circuit voltage is the most common and accessible method for estimating the charge level of alkaline batteries, its accuracy is limited. Battery testers or internal resistance measurements can provide more reliable information but might require specialized equipment. The bounce test is a quick and informal method, but it’s not very precise.

Several factors can contribute to a reduced charge in storage batteries, even when they are not actively in use. These factors can impact the battery’s ability to hold a charge and its overall lifespan.  

1. Understanding Battery Degradation: Causes, Effects, and Solutions – ECO STOR

Here are some key reasons why the charge may be reduced in storage batteries:

1. Self-Discharge:

• Natural Process: All batteries experience self-discharge, a natural process where the battery loses its stored energy over time even when not connected to a load.   1. Battery Self-Discharge www.batterybuilders.com
• Rate Varies: The rate of self-discharge varies depending on the battery chemistry and temperature.   1. BU-802b: What does Elevated Self-discharge Do? – Battery University batteryuniversity.com
• Lead-Acid Batteries: These typically have a self-discharge rate of around 3-20% per month at room temperature.
• Lithium-Ion Batteries: These have a lower self-discharge rate, around 2-3% per month.   1. The Pros and Cons of Lithium Ion Batteries: A Deep Dive – Bioenno Power www.bioennopower.com

2. Temperature:

• High Temperatures: Elevated temperatures accelerate the chemical reactions within the battery, increasing the self-discharge rate and leading to faster capacity loss.   1. Self Discharge of Cells – Battery Design www.batterydesign.net
• Extreme Cold: While low temperatures slow down self-discharge, they can also reduce the battery’s overall capacity and ability to deliver current, especially during starting or high-load situations.

3. Age and Degradation:

• Chemical Degradation: Over time, the battery’s internal components and chemical structure degrade, reducing its ability to hold a charge.
• Sulfation (Lead-Acid Batteries): In lead-acid batteries, sulfation (the formation of lead sulfate crystals on the plates) can occur if the battery is stored in a discharged state for extended periods. This reduces the battery’s capacity and can lead to premature failure.   1. How Do I Know if My Battery is Sulfated? www.crownbattery.com2. What is a Sulfated Battery and How to Prevent It www.crownbattery.com

4. Parasitic Loads:

• Small Current Draws: Even when not in active use, some electrical systems on the vessel might draw a small amount of current from the batteries, known as parasitic loads. These can include clocks, alarms, standby electronics, or even slight leakage currents in the wiring. Over time, these parasitic loads can contribute to battery discharge.   1. What is the Parasitic Draw Impact on 12V Batteries? – Primary Mover www.primarymover.com

5. Improper Storage:

• Discharged State: Storing a battery in a discharged state for extended periods can lead to sulfation (in lead-acid batteries) or other forms of degradation, reducing its capacity and lifespan.   1. What is a sulfated battery and how do you prevent it? – Power Sonic www.power-sonic.com
• Extreme Temperatures: Storing batteries in hot or freezing environments can accelerate self-discharge and degradation.   1. Understanding Battery Degradation: Causes, Effects, and Solutions – ECO STOR www.eco-stor.com

6. Manufacturing Defects or Damage:

• Internal Shorts or Defects: Manufacturing defects or internal damage to the battery can lead to increased self-discharge or even complete failure.
• Physical Damage: Physical damage to the battery case or terminals can cause short circuits or leaks, leading to charge loss.

Prevention and Mitigation:

• Regular Charging: For lead-acid batteries, maintain a full state of charge through regular charging or float charging when not in use.
• Proper Storage: Store batteries in a cool, dry environment away from extreme temperatures and direct sunlight. For long-term storage, disconnect the battery terminals to prevent parasitic loads.   1. The Do’s and Don’ts of Storing Batteries – Secure Self Storage www.secureselfstorage.com
• Battery Maintenance: Follow the manufacturer’s recommended maintenance procedures, including checking electrolyte levels (for flooded lead-acid batteries), cleaning terminals, and testing battery health periodically.
• Monitor for Parasitic Loads: Identify and minimize any parasitic loads that might be draining the battery.
• Timely Replacement: Replace batteries when they reach the end of their service life or show signs of significant degradation.

By understanding the factors that can reduce charge in storage batteries and implementing preventive measures, you can ensure that your batteries remain in good condition, ready to provide reliable power when needed, and have a longer service life.