Freefall lifeboat does not start. Part 1. Troubleshooting

Lifeboats on a ship are usually inspected once a week, testing the starting condition of the engine on two batteries, rudder, telegraph-propeller, lighting, as well as the condition of batteries and chargers.

Despite regular checks, the lifeboat's engine may stop starting at any time. This is exactly the situation that occurred on the ship during the inspection of the boat by the port inspector.

Selecting a battery for starting the boat

When selecting the first (main) battery to start the engine, it turned out that the boat would not start, although all the lighting was working. The indicator on the charger lights up green, which indicates the normal state of the battery.

Electrical diagram of batteries, charging and lighting of the freefall lifeboat

After an unsuccessful attempt with the first battery, the engine was started using the second (emergency) battery. This time it was successful.

Lifeboat batteries

As a result of checking with a battery tester, it was discovered that the capacity of the first battery is near zero. Despite the fact that the battery indicator is green and the battery voltage is about 13V.

Checking the first battery (low capacity)

The voltage of the first battery is about 13V

Checking the first battery (green indicator)

We can conclude that the battery capacity for lighting is quite enough, but there is not enough starting current to start the lifeboat engine. In addition, it turned out that this battery is almost 4 years old since it was installed. Typically, the service life of maintenance-free acid batteries on a ship is about 4 years, after which it is recommended to replace them with new ones.

Checking the second (emergency) battery

Checking the second (emergency) battery also showed an unsatisfactory result, because its capacity is at the “weak” level. This battery was also installed about 4 years ago, so its capacity has dropped.

Checking a new battery (12V 62Ah 590A)

It is very important when receiving a new battery to immediately check its capacity with a battery tester, because it is not enough just to measure its voltage and look at the green indication.

Battery tester

After installing the new battery, the freefall lifeboat was tested and showed successful operation on both batteries.

By the way, if you work on tankers, then this battery tester will not suit you. I recommend using an electronic battery capacity tester.

Read also the second article on this topic: “The lifeboat engine does not start. Part 2. Troubleshooting,” which details another common problem with starting lifeboats, namely problems with the starter motor and relay of gear wheel.

Battery capacity is a measure of the amount of energy a battery can store and is typically expressed in ampere-hours (Ah) or milliampere-hours (mAh). It indicates how much current a battery can supply over a given period. Here's a detailed explanation of the key concepts related to battery capacity:

Key Concepts:

1. Ampere-hour (Ah) and Milliampere-hour (mAh):

   • Ampere-hour (Ah): This unit measures the charge capacity of a battery. For example, a battery with a capacity of 1 Ah can deliver 1 ampere of current for 1 hour.
   • Milliampere-hour (mAh): This is a smaller unit of charge capacity (1 Ah = 1000 mAh). It is commonly used for smaller batteries, such as those in smartphones and other portable electronics.

2. Voltage (V):

   • The voltage of a battery indicates the electrical potential difference between its positive and negative terminals. While voltage is not directly a measure of capacity, it is essential for determining the energy stored in the battery.

3. Energy (Wh - Watt-hour):

   • Energy stored in a battery can be calculated by multiplying its capacity (in Ah) by its voltage (in V). This gives the energy in watt-hours (Wh). For example, a 12V battery with a capacity of 10Ah stores 120Wh of energy.

Calculation of Battery Capacity:

1. In Ah or mAh:

   • If you have a battery rated at 2000mAh, it can theoretically provide 2000mA (2A) for one hour, 1000mA (1A) for two hours, and so on.

2. In Wh:

   • To find the energy capacity in watt-hours (Wh), multiply the capacity (in Ah) by the voltage (V). For example: $$\text{Energy (Wh)}=\text{Capacity (Ah)}\times \text{Voltage (V)}$$

Factors Affecting Battery Capacity:

1. Discharge Rate:

   • The rate at which a battery is discharged affects its capacity. Higher discharge rates can reduce the effective capacity due to inefficiencies and heat generation.

2. Temperature:

   • Extreme temperatures can reduce battery capacity. Batteries typically perform best at moderate temperatures.

3. Battery Age and Usage:

   • Over time and with repeated charge-discharge cycles, a battery’s capacity diminishes.

Practical Applications:

• Consumer Electronics: Batteries in devices like smartphones, laptops, and tablets are usually rated in mAh.
• Electric Vehicles (EVs): EV batteries are often rated in kWh (kilowatt-hours), which is a larger unit of energy (1 kWh = 1000 Wh).
• Renewable Energy Storage: Batteries used for solar or wind energy storage are also typically rated in kWh.

Understanding battery capacity helps in selecting the right battery for specific applications, ensuring that it meets the required energy needs and operational duration.