There are two types of batteries you may find on board:
- Wet or Flooded Batteries
- Sealed Batteries
Two checks are usually done on batteries:
-
Charge state check. Carried out for both batteries types.
Measure the terminal voltage and the specific gravity of the battery liquid. Below table gives rough correlation between terminal voltage and specific gravity of a typical 12V lead battery.
-
Liquid level check and replenishment. Carried out for Wet Batteries.
The level should always be maintained at the designated level as per the battery’s instruction. The replenishment liquid properties affect the battery life and must be of a proper type as per the manual (i.e. distilled water, dilute sulfuric acid, etc.).
Batteries maintenance
- Ensuring a long life
All lead battery will have a long life if it is always kept in a higher charged state. The battery life shortens when the charge is less than 50% and the performance decreases. All the lead battery should be ALWAYS kept at a charge of more than 50%. - Replacing batteries
Depending on battery usage, handling, ambient temperature etc, the battery life may be shorter than the designated interval. If a battery can only be charged to less than 70% (terminal voltage approximately 12.5 V, specific gravity 1.230@20 deg C ), even if the battery is charged by a proper charger, then the life of the lead battery should be judged to be finished, and the battery should be replaced. - Using floating charge voltage
Floating charge means always keeping the battery in a highly charged state to suppress the natural electric discharge. In order to verify the condition of the floating charger while a battery is being charged, regularly compare the terminal voltage on the battery to the value in the instruction manual (for example for a 24V rated voltage battery: 26.735–26.80 V) with a digital tester. If the terminal voltage is found dropping, the battery is likely to be deteriorated or a malfunction of the charging device is faulty. Proper troubleshooting should be done as per instruction manual. - Storage of batteries that have deteriorated A worn out battery should be disconnected from the charger and stored on board until disposal ashore. When it is stored, protect the terminal by using insulating tape to prevent a short circuit which may cause a fire. The battery should be kept in a room at normal temperature and in as dry a condition as possible.
