Load test or capacity test of a GMDSS battery

 

Load test or capacity test of a GMDSS battery

LOAD TEST OR CAPACITY TEST OF A GMDSS BATTERY (24VDC)

Over the years of experience as a radio surveyor, it has been observed that the most common mistake that the ship staff does is the maintenance of the GMDSS battery (reserve source). This emergency source is often misunderstood for compliance. In a nutshell let us have a look into what is this emergency source is all about:


As per SOLAS regulations it is mandatory for all vessels built after 1995 to have on board an emergency generator. Older ships might have an emergency generator or a battery bank as emergency source. When we speak of sources of energy it is as below:

  1.  Main source of energy - Main Generator.
  2. emergency source - This supplies power to emergency lights and other applications on board and it is  not the one supplying power to GMDSS equipment.
  3. The reserve source of energy is normally a 24V DC - lead acid battery which primarily caters to the communication equipment needs only. The AH capacity of this battery is normally in the range of 180 - 220 Ah (Ampere hour).
  4. This reserve source should be in a position to supply 24V DC for a period of 1 - 6 hours depending on the availability of Emergency generator. It should be 1 hour if the vessel is fitted with emergency generator or 6 hours if it is not fitted with emergency generator.
  5. The efficiency of the battery depends on many factors, viz: regular charging on/off load test etc. 
During Radio Survey or GMDSS SRC, it is most common that  the Class surveyor is questioning about the log book of GMDSS battery and it is often seen that a sheet of paper is being produced (by the electrical officer) as a log.This is to be avoided as far as possible. At this stage, let us skip the rig morale of going through the procedures of maintaining the battery as most of the people are aware of the same. 

The video below demonstrates in brief as to how to calculate the load of the battery. 

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Testing and Checking of GMDSS Batteries Required by SOLAS

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Testing and Checking of GMDSS Batteries Required by SOLAS GMDSS batteries constitute an important tool which provides power supply for GMDSS equipment operation in case of emergency.  Regulation 13, Chapter 4 of SOLAS sets the following requirements for GMDSS batteries: - batteries must be recharged to the required minimum in less than 10 hours; - the capacity of the batteries must be checked at less than 12 months;  - the batteries should provide power to operate GMDSS for 1 hour if GMDSS is getting the power from emergency generators, and  - for 6 hours if GMDSS is not getting the power from emergency generators.  Surely, to be ready for emergency the batteries should be kept in a proper condition. For this, they should be periodically tested and checked. There are three types of tests: 1. Daily on load/off load test  which ensures that all connections are intact and on loaded batteries do not drop voltage too quickly.  2.  Yearly capacity test  which measures the capacity of the bat
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รายละเอียดและข้อมูลของถัง SCBA

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  รายละเอียดและข้อมูลของถัง SCBA 1.              แรงดัน    1 Bar( บาร์ )   = 14.78 Psi( ปอนด์ )     /    300 Bar x 14.78 Psi = 4,500 Psi( โดยประมาณ ) 2.              การคำนวณอากาศในถัง SCBA เช่น 1 ถังมี แรงดัน 300 Bar และ ขนาดบรรจุน้ำ 6 Liter   โดยประมาณ คือ 6 Liter จะมี ขนาดบรรจุอากาศ ได้ 1, 800 Liter มาจาก 300 x 6 = 1, 8 00 Liter พอทราบขนาดบรรจุอากาศแล้ว นำมาหารด้วย อัตราการหายใจตาม NFPA ที่ 40 Liter/Minute   สูตรการคำนวณคือ      =           แรงดันที่วัดหรืออ่านได้ (Bar)     x     ขนาดบรรจุน้ำ (Liter water)        ( 300 x 6 )                                                            อัตราการหายใจตาม NFPA (40 Liter / Min)                                     40                                       =       จำนวนเวลาเป็นนาที (Min.) ที่สามารถใช้งานได้โดยประมาณ               45 นาที (Min.)                                                  
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