Emergency batteries as well as GMDSS batteries onboard serve an important function. During a black out, emergency generator need some power source to start in auto. Emergency batteries feed this required power to the emergency generator. If the emergency batteries are week, your emergency generator may not start in auto mode. You would then need to start the emergency generator manually from emergency generator room. This can take away vital time which may result in disastrous situations.

<a href="http://myseatime.com/blogadm/wp-content/uploads/2015/04/off-grid-battery-rolls-for-cabo-san-lucas_opt.jpg"><img class="aligncenter size-full wp-image-1001" src="http://myseatime.com/blogadm/wp-content/uploads/2015/04/off-grid-battery-rolls-for-cabo-san-lucas_opt.jpg" alt="emergency batteries" width="750" height="499" /></a>

Monthly testing of emergency generators tests just the components of emergency generator. It does not test other components like emergency batteries. So how do we know if our emergency batteries are good and can start the emergency generator? Apart from checking the health of the batteries, load test of the emergency generator does that. Usually this load test is performed quarterly. One of the rationale behind the load test should be to take away the main power source from the emergency generator and then blacking out to see if the emergency generator starts.

Coming to GMDSS batteries now. As per SOLAS GMDSS batteries should provide power to operate GMDSS for
<ol>
	<li>1 hour in case GMDSS has the power from emergency generators</li>
	<li>6 hours in case GMDSS does not have the power from emergency generators.</li>
</ol>
Now how do we test the GMDSS batteries to be sure that these won’t die down before the required time. Some of us confuse this test with the On load/Off load daily test of the batteries. They argue that we need to switch off the AC power to GMDSS and operate the GMDSS for 1 hour (or 6 hours) . But this is not correct.

Yard provides the specifications of the required batteries during  delivery of the vessel. If we have renewed the batteries with same specifications, we can be sure that the batteries would last for the required period. Of course this would not be the case if the capacity of the batteries has reduced during the life of the batteries. To be sure that the capacity of the GMDSS batteries is OK, a capacity test is performed every year. This is important test which ensures that in emergency your GMDSS batteries would last up to the required time.

Wishing you all fair winds following seas.