Stay in Charge


As another year starts some of you will have been faced once again with battery issues. These can range from straightforward ‘end of life’ to ‘catastrophic failure’. So, what should you be doing to try and prevent this happening again and avoid that awkward conversation with the Owner, Captain or guests on board.Firstly, have your batteries accurately tested once a year. The days have gone when we used a hydrometer, voltmeter and a drop tester. We now have some very accurate equipment available to test all types of batteries fitted for different applications. Testing can be carried out on board with a full discharge test taking approximately 6hrs or a conductance test takes about 10 minutes.

Engine start batteries which are not normally required to deep cycle, can be tested with a good quality conductance tester. This test uses the batteries rated cranking capacity. The test is 80-90% accurate. However, you will need someone who understands batteries to interpret the results. I have tested batteries which, with only 40-50% of their AH rating can still show approximately 90% of their rated cranking capacity which show as ‘GOOD BATTERY’. A final decision is made using at least three factors, including your test result, physical condition and battery temperature usually form an accurate result.

The most accurate test is a controlled discharge test. Good quality batteries will have their discharge rates published on the manufacturers website. We use a load bank and individual cell monitoring to show the exact condition of the bank and where the possible problems lie.

Once the results are in, its time to choose the replacement. Before going any further, you should consider the application and establish exactly what type of battery you require, as there are big differences between the battery types and the way in which they will perform in different applications. It is not enough to just replace a battery with the previous type fitted as this could be the start of repeating the same cycle that may have led to the initial failure.Probably the most important of all is regular battery maintenance. Is anyone checking the batteries and charging system on a regular basis? A battery is only part of a system but the battery is what will fail if there is an issue with the system. It’s a fact, most catastrophic failures are due to poor maintenance. Where no one has noticed the charger running a constant high output, and batteries in turn are left overcharging. This in some batteries leads to ‘gassing’, where they produce hydrogen sulphide gas, which is very poisonous (fatal at 100 ppm) and highly flammable.

All batteries should be checked on a regular basis for signs of failure. Look for physical signs, i.e. crystalline deposits on the terminals? Liquid condensing within the box, sides bulging, warm or even hot batteries and smells (like rotten eggs). A combination of these factors is normally due to either the battery failing or an issue with the charging system. Unfortunately, there is no such thing as a maintenance free battery. However, help is at hand, develop a simple maintenance plan and contact a professional for all your battery advice.

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