Batteries on your boat – issues to be aware of
AS A surveyor, I regularly come across a number of issues with craft which have 12v DC battery banks fitted.
In the last few years, I’ve seen a huge shift in thought towards the types of batteries that are used to store power from when just the standard lead acid batteries were carried. There has been quite a big movement towards the use of gel and lithium batteries especially since prices have become a little more attractive with some good benefits for those who are constantly cruising and permanently off grid.
Likewise, there are noticeable improvements in the costs and efficiencies of the latest generation of solar panels and regulating systems now available that almost make the need for shore power redundant for many. Sometimes if working towards high reliance/usage on batteries, it’s far better to actually run the whole DC system on a 24v as opposed to running a 12v DC system.
However it is also very important to consider the amounts of use and cycling of the batteries; on top of this it is essential if considering switching to lithium that you understand the costs to benefits properly and that charging systems are also correctly addressed. For instance you cannot mix the types of batteries to charge off one type of battery charger.
Locations again are important as many of the modern batteries don’t like low temperatures. Many just will not work under zero degrees Celsius which we regularly experience in the UK in winter and, more importantly, most will not like exposure to temperatures over 40C. From my own experience where I have dealt with a few that have exploded, the area they were stored in has clearly gone over 45C.
If you are thinking of fitting lithium it’s essential to ensure they are properly fitted and that you advise your insurance company. Currently there are moves afoot by some that are reviewing their use on vessels.
Air gaps
One thing I will say is that regardless of what you use for your DC power storage there are some very important things that across the board should be considered. Stowage is essential regardless of the type of battery; it should be properly ventilated, ensuring the batteries are not tight together but have about a 10mm air gap around them. They should be secured properly with covers on terminal connections and ensuring regular checks of security of cables to batteries is undertaken.
With high loads from a battery any loose connections will cause heat and potential arcing or fire; this is very noticeable on cranking of the engine and bow thrusters for instance. It is also essential to ensure cabling used is of suitable sizing for loads with proper isolators fitted including one for the inverter if fitted (check with the manufacturer’s recommendations as to type used), bow thruster etc.
When stowed within the counter ensure the batteries are well away from the engine exhaust, something you would think should be obvious. Unfortunately all too often I see batteries directly fitted under a dry exhaust with cables melting on to the pipework!
Lastly maintenance: my own craft gets high use for about six weeks constantly and then very little use the rest of the year. Very few batteries like this type of use, the combi charger/inverter I have does simulate a basic cycling of the batteries and helps maintain them. It is for this reason I’ve stayed on lead acid and I don’t expect them to last more than five years with this type of intended use.
This year while on board I noticed a strong bad eggy smell and thought immediately to check the batteries. I was indeed very lucky, I discovered that one had clearly developed a duff cell and the battery was red hot and the PVC casing had seriously expanded. Quickly I disconnected it and removed it on deck to let it cool.
Once in harbour I was able to dispose of it to the local boatyard, I was very fortunate that I was on board and I recognised the cause of the odour. One last point is that if for any reason you need to replace a battery within a bank, it’s important to know that you cannot replace an individual one, unfortunately the whole set should be replaced.
On my YouTube I’ve posted several important shorts on things to check and what happened to my own battery: www.youtube.com/watch?v=8GWlbjKl5zk
Please also just bear in mind that for thousands of batteries sold and fitted it’s a rare occurrence but regular inspection, good insulation and regular checking of connections etc is very important. YouTube link: www.youtube.com/ shorts/y7D3Fbr9dZU?feature=share