Buyer’s Guide - Batteries
Take charge of your battery bank
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How hard could it be to replace a 12V boat battery? Well, as Sam Fortescue discovers, there’s a world of choice to navigate
t will probably sneak up on you, the realisation that you need to replace your boat batteries. Perhaps you’ve had a few narrow squeaks cranking the engine, or noticed how the lights on board dim whenever the water pump kicks in. Like most components on a boat, batteries have a natural life. They may eventually fail spectacularly, but until that happens, their performance will increasingly suffer. If you were happy with your previous lead-acid batteries, and they
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lasted five or more years, then the easiest thing is simply to replace like for like. One of the trickiest elements of installing new batteries can be ensuring they fit into a tight space, and that the existing cables will fit the terminal layout. By using identical batteries, you can be sure of this (just check that the design hasn’t changed). Frustratingly, there are no standards when it comes to battery dimensions or terminal positioning. It is critical to replace all the batteries in the same bank at once.
DECEMBER 2021 Sailing Today with Yachts & Yachting
System performance is limited by the weakest battery in the bank, so the older ones will quickly wreck the new.
Time for change?
It is a big expense to replace good marine batteries – prices start around £100 for a 100aH wet-cell and range up to three times that for a top-quality gel or AGM. And bigger boats will have bigger battery banks, multiplying the cost further. So you want to be sure you’re buying exactly what your boat needs.
