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Warmer days have arrived and it’s time to once again take to the waves. Only problem is your marine battery has died a death in storage, cannot be recharged and needs replacing. The question is, do you simply purchase the same make and model as before or do you look for the best marine battery to suit your needs.
When it comes to deciding which battery is best for your boat, size matters. Small craft really only need a battery to start the engine and run a few small electrical connections. Larger boats, for extended periods out fishing or cruising, need to be able to use stored power for running an often large variety of electrical equipment which are required for comfort and vital for safety at sea.
Which Type of Marine Battery Do You Need?
To begin your search, you must decide on the type of marine battery you actually need.
Starting/Cranking Battery. If you only have a small boat for messing about on the river, then a “Starting” (or “Cranking”) battery is probably sufficient as it will supply enough power to start the engine as well as running the basics such as the bilge pump, lights etc. These batteries are also smaller than the Deep Cycle variety thus saving valuable space on board.
Deep Cycle Battery. For larger craft a “Deep Cycle” battery is necessary. For longer trips out on the water, there will be a need to run various equipment and appliances on your vessel for extended periods of time with the engine on and off. Deep Cycle batteries are specifically designed to be completely (or almost completely) discharged and then recharged, called a deep cycle, and they provide the power necessary in running radio equipment, lighting and safety lights, pumps and all electrical appliances required for the duration of your trip.
Dual Purpose Battery. Alternative three is to opt for a Dual Purpose Marine Battery. As the name suggests, this is a hybrid battery for both starting and deep cycling. These are ideal for smaller craft where space is at a premium although the best option, where possible, is to have separate batteries for cranking and deep cycling.
Having decided on whether to opt for a Starter, Deep Cycle or Dual Purpose Battery the next decision is which variety to purchase. This comes down to personal choice, amount of maintenance required, durability and, of course, the cost.
There are four different varieties to choose from, each with its own advantages and disadvantages.
Flooded or Wet-Cell Battery. These are the standard, traditional lead acid batteries containing sulfuric acid mixed with distilled water. Cost-effective and capable of up to a thousand deep cycles, flooded batteries do, however, require regular attention and top-ups with distilled water which add to your running costs.
Gelled Battery. Filled with a liquid electrolyte and sealed, these batteries are leak- and spill-proof. Gelled batteries can withstand shocks and vibrations and are ideally suited to marine usage.
AGM Marine Battery. AGM (Absorbed Glass Mat) batteries are extremely popular and reliable. Sealed to eliminate leaks and spills, AGM batteries are almost maintenance free and do not require distilled water to be added. They can also be fitted at any angle and are extremely resistant to shocks and vibrations.
Lithium Marine Battery. The new kid on the block, Lithium batteries are safe and reliable as well as being lightweight. Totally maintenance free, they have the added bonus of being impossible to accidentally overcharge. Ideal for using in boats, lithium batteries do, however, cost a lot more than the other varieties of marine batteries.
In my opinion, the Vmaxtanks MR107 is the best 12 volt deep cycle marine battery around. Weighing in at just under 60 pounds, this AGM battery can be mounted at almost any angle and is totally maintenance free. Well constructed and extremely resistant to shocks and vibrations, the MR107 can also withstand severe heat and extreme weather conditions.
Other attractive features include a relatively fast recharge time and an expected lifespan of between eight and ten years, if treated properly of course. The battery also has a low self-discharge rate of between 1% and 2% per month which extends the battery’s life.
Overall, the Vmaxtanks MR137 is the best marine battery I have used. With a great deep cycling rate, the MR137 can also be used for cranking although it is probably better to have a separate cranking battery for that purpose as continued use of the MR137 for starting purposes may reduce the battery’s longevity.
The Odyssey PC625 is a multi-purpose deep cycle battery that is equally at home on land or sea. A non-leaking AGM battery, it can handle the rough and tumble that comes with rough going or choppy seas and, constructed with pure lead plates, it delivers considerably more power than standard flooded batteries. As with all AGM batteries, the PC625 offers great protection against shocks and vibrations making it ideal not just for marine craft but for powersports from motorbikes and ATV’s to snowmobiles and gyrocopters.
I would recommend the PC625 for smaller marine craft as it is reliable and delivers the power you require for both cranking and deep cycling, delivering almost 400 cycles before recharging is necessary. Perhaps not quite as robust as the Vmaxtanks MR107, the Odyssey PC625 is up there with the best marine batteries available today.
For larger vessels that have a lot of electrical requirements such as running lights, air-conditioning, winches etc, the Optima 8014-045 is an ideal marine battery. As a dual purpose AGM battery, the Optima provides both the power required for cranking the motor and to run the electrics for extended periods on the water.
The Optima range of AGM batteries are known for their slow self discharge rate which reduces the amount of time spent on charging the batteries and require little maintenance even when stored during the winter months.
While it is always a good idea to have separate batteries for cranking and deep cycling, if space on board is limited the Optima 8014-045 is an excellent dual purpose alternative and will not lose its charge as can happen with batteries designed for a single purpose.