How to Charge a Deep Cycle Marine Battery

How to charge a deep cycle marine battery


The modern boat depends mainly on electrical power for approximately all of its essential functions from its on-board batteries. For marine/auto use, a deep cycle battery sometimes drops sufficiently below its required voltage to let your boat or its electronics run.

And that is why you must own a special charger so you may energize your battery with its recommended voltage. The charging process of a marine battery is relatively quick and unproblematic.

Poor battery performance is often the unfortunate result of wrong charging techniques of batteries paving us toward a significant limitation on enjoying success and making memories on the water. Even incorrectly charging a premium marine battery can be prone to a hazard in a quick amount of time. To avoid such unlucky murders, learning to feed deep cycle marine batteries the right usage and charging process is quite easy.

Charging Procedure of a Deep Cycle Marine Battery

Charging Procedure of a Deep Cycle Marine Battery

Terminal Cleanup

Going through the clean-up process of the battery terminals is not essential if there is no rust/corrosion, so you may just skip this section. But if it is a requirement, get proper supplies/materials to avoid accidents. For this, use rubber-gloves and protective-glasses for your protection and paper towels, wire brush, and grit sandpaper for cleaning up the acid build-up.

When we say corrosion, we point toward a white, and powdery substance that looks like it can blow away in the wind. This clean-up will get rid of the build-up along with any probable poor connection between the feeder and the battery. Poor connectivity just lengthens charging times with less available battery power.

Start with wearing latex gloves and safety glasses for protection and wipe away any excess amount of corrosion with the wire brush. You need sodium bicarbonate/baking soda solvent to spray onto areas that are heavily-corroded. Now, dilute 1 tablespoon of sodium bicarbonate in 1 cup of water in this solution. Wipe away the excess and using sandpaper thoroughly clean terminal posts off any remaining rust/corrosion.

Choosing the Correct Charger

Generally, before the beginning of any charging process, batteries terminals are supposed to be cleaned. And when it comes to the charging process, the usage of a proper type of charger is the practical demand of any kind of battery, not just a marine one.

So, before the positive and the negative lead engagement in a methodical arrangement to the positive and negative terminal, hunt for the correct charger type. Purchasing the wrong charger type will surely be a huge waste because besides not providing enough power for a full charge, it will promptly damage your battery.

A deep-cycle battery charger, more importantly, to reach full capacity will render the appropriate amperage as well as the voltage for the marine battery in a timely fashion. Smart chargers are considered the best chargers when it comes to marine dual-purpose batteries – starting and deep cycle.

This topper is also known as multi-stage charger since the charging process includes 3-phases. Smart chargers own the technology to charge your marine battery followed by its temperature and chemical structure.

The charger connection with the battery

The charging process can begin only in the absence of corrosion. Firstly, engage the marine battery terminals to the battery charger of the correct type. It is because placing a dumb charger with a battery will only increase the risk of lasting battery damage costing its lifespan.

Here, a smart charter will deliver energy in 3-phases that includes the bulk phase before the acceptance phase, and lastly, the float phase. When plugged in, it maximizes the charge while preventing any damage at the same time to the internal components of the battery.

In case you do not own a smart charger, it costs about $50 to $100 for high-quality smart marine battery chargers and we recommend it as it will extend the lifespan of your marine battery.

Charging the battery

Here, we are assuming you have found yourself the right charger type, so now engage the battery terminals with the charger clips. Switch on the battery charger after the connection and charging should start.

The charger, at this stage, will take the entire process in its management by adjusting the charging through the bulk method first and then to the acceptance method before moving to float phases. With a smart charger, the battery’s charging percentage will be shown on the LED display. 

However, it is significantly necessary to read manuals- both for the charger and the marine battery’s charging technique in case your charger is designed with adjustable charging settings before you set out for charging. Reading and understanding it will aid in processing the best speed for effective charging.

For an upper hand tip, a smart charger takes preventive measures against any damaging risk of the battery that may occur due to overcharging.

Removing the Charger

Shift the charger to the off position once you have a fully charged battery. Next, you have to withdraw the charging clips that you attached to the battery terminals. The process will be finished after reattaching the lead back to cover the battery box before moving it back in the boat and enjoy its service. If you own another marine battery onboard you can just repeat the whole process for gaining a full charge.

Battery Charging Cycles

Regardless of the design, a typical marine deep cycle battery has, it only allows a significant discharge depth. You can only spend a fraction of the actual capacity of the marine battery from consumption for many cycles before recharging it to the full capacity over its lifetime.

A normal cycle that a deep cycle battery is designed with surely starts at the full capacity (100%) that pushes a battery discharge down of about (20-50)% of the actual capacity before recharging it back to reach 100%. The battery lifespan also hugely get influenced by their general depth of discharge.

A battery that frequents a 50% depth of discharge is expected to live for a longer period than a battery allowed to go a greater discharge depth. Repeated shallow discharge down to 5-10% simultaneously contributes to lifespan shortening. Quality deep cycle batteries, from a pragmatic outlook, discharges as it is designed to before recharging it to full capacity.

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