How marine batteries differ from other batteries

The next step is to head back to his tow vehicle and take its’ battery out and place it in the boat. The motor starts and he is away for the day. It begs the question: if a car battery will start the engine, why not just stick with it and not replace it with a dedicated marine battery?

NZ Fishing News Editor Grant Dixon posed this question and other frequently asked ones to Century Yuasa’s technical advisors, who came up with the following responses…

What is the difference between a car battery and a marine battery?

Unlike car batteries which generally travel on smooth, sealed roads, marine batteries must be able to resist vibration from wave pounding and trailer transport. Repeated vibration and wave impact on non-marine batteries can cause damage to the battery’s internal components that ultimately lead to battery failure.

Car batteries are designed to deliver concentrated bursts of power to crank over and start the engine. The capacity used is replaced by the alternator which charges the battery during the journey. Marine batteries must not only have the starting power to crank over high compression engines but also provide the reserve capacity needed to run on-board accessories.

What is the difference between a marine battery and a deep-cycle battery?

A marine batteries’ primary function is to deliver power to start the engine and provide reserve capacity to run basic onboard accessories including control instruments, UHF/VHF radio and bilge pumps. Deep-cycle batteries are designed to deliver continuous power, to run electrical loads over extended periods of time. They are built using heavy duty plates, and advanced active material to handle deep discharge use – to run optional accessories including fridges, bow thrusters, fish finders and GPS navigation.

Can I use a marine battery in a four wheel drive?

Century Marine Pro batteries are made for boats and are not recommended for installation outside marine use.

What are Marine Cranking Amps (MCA)?

Similar to Cold Cranking Amps, Marine Cranking Amps is used to measure the capacity that a fully charged battery can deliver to crank an engine. This is calculated by the number of amperes a battery can deliver for 30 seconds at a specific temperature, however with MCA the test is conducted at 0°C rather than -18°C.

MCA ratings are 20 – 25% higher than a CCA rating and commonly used to rate marine starting batteries.

When comparing battery ratings it is important to compare like for like. Always ensure the CCA rating is compared against CCA and MCA rating against MCA. Some manufacturers may rate the battery according to a CA standard. This test is conducted at the same temperature as the MCA rating and should not be confused with CCA.

Can I use a marine battery for my auxiliary battery?

Although marine batteries are designed to handle semi-cyclic applications we highly recommend using a dedicated deep-cycle battery for the secondary battery in a dual battery system. Deep-cycle batteries are ideal to use in boats with multiple accessories including fridges, lighting and entertainment systems.

My battery keeps going flat, why?

Imagine a battery is similar to a cup of water with a very small hole in the bottom. Over time the water will escape from the cup and there will be nothing left to drink.

Lead acid batteries operate in the same manner and will naturally self-discharge and go flat when not in use. This process can be accelerated when connected to an application with a constant current draw. You can check the current draw using a clamp meter to find out how many amperes are been discharged from the battery and with regular maintenance checks you can monitor the batteries’ condition and charge when required.

My battery won’t charge, why?

There are many factors that can prevent your battery from accepting a charge. Before assuming that you need to replace the battery, consider some of these troubleshooting ideas.

• What is the operating voltage of the charger? If the battery is below the activation voltage of the charger it will not activate and provide current to charge the battery.

• Is the charging current high enough to charge the battery? If the charging current of the battery charger is below five percent of the battery’s ampere hour rating, it may not have enough energy to charge the battery.

• Is the charging voltage suitable for the battery? A charger with a low charging voltage may not provide enough absorption charging for the battery resulting in insufficient charge.

• Has the battery been over-discharged? A 100% discharged battery has an OCV of around 11.52 volts. Discharging the battery below this voltage can cause serious damage to the internals that is not covered under warranty.

• Has the battery been left discharged for an extended period of time? Undercharging is the number one cause of premature battery failure. When a battery is left in a low state of charge for long periods of time the internals corrode, reducing capacity and causing battery failure. This is not covered under warranty.

My marine battery is leaking, why?

Overfilling of the electrolyte or overcharging is the most common cause of leaking. When a battery discharges, the sulphuric acid separates from the water in the electrolyte and absorbs into the plate surface. Sulphuric acid is heavier than water so when the separation occurs, the volume of fluid is reduced. If you top up the fluid levels when the battery is discharged, once the battery is recharged the volume of sulphuric acid is recombined with the water and the levels will increase, causing overflow and seepage.

Overcharging can also cause a battery to leak. If the charging rate of the alternator or alternative charging source (battery charger / solar panel) is over the recommended limits of the battery, this can cause bubbling and gassing of the electrolyte and in turn cause fluid overflow and seepage.

What should I do when the battery is not being used?

For batteries used in seasonal applications and stored long term, fully charge the battery prior to storing and keep in a cold dry place.

You also need to regularly check the batteries state of charge and should the voltage drop below 12.50 Volts, recharge the battery using the correct charger for the battery type.

When the battery is put back into service, follow the care and maintenance guidelines before using in the application.

How often should I get the battery checked?

The average life of a lead acid battery is 42 months. We highly recommend testing your battery annually to ensure it is performing at its best and meets the starting requirements for the application. To find an authorised dealer who can test your battery enter your post code on the “FIND A RETAILER” search on the Century Batteries website.

Connecting the leads to the battery

The majority of the Marine Pro range is fitted with twin terminals consisting of standard lead posts and threaded terminals.

Always connect the starter leads to the standard lead posts and the onboard accessories to the threaded terminals.

Connecting the starter leads to the threaded terminals can result in overheating of the internal components that can cause permanent damage the battery during excessive cranking of the battery.