How to choose the correct marine battery

Understanding the power demands of your vessel is key to finding the right battery. The Yuasa YBX Active Marine range features a wide variety of batteries, including EFB (Enhanced Flooded Battery) battery types.

What battery technology you need depends on the specific power demands of your vessel. Our YBX Active Marine batteries are perfect for applications in which engine starting is the primary purpose. These batteries are constructed for engine starting and to support minimal hotel loads.

For vessels with auxiliary systems such as navigation systems, lighting and other energy-intense applications, our YBX Active Dual Marine EFB batteries are the perfect fit. These battery types have thicker plates, ensuring they not only provide reliable starting power but also support for numerous hotel loads. The dual in their name refers to this purpose.

Terminal design

All YBX Active Marine batteries feature a dual terminal design. The benefit of this is that they’re able to provide sufficient starting power for the vessel’s engine using one connection and supply power to any on-board electrical systems with the other.

Connection type

Weight is an important consideration, especially when choosing a marine battery. Whether traditional lead acid or EFB, any battery will bring significant weight. However, the most important factor is choosing a battery that meets the starting and auxiliary demands on your vessel. Remember, while it may seem sensible to simply fit the most powerful battery available, this can have a negative impact on overall weight.


Engine starting

The starting specification of a marine battery can be identified by the amount of Marine Cranking Amps (MCA). Put simply, the higher MCA rating, the more powerful the battery.

Marine Cranking Amps determine the amount of cranking power the battery is able to provide to start the engine. It is the number of Amperes it can deliver for 30 seconds. Unlike CCA / A (EN), MCA is measured at a temperature of 0°C as this is more relevant to marine use.

For the more technically minded, Marine Cranking Amps are determined using the SAE testing standard and are calculated at 0°C. This is due to the seasonal use nature of the applications marine batteries are designed for. For comparison, a similar test to determine the Cold Cranking Amperage (CCA) of a vehicle battery is conducted at a much higher 18°C. While both a measurement of cranking amps, it is important to note that MCA and CCA are not the same.

MCA can be a helpful guide to specifying the correct marine battery. Often, your vessel’s engine OE manufacturer will specify the minimum rating required to ensure sufficient starting power.

For vessels with an outboard engine and minimal electrical consumers, the Yuasa Active Marine battery range should be your go-to choice. These batteries have been designed for applications in which engine starting is their primary role.

If however, your vessel has an outboard, stern drive or small inboard engine and high levels of electrical equipment, then a more powerful battery will be required. The Yuasa Active Marine EFB range possesses increased cyclic performance, enabling it to power both engine starting and numerous electrical consumers.

Hotel load support, Ah ratings & calculations

After MCA, the Amp hour (Ah) rating should be considered. Ah is the measurement of a battery’s capacity. For marine batteries it is the amount of electricity a battery will deliver for a period of 20 hours before its voltage falls to 10.50V. Again, the higher the Ah rating, the more a battery can do. For example, a 90 Ah battery will deliver 4.5 Amps for 20 hours before it falls to 10.50V.

The total Ah requirements of your electrical consumers should be factored in when specifying the correct marine battery. To do so, you will need to calculate the electrical consumption and time each consumer will be in use, both when the vessel is at sea and at anchor. Examples include:

On top of the above, we recommend factoring in an additional 20% safety margin as the figures used can vary depending on a variety of factors. These include vessel usage and weather conditions.


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