Battery maintenance for boat owners: How to look after your boat batteries.

For all but the smallest and simplest of craft a reliable supply of battery power is essential to keep both vital safety systems and domestic comforts running. They’re therefore an integral part of a boat’s reliability and resilience. Looking after batteries also makes good financial sense – if treated badly they can fail within a couple of seasons, but if well maintained may last for six to eight years

It’s clearly important to have a good understanding of the configuration on your boat and its inherent pros and cons. It’s good practice to have two battery banks, so that one can be reserved solely for engine starting, while the other is used for domestic loads, lights, electronics and so on. Some vessels may have a third bank for a windlass, bow thruster or other high-power devices.

Each bank may comprise of just a single battery, or of several batteries connected in parallel.

How to use the power supply

Before sailing, you should:

Charge Batteries

Prevent short circuits by making sure that there is a lid on any battery box or boots on the battery terminals.

Ensure that connections to the batteries are clean, bright, and well made.

When hooking up a battery, ensure that you connect the terminals the correct way

Before starting the generator, you must turn off all communication equipment on board to avoid decreasing battery capacity and communication equipment fluctuation. In addition, it is also possible to avoid sudden increase of electric impulse that endangers communication equipment.

Currently, there are still a number of fishing vessels taking electricity directly from the battery 12V DC used for communication equipment. With such usage, the ability to transmit and receive signals will be limited because communication equipment requires a supply of 13.8V DC. Therefore, ships should use voltage stabilizers (24V DC-DC 13.8 power converter).

For a voltage stabilizer that converts 24V DC to 13.8V DC for communication equipment, before turning on the device, it is necessary to observe the voltage indicator on the meter whether it displays 13.8V DC or not. If the indicator needle is over the specified line, communication device should be disconnected from this adapter to avoid being damaged.

When using ICOM for communication, you should turn off the power of equipment such as TV, CD player to ensure enough power for ICOM.


In addition to using, maintenance is one of the most important steps to maintain power source system and equipment as well as ensure safety during use. Therefore, you need to pay attention to the following:

Clean terminals and the case with a paste made from baking soda to neutralize any acid. More than one battery has died because the grease and acid film across the case became conductible and connected the two terminals.

Fill cells of flooded electrolyte (“conventional” batteries) with distilled water if they are empty or low. Tap water may contain minerals that can have a deleterious effect on the internal plates. 

Keep the battery compartment well ventilated. Gasses escaping from the battery, particularly from overcharged lead-acid batteries, can be explosive

 If you’re going to install a battery charger on your boat, make sure it’s a “smart” three-stage marine unit, that offers a sophisticated charging regime. Cheap auto parts store chargers may, with long-term use, shorten battery life

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