Boat Batteries

Photo by: National Boating College

A common cause for breakdown on the water is due to battery problems. Batteries are the centre of your vessel’s electrical system. If they stop so does everything else.

Boat battery checklist:

  • Do you have the correct size battery for your engine? The size of your vessel’s engine and the compression ratio required to turnover and start your engine determines the size of marine battery you need. Talk with your local marine dealer or a specialist battery retailer for advice.
  • Do you have dual battery system on board? One for engine cranking and one for auxiliary power use such as navigation lights, VHF radio and general lighting. A dual battery is the safest option as it ensures that the engine cranking battery is fully charged for the sole purpose of starting the main engine.
  • Make sure you fit a dual battery isolation switch to alternate from bank to the other. Isolate (turn off) your battery bank at the end of each trip.
  • How old are your current boat batteries? The life expectancy of a marine battery is approximately 2-3 years. Signs of battery failure include; sides bowing out, corroded terminals, fluid inside battery has become milky or oily. Don’t forget to mark or record the date you purchased your batteries. For peace of mind have your “battery plate” tested by a qualified electrician annually.
  • Don’t install anything but marine grade batteries on your vessel. Marine grade batteries are designed specifically for the marine environment and are constructed with extra supports to accommodate vibrations and movement at sea.
  • Check that your battery cables are the correct size, terminals are firm and lightly lubricated with vaseline or light-grade grease to help prevent corrosion and salt build up.
  • Check battery water levels every three months. Fluid should just cover the plates.
  • Do not overcharge your battery by trickle charging continually. If your battery has completely discharged you may need to replace it.
  • Make battery checking part of your pre-departure check list. Keep a hydrometer in your tool kit to check the state of the battery charge for each battery cell.
  • Batteries on board should be well ventilated, housed within a box and secured firmly with straps. Take the batteries out of their box at least annually to clean the inside of the box, checking that the battery ties downs are still in good working order.

Battery servicing
Battery checking should be part of your 100 hour engine servicing program. Keep a servicing log. Don’t hook up an old battery with a new one as the ability of the new battery to recharge maybe affected by the old battery. It’s a good idea to buy your battery banks at the same time.

Attention to your batteries will help to ensure a trouble-free boating experience.

Written by NATIONAL MARITIME COLLEGE

The National Maritime College (NMC) is a Registered Training Organisation providing competency-based boat training and education. The College offers boat licence and jet ski (PWC) licence courses and tests designed to improve boating skills and awareness. You can expect friendly and professional training from from us. It is the "personal touch" and dedication to improving safety on the water whilst instilling - confidence, knowledge and good boat handling skills that sets us apart.