Boat Battery Maintenance

A dead or failing battery is one of the most common reasons a boat won’t start.

When you can’t get your boat started, the vast majority of the time your problem is either related to ethanol gas, or a bad boat battery. And when the battery is the problem, quite regularly the failure can be traced back to a lack of battery maintenance. Truth be told, most of us tend to put in the battery or batteries and then forget about them – right up until the day the boat doesn’t start. To make sure battery issues don’t ruin your day of fishing, be sure to follow this boat battery maintenance routine.

battery maintenance
It’s easy to put the battery in, and forget about it. It’s also one of the most common reasons a boat won’t start when you turn the key.
  1. Always, always, always turn the battery switch off. Some older boats will have an electrical “leak” somewhere in the system which will kill a battery over time, but even on a new boat, that switch should always be flipped into the off position as your final act after a day on the water. The problem is that you never know when something was accidentally left on, or switched on without your knowledge. A friend may have been looking for the washdown pump switch and flipped on the courtesy lights by accident. You’ll never know it until you turn the key a week later and nothing happens.
  1. Give the battery a visual inspection before and after every trip. The terminals should be clean and tight; if they aren’t, fix them asap. Also, look for damage to the batteries’ casing and if you see any, replacing the battery is probably the best move. And check to be sure it’s tightly secured in the battery box. Boat batteries take a beating, and vibrations can damage them. (If your boat kills batteries thanks to excessive vibration consider getting a gel matt battery, which is much more vibration-resistant than a wet cell battery).
battery maintenance
Give the batteries a visual inspection every time you use the boat.
  1. Hit the terminals and connectors with a protectant. A battery terminal protector like CRC or Yamalube Battery Terminal Cleaner & Protector goes a long way in making sure the terminals and connections stay in good shape.
  1. Where and when possible, keep your batteries on a trickle charge. Most modern chargers are “smart” and can feed the power-packs a trickle charge that will keep them topped off without doing any harm. Obviously, this is something you’ll want to do during the off-season when those boat batteries may go for months at a time without use. In some cases, your boat will have an onboard charger you can plug in. But you can also put a trickle charge on a boat even when power isn’t available, with a solar panel. There are several on the market these days which you can alligator-clamp onto the battery when you know the boat will be sitting for a while.
battery maintenance
Modern chargers can be left on all the time and will regulate the charge so they don’t damage the batteries.
  1. Replace your boat battery regularly. Boat batteries have a limited lifespan, and you can’t expect them to last forever. If you get five years out of one, consider yourself lucky and replace it. If you have a boat with multiple batteries, it’s a good idea to replace them on a rotating basis so you always have at least one relatively fresh one aboard.
battery maintenance
Replace marine batteries with new ones regularly, whether they need it or not.
  1. Every month or so, pop the top on wet cells and make sure they’re filled with water. Remember that the plates should always be covered (or they’ll suffer corrosion damage) but you don’t want to fill to the cap or the batteries may overflow and lose acid in the process. Also remember to use distilled water, to be sure you don’t accidentally add water with a high mineral content.
  2. Regularly clean off the top of the battery. No, a bit of crud on the outside won’t hurt anything, but you want to keep the batteries clean so that when you need to check water levels or add water (see above), no contaminants get in there.
battery maintenance
You can’t get to the fish if the boat won’t start, so make sure those batteries are in good shape.

Take care of those batteries, and hopefully, you won’t be left at the dock by a lack of juice. But just in case you do have an issue, we have one more recommendation: get a li-ion jumper battery and leave it stowed aboard the boat. These days you can get one that practically fits in your pocket, yet has enough kick to turn a V-6 outboard. One day it might save a fishing trip and another day, it might save you from needing a tow. That’s a nice safety margin to build in – and we can only wish for such a simple solution to that ethanol issue.

Get more great boating information and tips from Lenny Rudow on BD.

Lenny Rudow …has been a writer and editor in the marine field for over two decades, and has authored seven books. He is currently the Angler in Chief at Rudow's FishTalk Magazine, is Electronics and Fishing Editor for BoatUS Magazine, and is a contributing editor to several other publications. His...