A marine battery takes an incredible amount of abuse. In the Northeast, batteries sit idle in freezing temps during the winter lay-up period. Most boat owners may go days without using their boats and even then don’t run the boat long enough to do much charging.
Many parts of the boat begin to deteriorate as a result of not being driven for a longer duration and boat owners becoming negligent in their maintenance. It is because of this reason that there are so many boat accidents. However, they should ideally thoroughly inspect everything before taking it in water.
Additionally, they also need to check if any type of electrical fixtures are required in the boat. That’s because Fishing boats are notorious for having various electronics that drain the batteries including bilge pumps, bait pumps, washdowns, lights, sonar, radar, stereos, and others. When you factor in the marine environment and a few corroded connections you have a recipe for disappointment.
Testing Your Marine Battery - Step by Step
Time requred: About 1 Day 14 Hours
Supplies needed:
- Distelled Water (unsealed batteries)
Tools required:
- Battery Load Tester (optional)
1. Disconnect Battery
2. Check Fluid Level
3. Charge Battery
4. Rest Battery
5. Load Test Battery
6. Reconnect Battery and Retest
Charging Your Battery
Never use a booster to charge your marine battery. A booster should only be used to start the motor and then removed. If you leave a booster on for any significant length of time, you may permanently damage the battery. Always use a trickle-charger. Serious boat owners invest in a full time automatic charger that senses the battery charge and charges appropriately. If you have multiple batteries, you should purchase a charger that will manage all of them individually.
Maintaining Your Battery
If you have a lead-acid marine battery with battery caps, pop the caps off and check the level in the battery. The level should be just at the bottom of the tube. Be sure to check all six cells. ONLY use distilled water (found in most drug stores and super-markets). Regular water has dissolved minerals and salts that will harm the battery. In contrast, distilled water is devoid of any minerals, and so the battery is not likely to be harmed by it.
Sealed batteries require no maintenance other than keeping the terminals tight and clean.
Marine Battery Terminals
Corrosion on battery terminals
It is critical that battery terminals are absolutely clean and properly tightened. If a terminal is warm (or hot) to touch, the connection is poor. Periodically remove all the connections and clean the posts and terminals. Replace the connections and spray the terminals with some type of corrosion preventative. Even the slightest bit of corrosion will affect the battery performance.
Is Your Battery Getting Charged?
Most motors (expect for the smallest outboards) have alternators that provide electricity to operate and motor and a charging circuit to charge the batteries. Use a volt meter and you need to see at least 13.8 volts. If you see much less than that (but still higher than the 12.6 volts the battery produces), you probably have a bad connection somewhere. If you still see 12.6 volts (battery voltage), you either have a bad connection or an alternator problem.
Marine Battery Troubleshooting Tip
Often times, marine batteries are being drained when the boat is not in use. With all the switches off, connect all the ground wires to the grounds terminal. Then attach the positive wires carefully watch for any sparks. If you see any, that means that something is drawing current (a stuck automatic bilge switch is a typical culprit).
Freezing Temps for Marine Batteries (Winterization)
Marine battery damage caused by freezing
Nearly all batteries lose about one-third of their power when the temperature falls below freezing (32 degrees Fahrenheit or 0 Celcius). Batteries can actually freeze and if they do, they are ruined forever. The plates will bend and the casing will crack. However, a fully charged battery will not freeze until temps reach well below -50 Fahrenheit. A fully discharged battery can start freezing at the same temps as water. It is important to note that a fully discharged battery is only 12 volts or less. It is critical that a battery is fully charged as part of the winterizing process. If the boat has been hauled, it should be disconnected from the electrical system to avoid discharge.
Frequently Asked Questions
To test your marine battery, first disconnect it from the boat. Check and refill the fluid level if it's not sealed, then charge the battery with a trickle charger for 24 hours. After resting it for 12 hours, use a volt meter to check the voltage (around 12.6 volts is healthy). Perform a load test to confirm its condition, then reconnect and try cranking the motor to see if it performs well.
Lead-acid marine batteries with removable caps need regular fluid level checks, ensuring fluid reaches the base of the site port. Use only distilled water to top off cells to avoid damage from minerals. Maintain clean and tight terminals to prevent corrosion, which can degrade battery performance.
Boosters are designed only to start your motor by providing a surge of power. Using a booster for charging can damage the battery permanently. Instead, always use a trickle charger or an automatic marine battery charger that senses and maintains the appropriate charge level.
Regularly inspect and clean battery terminals to remove corrosion. Tighten connections securely and apply a corrosion preventative spray to the terminals. Even small amounts of corrosion can reduce battery performance and cause connections to heat up.
Marine batteries lose about one-third of their power below freezing and can freeze and be ruined if discharged. A fully charged battery resists freezing at extremely low temperatures, but a discharged battery can freeze around 32°F. To protect your battery in winter, ensure it is fully charged and disconnect it from the boat's electrical system during storage.
Using a volt meter, check the battery voltage when the engine is running. It should read at least 13.8 volts. Lower readings indicate possible bad connections or alternator issues that may need inspection and repair to ensure proper charging.
Marine boats often have electronics like bilge pumps, bait pumps, washdowns, lights, sonar, radar, and stereos that continuously drain batteries. To manage power drain, regularly inspect your electrical system for corroded connections and consider investing in a quality charger that maintains battery charge effectively.
