How to Keep Marine Batteries Charged

Keep your boat's battery charged so that you can be ready to go at a moment's notice.

Marine and deep cycle batteries are both commonly used for a variety of applications, ranging from traditional power sources for boat engines and electronics to small-scale renewable energy applications. However, if your batteries are not properly cared for, they will quickly drain. In some instances a dead battery may need to be replaced if it has lost its ability to hold a charge. There are several ways to ensure that your batteries are fully charged and cared for, one of the most common of which involves using a trickle charger.

Things You'll Need

• Trickle charger
• Charge controller
• Battery cables

Instructions

Trickle Chargers

1. Install a trickle charger on your boat to keep the marine battery fully charged. Trickle chargers can either be plugged into a power source, if there is one available, or you can use solar battery chargers if you only use the boat intermittently. Solar chargers work best if they can sit for multiple days and charge the battery rather than quickly charging it in a few hours. Solar chargers should be sized based on the voltage of the battery they are charging.

2. Position the solar panel in as much direct sunlight as possible if you are using a solar-cell attached to a trickle charger device (sold commercially as one product). Conventional solar theory suggests angling the solar cell to the same degree as your latitude, plus 15 degrees in the winter and minus 15 degrees during the summer.

3. Clip the electrodes onto the terminals of the marine battery once the solar cell is positioned correctly. Look for an indicator on your trickle charger, such as a LED light or display telling you that it is hooked up correctly to your battery. Some trickle chargers, solar or otherwise, will also tell you when the battery is fully charged.

Charge Controllers

1. Install a charge controller attached to a generator if you are using multiple marina batteries and depleting the batteries on a regular basis. Charge controllers are designed to direct the flow of electricity to and from batteries in a way that prolongs their lifespan by keeping them adequately charged and prevents them from becoming overcharged.

2. Attach cables to the input terminals of the charge controller, allowing a power source, such as a wind turbine, solar cell or generator to send electricity to the charge controller. The cables at the input point should be sized based on the size of the current going to the batteries from the power generating source.

3. Attach the same size cables with eyelet's wired to the ends of the cables so they can attach to the marina battery or battery bank. Any time a charge controller is being used, it is also advisable to install a dump load to the charge controller's secondary output terminals. Dump loads are commonly used in renewable energy applications as a heat sink that dissipates extra electricity that is diverted away from the battery bank by the charge controller.

References

• Home Power: Wind Electricity Basics
• Wind Sun: What Is a Solar Charge Controller
• Go Green Solar: Solar Trickle Chargers

Resources

• Power Stream: Wire Gauge and Current Limits