If we ask you to think about what keeps your boat moving on the water, your answer would probably be the motor, right?
Most people have that answer, but few people think about the battery. The battery is essential for the functioning of the electronics aboard your vessel. There’s nothing to start the engine, power the steering, or keep the navigation up and running without it.
However, spend enough time out on the water. Eventually, you’ll run into the problem of the battery going flat on you. Instead of calling the Coast Guard for a tow, you can try charging the battery yourself.
This guide gives you everything you need to know about how to charge a boat battery on the water.
Contents
A Note on Charging Marine Batteries
When charging marine batteries, we recommend going with a low-ampere charge. Use the lowest charge supported by the battery, giving it a longer charging time. The longer and lower-amp the charge, the more service life you get from the battery.
Most marine batteries suit a 10-amp to a 20-amp charger. With a 10-amp charger, you can expect a five to ten-hour charging time for the battery from totally flat. The ambient temperature also makes a difference in charging times. You can expect it to slow in temperatures above 80 degrees Fahrenheit.
The Types of Boat Batteries
AGM Batteries
AGM (absorbed glass mat) batteries feature a design with a special glass mat for wicking electrolytes between battery plates. These AGM models contain enough liquid to soak the mat with electrolytes. If the battery housing cracks, no additional fluid leaks from the casing.
AGM batteries have a life cycle expectancy of five years or more. The service life depends on the maintenance and operating conditions. It’s important to note that you can’t discharge the battery more than 60% between charges, or you dramatically reduce service life.
Gel Batteries
Gel cell batteries contain silica-type gels suspending the battery electrolytes. This viscous, paste-like material allows the flow of electrons between plates. However, it doesn’t leak if the case cracks. A Gel Cell battery is less forgiving about holding a charge than an AGM.
If you don’t recharge a Gel Cell correctly, you risk permanent failure of the unit. The battery charger must have a specific designation for Gel Cell batteries. These batteries are usually more affordable than AGM models.
- 30lbs - The lightweight design of the Newport deep Deep cycle battery makes it easy to transport and install in your marine vessel. Enjoy powerful and reliable performance without adding unnecessary weight to your boat.
- Sealed AGM Lead Acid - Trust in the durability and reliability of this heavy-duty marine battery. Designed with advanced technology, it provides superior power and performance, making it an ideal choice for all your boating needs. Get peace of mind with its sealed, leak-proof construction.
- Trolling Motor Compatible - Power up your boating adventures with our 12V marine battery, specifically designed to work seamlessly with trolling motors. Enjoy long-lasting and reliable performance on the water.
- 12V50Ah - This deep cycle battery is built to deliver reliable, long-lasting power for marine use. With a 12-volt output and 50Ah capacity, it is a perfect choice for powering your boat's electrical systems. Trust in its durability and performance for all your marine adventures.
- 50Ah battery - A powerful rechargeable battery with a capacity of 50 amp hours, perfect for heavy-duty marine use. Experience long-lasting performance and reliability with this deep cycle battery.
Tips to Keep Your Battery Healthy
Charging your battery is only one part of the maintenance involved in extending its service life as long as possible.
Don’t mix the battery brands and types if you have a battery bank. Keep everything consistent.
Store the batteries in a cool, dry place during the off-season, and keep them clean.
Check batteries before every trip for signs of corroded terminals. Clean corrosion using a mixture of baking soda and water.
The Types of Chargers for Boat Batteries
There are two types of charger models available for boat battery maintenance. There are dozens of models from hundreds of brands, and they vary in price. When buying a charger, you have different options at varying price points. Here are the basics of what to look for in your battery charger.
Built-in Chargers
Built-in chargers come wired into the electrical system. These chargers vary in performance, with fast-charging models available.
Some models require manual operation, while others offer autonomous operation, automatically kicking in when the battery needs charging. They are more expensive than portable units, but the convenience of the automated charging units makes it worth the money.
Portable Chargers
The portable charger allows you to take it with you anywhere you go. It’s an essential piece of kit for any captain, and you should stow it away with your other electronics gear.
They cost less than half of what a built-in model retails for online. Most of them have a universal function for charging any battery brand (but not the model).
- Meet the GEN5X2 - Similar to our GENM2, only better. It's 37% smaller and delivers 43% more power. It's one of the best performing onboard marine battery chargers we have ever made.
- Multiple banks - A two-bank onboard battery charger rated a 10-amps - 5-amps per bank - for 12-volt batteries, including marine, boat, starter, and deep-cycle batteries.
- Charging modes - Independently charge and control each battery bank with selectable charging modes - including 12V, 12V AGM, 12V Lithium, and 12V Repair Mode - for all types of lead-acid and lithium-ion batteries.
- Enjoy precision charging - An integrated thermal sensor detects the ambient temperature and alters the charge to eliminate over-charging in hot climates and under-charging in cold climates.
- Charge dead batteries - Charges batteries as low as 1-volt. Or use the all-new force mode that allows you to take control and manually begin charging dead batteries down to zero volts.
Safety Tips When Charging Boat Batteries on the Lake or at Sea
As you can imagine, electricity and water don’t mix. Therefore, safety is the most crucial aspect to keep in mind when charging your battery on the water. Follow these instructions to stay as safe as possible while handling the battery and charger.
- Use gloves and safety glasses when working with the battery. Make sure you’re wearing rubber-soled shoes.
- Always charge the battery in a cool, well-ventilated area.
- Turn off the engine ignition before disconnecting the battery.
- Test the battery if it’s a while since last use.
- Don’t let the battery overheat when charging.
- Don’t charge the battery when frozen.
A Step-by-Step Guide to Charging Your Boat Battery
Step 1 – Examine the Battery
Before you inspect the battery, it’s a good idea to know which battery type you have, AGM or Gel Cell. Typically, boat manufacturers stash the battery away in a hard-to-reach compartment to save space. However, that means that it often is challenging to remove, and by the time you check it, it’s covered in dirt and grime.
Start the quality check by turning the power to the circuit off and carefully removing the battery from the housing. Inspect wiring and electrical connections for grime and corrosion and clean them where necessary.
Inspect the terminals regularly to ensure they fit securely and are free of corrosion. We recommend using Nylon lock nuts to reduce the chances of the connections coming loose due to vibrations from the boat.
Step 2 – Choose the Appropriate Aftermarket Charger
You can buy the charger online from a site like Amazon. Choose a suitable model for the type of battery and the charge you need to produce. Typically, we recommend a 10-amp to a 20-amp charger for the job.
If you have an AGM battery, use a multi-stage smart charger. This smart charger stops damage to the battery, preventing overcharging. You also have the option of choosing the standard multi-phase charger, including phase, bulk, and float, reducing the chances of overcharging the battery.
Three-stage chargers are the best choice for prolonging the battery’s service life, but they have an expensive price tag. The three-stage charger also increases capacity, reducing electrolyte loss while improving the frequency of use for long trips.
Trickle chargers are also another choice for keeping batteries topped up between trips.
Step 3 –Connect the Charger and the Battery
After selecting the right battery charger, it’s time to connect it to the battery. Attach the clips on the charger to the corresponding black and red terminals on the battery casing. Smart battery chargers usually have an LCD interface showing it the battery is connected successfully.
Smart chargers also give you a brief battery analysis, telling you if the battery is dead and capable of charging or if it needs servicing or replacement.
If your battery is suitable for charging, start the process and wait until it finishes. In some cases, fast chargers can take two to three hours to charge the battery from around 40% full. The battery charge time is anywhere up to 5-hours or longer from totally dead.
After the battery charger alerts you to the battery status being full, remove the clips and return the battery to the battery platform. Strap the battery back into the mat using the clips or clamps, and rig up the connections.
Make sure that you tighten the connections properly. Loose connections interrupt the battery’s delivery of power, damaging the electrical system. However, don’t overtighten the connections as you may strip the threads on the clamps.
After you finish with the connections, cover the battery in the containment bow to prevent the salt air and water from entering. A dry box means less corrosion on the battery terminals and longer service life.
Make it routine to check that your battery is at full charge before you take the boat out on the water, It only takes a few seconds, and it can save you a lot of grief later in the day. Charge the battery between trips if you use the boat frequently. A trickle charger will keep the battery at 100% without overcharging and damaging the unit.
When storing your batteries during the off-season, place them on a trickle charger and check the battery health every two months.
Final Thoughts – Using Solar Power to Charge the Battery
Batteries require chargers linked to batteries or power outlets to charge them. However, there is a much easier solution to keeping your batteries in tip-top condition.
Solar power systems use panels mounted on the boat to collect energy from sunlight. The panels send the energy to the batteries for storage, ensuring your battery bank remains topped up at all times.
Solar systems even work in low light conditions, and the technology becomes more affordable as the world adopts green energy.
You can complete a DIY installation of the panels and the inverter required to get the energy into the batteries. Or you can have a professional installer do it for you. Obviously, you get a guarantee with a professional and the best job possible.
However, once you have the solar system in place, you never have to worry about a battery dying on your again.
