How Do You Charge An Electric Boat?

1️⃣ Dock Safely: Ensure the boat is securely docked and turned off.
2️⃣ Connect Charger: Plug one end of the charging cable into the charging port and the other end into shore power or a power outlet.
3️⃣ Set Charging Mode: Some boats have different charging capabilities (DC fast charge, standard AC charging).
4️⃣ Monitor Charging: Check the boat’s display or charging indicator to monitor the charging progress.
5️⃣ Disconnect Charger: Once fully charged, safely unplug the charger from the boat and then from the shore power.

This is a really brief step-by-step of how to charge an electric boat. There are several things to be familiar with when connecting your boat, which this article will dive into.

But before we do, I should point out that having some foundational knowledge of electric boat batteries will make this discussion easier to follow.

πŸ”Œ Charging Methods

There are several mechanisms available that can be used for charging, as follows.

The discussion regarding the different charging equipment used on a boat is generally informed by the size of the vessel and its electrical system. 

Onboard Chargers

A permanently installed charging solution will generally be used on large boats that use battery power extensively.

Onboard batteries fall into two primary categories: Linear and Multi-Stage.

Linear batteries are an older technology slowly making way for multi-stage batteries. This is because linear batteries switch off when fully charged. They only switch back when the battery discharges to a specified value (say 90%).

This “cycling” technology harms battery life. 

Multi-stage batteries (aka smart chargers) can vary the charge rate according to the battery’s charge status. This helps prolong battery life.

Onboard chargers offer the following benefits.

They Are Convenient To Use

There is no wiring up required. All that is needed is to plug the unit into a shore-based power supply and start charging immediately.

This means there is no danger of reversing polarities or other user errors creeping in. 

External Chargers

External, also called portable chargers, are carried separately and only connected to the battery when needed.

Although the technology used in many models of External Chargers is as good as Onboard Chargers, they have the following disadvantages.

Advantages of External ChargersDisadvantages of External Chargers
They tend to be cheaper than onboard chargers.It is inconvenient to carry them separately.
They can be used for various charging purposes and are not restricted to the boat.Each time they are used, they have to be wired up. This can be less convenient after a tiring day in the sun.
Because they are loose (not installed), they are easier to steal.

Shore Power

Shore power is the term used to describe the electrical connections available back at the dock.Β Portable and Onboard Chargers can be hooked up to the shore power and used to charge the batteries.

Solar Panels

Solar panels are a viable source of electrical current that can be used to recharge the batteries.

As described in my article on marine solar panel installation, they need to be linked to a complete solar system before it can be used to power a boat.

In this instance, the solar charge controller replaces the battery charger and regulates the flow of current to ensure that the battery receives an optimal electrical current.

If this sounds like gibberish, you can learn about the benefits and mechanics of solar-powered boats.

⚑ Charging Station Considerations

When choosing the optimal method to keep the boat’s battery(ies) charged, you need to consider several variables.

The Number And Size Of Electrical Consumers

 A boat primarily driven by an electric motor has a large-capacity battery system and a substantial secondary electrical system that requires a different charging facility than a boat with minor battery-powered systems.

This will be affected by the following variables.


A large boat must plug into a large-capacity electric charger to achieve any speedy charge. 

A small bass boat, on the other hand, can be plugged into virtually any electrical outlet. The only factor that will vary is the charge time. This is not an issue if the boat is not being used regularly. 

If the boat is expected to be used away from formal infrastructure, it must have a self-contained charging capability. This may include solar panels or wind turbines (or a combination of the two).

The larger the number and capacity of batteries, the greater the required renewable power supply.

The calculation regarding the size charger needed is simple.

A 5kw, 44-volt battery (Torqeedo Power 48-5000) that discharges at 60 amps will be charged in 8 hours when connected to the solar charge controller for Power 48-5000.

A larger battery (size or number) will take proportionally longer to charge. The charger time is also dependent on the capacity of the solar panels installed.


Accessibility is a key factor when considering charging locations. If you have a small Jon boat that uses a 5hp electric motor, it will be easy to find an easily accessible shore-based power supply or charger.

If you have a 50-foot catamaran, the opposite is true. A large vessel requires planning to ensure that there is a suitable charging facility that is available.

This is another argument for installing a standalone solar system if this is feasible.

Power Requirements

Once again, the shore-based facility must have a suitably sized charging system to ensure the boat’s batteries can be recharged in a realistic time frame.

Electric car manufacturers have adopted a standardized recharging methodology. This also (in America) includes standardizing several connectors.

The result is that most cars can be recharged anywhere (even at Tesla charging stations that have been enabled).

The same level of standardization does not exist in the boating industry. As electric boats become more mainstream, the charging networks will hopefully become standardized.

At present, however, the boat owner needs to be aware of the available charging facilities and plan accordingly.

βŒ› Charging Time Factors

The main criticism against electric boats is the inconvenience of recharging the batteries. Not only does it require specialist equipment, but it is also a time-consuming process.

The factors affecting the speed at which a battery recharges depend on the following variables.

Battery Capacity

The larger the battery capacity (and number of batteries), the longer it will take to recharge. Of course, the benefit of a substantial battery facility is that it can provide power for longer periods before recharging is required.

The capacity is expressed as kilowatt-hours or kWh. A 5 kw/h battery will take five hours to recharge if the solar systems can generate 1 kw/hour of electrical energy.

Charger Power

The charger power is determined by the energy produced by the external power source. The external power source may be any of the following:

Charging MethodDetermining Factor for Charge Rate
A shore-based chargerThe charge rate will be determined by the level charger installed at that location.
An onboard chargerThe charge rate will be determined by the charger’s rating.
A portable chargerThe charger’s rating will determine the charge rate.
A solar panel arrayThe solar panels’ capacity will inform the charge speed.
A wind turbineThe wind speed and the turbine’s capability will determine the charge rate.

As discussed previously, the greater the electrical energy the external power source supplies, the faster the battery will charge.

πŸ›‘ Safety Measures

It must always be remembered that despite a solar system’s ease of use and seemingly benign appearance, it does represent a real potential danger.

DC Solar Systems Can Be Dangerous

While AC (current) remains the biggest risk, it is easy to assume that DC is not dangerous. Nothing could be further from the truth; any current that travels through the body can be lethal. 

The dangerous value of DC voltage is any current over 10 mA. At this level, it will produce a severe shock.

At 100 mA, I become lethal! If you are working with a marine solar system, ALWAYS wear insulated rubber gloves to protect you from being shocked.

Proper Ventilation

Ensure sufficient ventilation in the battery compartment and securely store the batteries.

This is especially true for lead acid batteries, which may produce dangerous emissions that must be ventilated.

Fire Extinguishers

Always ensure an appropriate fire extinguisher is easily accessible to fight fires in the battery compartment.

The designated fire extinguisher for Electrical Compartments is a Carbon Dioxide CO2 or Wet Chemical unit.

This is categorized as a class E device suitable for Battery installations, Inverters, Autopilot equipment, radios, and other electrical devices.

Follow this link for more information on the US Coast Guard requirements for marine fire extinguishers.


It goes without saying that a boat’s batteries must be completely sealed and protected from the danger of any water ingress.

Not only does this ensure the continued operation of the battery, but it also protects the boas occupants from the risk of receiving an eclectic shock.

If a boat’s battery is splashed or compromised by any quantity of water, the following process should be followed:

β–ͺ️ Switch off all electrical systems.
β–ͺ️ Put on a pair of rubber gloves 
β–ͺ️ Disconnect the battery and remove it from the compartment
β–ͺ️ Carefully dry the battery and check for any external damage.
β–ͺ️ Use a voltmeter to check the electrical production.

If the battery produces the correct voltage, carefully dry out the battery compartment and reinstall the unit. Check that it energizes the boat’s electrical systems.

If so, you are good to go.

If the battery does not produce the necessary current, it may mean that it has been damaged.

In this instance, we recommend taking it to an approved battery center for checking and possible replacement.

Overcharge Protection

A battery must never be overcharged because this will seriously damage (ruin) it.

Luckily, most charge controllers and Multi-Stage battery charges have built-in systems to ensure this does not happen.

I’m the founder and chief editor here at Kite Ship. The electrification of boating is the most exciting thing to happen to the marine industry in a generation! Welcome, and I hope that we can provide the portal you need to dive into the world of electric propulsion and power.