Electric outboard extending the range with solar or added battery

Before buying a Spirit1 electric outboard, a few owners are concerned about range and ask about the need for a second battery.  I always recommend to try using one battery at first.  With all the information on the tiller it soon becomes apparent their range anxiety was not warranted.  After becoming familiar with electric propulsion the majority of owners find their range anxiety diminishes and they are instead amazed how far they can go on one charge.

Not Convinced?

What are the options for extra range?


The simplest option is another battery. With only one plug and one clip it is an easy procedure to change. The easiest way to remove the battery when you are in the boat is to turn the outboard around 180 degrees so the tiller is facing away from you and the battery is towards you in the boat.  This makes lifting the battery more accessible to lift off.  Although this is the simplest way to get more range, it not the only way. 



The solar charger can be used while you are motoring or stopped, turning your electric boat into a solar powered boat fuelled by the sun.

There are some limitations on this which need to be considered. The maximum solar panel size the charger can take is 180 watts and panel voltage must be less than 35V.  The motor can draw a maximum of 1000 watts and the battery stores 1kWh (1000Wh).

What does this mean to your motoring if you have full sunshine and 180 watts of solar after losses (cable and charger) at the motor? You will have 150 watts available which is less than your full power of 1000W. This does not sound good but does this mean it doesn't work? No, because in practice you do not motor all day and when you stop the solar is continually storing power in your battery.


How much power will you get from solar during a day?  This depends on how big the solar panel you have is, whether it is winter or summer, how sunny the day is, the angle of the panel relative to the sun and any shade of the panel during the day.  As a rough guide, for a panel exposed to full light in Australian conditions, take the wattage of the solar panel and multiply by 4 . Example: 180 watt panel X 4 would generate 720Wh per day.

As I said before much depends on how much sunlight there is to harvest. The charger can accept 180 solar watts, and you can wire it differently to use more solar, see below...




The solar charger can be used extract power from a 12Volt battery and raise it to the voltage needed by the electric outboard's battery. This has the effect of making the 12 volt battery another power store onboard if needed.  The charger will charge at a maximum of 120 watts from the 12 volt battery. Some charge must be remaining in the outboard battery for this to work.  Note: you will need to control this by a switch because if the power stored in the 12V battery is less that the electric outboard needs it will drain all the power out of the 12V battery over time.


The Spirit1 battery is 1kWh and weighs only 8.5Kg.  By comparison, a lead acid 12V battery with 100Ahr capacity is approximately 1kWh and weighs about 30Kg. 

The advantage of this method is that via a 12V solar regulator of appropriate rating you can have a  solar system larger than 180 watts depending on the size of your 12 volt battery and what charge it can reasonably accept.  By having a 12V power source on board you can now run other devices you may wish to power such as phones, radios, lights, navigation light, echo sounder etc with the added benefit of been able to redirect power to your electric outboard battery if needed.

Care needs to be taken to install correct isolation and current protection for the 12V system. For those wishing to use this method please notify us when purchasing an outboard from us and the necessary equipment and instructions to install a safe system can be provided.

As I said before much depends on how much sunlight there is to harvest and this will be no different for the 12V battery.


Just as no two boats are the same nor will be the electrical systems. Similar boats with different owners, uses and expectations can require very different systems. Even the choice of primary power source will vary depending on where you are in the world. Solar, wind, mains power and generators all have their place in the varied world of sailing. All of these differences is what makes boating interesting. 


Betts Boat Electrics can be contracted for boats in Australia to do a technical assessment of the pros and cons of each method for your boat.  There is no right or wrong way. The best way is the way with which way the you, the owner, feel most comfortable and meets your needs.

Written by  Mal Betts

Betts Boat Electrics


Betts Boat Electrics
Deception Bay QLD  Australia 
Mob 0419674135
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