Whilst the electric motor is the heart of the drive system, the batteries are your ‘fuel tank’. We can offer the right power source to match your performance and range expectations.
Generally speaking, there are 2 options for electric boats:
Lead Acid batteries
Conventional lead-acid batteries are still a sensible choice in most displacement style electric boats. Whilst they are heavy & bulky, many displacement craft have plenty of space under floorboards and under seats to store batteries. We prefer lead-acid batteries of the AGM (Absorbed Glass Matt) type, which are maintenance free, do not gas when charging and can be installed lying on their side, giving you more flexibility on the installation lay-out. Also keep in mind that many displacement boats, such as sailboats need ballast below the waterline. Often existing ballast can be removed and replaced by batteries, so they serve an extra purpose, instead of being just ‘dead’ weight.
The main benefit of lead-acid battery is their price which is relatively cheap. The drawbacks are that they are bigger, heavier and can’t be charged or discharged as deeply and quickly as Lithium batteries.
For displacement style boats that require a running time of a few hours, traveling at 4 to 7 knots and when budget is limited we usually recommend lead-acid batteries
There are several chemistries within the lithium family, for boats the most common types are Lithium-Ion Phospate and Lithium-manganese. Lithium batteries have a higher energy-density so are much smaller and lighter than lead-acid batteries. However they also are considerably more expensive. Lithium batteries can be re-charged quicker and can be discharged deeper and quicker than lead-acid batteries and they can be left sitting in a discharged state without any ill effects.
Essentially Lithium batteries win it on every aspect from lead-acids, but given their price is easily three times higher than a lead-acid battery bank of similar capacity they are for many boats not financially viable.
Whilst there are many ‘cheap’ lithium cells available on the market, one does need to understand that for boating applications it’s best to use professionally designed, marine grade lithium packs with an integrated BMS (Battery Management System). Simply wiring up some cells bought off the internet without a proper understanding of how lithium cells work and need to be electronically balanced will result in a very short battery lifespan or worse, overheating or fire of components on-board.
Both lead-acid and lithium batteries will need to be replaced after a maximum of 10 years, regardless of the number of charge & discharge cycels. Typically lead-acid batteries can perform up to 500 cycles, a lithium battery may be able to perform up to 1,500 cycles (3 times as many). For recreational boaters, that use their boat on average 20 times per year (or 200 times in 10 years) this is not a real benefit. For commercial operators however the use of Lithium batteries can work out considerably cheaper in the long run as they might be going through 5 sets of lead-acid batteries in 10 years where otherwise 1 set of lithium batteries would offer the same performance.
Below you will find 2 examples of batteries that are suitable for use in boats. They are foolproof products that can be used by everyone without specific knowledge of electronics. These batteries meet specific design criteria for use in a marine environment, such as water-resistance, shock resistance and built-in safety features to prevent damage from overcharging, overheating and immersion in water.
There are too many batteries sizes, capacities, shapes and details on list on this website, and as a result of that each electric boat project will require a tailor-made advice in terms of what battery bank best matches the desired range, performance and budget.
Feel free to contact us to discuss your specific needs and requirements and to obtain advice on whether for your boat lead-acid or lithium batteries would be the best match.
As an example, please see below for more info on two popular types of electric boat batteries supplied by Eco Boats Australia: