Depending on how fit you are in handling batteries, we recommend ready-made solutions or at least individual components. Complete systems are usually easy to connect via plug & play.
However, you can save a few euros if you do the wiring yourself or don’t use a protective plug and instead join the poles directly to the cable.
In the high-voltage range for motors from 15 kW, the installation must be carried out by a master electrician. If possible, we recommend engines in the low-voltage field. This also simplifies the connection of the onboard electronics and increases safety.
Differences in Lithium Batteries – What to look out for?
Lithium batteries come in different sizes and capacities. You will find all variants from 0.1 kWh to 112 kWh capacity in our shop. There are no upper limits, but the marine battery should be designed sensibly.
Depending on the requirements, you need around 0.5 kWh of power per tonne per hour of travel time in displacement travel and exponentially more in planning trips.
The batteries are connected directly to the motor via a cable. The closer the batteries are to the engine, the fewer losses are caused by cable lengths. If you have any questions about cable thickness, we’re happy to help!
Your electric boat motor is controlled as you know it using a tiller or remote throttle and steering wheel. Depending on the controller, you have a display with information about the speed, remaining range, current battery capacity and current/voltage.
Up to 1.8 kW, you will find electric outboards with an integrated battery. Thanks to Plug & Play, the models are significantly more convenient, flexible and user-friendly. It would help if you had an external battery connected to the electric drive for more power. Here we recommend any size depending on the application.
Lithium cell weight
Lithium batteries have a different weight depending on the cell technology used or the production. As a rule, one kWh should weigh at most 10 kg. There are lighter and heavier batteries, depending on the cell technology.
Especially with planning boats, you should tend to the light ones. With the others, the weight per kWh is often irrelevant. You should pay attention to a comfortable weight to carry if you usually have to transport the battery.
Prices, brands and cell technology
The prices depend on various factors. A cost per kWh of €500 to €750 is reasonable. In individual cases, prices of over €1,000 per kWh are possible, which are justified by special certificates or safety technologies. Quality cells from Sony or Panasonic are recommended. But the CATL, CALB or Winston cells are also good to use.
Most lithium-ion accumulators are manufactured based on lithium iron phosphate (LiFePO4). Different compounds in combination with yttrium or sulfur are possible depending on the battery type. In general, batteries are very safe because they are non-flammable. They also have the most extended lifespan of any cell technology on the market.
Alternatively, there are NMC and NCA batteries that contain cobalt. The advantage of these batteries is a higher energy density. The disadvantage is that they have a shorter service life and are flammable. If low weight is essential, these cells can be used.
Charging cycles of a lithium boat battery
The charging cycles can be very different, depending on the processing and quality of the individual cells. The charging cycles are usually specified with a degree of discharge. (DoD = depth of discharge) The deeper the batteries are discharged, the lower the charging cycles.
At 80% DoD, good lithium batteries (LFP) last 3000 cycles. This means that most batteries have a service life of more than ten years, depending on their use. Batteries from NCA or NCM often last for slightly fewer cycles (500 to 1000).
Regardless of the number of cycles, batteries are subject to a calendar lifespan. As a rule, they lose around 4% per year.
Battery Monitoring (BMS)
The BMS usually monitors the state of charge of the battery. Most of them show this on a small display. Other important parameters are voltage, charging and discharging currents and the temperature during charging and operation.
The most important thing about the BMS is its function for securing individual cells. The positions are deep discharge protection, overcharge protection, temperature monitoring or protection in the event of short circuits. Otherwise, the battery management system offers load limitation and cell balancing and takes care of most communication.
The battery models for the matching motors are prevalent in the leisure sector. Torqeedo, propulsion, Aquamot, RiPower or even offer their battery packs. Especially the latest battery models from propulsion offer the best conditions with an unbeatable price-performance ratio.
Application of lithium batteries
We always recommend a complete package from a manufacturer as it makes sense to save additional costs and ensure functionality. However, some electric motors do not have batteries since almost all lifepo4 batteries can be combined with the engine.
If you use your boat as a rental company or in the industry for commercial purposes, we recommend specially designed batteries from the premium segment. Antron offers a special certification and is one of the only suppliers here. These are often installed in ships in combination with herbs.
The same applies to higher travel times (50+) per year. The lithium cells from Otherwise, Renogy is also a manufacturer with high-quality components ideal for this. Here it is recommended to use the correct battery for the chargers of the market leaders.
Pros and Cons of Lithium vs AGM
A significant advantage is the depth of discharge and the capacity that can be used per kWh. Lithium batteries can usually be discharged up to 95%. Depending on the technology, AGM batteries are already damaged from 50% discharge and should not be deeply discharged.
In addition, a 12v lithium battery weighs only a third of an AGM battery. In addition, lithium batteries with up to 3000 cycles have a longer service life than AGM batteries with mostly 750 cycles.
LiFePO4 batteries can also be charged and discharged quickly without degrading performance. The only downside is a higher price, which is significantly higher. The bottom line is that the advantages of the lithium battery are clear, mainly when you include the lifespan.
We, therefore, recommend lithium batteries, but AGM batteries could make more sense for occasional use from a cost perspective.
Installation
Depending on how fit you are in handling batteries, we recommend ready-made solutions or at least individual components. Complete systems are usually easy to connect via plug & play. However, you can save a few euros if you do the wiring yourself or don’t use a protective plug and instead join the poles directly to the cable.
In the high-voltage range for motors from 15 kW, the installation must be carried out by a master electrician. If possible, we recommend engines in the low-voltage field. This also simplifies the connection of the onboard electronics and increases safety.