What to Consider When Switching Your Yacht to Marine Lithium Batteries

Marine lithium batteries have a lot of advantages and can be well worth the initial cost for many sailors, but there is a lot to consider before making the switch. This is not a complete tutorial and if you decide to move forward with switching to a lithium battery system, we recommend doing extensive research to ensure compatibility and a smooth transition for your vessel. 

We asked Craig Allison from Maz Ocean in Fort Lauderdale (also in the West Palm Beach area) to do the lithium ion battery installation for us. We decided to go with Lithionics Batteries after evaluating all the options currently on the market. Our goal was to upgrade our battery bank capacity using existing programmable equipment on our boat to make it as cost effective as possible. We opted for a very basic installation but there are many upgrades available to the basic system such as running air-conditioning which we may consider in the future. The best thing to do is to discuss your needs and goals and the cost involved with a specialist like Craig who will do a customized installation for each boat owner.

Advantages of Lithium Batteries for Boats

Efficient – Lithium batteries don’t waste power on heat the way that lead acid batteries do. Standard lithium batteries have a life of 2000 cycles and discharge around 90 percent while lead acid batteries have 500 cycles and discharge around 50 percent.

Higher Voltage – With higher constant voltage, your equipment runs better. Some live-aboard sailors have to time their electrical use activities with when their generator is on. For example, doing laundry or cooking might have to wait for when the generator is on, but with lithium batteries this inconvenience is eliminated. 

Lighter – Lithium batteries are about 1/3 lighter than lead acid batteries and can cut down on hundreds of pounds of weight, which is a big deal on a boat.

Long Lifespan – Lithium batteries average a 10 year lifespan, making them very cost efficient for the sailors planning on living on their boat for 10 years or more. Many companies also offer a 10 year warranty.

Less strain on generator – Marine lithium batteries reduce the use and time of the generator working, which means you don’t have to service it as often. While you may be servicing your generator every 6 weeks or 8 times per year, with less wear on your generator thanks to lithium batteries, you can cut it down to servicing 2-3 times per year. 


What to Consider When Buying Lithium Batteries for Your Yacht 


Cost of Lithium Batteries

The number one con is the cost. To properly install lithium batteries the cost could be around $7,000 or much more depending. It’s important to shop around, do your research and ensure that the company that provides your batteries and equipment has good customer service.

Additionally, lithium batteries are not direct drop in, even if some manufacturers say they are. You still have to consider your charging sourcing and make sure everything you have can be programmed to charge the lithium properly.

Safety of Lithium Batteries

Some people might hear lithium and think they are unsafe, but Marine Lithium Batteries are Lithium Iron Phosphate (LifPo4), which are much safer than traditional lithium batteries in a laptop or cell phone. 


Battery Management System

A Battery Management System (BMS) is the key to ensuring your lithium batteries are balanced and prevent any harm. For example, if your batteries are depleted 100 percent they are effectively dead, which is a huge cost to replace them. With a BMS, the batteries will be cut off before hitting 10 percent and ensuring they can be recharged. Additionally, lithium batteries cannot self-balance the individual cells in a battery so a good BMS with a balancing function to bring all cells up to the same voltage when certain preset conditions are met is needed.



An external alternator regulator is recommended as well as an Alternator Protection device recommended to protect the alternator from a sudden shut-off triggered by the BMS in systems where the alternator charges the lithium battery bank directly.

The alternator works very hard with lithium batteries, so if you eat fan belts with lead acid you will really eat them with lithium. Therefore, you have to limit the alternator output and also put a temperature control/sensor.

Charging Sources

  • Charge Profile – Must be programmable between:
    • 13v and 14.4v (12V system)
    • 26v and 28.8v (24v System)
  • Chargers that charge at constant current/ constant voltage are recommended. 
  • Up to 1C (charge current = battery bank capacity i.e. 600amp battery bank could theoretically accept up to 600amp charge current).
  • Ideally, choose charging sources that can be networked together and controlled by the BMS.


Due to the higher discharge ability of lithium battery banks you may want to invest in a high output Inverter or even an inverter charger. If one of your goals is to have the ability to run high current appliances such as air conditioning you need to match your inverters to the expected loads. Since using inverters to run AC appliances can cause a significant draw on your batteries, it is always a good idea to have some means to turn the inverter off before it causes the BMS to disconnect all loads including lights and navigation equipment. If your batteries have an internal BMS you could achieve this by setting up parameters when you program the inverter to shut down based on state of charge or battery voltage.


Battery/ Engine/ House Switches

Ensure that the switches are rated to manage the increased charging and or current draws that the lithium system will introduce (Bigger inverter loads etc.)

The greater charge acceptance of lithium batteries will mean that your battery switches/ cables/ alternator etc. will all be forced to operate at a much higher amperage than the lead-acid system the lithium replaced.

Increased electrical currents, which are sustained at a higher amperage for longer may very well exceed the design specifications of many components in the charging system.

One of the most overlooked items when switching to lithium is the design rating of ALL electrical components in the charging system.


Battery Cabling and Bus Bars

Use the Bluesea Systems Circuit Wizard to verify that the battery cabling on your boat of sufficient rating to withstand greater charging/ discharged loads which your redesigned battery system will introduce.

When entering data into the calculator, pay particular attention to the number of minutes that will be sustained at the newer higher amperage.


Battery Fuses

All batteries should be fused as close to the batteries as possible (preferably within 7″ or 23cm) with Class-T Fuses appropriate for the cabling and expected current draw.

Remember that a fuse just too small for the load is a fire hazard. Too large and it’s ineffective. Use the circuit wizard to calculate or consult a professional marine installer.


Battery Shunts

Appropriately sized shunts for expected current loads.


Battery Monitor 

An accurate battery monitor is essential for monitoring lithium battery banks on boats to ensure that you maintain your bank within an acceptable voltage range.




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