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Lithium Ion Marine Battery

Lithium Ion Marine Battery. For a very long time, boat owners have relied on the lead-acid battery to start their engines, power their electric lights. And, more recently, power their inverters, which allow them to run a variety of domestic appliances, including kettles, microwaves, and more.

However, lithium ion batteries provide far superior performance and a longer lifespan, but at a significantly higher upfront cost. Is it time for you to upgrade from the technology of the 19th century to that of the 21st century?

When it comes to lead-acid batteries, the rule of thumb is that the capacity of your best marine battery pack should be double the amount that you are likely to consume in a single day, or the amount of time between recharges. This is due to the fact that the majority of lead-acid batteries should not be routinely drained to a level that is lower than 50 percent of their capacity.

Lithium Ion Marine Battery
Lithium Ion Marine Battery

Otherwise, the cycle life of the batteries will rapidly decrease. There are certain lead-acid technologies that will make this better, albeit at a much higher price.

When you use power from a lead-acid battery at a higher rate for a longer period of time, the total capacity of the battery will decrease. If you discharge a battery at 5A for 20 hours, it will give you 100Ah; if you discharge it at 20A for 5 hours, it will only give you 80Ah.

And if you discharge it at 100A for 1 hour, it will only give you 50Ah. If you drain a battery at 100A for 1 hour, it will only give you 50Ah.

When you are operating an electric boat or powering an inverter, the significance of this fact becomes much more apparent. Because of this, the nominal capacity of your lead-acid battery will need to be increased even further if you consistently draw large currents.

In addition, the number of usable cycles any battery will offer you over the course of its lifespan is determined by two factors: the depth to which you discharge it after each usage, often known as the depth of discharge (DoD), and the rate at which you deplete its power.

At best, the lead-acid leisure battery that costs the least and can be purchased in local chandlery will provide you with 100–125 cycles when discharged to 50 percent capacity. If you do this on a regular basis, the number will drop to 25-30 cycles, at which time you will probably only have 50-60 percent of the full capacity that was originally available to you.

When the capacity is reduced to 90 percent DoD, often known as when the lights begin to fade, you will probably receive no more than 10 to 20 cycles at the very most.

Last update on 2022-06-20 / Affiliate links / Images from Amazon Product Advertising API


  • High capacity of 300Ah
  • Discharge depth of 100%
  • Lower cost per Ah.
  • High discharge cycle of up to 5000 counts
  • Lightweight
  • Eco Friendly and does not contain hazardous substances
  • 3-year replacement and 10-year service warranty


  • High price point

How to test the battery

Lithium batteries may completely subvert all of these performance assumptions. They claim that their discharge capacities may reach almost one hundred percent even when operating at discharge currents of one hundred amperes, and that their cycle lifetimes can exceed two thousand even while operating at discharge currents of eighty percent.

The purpose of our activity was to investigate the veracity of these assertions.

Each battery that was put through its paces in the test was given a charge using an authorized lithium charger, which could have been the one that came with the battery, a Victron Smart Charger, or a Mastervolt ChargeMaster Plus.

This was done so that the results would be comparable across the board. After that, we carried out three measured discharges (with each one being followed by a subsequent recharge), and we measured the amount of Ah that each one delivered:

  1. Utilizing an MK constant current discharge tester while operating at 25A
  2. At 100 Amps, by connecting each one to an inverter and plugging a 1 Kilowatt electric heater into it
  3. At 150A, the same as the previous example, but with a 1.5kW heater
  4. Finally, we determined the maximum current that they were capable of supplying for a period of five minutes because this is the amount of time required to bring a kettle to a boil or to power a microwave.

While some batteries were capable of delivering the 150A, some were not. Different manufacturers chose different cut-off points that they believed would enable their unit to deliver the best long-term results and cycle life. In all cases, it was the internal battery management system (BMS) that determined when they turned off, and different manufacturers chose different cut-off points for their products.

Because the majority of manufacturers declare their capacities were obtained at 25 degrees Celsius, they were bound to be slightly lower than the values that were claimed, by around 2 to 4 Ah.

None of the lithium batteries claimed to be appropriate for kickstarting an engine. For this purpose, you require a very high current for brief bursts, on the scale of 200–400 A, but they are not intended to produce currents of this magnitude on a consistent basis.

Warranties for lithium-ion batteries

It is important to use caution when considering the lithium battery warranty estimates that are provided. The majority are based on figures that were provided by the manufacturers of the cells.

However, these figures are frequently qualified by certain caveats, such as reducing replacement values rather than full replacement, and stipulations about how the battery has been charged and discharged, both of which may be difficult to prove in the event that you need to make a claim.

For this reason you should read the tiny print carefully, and not assume that a product with twice the guarantee time is necessarily twice as good.

Although we were unable to independently validate the cycle life claims made by the batteries we tested, we were able to determine that each of the batteries had a DoD (depth of discharge) of between 80 and 80 percent. This suggests that the cycle life claims are likely accurate.

However, when we asked the suppliers how they arrived at these cycle life claims, most of them admitted that they had not cycled the actual battery 5,000 times by themselves. Doing so would take around 10 years. Instead, the cycle life claims were based on figures quoted by the manufacturers of the individual cells that are contained within the batteries.

And with that, we reach one of the potential problems that are associated with lithium batteries. It is difficult to check manufacturing standards and safety requirements in the manufacture of lithium cells due to the fact that nearly all of the production of lithium cells takes place in the Far East.

There is one globally accepted standard for transportation, which is known as UN38.3, but as far as we can tell, there are very few, if any, internationally agreed-upon standards for the manufacturing of batteries.

This is a problem that the Government Office for Product Safety and Standards in the United Kingdom is concerned about. PBO had a conversation with them while we were conducting the test, and they confirmed that they are looking into the question of the safety of all batteries, including lead-acid batteries.

But more specifically lithium batteries, in terms of the safety of their use, the safety of their claimed performance, and the safety of their transportation.

They are looking at the chemistry as well as the labeling, capacity, and composition, and their first report should be out very soon.

This does not imply that the batteries we tested were hazardous. However, it is recommended that you contact the vendor of any battery that you are considering purchasing to provide you with any relevant test results verifying the battery’s compliance and safety before making a purchase decision.