Marine Battery Information | Essential Guides & Tips

First of all, it depends on the generation of cells and their design chemistry. Normally a manufacturer specifies this in the documentation. In the Cruiser battery series, we use the latest generation of lithium-iron-phosphate (LiFePO4) cells with 10,000 cycles before degradation.

But this is only a physical test of the cell, under ideal laboratory conditions, and many parameters reduce this number during real operation as part of an assembled battery.

The tests are carried out at a temperature of 25 degrees Celsius and increasing the temperature dramatically reduces the number of cycles. For example, an average cell designed for 6000 cycles at a temperature of 25 degrees will show a result of only 2500-3000 cycles at a temperature of 45 degrees Celsius.

Many of us use batteries in the tropics and subtropics with ambient temperatures of 30+ degrees Celsius.

The marine battery has a close, moisture-proof housing with a waterproof rating of at least IP64.

As a result, the temperature inside the battery case is always significantly higher than the surrounding environment. The voltage drop in a wire is transforming into heat. The only way to reduce the temperature increase is to reduce the internal resistance of all battery elements: BMS, and wires. That is why we use internal wires with a cross-section of at least 70 square millimeters and a 300-amp BMS with low internal resistance.

But thick copper wires and powerful BMS are expensive and most manufacturers use the minimum cross-section and small BMS without worrying about voltage drop and generation of additional heat. Wire thickness and internal resistance matter!

During manufacturer tests, prismatic cells are compressed. If compression is not used, the number of cycles decreases, sometimes by 20%. Compression is especially important at high currents close to 0.5C and more. We often see such currents in marine applications, since we often use a 12-volt system and are also limited by the space for placing batteries: small total capacity and high current mean high C-RATE.

In the “Cruiser” battery series the cells are compressed between stainless steel plates. However, most manufacturers do not perform compression, because of cost savings. Compression matters for marine applications!

Cell balancing is important!

Each cell changes its internal resistance over time. All cells are connected in series inside the battery, and different internal resistances result in voltage differences. The difference in voltage leads to the battery stopping working or, if there is no protection, to the battery failure and fire. Cell balancing is critical. There are 2 methods of internal balancing. The first one is the passive balancing. It is not suitable for marine batteries. The voltage difference is leveled by dissipating energy into heat.

This is not effective and leads to an increase in temperature inside the case, which leads to a reduction in battery life cycles, as we discussed above. In addition, the capabilities of passive balancers are currently limited to 50 to 400 milliamps. Most often, more is needed.

The second way is Active balancing. It’s integrated into our batteries. It is much more efficient with balancing current up to 2 amps (Cruiser series) with voltage distribution between cells and the absence of extra heat.

Often manufacturers save on the balancing mode or equip batteries with only passive balancing. This is unacceptable for marine batteries.

Safety is extremely important when you are at sea on a boat.

Any marine battery must have the following protection:

Over-voltage protection (protection against over-charge and over-discharge, performed by BMS). Due to an imbalance or improper charger adjustment, the cells may be damaged and cause a fire. If the voltage goes beyond the permitted limits, the BMS physically disconnects the battery. This function is usually present in all batteries, even the cheapest ones, with BMS.
Over-current protection (performed by BMS and fuse). If the load does not match the battery's C-RATE, this will lead to overheating of the wires and a fire. Unfortunately, this function is either absent or not adjustable on cheap batteries. In our batteries, the BMS allows us to set the maximum permitted current precisely.
Over-temperature protection (performed by BMS with temperature sensors). Temperature sensors measure the actual temperature of the cells inside the battery. The cells should not operate at temperatures below 5 degrees and above 55-60 degrees Celsius. Cheap batteries do not have this function. Batteries often operate at very high temperatures and degrade. In our batteries, the temperature sensors are connected to the BMS. The BMS monitors the temperature.
Short circuit protection (in most cases, proper way - performed by fast fuse). In case of an accident, or a short circuit on the DC bus, the battery must be disconnected, otherwise wires and components will be damaged and it will cause a fire.

Cheap batteries may not have protection at all! In most batteries, protection is performed by the BMS itself. The best BMSs interrupt a MAX current of 7C, but this is not enough in most cases, since modern batteries produce a short-circuit current of 10 or 12C. The BMS is not able to interrupt such a current. In the best case, the battery will lose its functionality, in the worst case, it will cause a fire. Unfortunately, most batteries do not have internal short circuit protection (FUSE or CB). A battery without protection is like a car without an airbag.

We want to provide the highest level of protection. The life of the crew, the safety of the boat, and the maintenance of service in the open sea (availability of electricity) are our priorities. That is why our cruiser series batteries are equipped with a fast current limiting fuse class-T, with a limiting capacity of 20,000 amps, and arc protection. In most cases, this helps not only to prevent fire but also to save your battery and quickly restore the service at sea.

We often hear that all LiFePO4 batteries are the same, you can buy the cheapest battery and put it on your boat. Unfortunately, many cannot imagine possible negative scenarios, that are directly related to the battery characteristics. A bad battery is like a bad car without an engine temperature sensor, seat belts, speedometer, tachometer, airbags, and bad brakes. It seems to be ok to drive, but would you like to put your family in this car?

Key Features

of the CRUISER Marine Battery

Smart Technology Integration
The CRUISER battery is fully adjustable via Bluetooth, allowing users to monitor and manage battery performance using a smartphone. Additionally, data can be output to a remote personal touchscreen display, providing real-time information at your fingertips.

Advanced Battery Management System
Equipped with a powerful 300 amps BMS, the CRUISER battery includes the most modern active cell balancing function, with a balancing current of up to 2 amperes. This system ensures optimal performance and longevity of the battery cells.

Superior Safety Features
Safety is a top priority for the CRUISER series. Each battery is equipped with the fastest current-limiting, short-circuit, and arc-preventing T-Class fuse. Additionally, it includes temperature sensors, high and low-temperature protection, voltage&current&short circuit protection, and a personal emergency valve for each cell, ensuring maximum safety in all conditions.

What is a real marine battery ?

Don’t buy any lithium batteries until read

WHY CHOOSE US

so many LiFePO4 batteries on the market, but..

There are so many LiFePO4 batteries on the market starting something around 150-200 USD per 100 amp hours. But not every battery is suitable for installation on a boat. Often the battery will not last long on the boat and can also be a source of fire.

Read carefully!

How long does a lithium battery last before it degrades?