company news about How to install lithium boat batteries

In light of the ever increasing demand for power on current cruising yachts, LILEAD looks at lithium-ion batteries and explains what is required to ensure a safe, trouble-free system.

Those who do a lot of sailing, like the Blue Water Cruiser, will be able to benefit from the extra capacity of the lithium-ion battery, which can be powered by multiple sources.

How to install lithium boat batteries

The modern solution to the rising electricity demand for blue-water yachts is to install lithium ion battery banks, especially if one plans to eliminate LPG in cooking.

But lithium ion batteries can be complicated and problematic, and if not handled properly, they can be a serious fire hazard.

First of all, Lithium-Iron-Phosphate (LiFePO4), commonly abbreviated as LFP, is currently recommended as safe for use on board ships.

The cells themselves are virtually fireproof, and have been extensively tested by fire authorities in a number of countries, though they can still cause a fire (as can any battery) if they are installed or used improperly.

Use of automotive lithium-ion blends with such elements as nickel, cobalt and manganese are strongly discouraged for use on a boat as they are far more prone to 'thermal runaway' should they fail.

This effectively eliminates the need for old electric car batteries, since there is no real way to transfer the complex protective system they were originally designed to work with.

Electrically propelled yachts will usually have a higher voltage system (usually 48V, 72V or 96V), which requires a very carefully designed control system.

To do this, it is tempting to incorporate higher-density lithium batteries, for example, Lithium Cobalt (LiCoO2), but this requires specialized design and installation, and is extremely costly.

Moreover, if you can't get your ship insured with a battery like this, what's the point of doing that?

Why do you opt for LFP batteries?

The main advantage of an LFP battery is that it can receive a very fast, high current charge, and it can be drained to near empty state of charge without regular recharging to 100% state of charge (SoC), as is the case with lead-acid (LA) batteries.

Actually, they're more comfortable sitting in 20 to 80 percent of the time. You can even turn off an LFP without damaging it, even though most built-in Battery Management System (BMS) switches it off at about 12 V, or about 10% of SOC.

This is the case when they are fully charged – the BMS should turn off the charging source at about 14.2V to avoid overcharging.

LFP batteries also offer far more charging cycles than an equivalent LA battery, and, ultimately, they are significantly lighter than any LA battery, which can significantly improve the balance and performance of a yacht.

Change to LFP?

Capable of receiving and discharging very high current, any related wiring and circuitry for LFP batteries should be tailored to their needs.

All LFP banks need an integrated Battery Management System, which provides reverse polarity protection, individual cell balancing, charge and current limits, administration and emergency disconnection, battery and alternator temperature sensing, discharge current limitation and management – plus visual/audible alarms.

It is also important to note that, with many of the so-called 'drop in' LFP batteries (those with integrated BMS), it may not always be possible to connect more than two in series or in parallel to create a bigger bank.

If you want more capacity, it's usually best to build your own bank out of individual 3.2V cells and connect one external BMS to control the whole bank.

If you really want to build your own battery bank out of a single cell, you'll have to purchase a new, A-grade cell.

Many of China's budget purchases are pre-made cells, often replaced with Uninterruptible Power Supply (UPS) or equivalent.

Although your luck is good, it's not worth the risk as it's practically impossible for you to return them.

Ideally, the cells will have been tested and the voltage levels are about the same, but you'll still have to balance them first to make sure.

Although it is possible, LFPs are not recommended for starting the engine or for anchoring windlass and bow propulsion. Most won't work anyway as such an instant heavy current draw these devices demand can often exceed their BMS output threshold.

The most worrying element in an LFP installation is how to make the system secure for charging.

Like most things on a ship, there are individual decisions and practical decisions to be taken into account, and many of them will differ according to the size of the ship and its type.

Maximum Cell Life

Compared to the Lead Acid (LA) type, LFP batteries have very low resistance, allowing them to be charged and discharged at a much higher rate – even up to 1C (1 x capacity, or 100A for a 100Ah battery).

In general, however, they are charged from 0.5 to 1.0 C until the charge current falls to between 0.015 C and 0.03C, at which point they have to stop charging in order to avoid overcharging the cells.

Some manufacturers even suggest that you stop charging at 0.1C to further reduce cell stress and prolong life.

Unlike an LA battery, the SoC can't be determined solely by battery voltage, which can reach its peak when an LFP battery is only half charged.

In addition, a fully charged 12.8 V LFP battery has a resting voltage ranging from 13.4 to 13.6 V, which is much higher than the 12.7 V of a normal lead-acid battery. At 20% SoC

It's still going to say 13V, when the LA battery is going to be 11.8V.