The power of the right battery

Do you recognize the problem that when you anchor for a night you start calculating how long your fridge can stay on before you have to turn off the power? Or do you want to be off-grid for longer, exploring your horizon without worrying about battery capacity? Then we have the solution for you.

At Zarcillo Smartmarine we offer everything to being off-grid with your boat, including the powerful LiFePO4 (lithium) batteries, in the combination with our high quality Electromaax dynamos and our solar panels are perfect for long-term, reliable energy storage.

On this page we will explain the basics of the different battery types and focus on the advantages of LiFePO4 batteries. How do you know which battery suits your sailing style best? Don't worry, we are happy to help you! The right battery and battery capacity can make the difference between a carefree sailing trip or anchoring full of stress about a power outage.

To help you make a well-considered choice for your on-board energy system, we will list the advantages and disadvantages of lead-acid batteries, AGM batteries and lithium batteries. 

We only sell lithium batteries because we believe this is the smartest choice and we fully support it.

Off the grid

Content

Battery types and their characteristics

Lead acid batteries

The traditional choice, the lead acid battery, has proven its worth over the years. This type of battery is reliable and cost-effective, and can operate under a wide range of conditions. It is still one of the most common types of batteries on boats, mainly because they are relatively cheap to begin with.

Benefits:
  • Low purchase costs, making them attractive to sailors on a budget.
  • Reliable performance under normal use.
  • Easy to recycle.

Cons:
  • Limited lifespan and charge cycles. This means they need to be replaced relatively quickly compared to other battery types.
  • They are heavy and large, which is detrimental to the weight distribution on board.
  • Very sensitive to deep discharge, which can drastically shorten their lifespan.
  • Not suitable for sailing under a heel, which can be a disadvantage on a (sailing) boat.

AGM batteries (Absorbent Glass Mat)

AGM batteries are an improved version of lead-acid batteries and offer several key advantages. They are low maintenance, fully sealed, and can be installed in a variety of positions. This makes them popular with sailors looking for a more robust and reliable option, without having to switch straight to lithium.

Benefits:
  • Little to no maintenance required.
  • They are safer than traditional lead-acid batteries because there is less chance of leakage.
  • Resistant to vibrations and shocks, which is a great advantage in rough seas.

Cons:
  • Higher cost than traditional lead acid batteries, but you pay for better quality and performance.
  • Still heavier and larger than lithium batteries, making them less suitable for situations where weight is an important factor.

Lithium / LiFePO4 batteries

Now for the game changer: the LiFePO4 battery. This modern powerhouse offers unmatched performance and energy density. Compared to lead-acid and AGM batteries, LiFePO4 batteries last much longer, can be discharged deeper without loss of performance, and can handle high currents better.

They are the idealThe choice for those who are serious about off-grid living or want to spend extended periods of time on the water without worries. It is therefore common for customers to say after switching to lithium: 'I wish I had switched sooner!'

Benefits:

  • Lightweight and compact: on a boat where every kilo counts, this is a huge gain. It helps the overall performance and stability of the boat.
  • A much longer lifespan, with significantly more charge cycles than lead acid or AGM batteries. You don't have to worry about your battery giving up after a few years.
  • Faster charging and higher discharge capacity, meaning you can get more out of your power supply without draining your battery quickly.
  • Can be placed in different positions, and can be used under a slope without any problems, perfect for boats in rough conditions.
  • No maintenance required, giving you more time to enjoy sailing instead of fiddling with your batteries.

Cons:

  • Higher initial cost: Lithium batteries are more expensive to purchase, but their longer lifespan and better performance make them an investment that will pay for itself in the long run.
  • Sensitive to extreme temperatures: they should always be in combination with a Battery Management System (BMS) to prevent damage from high or low temperatures.


There is one more feature that needs some explanation, namely that the LiFePO4 batteries are powerful and smart, especially thanks to the built-in BMS (Battery Management System).

BMS (Battery Management System)

This smart system sometimes brings with it extra points of attention. We are happy to explain why this is not something to worry about and how you can easily make adjustments to optimally enjoy the benefits of LiFePo4.

Because LiFePO4 batteries can be discharged more deeply and can handle high currents during charging and discharging, it may be necessary to modify some parts of your electrical system.

1. Charger
Fortunately, most modern chargers, such as shore power and MPPT chargers, already support a lithium charging profile, or give you the option to create one yourself. It is possible that your charger does not. If you have any doubts about whether your current charger is suitable, please do not hesitate to contact us. We are ready to advise you and help you with any adjustments.

2. Dynamo
Where a standard dynamo is perfectly suitable for charging a lead-acid starter battery or service bank, a LiFePO4 battery demands more from the dynamo. The LiFePO4 can even overload the dynamo and in extreme cases burn it out. How quickly this happens depends on the use, but that it will happen is certain.

You are probably now charging your starter battery and service bank via a diode bridge, such as an ArgoFET. This system works well for lead acid batteries, but will have the aforementioned problems when charging LiFePO4.

Fortunately, there are excellent solutions to prevent this problem, suitable for everyone's needs and budget.

Read below two options for charging your Lithium batteries with a dynamo.

The BMS is indispensable

This electronic system ensures that your battery is protected against overcharging, deep discharging and overheating. The BMS also monitors the status of your battery, such as voltage, current, temperature and charge level, and ensures that the cells of your LiFePO4 battery are charged and discharged evenly if it has a balance function.

A BMS ensures safety and extends the life of your lithium battery considerably. Without a BMS, the battery can overheat or even cause dangerous situations such as fire. That is why it is essential to always use a BMS in combination with a LiFePO4 battery.

Charging lithium battery with dynamo

The simple solution

The cheapest option is to remove the diode bridge from the system. Instead, charge the starter battery directly via the alternator, and install a DC-DC charger (for example a Orion 30A) between the starter battery and your service bank. The alternator is not overloaded, and your starter battery charges safely. Your service bank is recharged via the starter battery by means of the DC-DC Charger.

Disadvantage: This solution can be slow, especially if you have a large lithium bank. It may take days to fully charge it, as your current alternator probably doesn’t provide enough power.

The advanced solution

Want to charge faster and get the most out of your system? Then choose a new alternator, such as an Electromaax alternator, which charges your service bank directly. In this setup, the starter battery is charged from the service bank via a DC-DC charger. This is the most efficient solution, which can easily supply 120 amps to your service bank, for example.

This option comes with a different price tag, but the benefits – fast charging and no overloading of your alternator – definitely make it worth the investment.

More information about dynamos can be found here and over DC-DC chargers here.

Battery capacity in Ah

Batteries are expressed in Ah, which stands for Ampere-hour. This indicates how much current a battery can deliver over a certain period.

Suppose you have a 100 Ah battery. In theory this battery can:

  • Deliver 1 amps for 100 hour.
  • or deliver 10 amps for 10 hours.

To translate this into a practical example:
If your refrigerator draws 6,5 amps, a 100 Ah battery would run it for about 15,4 hours (100 / 6,5).

Please note: This is purely theoretical and assumes the battery is 100% full and is fully discharged.

Lead acid batteries

For lead-acid and AGM batteries, you should only discharge the batteries to 50% of their capacity to prevent damage and extend their lifespan.

This means that a 100 Ah lead-acid battery actually only has 50 Ah usable.

So, in the case of a 100Ah lead acid battery, you can only use it up to 50Ah. Your 6,5Ah fridge can now only run for 7,7 hours, instead of the previously mentioned 15,4 hours.

In addition, the efficiency of a lead-acid battery decreases as it is less than 100% full. The lower the charge, the worse the performance, and the faster the battery deteriorates in quality.

LiFePO4 (lithium) Batteries

These batteries can be discharged between 80-90% of their total capacity without compromising their lifespan or performance!

We're going to use the example of 80% usable. So, in the case of a 100Ah lithium battery. You can effectively use 80Ah. That means your 6,5Ah fridge can now run for about 12,3 hours.

Comparison in use 6,5 A refrigerator

Battery typeUsable capacityUsage time
100 Ah
lead acid		50 Ah7,7 Hours
100 Ah
lithium		80 Ah12,3 Hours

As you can see, a lithium battery can provide power for much longer without damaging the battery or losing its efficiency. That is one of the reasons why we are so fond of lithium batteries.

Lithium batteries

View all lithium batteries
Victron

Victon is known for its high-quality technology and excellent compatibility within its product range. Their lithium batteries are designed for optimal communication with other Victron-products, although a BMS must be purchased separately.

Solar Mobile

Solar Mobile is an excellent value for money choice. These batteries are high quality and come with a built in BMS. They are easy to install and have the option of a heating element for use in cold conditions and/or a Canbus for the Victron-connectivity.

Ready for carefree sailing?

At Zarcillo Smartmarine we understand how important the right battery is for your adventures on the water. Whether you want to keep your old lead acid system or purchase a modern LiFePO4 battery, we are here to help you find the best solution for your situation. Our team is always ready to advise you and ensure that you can enjoy a sense of freedom on your boat with peace of mind off-grid.

 

Need help? We're here for you!

Questions about batteries or other products? Feel free to contact our expert team. At Smartmarine is all about service and satisfied customers. We are happy to advise you, so that you can sail carefree and without annoying annoyances.

 

Ask us for advice