Choosing Batteries for Boats

Batteries are the beating heart of a solar boat

The best batteries for canal boats

As canal boat owners, we're always looking to combine sustainable living with the freedom of navigating our beautiful waterways. We've found that one of the best ways to do this is by installing a solar power system on your boat. This both enhances our off-grid capabilities and reduces our reliance on fossil fuels.
A crucial component of any solar power setup is the battery system, which can store akk the energy generated by your solar panels. Making sure to choose the right battery can make a significant difference to the boat's performance and longevity.
Here's a short guide to what we consider the best battery types for solar-powered canal boats.

Understanding battery types

Our findings have shown that the three primary types of batteries best suited for solar applications are lead-acid, lithium-ion, and AGM (Absorbent Glass Mat). Each type has its advantages and disadvantages, making it important to consider your specific needs before making a choice. Here's a breakdown of the pros and cons for each type.

Lead-acid batteries

Lead-acid batteries are the traditional choice for most marine applications. They are widely available, relatively inexpensive, and have a long history of reliable performance.
These batteries come in two sub-types: flooded lead-acid (which require regular maintenance, such as fluid level checks and watering the cells) and sealed lead-acid (which require no maintenance and are less likely to leak).
We feel that while lead-acid batteries overall are generally cheaper upfront, their lifespan and performance may not compare favourably against lithium options if you intend them for regular, high-use.

Lithium-ion batteries

Lithium-ion batteries have become increasingly popular with boaters due to their impressive performance. They are lighter, offer deeper discharge capabilities, and have longer lifespans (often lasting over 10 years).
These batteries have a higher energy density and can store more energy in a smaller footprint, making them a great choice for a canal boat where you obvioulsy you have limited space.
However, we've found that a significant downside for this type of battery is the initial cost. Lithium-ion batteries are noticeably more expensive than lead-acid types.
But considering their longevity and efficiency, many boat owners find they are worth the investment in the long run. Brands like Battle Born, Renogy, and Victron Energy are well-regarded in the boating community for their quality lithium options.

AGM batteries

AGM batteries are a solid option that combine the benefits of lead-acid and gel batteries. They are spill-proof and have a lower self-discharge rate than conventional lead-acid batteries.
AGM batteries provide solid performance, can handle deep cycling, and are resistant to vibration, making them suitable for marine environments such as canal boats.
The biggest downside for these batteries is that, like lithium-ion batteries, they are generally more expensive than traditional lead-acid batteries. Yet AGM batteries are often preferred for their maintenance-free operation and resilience. Notable manufacturers of this battery type include Lifeline and Trojan.

Capacity and usage

Capacity is measured in kilowatt-hours (kWh) and this indicates the maximum amount of electricity a solar battery can store. Most of the battery types we've recommended will be "stackable", so multiple batteries can be combined to increase the maximum capacity.
When choosing batteries for your solar canal boat, we recommend you carefully consider your energy consumption needs.
Appliances such as fridges, lights, cookers and navigation systems demand varying amounts of power. It's a good idea to calculate your daily energy usage first and choose a battery with sufficient capacity for your needs.
We've found that a good rule of thumb is to aim for power storage of at least twice your daily consumption. It sounds like lot of spare capacity, and it is, but it ensures you never get stuck with no power.
As well as working out the battery capacity you'll need, it's also useful to consider the battery's power rating. This rating tells you how much electricity a battery can provide at a given moment, measured in kilowatts (kW). It sounds confusing so consider a simple example of how power rating differs from capacity.
A high capacity battery with a low power rating will provide the low level of electricity needed to power appliances with low power requirements for a long time. A low capacity battery with a high power rating can power all your appliances but only for a short time.
We recommend that you consider both attributes carefully to determine the best battery for you.

The choice is yours

In summary, the best battery for your solar-powered canal boat will depend on your budget, energy needs, and willingness to perform maintenance.
Lead-acid batteries can be a great option for those wanting an economical solution and who don't mind the extra work needed to maintain them.
Lithium-ion batteries stand out for their efficiency and longevity, at a higher price point, and AGM batteries offer a great compromise between the two.
Spending some time on research before buying boat batteries can avoid potential problems in the future. If you opt for a lead acid battery it will cost less up-front but you may have to replace it a lot sooner. A lithium marine battery will cost more to start with but can end up lasting much longer if you treat it properly.
Ultimately, we emphasise that investing time to research and consider your options will pay off in terms of performance and reliability on the water. With the right boat battery system in place, you can fully embrace the sustainable lifestyle that solar power provides whilst enjoying the tranquil beauty of canal boat living.