Marine batteries: let’s compare the different types of batteries for boats


Marine batteries: let’s compare the different types of batteries for boats

Marine batteries are a key item for sea autonomy. They influence the engine, the instruments, the sailing lights and several other elements.

Not all marine batteries are the same

There are four different types of batteries for boats:

  • Lead acid
  • Gel
  • AGM
  • Lithium 

Each type of battery used for boating has its own specific characteristics and presents substantial differences.

Lead acid boat batteries

Lead acid boat batteries are immersed into sulphuric acid that acts as an electrolyte. This technology needs air circulation as it produces gases that can easily catch fire. Lead acid boat batteries can only be mounted horizontally to avoid acid leakage. This type of battery requires a regular electrolyte check, needing to be refilled with distilled water in case it goes under the minimum level.

Gel maritime batteries

Regarding gel maritime batteries, the electrolyte is immersed into a gelatinous substance. These batteries are sealed so that there is no gas leakage. The gel maritime battery can be mounted inside the cabin, and it does not necessarily need to be installed horizontally. It does not require any kind of maintenance, and can tolerate deep discharges and a large number of charging and discharging cycles.

AGM maritime batteries

In AGM maritime batteries, unlike other batteries, the electrolyte is placed inside spongy elements made in glass fiber. There are several advantages to installing AGM batteries in boats: because they are sealed, they do not require any maintenance, they do not exhale poisonous gases, they prevent electrolyte leakage even in extreme conditions, and therefore they can be mounted everywhere. 

Furthermore, they have higher quality compared to other maritime batteries. In fact, they are stronger, with a longer life, a shorter charge time, and a low self discharge rate when they are not used for long times (about 3% per month). An AGM battery for a boat grants a good functioning in almost all positions, having a top resistance to vibrations and a low sensitivity on temperature jumps.

Lithium boat batteries

“Deep cycle” lithium batteries are the most recent on the market. Having the standard lithium characteristics of a low weight, a high energy density, the potential to supply big currents, several charging cycles and, most notably, the fact that they do not require any maintenance. The price is certainly a disadvantage, which is higher than standard lead batteries and with a lower safety compared to lead batteries. 

How to preserve marine batteries

After showing all main marine batteries characteristics and the advantages of AGM marine batteries, let’s have a look at how to avoid their degeneration. 

A battery can deteriorate in two ways: from mass leakage or corrosion

For example, intensively discharging and recharging the boat battery may lead to the active material consumption, threatening its functioning over time.

At the same time, corrosion may arise at the end of the charging cycle, when the maritime battery tension is high. This may lead to degradation of positive plates. To reduce the damages, it is necessary to use a battery charger with different charging cycles and keep maritime batteries in an cool and ventilated place, and properly lubricating the clamps.