Boat batteries at a glance

Do you want to buy a battery for the boat or inquire which battery is the most suitable? We would be happy to help you with the topic of batteries, enjoy reading!

There are a few basic things to keep in mind when installing your battery system. The most important is the information from the manufacturer! If you observe the following 10 points, almost nothing can go wrong!

The determination of the capacity of your battery on the boat can be found in our advisor article. Just make sure you stop by!

A series connection of several batteries is only as strong as your weakest link. Different charge levels lead to reduced capacity and lifespan of a battery system, which is prevented by a balancer. Chargers cannot compensate for this!

Failure of a single cell can damage the entire parallel connection until cell death. The cause is high equalizing currents between the batteries. Again, use fuses or balancers so that a single, defective battery cell does not damage all others within the battery system.

With the lithium battery, the balancing of the cells is carried out by the BMS, so that small differences can be compensated for. Cell balancing can be active or passive. Active balancers transfer the energy from cells with a higher charge to cells with a lower charge. In contrast, passive balancers function like a charge limitation, so that all cells are charged to the same extent.

You should have read these instructions before operating:

The housing protects battery cells from environmental influences. For boats, the housing should at least be splash-proof or waterproof. The standard material for battery housings is ABS plastic with a low weight. This is robust, weather and aging resistant, so ideally suited. Some manufacturers of particularly high-quality battery systems, some with high capacity, use stainless steel or aluminum alloys.

Batteries that are not primarily designed for the boat sector often do not have a high IP protection class. Compared to boat batteries, solar storage systems are neither particularly dust-protected nor water-protected. If you want to use these batteries, they must be installed in a water-protected place. Alternatively, you can use a battery case.

A battery management system (BMS) protects the lithium batteries against dangers and damage, as well as other safety risks. For this reason, we always recommend using a BMS for lithium batteries. Lithium-ion cells are particularly susceptible to over- and deep discharge.

Leaving the voltage range recommended by the manufacturer can lead to a short circuit and destruction of the cell. Another important function is the balancing of the cell voltages. Temperature monitoring and load limitation ensure that the electricity is interrupted in an emergency. The battery cannot be damaged and hazards such as fires or explosions are prevented.

Important parameters that are monitored:

It is usually important to be able to read the remaining capacity of the battery and to have certainty about the remaining range. An LED indicator is often attached to the electric outboard. This is usually not very precise but is usually sufficient. A battery monitor shows you the state of charge in more detail.

The voltage is the most important parameter because the charge level can be determined from it. Many displays show the relevant charge level directly and not the battery voltage. For battery monitors or on-board computers, the voltage is a standard value. With chargers, the battery voltage is always displayed during charging.

The charging current is controlled by the charger. Many chargers offer the possibility of displaying the current charging current. The charging power can also be determined on the basis of the charging current and the charging voltage (V * Ah = Wh). The higher the charging current, the higher the charging and charging speed of the battery

You should always make sure that the battery can handle the charging current. If not, it can result in loss of capacity or even the destruction of the battery. The same applies to the discharge current. The remaining driving time can be calculated on the basis of the discharge current and the charge level.

The remaining driving time can be calculated relatively easily. If you measure the current power consumption and know the usable capacity of the battery, you can calculate the remaining driving time. The remaining range can also be calculated based on the current speed and the remaining driving time. Since both values cannot be measured directly, they are not displayed by engine displays and on-board computers by default.

A frequently monitored characteristic value is the temperature of the battery when charging. The temperature must not exceed about 55 ° C, otherwise, it will be damaged. The danger is usually only with fast chargers or excessive charging currents. We therefore always recommend a suitable charger.

The best way to store or hibernate the battery varies slightly depending on the type of battery. AGM, gel and lithium batteries can usually hibernate on the boat. Cold temperatures do not harm them thanks to their low self-discharge. The batteries could only be damaged below -20 ° C, as the electrolytes will freeze at some point.

Lead batteries (AGM and gel batteries) should, if possible, be stored in a fully charged state. You should disconnect the batteries and if possible connect them to a charger with trickle charging. If this is not possible, we recommend checking the charge level of the battery and charging if necessary. It is best to observe the manufacturer's recommended final discharge voltage.

Lithium-ion beverages are best stored in a charge level of 50-75%. Lithium-ion beverages will also be disconnected, but under no circumstances will they be a trickle charger. Due to the very personal self-discharge, the battery should survive the entire winter. You can charge your battery after a few months to include a deep discharge.