Can I also replace the on-board battery with several starter batteries?

The use of a starter battery is generally not recommended. Starter batteries are designed for short-term power output, so that they can be recharged immediately after starting the combustion engine. On-board batteries are designed for a cyclical load. They can deliver relatively low currents over a longer period of time.

How big do my batteries need to be?

Lead-acid on-board batteries last a very long time if they are always full as often as possible and are discharged as little as possible. The following standard errors occur again and again in practice: The batteries are selected so large that the charger, wind generator or solar panels do not supply the necessary charging current to fully charge the batteries. This damages the batteries in the long term. The capacity decreases. A charger that is designed for the battery capacity provides a remedy. The batteries are too small. The refrigerator or the daily TV programme draws so much current from the on-board batteries that a deep discharge occurs and the batteries are damaged as a result. In this example, the battery capacity needs to be increased. Please seek advice from us or your caravan / marine specialist before investing. The following sample calculation can be used to roughly determine the required capacity (Ah) of your battery system: (power 60 watts (W)) / (voltage 12 volts (V)) = amperage 5 amps (A) * duration of use / day in hours (h), e.g. 10 h = required capacity in ampere hours (Ah) 50Ah This calculation can be used to calculate the consumer individually and determine the required total capacity by adding them together. As the usable capacity is not the same as the specified capacity, the calculated capacity must be multiplied by a factor depending on the battery type. In this case, we suggest the following factors: 50Ah * factor liquid battery 1.7 = 85Ah 50Ah * factor AGM / gel battery 1.4 = 70Ah

How do I choose the right charger?

While travelling, the on-board batteries are charged by the engine's alternator. However, an optimum full charge is usually only achieved using a charger with a 220 V connection. For this reason, every opportunity for charging should be utilised. Wind generators and solar panels are usually only used for supplementary charging, i.e. a charger is required to optimally charge the batteries and thus maximise their service life. We will be happy to help you select a suitable charger. Be careful with the different batteries! There is different charging technology for acid, gel, AGM and lithium batteries. The wrong charger can damage the battery and, in the worst case, can lead to an explosion. Always seek advice! Please do not experiment!

Which connections are required to connect a battery?

The following diagram shows the most common connection types for lead-acid batteries. A frequent connection problem arises when installing AGM batteries in older electric wheelchairs because autopoles were originally available and the new batteries do not have them as standard. In this case, we are happy to supply autopole adapters that are screwed into the screw connection of the batteries.

Batteries for boats

Whether for yachts, sailing boats or motorboats - reliable power supply on the water is crucial. With our wide range of Starter, supply and dual batteries we offer you the perfect solution for all marine applications. Benefit from our extensive expertise and our large stock - we are your strong partner for high-quality marine batteries.

Our top brands for boat batteries

Your advantages

Expert advice:

Our team of experts will help you select the right boat battery to suit your individual requirements.
Fast delivery:

Thanks to our well-stocked warehouse and efficient logistics, your orders will arrive quickly.
Quality and reliability:

Our range of batteries for boats fulfils the highest standards. You can rely on stable performance, high cycle stability and a long service life - ideal for any marine application.
Flexible and uncomplicated ordering:

Order conveniently online, by e-mail or by phone - whether you want a single item or a bulk order, we are here for you.

Overview of different battery technologies

There are three types of batteries that are generally used in the marine sector: Supply batteries, starter batteries and dual batteries.

Starter batteries are specially designed to start the engine. Further information can be found here: Starter batteries

Supply batteries

Supply batteries for the marine sector, also known as on-board batteries, reliably operate electrical consumers on boats and yachts. Different battery types offer different advantages:

AGM (Absorbent Glass Matt)

Fast loading time
High currents can be drawn
Suitable for solar applications
Best choice in combination with inverter
Maintenance-free and vibration-resistant

Gel

Long shelf life
Very good resistance to high temperatures
Very durable
High discharge depth and cycle-proof
Maintenance-free, vibration-resistant & position-independent installation

SEM (traction and lighting batteries)

Particularly low self-discharge
High cycle stability
Suitable for low power consumption
Inexpensive and durable
Low maintenance due to simple acid regulation

LiFePO4 (lithium iron phosphate)

Significantly lower weight compared to acid, gel and AGM
Very low self-discharge
Long service life thanks to high cycle stability
Particularly high current capability
App monitoring via Bluetooth from a capacity of 75 Ah
Maintenance-free

Dual batteries

Dual boat batteries are ideal if a single battery is to be used both as a starter battery for the engine and to supply the on-board electronics. With AGM or wet technology, they offer a practical solution for boats with limited space.

AGM

Developed for demanding boats and yachts
Extremely durable
Shock and vibration resistant

EFB

Developed for mid-range boats and yachts with high energy consumption
Minimal self-discharge
Durable and resilient
Cheaper than AGM

All from a single source

We offer you everything your customers need for a self-sufficient energy supply at sea:

Chargers are necessary for a complete and efficient charge of your on-board batteries, regardless of the energy source. An optimum charge maximises the service life of the batteries.

Charging booster supply consumer batteries with energy while driving and can be used as jump starters.

Inverter convert 12 V DC voltage into 230 V AC voltage and are ideal for sensitive electrical appliances thanks to their pure sine wave.

Weatherproof solar panels and MPPT charge controller enable a self-sufficient power supply and the efficient use of solar energy.

With intelligent Battery monitorswhich can be operated via app, you always have an overview.

With these components, you ensure maximum flexibility, self-sufficiency and efficiency - perfectly tailored to the needs of your customers.

Helpful downloads for boat batteries

Professional disposal of old lead

We take care of the certified and professional disposal of all types of batteries. In most cases, the raw materials can even be completely recycled.

Frequently asked questions

Do you have questions about boat batteries?

Here you will find a summary of general questions and answers.

If your question is not listed, please contact us.

We will be happy to help you.

What is the difference between starter and supply batteries?

There are two main types of battery on boats. Starter batteries are specially designed to start the boat engine. They supply high currents for a short time and are then recharged directly by the engine.

Supply batteries, on the other hand, provide power for electrical devices such as navigation systems, lighting, refrigerators or entertainment electronics on board. These batteries are designed to deliver consistent amounts of energy over a long period of time.

It is important to separate the two battery types so that the supply batteries do not discharge the starter batteries and thus prevent the engine from restarting.

Can starter batteries replace supply batteries on boats?

The Use of starter batteries to supply electrical consumers on boats we do not recommend. Starter batteries are designed to supply high currents for starting the engine in a short time, while supply batteries are designed for cyclical loads. You can deliver consistent amounts of current over a longer period of time without being damaged. Starter batteries would wear out prematurely if used in this way.

Which battery technology is best suited for boats?

The supply batteries with AGM technology impress with their versatility and are the ideal choice in combination with an inverter.

Gel batteries are one of the most popular solutions for supplying power to electrical consumers in the caravan/marine sector. They are characterised by their easy transportability and can easily withstand longer storage periods.

Lithium iron phosphate batteries are becoming increasingly popular, particularly due to their low weight combined with high energy density. Although the purchase costs are higher, these are offset in the long term by their impressive longevity and outstanding cycle stability.

Let us advise you!

What do the indications C10 or C20 on the battery type plates mean?

The values C10 and C20 indicate the capacity of the battery in ampere hours (Ah) and refer to the discharge time.

For example, a specification of 225 Ah (C10) and 242 Ah (C20) means that the battery can release more energy over a period of 20 hours than over 10 hours. The faster a battery is discharged, the lower its actual available capacity.

Is it worth converting to gel or AGM batteries?

Converting to gel or AGM batteries can be worthwhile, especially for boats with higher energy requirements. Both battery types are maintenance-free, non-gassing and offer a longer service life and higher cycle stability than classic liquid batteries.

However, before you convert, you should check whether your charger is suitable for AGM or gel batteries. A liquid battery may be sufficient for occasional journeys. However, for intensive use and higher loads from electrical consumers, a conversion is advisable in the long term.

How large should the capacity of a battery be?

The capacity of a boat battery should be carefully matched to the energy requirements on board. Batteries last longest when they are regularly fully charged and only discharged a little. Common errors in dimensioning are

Too big: The charger, solar panel or wind generator does not supply enough power to fully charge the battery. As a result, the capacity decreases over time.

Too small: Consumers draw more current from the battery than it can supply, which leads to deep discharge and permanent damage.

A rough calculation of the required capacity (Ah) is made as follows:
Power (W) ÷ voltage (V) = amperage (A)
Amperage × duration of use per day = required capacity (Ah)
Example: 60 W ÷ 12 V = 5 A
5 A × 10 hours = 50 Ah

This calculation can be used to determine the consumption of each individual device and the required total capacity can be determined by adding the results. As the actual usable capacity differs from the specified capacity, the calculated value must be adjusted with an appropriate factor depending on the battery type.

Liquid batteries: Factor 1.7 à 85 Ah

AGM/gel batteries: Factor 1.4 à 70 Ah

How do you choose the right charger?

The engine's alternator charges on-board batteries while driving, but a full charge is usually only achieved using a charger with a 220 V connection. A suitable charger maximises the service life of the battery and ensures optimum charging.

Solar panels and wind generators only offer supplementary charging options. A suitable charger is required to fully charge your boat battery. Make sure that the charger is suitable for the battery technology (acid, gel, AGM or lithium batteries). Incorrect chargers can damage the battery and, in extreme cases, even cause an explosion. You should therefore seek advice from our experts.