Boats

All kinds of boat batteries

There are three different types of batteries for boats: The starter battery is used to get the engine running and on-board batteries are used to power navigation equipment, the on-board refrigerator or lighting. Dual batteries perform both tasks. We show you which battery fits your boat.

More info about battery types
Frequently asked questions

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Supply batteries for your boat

Supply or consumer batteries are responsible for the reliable power supply of all electrical consumers in motor, sailing and electric boats.
There are different types:

Electrolyte is bound in a fleece
(Aborbent Glass Matt).

AGM technology

Short charging times
Deliver high currents, e.g. for bow thrusters or winches
also suitable for solar applications
low self-discharge
Maintenance-free: no refilling of distilled water
vibration-proof & position-independent installation possible

Electrolyte is thickened by silica
and gel.

Gel technology

ideal as a consumer battery due to its high number of cycles
low self-discharge
can be stored for a long time and is maintenance-free
vibration-proof & position-independent installation possible

Tips:

When choosing your charger, make sure it is designated for your battery type

The depth of discharge should not exceed 50%

How to calculate the approximate required capacity (Ah) of your battery system - see example

Consumer batteries for marine

These batteries are also called motive power batteries or semitraction batteries and can be used when a constant power supply is needed over a longer period of time a constant power supply is needed. This is roughly the case with electric motors. Due to their low Self-discharge they are also particularly suitable for storing solar energy.

Reinforced grid plates
and liquid electrolyte

SEM Technology

particularly low self-discharge
designed for many charge and discharge cycles
suitable for low power consumption
low-cost battery variant
low maintenance due to simple acid control

Tips:

Select the battery capacity so large that connected wind generators or solar panels also provide the necessary charging current to be able to fully charge the batteries.

Watch out when comparing batteries!
Meaning of the information C10 or C20 on the battery type plates:
The number after the C indicates in what time (always in h) the corresponding capacity (Ah value) is dischargeable.
Example: 100Ah (C20) 100 Ah / 20 h = 5 A (ampere). this means, the battery would be loaded with 5 A,
would be discharged in 20 hours.

Starting and supply batteries for small boats

These dual batteries are used when only one battery is installed in the boat and power is needed both to start the engine and to power the onboard electronics. With these all-rounders, the technology is geared toward universal use Aimed and it is not to achieve maximum performance.

Dual batteries, however, are also commonly used for special applications such as windlasses and castle thrusters. These combination batteries are designed for smaller boats and are very suitable for seasonal use.

"Absorbent Glass Matt" batteries with electrolyte bonded in fleece, maintenance-free and sealed.

AGM technology

Developed for demanding boats and yachts
very durable
shock and vibration resistant

Tips:

If the boat allows two batteries, it is recommended to use a car battery for starting and a supply battery for the electrical devices.

Old batteries can be disposed of through us professionally and certified! More information about this

Victron inverter

Battery supplies for boats

Are you interested in battery supplies?
We offer innovative chargers, charge boosters, inverters and much more from Victron Energy.

More about Victron

Our top selection of boat battery brands

Our top selection of brands

FREQUENTLY ASKED QUESTIONS

You have questions about batteries for boats?

Here you will find a summary of the general questions and answers for the marine sector.
If this does not answer your questions, please contact us by e-mail or telephone.
We will be happy to help you. info@akkusys.de +494101 37676-0

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 in order to be recharged immediately after starting the combustion engine.

On-board batteries are designed for cyclic loading. They can deliver relatively low currents over a longer period of time.

Is it worth switching to gel or AGM batteries?

If you are currently using a liquid battery and are considering a switch because of the maintenance-free, non-gassing, longer service life and higher capacity, you should first clarify whether the existing charger is also suitable for AGM or gel batteries. At the same time, one should keep the operating conditions in mind.

If you only use your onboard batteries a little, you will probably be able to get by with the inexpensive liquid version. On the other hand, those who plan to load their batteries more cyclically and assume a high power demand will not be able to avoid a conversion in the long term.

How big do my batteries need to be?

Lead-acid batteries last a very long time if they are always full as often as possible and are deeply discharged as little as possible. The following standard errors occur again and again in practice:

The batteries are chosen so large that the charger, wind generator or solar panels do not provide the necessary charging current to fully charge the batteries. This damages the batteries in the long term. The capacity decreases. The remedy is a charger that is designed for the battery capacity.
The batteries are chosen 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, an increase in battery capacity is necessary. Please consult us or your caravan / marine specialist before investing. The following sample calculation can be used to roughly determine the necessary 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

Through this calculation, one can calculate the consumer individually and by adding it up, find the total capacity needed. Since the usable capacity is not equal to 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 driving, the onboard batteries are charged by the alternator of the engine. However, an optimal full charge is usually only achieved via a charger with a 220 V connection. For this reason, every opportunity for charging should be used. Wind generators and solar panels are usually only used for supplementary charging, i.e. a charger is necessary to optimally charge the batteries and thus maximise their service life. We are happy to help with the selection of a suitable charger.

Watch out for the different types of batteries! There are different charging techniques for acid, gel, AGM and lithium batteries. The wrong charger can damage the battery and in the worst case it can lead to an explosion. Be sure to get advice! Please do not experiment!

Which connections are necessary to connect a battery?

The following illustration shows the most common connection types of lead batteries. A frequent connection problem is caused by the installation of AGM batteries in older e-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. (Link image)