Boats

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 to withstand cyclical loads. They can deliver relatively low currents over a longer period of time.

If you are currently using a liquid battery and are considering a conversion due to 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, you should bear in mind the operating conditions.

If you only use your on-board batteries a little, you will probably get by with the inexpensive liquid version. If, on the other hand, you plan to use your batteries more cyclically and expect a high power requirement, you will not be able to avoid a conversion in the long term.

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 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. 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. In this example, the battery capacity needs to be increased. Please consult 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 load individually and determine the total capacity required 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 * liquid battery factor 1.7 = 85Ah
50Ah * factor AGM / gel battery 1.4 = 70Ah

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. An incorrect charger can damage the battery and, in the worst case, can lead to an explosion. Always seek advice! Please do not experiment!

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.
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