Are designed to supply the high current required to start the engine for a few seconds. Only a very small part of the battery capacity is used. However, they are not suitable for use as consumer batteries, as they would wear out very quickly due to constant discharging and charging.
Can be used both as a starter and consumer battery. AGM batteries have a high cycle stability and thus a long service life, if care is taken that only a maximum of 50% of the specified capacity is taken. In general, the less deeply the battery is discharged, the longer the service life. If you want to determine the energy requirement of a sailing day, you can determine it here. In AGM batteries, the acid is not present in liquid form, but is bound in a glass fleece separator, can therefore also be operated in inclined position (observe the technical data of the battery!) and is leak-proof.
capacity of a battery
The capacity is indicated in ampere hours (Ah). Theoretically, a 60Ah battery could deliver 2 amperes of current for 30 hours until it is empty. In practice, however, an AGM battery, for example, may only draw 50% of its capacity. In the above example, this means that a current of 2 amperes can only be drawn for 15 hours. In addition, the higher the current drawn, the lower the usable capacity of a battery. The battery manufacturers therefore specify the battery capacity at different currents. A common specification for consumer batteries is e.g. 100 Ah ( C20 ). This means that if the battery is loaded with a twentieth (5 ampere) of a current, it has a capacity of 100 Ah. If a current greater than 5 amperes is drawn, the same battery has a smaller, usable capacity. When buying a battery, we must pay attention to the discharge current to which the capacity specification refers.
Cautions when handling batteries
Check the safety instructions of the manufacturer
do not place any tools or other parts on the battery
attach the supplied pole covers
do not use the battery area as additional storage space
Cables which are connected to the battery must always be protected by a fuse adapted to the cable cross section
avoid deep discharge. Use max.50 % of capacity for AGM, max.10 % for starter batteries
prevent overcharging, use regulated charger with IUoU characteristic curve
adjust the charger to the battery type to be charged. AGM batteries are destroyed by too high a voltage
use charger with temperature sensor for battery temperature
batteries must be fully charged regularly
To avoid irreparable damage, batteries must be recharged at the latest when the voltage falls below 12.50 V. Winter storage!!