Samlex Solar SCC-30AB Mode D'emploi page 27

As explained, tt will be seen from the above that the final rated capacity of the batteries
is almost 2 times the energy required by the load in AH. Thus, as a Rule of Thumb, the AH
capacity of the batteries should be twice the energy required by the load in AH.
For the above example, the 12 V batteries may be selected as follows:
• Use 6 Group 27/31, 12 V, 105 AH batteries in parallel to make up 630 AH, or
• Use 3 Group 8D, 12 V, 225 AH batteries in parallel to make up 675 AH.
Battery Charging Stages and Charging Currents
It is recommended that the batteries may be charged at 10% to 13 % of the Ampere
Hour capacity of the battery (20 Hour Discharge Rate). Also, for complete charging
(return of 100 % capacity), it is recommended that a 4 stage charger may be used:
• Constant Current Bulk Charging, followed by;
• Constant Voltage Boost / Absorption Charging, followed by;
• Constant Voltage Float Charging, followed by;
• Constant Voltage Equalization. Equalization is carried out only when some cells do not
charge fully and the individual cell voltages differ by more than 0.2 V cell. Also, equalization
is carried out only for non-sealed / vented / flooded / wet cell batteries.
Batteries and Battery Charging in Vehicles / RVs – Alternators,
Isolators, Inverters
It is recommended that for powering an inverter, one or more auxiliary deep cycle
batteries should be used that are separate from the starter SLI batteries. The inverter
should be powered from deep cycle batteries. For charging the starter SLI and the
auxiliary deep cycle batteries, the output from the alternator should be fed to these
two sets of batteries through a battery isolator of appropriate capacity. The battery
isolator is a device that will allow the alternator to charge the two sets of batteries
when the engine is running. The battery isolator will allow the inverter to be operated
from the auxiliary batteries and also prevent the starter SLI batteries from charging
the auxiliary deep cycle batteries when the engine is not running. Battery isolators are
available from auto / RV / marine parts suppliers.
A majority of smaller vehicles have 40 to 105 Ampere alternator and RVs have 100
to 130 Ampere alternator. When in use, the alternators heat up and their output
current capacity can drop by up to 25%. When heated up, their charging voltage may
also not reach the desired Absorption Voltage and will result in return of only about
80% of the battery capacity. In case the current output of the standard alternator is
not adequate to charge the two sets of batteries rapidly and fully to 100% of their
capacity, use heavy duty alternator that can produce higher current and voltage
required to charge multiple battery systems. These alternators are available with auto
/ RV parts suppliers.
GENERAL INFORMATION: BATTERIEs
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