Changes

To determine the <i>Basic Charging AH</i>, multiply the <i>House Bank Required</i> in AH by the <i>Charging Factor<i>. To this, add the battery load while charging, i.e., the <i>Fixed DC Load</i>, <i>Fixed AC Load</i> and <i>Other DC Loads</i>. This total gives you the <i>Required Charging Capacity AH</i>. The larger this is, the bigger and more expensive the alternator required.

Finally, we need a reality check. How long will it take each day to re-charge the batteries? An hour would be nice. Several hours would be insufferable, and counter-productive. To determine the <I>Daily Charging Period</I>, divide the <i>Battery Drain Between Charges</i> by the <i>Required Charging Capacity</i> (other loads net out). In the example shown, a flooded cell bank will take 55 min to charge, a gel cell 34 min and an AGM cell 28 min. Obviously a gel or AGM is the way to go, provided you can manage the larger alternator and charger system. Remember that these times are for a hypothetical house bank of 1100 AH capacity. A real example is likely to be several times larger.