Consumption over 24 Hour Period when Sailing Consumers Consumption Time   Consumption 24hrs   Watt Amp 24hrs %on kWh Ah(12V) C Navigation instruments   0.2 24     5 C GPS   0.2 24     5 C VHF standby   0.1 24     2 transmitting   5 0.2     1 C Refrigerator, air-cooled heat exchanger 50 4.2 24 50   50 L Tricolour navigation light or anchor light 25 2.1 8     17 L Autopilot   5 20 30   30 L Radio   1 3     3 S Cabin Lighting 200   0.6     10 S Other           5               Total consumption per 24 hour period         1.5 128 Average consumption per 24 hour period 64 5.3                       Minimum battery capacity required, assuming 2 recharges per day           256 Consumption over 24 hour at Anchor without 230 V Shore power pick up Consumers Consumption Time   Consumption 24hrs   Watt Amp Hours %on kWh Ah(12V) C Refrigerator, air-cooled heat exchanger 50 4.2 24 50   50 L Masthead Light 25   8   0.2 17 L Radio   0.1 3     3 S Cabin lighting, ten 20 W lighting points 200   0.6     10 C Other           5               Total consumption per 24 hour period         1 85 Average consumption per 24 hour period 42 5.3                       Minimum battery capacity required, assuming 2 recharges per day           170