10.2.7. Other consumers
We are assuming more use of pumps (e.g. for the shower) and we are working on 10 Ah at 24 V.
10.3. Sailing
As has been done in chapter 9, we will know calculate the power consumption over a 24 hour period, when sailing.
Consumers
Consumption
Time / 24- hours
% on Consumption / 24- hour period
Watt Amp
Hours
% kWh Ah (24 V)
C Navigation equipment
2 1 5
24
1.2 0.2 0.8 0.9 0.1 0.5 0.2
48
L Navigation light
25
8
8
L Autopilot
20 24
30
30 38
C Refrigerator & freezer, water cooled
50 + 50
25 + 50
S Radio
2
3
6
S Cabin lighting
400
1.2
20 10
S Other
Total consumption per 24-h period Average consumption per 24-h period
3.8
160
160
6.7
Minimum battery capacity required, assuming 2 recharges per day (see sect. 8.4.2)
320
What can be learned from this table:
- By investing in efficiency and insulation, the power consumption of the refrigerator and freezer is now in line with that of other consumers. All too often bad design results in the compressors running nearly full time, which would add another 60 Ah to daily power consumption!
- When sailing, the minimum energy consumption on a 12 to 18 m sailing boat is approx. 4 kWh per day. This is equivalent to about 160 Ah from a 24 V battery or 320 Ah from a 12 V battery.
- The average DC current taken from the battery is only 6.7 A at 24 V, not of any significance when motoring
10.4. At anchor or moored without 230V shore power pick-up
The following table is valid for motor boats as well as sailing boats
Consumers
Consumption
Time / 24- hours
% on Consumption / 24- hour period
Watt
Amp
Hours
%
kWh
Ah (24 V)
L Anchor light
25
8
0.2 0.9 0.1 0.5 0.2
8
L Refrigerator & freezer, water cooled
50 + 50
24 25 + 50
38
S Radio
2
3
6
S Cabin lighting
400
1.2
20 10
S Other
Total consumption per 24-h period Average consumption per 24-h period
2.0
82
82
3.4
Minimum battery capacity required, assuming 2 recharges per day (see sect. 8.4.2)
164
53
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