En 
SvEnergy balance
How does energy balance work in practice?
The table below shows examples of what common appliances on board a family boat consume over a 24-hour period.
The charging in the example assumes good charge acceptance, for example two to three 75 Ah service batteries (if they are fairly new, otherwise more) and well-dimensioned connections and cables in good condition.
With a healthy electrical system, you can be self-sufficient with one hour of running per day, even without shore power, solar panels and wind generators.
If you want a relaxing holiday, it is important that you learn your energy balance, since it varies from family to family how consumption is prioritized.
We recommend installing a solar panel to always top-charge your batteries. A good solar panel could in theory power a newer refrigerator entirely on its own, which means less consumption to recharge.
Overview of Charging and Consumption
A 50 A alternator provides about 45 Ah in one hour of operation if the batteries are discharged and there are many of them. Otherwise, less.
Charging: 45 Ah
A 25 W solar panel can provide about 2 A when it is sunny. During the summer, you can get around five hours at that output. In cloudy weather, the output is naturally reduced.
5 × 2 = 10 Ah
Charging: 10 Ah
Total
Total 55 Ah per day
Consumption of electricity
NASA Marine’s monitoring instrument draws a maximum of 5 mA. Over a 24-hour period, this becomes
0.005 A × 24 hours = 0.1 Ah
Consumption: 0.1 Ah
Four LED lamps with a total of 10 W that are on for 4 hours.
10 W × 4 hours = 0.04 kWh = 3.3 Ah
Consumption: 3.3 Ah
A refrigerator with a compressor that draws 4 A but normally only runs 25% of the time, i.e. 6 hours per day.
6 hours × 4 A = 24 Ah
Consumption: 24 Ah
0.5 hours × 10 A = 5 Ah
Consumption: 5 Ah
A TV that is used draws between 50 and 100 watts, i.e. between 4 and 8 A. For example, assume one hour of viewing per day.
1 × 8 = 8 Ah
Consumption: 8 Ah
Freshwater and bilge pumps together usually consume about 1 Ah per day.