Energy balance

The table below shows examples of what ordinary appliances on board a family boat consume for a day.

The charging in the example requires good charging receptivity, for example two to three 75 Ah consumer batteries (if they are fairly new, otherwise you need more) and well-dimensioned connections and cables in good condition.

With a fresh electrical system, you can be self-sufficient with one hour of driving per day even without land power or wind turbines

If you want a calm holiday, it's important to learn you energy balance, since it varies from family to family how you prioritize your consumption.

We recommend installing a solar panel to always top charge your batteries. A good solar panel would in theory be able to provide a newer refrigerator all by itself, which means less consumption to charge with the engine.



  A 50 A generator generates approximately 45 Ah in one hours drive if your batteries are discharged. 45 Ah
Solar panel
  A 25 W solar panel can give about 2 A when it is sunny. During the summer you can get out about five hours with that effect. In case of cloudy weather, the effect of course is reduced.
5 x 2 = 10 Ah
10 Ah

Total sum:


55 Ah per 24 h



Battery monitoring

Nasa Marines monitoring instrument uses max 5 mA, on 24 h it draws:

0,005 A x 24 h = 0,1 Ah

0,1 Ah
Light   Four led lights with a total of 10 W that shines in 4 h draws:
10 W x 4 h = 0,04 kWh = 3,3 Ah
3,3 Ah
Refrigerator   Compressor refrigerators that uses  4 A, normally only works 25% of the day, on 24 h it draws: 6 h x 4 A = 24 Ah 24 Ah
Diesel heater

A diesel heater on 10 A and runs for half an hour, to warm a bit before bedtime draws: 0,5 h x 10 A = 5 A

5 Ah
TV or computer  
A TV that is being used draws between 50 och 100 watt, ie between 4 and 8 A. So one hour viewing per day draws: 1 x 8 = 8 Ah
8 Ah
Pumps   Pumps for fresh water and bilge pump usually draw about 1 Ah per day together. 1 Ah


Total sum



41,4 Ah per 24 hour



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