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SvFrequently asked questions & answers
Frequently asked questions about electrical systems and batteries
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What do the units mean?
Current is measured in amperes A
Voltage is measured in volts V
Power is measured in watts W
Energy is measured in watt seconds Ws, watt hours Wh or kilowatt hours kWh.
Example: a 5 W lamp draws: 5 W / 12 V = 0.42 A. Over 5 hours it draws 5 × 0.42 = 2.1 Ah.
In boats and cars, ampere-hours (Ah) are used as a measure of energy. For this to be correct, the voltage must be known. A 75 Ah battery contains twice as much energy if it is at 24 V compared to 12 V.
What type of main switch should I buy?
If you want a main battery switch, it is important that you choose one of high quality.
Our tip is that you choose a switch from a well-known manufacturer.
There is a good model on the market where both the switch and the key-operated knob are made of metal. This reduces the risk that the switch cannot be turned off due to a melted key.
Why does the fridge not start?
The fridge has a built-in voltage monitor that switches off if the voltage is too low, often 10.5 V. This is to protect the compressor motor.
These voltage switches are common because electric motors risk burning if they try to start at too low a voltage.
If the cable to the fridge is too thin, the fridge will switch off automatically, so quickly that you won’t even notice that the fridge has tried to start.
