Eight doubts about inverters: get to know this essential device
Except for rowing canoes and small sailboats, there is practically no vessel that does not depend on any type of energy to ensure comfort and safe navigation. However, in boats, the problem starts with how to “produce” this energy and store it. In the past, there were only two options: using the surplus produced by the alternator to charge spare batteries or having a fuel generator on board - but this, due to its size and cost, is restricted to larger boats. For minors, only batteries. It was also necessary to look for 12 V or 24 V devices in direct current (DC), much rarer than domestic devices, with voltages of 110 V or 220 V, in alternating current (AC or AC, in English). Until power inverters appeared, devices capable of transforming one type of energy into another, To know more, check out: power inverters for cars
1- Is an inverter a simple “electrical transformer”?
No. It first transforms the battery's direct current into alternating current, and then changes the voltage value. It is a much more complex device.
2- Is the energy supplied by the inverter the same as that at home?
It is very similar, but not exactly identical. The domestic alternating current energy is called “sinusoidal”, because the voltage varies between a maximum positive value and a minimum negative value. In Brazil, this variation occurs 60 times per second, which is why we say that the frequency of our electrical network is “60 Hz”. The inverters, on the other hand, operate with the so-called "modified sine wave", or "approximate", which, however, does not cause damage to the devices.
3- Can the batteries that power the inverters be the same as those for the motor?
Not! For two reasons. 1) Safety: the engine starting system must have one or more exclusive batteries, to prevent the use of electrical devices on board to discharge the batteries; 2) Battery type: those used to start the engine are made to supply a lot of energy for a few seconds, while those indicated for inverters are “deep cycle” batteries, which provide energy for long periods and better resist the load cycles and discharge, therefore having a longer useful life.
4- Does the battery capacity depend on the power of the inverter?
Yes, because the greater the power supplied by the inverter, the greater the electrical current drained from the battery. To get a rough idea of the electrical current that will be required from the battery in Amperes (A), divide the power of the inverter (in watts) by the battery voltage (in volts). For example: a 12 V battery will need to supply about 100 A of current to power an inverter of 1,200 watts of power.
5- How to choose the correct battery capacity for an inverter?
It depends on some factors, but one of the most important is the maximum electric current that will be supplied by the battery and for how long. A 12 V battery, with a nominal capacity of 150 Ah, can supply this energy only if it is discharged over 10 or 20 hours, depending on the manufacturer. If it discharges in an hour, it will only provide about 60% of its capacity.
6- How to choose the capacity (in watts) of an inverter for the boat?
A very simple way is to add the energy consumption of all equipment on board (if the consumption is not in watts but in A, multiply the value in amperes by the equipment voltage and you will have approximately the consumption in watts), adding safety margin in the inverter capacity.
7- Is it worthwhile to connect the inverter to two 12 V batteries connected in series?
Yes. Inverters that operate with a 24 V electrical voltage require about half the electrical current of those that operate on 12 V, thus being able to use electrical wiring of smaller gauge and batteries of smaller capacity.
8- What is better: having an inverter or generator on board?
It depends on the boat. In general, when the consumption of equipment on board is less than 2500 watts, inverters and an adequate set of batteries already do the job. Generators, on the other hand, are practically only indicated for greater power and for long periods, in addition to requiring larger boats, as they have a much more complex installation. Yeah man.