How to choose your inverter?

Get the best performance of your equipment with our advice on choosing the inverter adapted to your needs at President Electronics.

How to choose the appropriate power of the inverter?

It is necessary to take into account the peak power, i.e. the power required by a device at start-up, which is much more important than that used during normal operation. On each electrical device the rated power in Watts absorbed under 220 VAC is indicated.

If the peak power is not documented, a minimum multiplier factor of 3 must be applied to choose the most suitable inverter.

Apparatus
Size factor for inverter*
Dishwasher, Washing machine 3
Sump, well or submersible pump 3
Boiler fan 3
Industrial motor 3
Portable heaters powered by Kerosene or Diesel 3
Circular saw, Bench grinder 3
Lighting 3
Cutting device 3
Microwave oven (when nominal output power is also cooking power) 3
Illuminating lights, stroboscope 4
Air compressor 4
Laser printer, Device using Quartz lamps for heating 4
Air conditioner, refrigerator, freezer (compressor) 4

*Multiply the active rated power (Watts) of the device by this factor to find the continuous nominal power of the inverter to make it work.

 

How can I adapt the power of my battery or my series of battery, depending on the choosen inverter?

A battery or battery block allows you to make the best use of the chosen inverter.

To choose the right battery or battery block, you need to know how much power (watts), absorb the products you want to plug in, and for how long you want to use them.

The table below highlights, for batteries that provide 12 Volts DC, their capacity and energy absorbed in time, as well as the time of use. By using 24 Volts DC batteries, the usage time is doubled.

  50Ah 75Ah 100Ah 200Ah 400Ah
50 W 9 hours 14 hours 20 hours 40 hours 80 hours
100 W 4 hours 7 hours 10 hours 20 hours 40 hours
200 W 2 hours 3 hours 4.5 hours 10 hours 20 hours
300 W 1.3 hours 2.2 hours 3 hours 6 hours 12 hours
400 W 1 hour 1.5 hours 2 hours 4.5 hours 10 hours
600 W - - 1 hour 2.5 hours 6 hours
800 W - - 50 minutes 2.5 hours 4 hours
1000 W - - 40 minutes 1.5 hours 3 hours
1500 W - - - 30 minutes 2 hours
2500 W - - - 12 minutes 48 minutes

This table is given as an example and it is not guaranteed that it is accurate in all cases. Multiple external events, e.g., peak power, temperature, load state, battery conservation and use, may influence the usage time.

 

Practical case

Connected devices

By adding the daily consumption of each device, you obtain the total daily energy required.

In our case: 660+250+150+270=1330 Wh

With the formula Watt/Volt = Ampere, you deduct the total daily intesity required.

With a 12 Volts DC: 1300/12=110,83 A. You therefore need, at minimum, a 110 Ah battery.

If all these devices are used at the same time the consumption will be 1560W.

As a minimum multiplier factor of 3 is required to choose the best-adapted inverter, it is therefore necessary to provide a 4500W inverter.

With a 12V battery you will need a capacity of 400Ah and with a 24V battery you will need a capacity of 200Ah.

22'' LCD TV
Consumption: 220 W
Usage time: 3 hours
Total consumption per day: 660 Wh

Microwave oven
Consumption: 1200W, set to half power
Usage time: 5 minutes, 5 times per day
Total consumption per day: 250 Wh

DVD Player
Consumption: 50W
Usage time: 3 hours
Total consumption per day: 150 Wh

Laptop computer
Consumption: 90 W
Usage time: 3 hours
Total consumption per day: 270 Wh
 
 
Choose a battery or a battery block that is able to provide you with more power than you need, so as not to completely discharge the battery.
 
 
Periodically check the battery or battery block efficiency to avoid problems you may encounter while using the inverter.
 
 
When you change one or more batteries in the battery block, you have to change them all. Do not mix new and old batteries. In addition, it is very important to charge each battery separately and then connect the cables to the battery block.
 
 
With a very high power, a specific accumulator must be used (a secondary accumulator) for this use. The compatible batteries are those called AGM (e.g. motor-homes batteries), because they provide maximum energy at 12 Volts voltage.
 

How to choose the diameter of the cable connected to the battery?

The choice of the cable diameter connected to the battery is made according to the power of the inverter.

Length (Go + Return) between battery and inverter
  ≤1m ≤2m ≤3m ≤4m ≤6m ≤8m ≤10m ≤12m ≤14m ≤16m
150 W 0.75 1.5 2.5 4 6 6 10 10 16 16
300 W 1.5 4 6 6 10 16 16 25 25 25
600 W 4 6 10 16 25 25 35 35 50 50
1000 W 6 10 16 25 35 50 50 70 95 95
1200 W 6 16 25 25 50 50 70 95 95 120
1500 W 10 16 25 35 50 70 95 95 120 120
1700 W 10 25 35 35 70 70 95 120 150 150
2000 W 10 25 35 50 70 95 120 150 150 -
2500 W 16 35 50 50 95 120 150 - - -
3000 W 16 35 50 70 95 150 - - - -
4000 W 25 50 70 95 150 - - - - -
5000 W 35 50 95 120 - - - - - -
6000 W 35 70 95 150 - - - - - -
Length (Go + Return) between battery and inverter
  ≤1m ≤2m ≤3m ≤4m ≤6m ≤8m ≤10m ≤12m ≤14m ≤16m
150 W 0.5 0.5 0.75 0.75 1.5 1.5 2.5 2.5 4 4
300 W 0.5 1 1.5 1.5 2.5 4 4 6 6 6
600 W 1 1.5 2.5 4 6 6 10 10 10 16
1000 W 1.5 2.5 4 6 10 10 16 16 25 25
1200 W 1.5 4 4 6 10 16 16 25 25 25
1500 W 2.5 4 6 10 16 16 25 25 25 35
1700 W 2.5 6 10 10 16 25 25 35 35 35
2000 W 2.5 6 10 10 16 25 25 35 35 50
2500 W 4 6 10 16 25 35 35 50 50 50
3000 W 4 10 16 16 25 35 50 50 50 70
4000 W 6 10 16 25 35 50 50 70 70 95
5000 W 6 16 25 25 50 50 70 95 95 120
6000 W 10 16 25 35 50 70 95 95 120 120

Section mm² 0.75 1.5 2.5 4 6 10 16 25 35 50 70 95 120 150
Diameter mm 1 1.4 1.8 2.2 2.8 3.6 4.5 5.6 6.7 8 9.5 11 12.4 14