Understanding inverters – buying guide 

So you have decided to run some mains powered equipment when you are not at home and your caravan or boat is not stranded in ehu or shore power. 

Before we look into the options for inverters and controls, we need to ask a few questions first. What do we want to judge? If this is the case you should be charging your phone or laptop, then maybe an inverter is not the best way to do it. There are a number of manufacturers that offer a wide range of accessories for charging your phones. The old phone may need a 12 dedicated charger, but modern phones are usually charged via usb port and there are a number of devices that provide usb charging from 12 volt ‘lightweight’ type plugs. For laptops, it’s even harder, but there are options. Companies such as Lenovo, Kensington and Targus offer similar devices. I have not included any references within as manufacturers usually update their sites but you can search for them as “universal auto / air laptop charger” 

Inverter success

Sometimes bigger is not better. What we really need to know is what part of the power that goes into the inverter dc to ac from the battery goes out to the other side like ac power. To make this reading more difficult, the performance of the inverter varies with the output load placed on it. If a small load is placed on the inverter it may be around 50% working. Thus increase the load to close to the mentioned inverters which is a more continuous load and efficiency will rise to 90%. 

The 3000-watt inverter can be drawn around 20 watts of electricity from a battery when connected and turned on without any sacrifice in the outlet. This power is what the inverter needs to run battery check circuit, alarm circuits, and maybe a small fan. Now if we sacrifice a small ac load .. Say 20 watts. The total load on the battery is now 40 watts (20 for inverter +20 load) so a little mathematical – 40 watts inside – 20 watts outside shows 50% efficiency. 

Now if we look at this again with a small 150-watt inverter – connected to a load less battery it takes about five watts to run the inverter. Now if we plug in the same 20 watt load we have 5 watts of inverter plus 20 watts of load giving a full load on a 25 watts battery. So 25 watts inside and 20 watts outside gives us an efficiency of up to 80%. 

This means that you can run your device 12v 2000watt inverter andlonger for one battery by choosing to use the 150-watt inverter instead of the 3000 inverter.So size matters. But bigger is not always better. Matching your inverter size to your load size to increase your battery speed is important. 

What is more?

Well, find out some of the following:

  •         Low voltage alarm
  •         Battery auto cut
  •         Over time/cut out
  •         Remote control
  •         Power to maintain sleep patterns

The low voltage alarm is a must-have. It will let you know when the voltage on your battery has dropped to a level you could start to completely damage your battery by allowing it to drain too much. On some modes, this voltage may be set separately for the type of battery you are using. The battery auto cut will shut off the inverter when this critical voltage is reached. 

Since the inverter of this size is holding a large current, some of the internal components are very hot, it is important to install it to pay more attention to the manufacturers of the installation instructions to make sure it is available correctly. Almost all good inverters will have a temperature sensor and cut off which stops your inverter from overheating. 

The following two are “good to have” … If your inverter is turned on, even if nothing is plugged into it, it consumes valuable battery power. Some of the hardest units have a sleep mode, which means you can leave it turned on and it only consumes a few. Until the load is put inside. Some units do not have this, instead, they have a remote control that allows you to turn on the inverter without pressing a button on the unit. This allows for some flexibility in place when you place it.

If you are installing an inverter in your trailer, car, boat or rv then make it a point to follow the manufacturer’s instructions. Try to place the unit as close as you can to the battery to keep the mains as short as possible and make sure you have installed the isolator switch and fuse between the inverter and the battery. Modern recreational batteries store incredible power which, if released immediately, could be dangerous and potentially deadly. Like any electronic device … If you dont know – ask and stay safe.

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