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Power inverters are great addition to a vehicle for anyone that spends extended time out on the road.

Whether you’re a truck driver that requires the convenience of being able to use a handy home appliance while on a stopover, or maybe you’re on a road trip in a family SUV and need to plug something in – having the ability to convert standard battery (DC) power to AC household power – from the comfort of your own vehicle can be a lifesaver.

However, as we covered in our recent power inverter review round up, knowing which product to buy can be confusing.

With different brands, power capacity, and even power types to consider you can end up get overwhelmed with the choice before even having an idea on which is the best option for you.

Well, we are here to help.

As a backup guide to the reviews, here’s our top 5 list on what to consider when buying a new power inverter for your auto.

1. Working out the size of power inverter you need

To narrow down the buying options you should first ascertain what size inverter you need.

You can do this by thinking about what sort of devices you aim to power, (a single truck driver will have different needs to a family of 5 for instance).

And while it is tempting to think that the bigger the better, (i.e you’ll be covered whatever you decide to plugin) that’s not always the best approach to take.

Inverter sizes range from 300-watt cigarette lighter plug-in inverters to 5,000-watt units that need to be specially installed.

Someone with minimum power needs should not go to the expense and time consuming process of installing the largest inverter available.

An important consideration is how many items will you be using at the same time. If a heater, television and laptop are all powered at the same time, you are going to need an inverter up to the task.

There’s a simple bit if math you can do to understand your power requirements.

On all the devices you plan to use you will see a wattage number. (A heater might be 1000 watts, a TV only 250 watts for instance).

Add them all up together up to see how much continuous power you’ll need. Then add 20% on top for contingency.

Your figure using our example (including laptop) would be around 1700 Watts.

And that’s the ball park power rating inverter you could focus on, with an 1800 watt unit doing the job nicely.

However, also consider the surge power capacity, (units can sometimes use double their wattage on initial load and power up).

A good rule of thumb here is to have opt for an inverter that doubles up its normal capacity in its surge protection.

2. Ease of installation

Once you’ve determined the amount of power you need, another important consideration is ease of installation.

If you’re doing this yourself and have limited experience in the area of electrics and /or motors, you will want something that comes as close to plug and play as possible.

With that in mind it is actually recommended that any inverter over 300 watt capacity be hard wired and fused.

Location of the inverter is also important as heat dissipation and protection from moisture are also very important.

If at all possible, buying from a supplier that offers warranty covered factory installation is the best route to take.

In other words, you should leave it to the professionals.

A simple inverter for your cigarette will clearly not cause any issues. Just be careful not to overload it.

3. Unit Reliability

car power inverter

Next on the list of factors is reliability.

This comes down to quality of unit and installation.

Look out for ‘Regulatory Listed’ approval – such as UL or ETL with UL458 rating. This will ensure a level of quality that will clearly translate to overall reliability.

Knowing that the unit you are using has been tested, inspected and approved by an independent agency will definitely give you peace of mind. We are talking about electricity here after all.

We are also talking about the fact there will be times when you’re out in the middle of nowhere and are completely reliant on your inverter to power important devices. Reliability is key under such circumstances.

There’s also the safety issues to think about. We have already mentioned surge protection, and the need for careful installation to avoid over heating or moisture.

However, a good device will also have the means to shut down in testing circumstances before any harm is done.

Top brands will offer error messages to give you an idea of what went wrong. In most cases you will be able to let the unit cool, press reset and be up and running again.

A less reliable unit without such safety options could permanently fail on you, exactly when you need it most.

4. Sine or Modified Sine Wave Power

Another consideration is the type of power the inverter outputs; pure sine or modified wave.

This is important because it will impact the type of devices you should run on the unit. For instance, Sine wave is the best type of inverter for running sensitive electronics or products that are plugged into their own chargers, such as power tools or toothbrushes.

For most people this actually means sine inverters are the preferred choice. Being the same as what we have in the home, you can be comfortable in the fact your home devices are safe using one of these inverters.

The voltage is consistent throughout the drain, with no spikes or drops that can harm your electrical equipment.

That being said, modified sine wave will power most electronics and appliances with the exception of few ultra sensitive applications.

Normal, high wattage sine wave inverters generally cost 15% to 20% more than a modified inverter as you are paying for that extra consistency and the ability to run sensitive equipment.

5. Shore power option

Finally, one extra issue to think about is whether the unit you choose has shore power options.

Using ‘shore power’ (i.e being able to connect to electrical outlets at home or on at the campsite etc), means you can run everything on your inverter without draining your vehicle battery, while at the same time actually charging your battery.

Clearly, the more opportunity you have to use shore power, the less wear and tear on your vehicle battery.

And that can only be a good thing.