Wednesday, October 13, 2010

Selection,Preparation, and Installation of a Power Inverter for an Automotive Application

Selection,Preparation, and Installation of a Power Inverter for an Automotive Application
By. Jon Hardwick


In this article we will discuss how to select the appropriate power inverter for your application and your vehicle. We will also provide an overview on preparing for an installation, actual installation of the inverter, and what situations warrant the use of additional accessories such as battery isolators, fuses, and DC breakers.


When selecting a power inverter for use in your vehicle you must have an idea of what you are trying to operate in your car or truck. Are you trying to provide power for a mobile office, a gaming system, tools, or just to have some emergency power. The process is pretty much the same in all applications with one exception; whether or not to choose a pure sine wave inverter or a modified sine inverter. This can be tricky if you don’t know what kind of loads you will be running. That is why planning is crucial to selecting the right inverter. For example, let’s say for the sake of argument that you will be sizing this system for a mobile office. You are looking to run a laptop computer, all-in-one laser printer, wireless router, modem, and some miscellaneous rechargeable devices. Refer to the list below for specifications:

· Lenovo ThinkPad – 2.0A
· Brother All-In One Laser Printer/Fax/Copier/Scanner – 8.8A
· Linksys Wireless Router – 1.0A
· ClearWire WIMAX modem – 1.0A
· Smartphone - .02A

Total requirement for all of the devices running at the same time is 12.82A or 1474.3 Watts. It is recommended to size the unit 25% above the actual requirement, bringing the total to 1842 Watts. Since you won’t find a power inverter rated exactly at 1842W you will need to find the closest unit by rounding to the total to the nearest thousand; which would be a 2000W. Now that we have determined what size we will need to power all of the devices we need to decide what output waveform we will need for this application. Since we will be dealing with a laser printer we need to select a pure sine wave.

(Note: We arrive at this conclusion based on my experience and the research I have conducted on this type of application. For most, this would take some research or simply trial and error. But there you go, I have cut out the time it would have taken you to research the waveform required for the laser printer. FYI, if you want to know why they don’t work on modified sine it has to do with the fuser and laser unit.)

Pure sine wave is a guarantee that you will not have any problems down the road with any device. Modified sine wave will work with most everything except sensitive electronics, medical devices, and variable speed motors.

Additionally, selecting a pure sine wave will not interfere with the radio in either the wireless router or WiMax modem. This is important if you want to get Internet in your vehicle. We have heard reports that if you use a wireless router on modified sine wave it significantly slows the speed of data transfer. However, with the exception of the laser printer all of the remaining devices would work on modified sine wave it’s just not recommended. Pure sine wave should be used on all battery integrated devices as it will not affect the battery life of the devices.

Now that we know what size inverter is required and what type we need. We can move forward with what will be required for planning the installation and moving toward the actual installation.
Vehicle Assessment

Before installation we need to ask a few questions about the vehicle the inverter will be installed in. For this example we will use a Ford F-150. The information we need off the vehicle is alternator size, location where the inverter will be installed, and whether or not we need to upgrade or add additional batteries.

First, let’s take a look at our alternator and figure out what size we have. For the 2004 Ford F150 there is a 130A alternator. Not bad, this alternator should not have a problem keeping up with the continuous loads we have. Now let’s look at the battery. In most cases you will find a heavy duty starting battery under the hood of a stock Ford F-150. This is a problem. We have a couple of choices pertaining to replacing this battery. Since the battery is in decent condition one could simply leave the battery alone and not replace it until it has been cycled past the threshold. Or, replace it now with a dual purpose deep cycle battery. The choice is ultimately yours. My opinion is to do it right, and do it once. A single battery configuration for this application would be all you would need to get rolling if you plan on using the system mostly while the vehicle is running and with minimal printing. However, for this example, let’s say that we are going to use the equipment a lot while the vehicle is not running and with some moderate printing and scanning. This would require the addition of a second “Auxiliary” battery. We will address this in just a moment. Since we have decided to install a second battery, and will upgrade the starting battery we need to determine the best place for the inverter to be installed. In this case, under the rear seat is the best place to locate the inverter. This provides the best central location to both the starting battery and the auxiliary battery which will be located in the bed.

Auxiliary Battery Installation

Choosing to install a second battery for this application is the best choice for a couple of reasons. It will help to absorb the surge from the printer, be closer to the inverter, and provide a longer run time for the mobile office equipment. Now we must decide whether or not to install a battery isolator. For this application one is not required since the starting battery will be replaced with a dual purpose deep cycle battery. For installations where replacing the starting battery is not an option an isolator would be required. If you wanted to add an isolator to this system you would simply size it around the size of the alternator and use this chart to determine which one is required for the vehicle.

Installation & Running cables

Now for the fun part, running the cables to the inverter. For the example we have outlined in this article we will need to run a cable from the battery under the hood to the auxiliary battery in the bed. We would choose to run the cable from the starting battery to the bed by running along the frame of the vehicle and drilling through the bottom of the bed, then running another cable to the inverter by drilling a hole in the back or bottom of the cab (whichever option you choose). Once the cables have been run they will need to be secured tight to the frame and away from any exhaust components as this could melt the coating on the cables or create a potentially dangerous situation later as you’re vehicle is in motion.

Fuses & Safety

Quick note about fuses and DC breakers, it is good practice to install a fuse or breaker in every inverter installation on a vehicle. However, there are some installations that don’t absolutely require a fuse. One example is; installation inside a van where the inverter is installed right next to the sealed AGM battery. This is fine as long as there is no possibility of the battery cables being damaged. My personal opinion on fusing is to install a fuse just in case. It is really good insurance and they are relatively cheap.

Sweet! We now have power in our truck. We can run our mobile office and help our clients while on the road. By installing this inverter and adding power we have accomplished adding a computer, printer, and a wireless Internet hot spot. The possibilities are absolutely endless.

If you have any questions about this article or you would like to learn more feel free to shoot me an e-mail at:

Tuesday, October 12, 2010

New Product Alert!

Goal Zero Portable Solar Products

DonRowe.Com would like to announce the recent addition of the Goal0 portable solar products to our website. You can find them at the following URL:

The products we will be carrying include the following:

Goal0 Elite Series:

· Sherpa 120 Battery
· Sherpa 50 Battery
· Sherpa UI Inverter
· Nomad 27M Solar Panel
· Nomad 13.5M Solar Panel

The Elite Series is a scalable solution that can be configured to provide power for your small rechargeable devices such as a Laptop computer, Smart Phone, Portable Navigation and Camera Equipment. The Elite Series is a must for any outdoor enthusiast.

Goal0 Escape Series:

· Scout 150 Battery
· Escape 30M Solar Panel

The Escape Series is a versatile, rugged portable solar solution that can be used for power anywhere. The handles on this system make it very easy to carry and the compact size makes for easy storage in an RV, or car. This beats the heck out of a standard power pack or jump starter.

Goal0 Extreme Series:

· Boulder 30M Solar Panel
· Boulder 15M Solar Panel
· Ranger UI Inverter
· Ranger 350 Battery

The Goal0 Extreme series is the largest portable solar system on the market. This system can be configured to produce enough power for an entire base camp in the Himalayas if needed. No need to pack a generator to recharge those radios or cameras anymore.

If you have any questions about this product please contact us at 1-800-367-3019.

For more information about the Goal0 Company please visit their site at:

Tuesday, October 05, 2010

What do these "specs" mean?

Power Inverter Specification Breakdown:

What do these “Specs” mean? This is a question that comes up quite often and quite frankly if you do not work in the industry or have some sort of electrical background, can make selecting the right inverter pretty confusing. So let’s talk about the terminology and work our way through the specifications. While reviewing and contrasting the specifications between multiple inverters you will come across some very specific terms as well as some broad ones. Here is a list of terms you may come across while shopping for an inverter.

  • Maximum Efficiency – This indicates how much battery power is lost during the power inversion process.

  • No Load Draw (Switch Off) – This indicates how much power while idle the inverter is drawing with the power switch off.

  • No Load Draw (Switch On) – This indicates how much power while idle the inverter is drawing with the power switch on.

  • Output Wave Form – This indicates what waveform the inverter is producing. Typically, Modified, Square, or True/Pure Sine.

  • Total Harmonic Distortion – Refers to how much “Noise” is emitted from the output of the inverter.

  • Input Voltage – Indicates what the rated input voltage is, or indicates the rated input voltage range.

  • Output Voltage – Indicates what the rated output voltage is and in some cases what the voltage is regulated at.

  • Low Voltage Alarm – Indicates the input voltage at which the audible alarm will sound.
  • Low Voltage Shut Down – Indicates the input voltage at which the unit will shut off.

  • Overload Shutdown – Indicates whether this protection is available. (Yes or No)

  • Thermal Shutdown - Indicates whether this protection is available. (Yes or No)
  • Short Circuit Shutdown - Indicates whether this protection is available. (Yes or No)

  • Reverse Polarity Protection - Indicates whether this protection is available. (Yes or No)
  • AC Back feed Protection - Indicates whether this protection is available. (Yes or No)

  • Transfer Relay Rating – Indicates the current rating for the transfer switch (Not applicable to most standalone inverters)

  • Transfer Relay Time – Indicates how quick the transfer occurs once voltage drops on the AC input.

  • Continuous Output Power – Indicates how much power the inverter will produce continuously.

  • Peak Output Power – Often referred to as “Surge”, Indicates how high the unit will surge for starting heavy inductive loads.

  • Frequency – Indicates how fast the output voltage is flipping and flopping. (in the US 60hz is the standard for all appliances)

  • AC Regulation – Indicates how much deviation from the rated output the unit is allowed.

  • Operating Temperature – Indicates the temperature range in which the unit will operate properly at maximum efficiency.

  • Regulatory Compliance – Lists the UL, ETL and CSA standards the unit meets or is certified to.

  • AC Receptacle Type – Indicates what type of receptacle is installed on the inverter.

    Now that we have identified the terms listed in the specifications of a standalone inverter we can break them down further by looking at an example product page of an inverter.

Product Page Comparison:

The Breakdown:

Maximum efficiency 88% - This is basically stating that the inverter will lose 12% through the process of inverting. In other words, the unit is using 12% of the available battery to operate while inverting. Ideally, you are looking for a unit that has a high efficiency rating. The highest this author has seen is 96%. This unit appears to be a touch below average (90%). You will also find that with higher efficiency comes higher cost.

No-load draw <0.6> – This figure represents that the Cobra 2500 uses less than .6 amps DC in idle with the switch on. You will find inverters that give ratings for the remote on as well as with the remote off. For the most part 99% of the inverters are listing this rating for no load draw while the switch is in the on position. Again, remember the lower the rating the better.

Output Wave Form Modified Sine Wave – This is telling us that the unit produces a modified sine wave.

Input Voltage Range 12V (10.4vdc – 14.4vdc) – The figure represented here indicates that this unit has a voltage input rating for the low end of 10.4 volts DC and a high end of 14.4 volts DC. When sizing your inverter for use with a vehicle you will need to take your vehicles alternator output into consideration when selecting a power inverter. This inverter would work for most vehicles. However, the newer GM vehicles (2007 – Present) produce up to 15.5 volts DC. Just something to keep in mind while sizing your inverter.

Output Voltage Range 115vac 60hz – This Specification is pretty much standard for all inverters used in the US with US appliances. You will not see any deviation from this except on European (230vac, 50hz) inverters.

Low Voltage Alarm 10.5 +/- 0.3vdc – This is when the alarm will sound indicating it is close to shutting down due to low battery. Notice the +/- voltage, this represents the deviation from 10.5vdc.

Low Voltage Shutdown 9.5 +/- 0.3vdc – This is the voltage at which the unit will shut down.

Overload Shutdown YES – This indicates the unit does protect against an overload fault condition.

Thermal Shutdown YES – This indicates the unit does protect against an over temperature fault condition

Short Circuit Shutdown YES – This indicates that the unit will not become damaged from a short circuit in the AC wiring.

Reverse Polarity YES – This indicates that the unit will not become damaged when the DC cables are hooked backwards. This believe it or not occurs fairly often and selecting a power inverter with this protection is a great idea.

AC Receptacles 3 –
This tells us that the unit has three AC receptacles. Also, note that it does not state GFCI. Some inverters will have GFCI protection. Typically this would be found on a marine grade inverter.

Warranty 2 Years – Length of warranty from manufacturer.

Inverter Weight 6.6 Lbs. – Weight of the unit without packaging materials.

Shipping Weight 9 Lbs. – Weight of the unit with all packaging from the manufacturer.

Product Dimensions 10.75"x 9.75"x 3.5" – Physical dimensions of the inverter.

This pretty much covers breaking down a basic inverter specifications chart. You should now have a general understanding of what some of these terms represent and the importance of the specifications. Don’t be intimidated by these terms and should you have any questions after reading this post, feel free to get in touch with me using any of the following methods:

Twitter: @donrowecom (Yes, I respond to our Twitter as well)
Toll Free: 1-800-367-3019

Important Links for Key Terms:

Inverter -
Pure Sine Wave -
Frequency -
Short Circuit -
Electrical Efficiency -
Total Harmonic Distortion -