Guide to 12-V car or truck voltage converters or transverters for portable, backup & other emergency use. Here we describe several methods for obtaining temporary or emergency electrical power from a car, RV or other 12-V or 24-V vehicle or system. We include a list of manufacturers and sources of DC - AC power converters, inverters, or transverters that permit using a car or other vehicle to power small electrical devices & tools.

This article series discusses the use of emergency generators for electrical power backup at residential properties. We describe generator size requirements, where to buy an electrical generator or voltage converter, and how to hook up or wire a portable or backup electric generator. We also describe methods for obtaining temporary electrical power from a car, RV or other 12-V or 24-V vehicle or system.

How to use a car, RV, truck or its battery as an emergency electrical generator for charging cell phones & operating tools

The methods we describe below permit use of a vehicle or just a vehicle 12-volt battery as an emergency power source sufficient to provide emergency cell phone recharging, computer use, lighting, even light power tool operation.

Reasonable uses & wattage requirements for car, boat, truck, RV and similar 12-VDC to 120V AC charging devices and transverters include

• Cell phone, PDA, charging & use, typically needing about 10 watts of power, can be attached to car power by their USB cable using a simple and tiny Car-USB adapter like the unit shown at left.
• Tablet computer charging & use, typically needing about 10-15 watts of power
• Laptop computer charging & use, typically needing about 100 watts of power. At this power level you could probably also operate a 13-inch TV.
• Flashlight recharging, typically needing about 10-15 watts of power
• Operation of battery re chargers for batteries used to operate small power tools such as drills & saws
• Power tools typically need about 400 watts, though you may be able to recharge batteries used in battery-operated power tools using a charger that itself requires lower input wattage

How to use ordinary cars, trucks, vans, etc. as light-use backup emergency electrical power sources - recharging a cell phone or operating a tablet or laptop computer

There are several approaches to using the 12-V electrical system in a vehicle for light-duty electrical use, such as re-charging a cellphone, flashlight, or computer, ranging in difficulty from trivial (just plug it in) to suitable for a handy person who has a knife and some small gauge electrical wires at hand.

Connect a 12-volt USB adapter to the vehicle's utility outlet or cigarette lighter socket

Standard cell phone chargers such as the unit provided by Samsung for our example here are intended to connect to a 120-V electrical receptacle or a 240V AC receptacle (most adapters handle both voltages) and to provide an output voltage of 5-Volts DC.

Because the current requirements to re-charge a cellphone is very small, you can do a lot of cellphone re-charging from a car battery without much worry about running down the battery even if the vehicle engine is not running.

At left, using a Toyota FJ Cruiser dash power outlet as an example, we illustrate the easiest way to re-charge a cellphone for emergency use when there is no electrical power in nearby buildings.

The Toyota FJ Cruiser also includes a built-in 120V electrical outlet in the rear of the vehicle.

Watch out: when using the built-in 115V electrical power outlet on the Toyota FJ Cruiser, the vehicle's engine must be in operation and the AC-115V switch must be turned on on the vehicle's dashboard instrument panel.

On this vehicle the power switch will glow yellow or green, indicating that a maximum of 115VAC at 100W (when the vehicle is being driven) or of 115V at 400 W is available at the power outlet.

To obtain 115VAC 400W on the FJ Cruiser the vehicle must be stopped, the shift lever must be in neutral (or Park for automatic transmission), and (for manual transmission) the clutch must not be depressed.

We used a Griffin 12-V car adapter to plug into the 12-V outlet in this FJ Cruiser, then connected our Samsung cell phone's USB adapter cable between the car adapter and the cell phone's charging connector at the phone base.

Below we illustrate the battery terminals in a Jeep Sahara - another possible point of connection to a temporary 12-V power source.

On the Toyota FJ Cruiser, on some Jeeps, and some other vehicles there may be two 12-Volt outlets, one switched by the vehicle's ignition and a second (shown here) that is "always on" provided that the vehicle has a functional battery.

The advantage of using the "always-on" circuit is that you don't have to turn on the vehicle's ignition (which in turn operates lights and other systems, reducing vehicle battery life if the engine cannot be run).

If the vehicle does not already have a built-in USB connection, if you've planned ahead you will have already purchased a 12-V adapter that plugs into the cigarette lighter or 12-V utility outlet on your car, truck, boat or other vehicle. Connect the USB-power cord for your cellphone to the adapter or to the USB connector in the vehicle.

Depending on individual vehicle's wiring, you may need to also turn on the vehicle's ignition switch. That source provides low-voltage electrical power sufficient to recharge a cellphone and some other appliances that connect via a USB cable such as a tablet computer or iPad.

Heavy duty car or truck power inverters / converters that are permanently mounted in the vehicle and that operate off of the vehicle's 12-V charging system to produce 120VAC at wattage ranges from 500 to 1800 watts are also widely available from a number of manufacturers.

Watch out: power inverters, particluarly those that plug into a cigarette lighter type power outlet in a vehicle vary in the quality and stability of the electrical 5voltage that they produce. If you are simply plugging in a telephone charger your charger will probably handle those variations with no trouble.

But other electrical equipment may be more fussy. Shown here is Xantrex's ProWattSW power inverter that the company describes as follows:

... the PROwatt SW Series makes it ideal for use in commercial truck, RV and marine applications. With True Sine-Wave output, the PROwatt SW Series can provide power for all types of electrical loads including, variable speed power tools, advanced electrical appliances, microwaves and much more. The PROwatt SW provides household AC power anywhere. - retrieved 8/23/14, original source http://www.xantrex.com/power-products/power-inverters/prowatt-sw.aspx

Car or Truck DC to AC Power Adapter Capacity Requirements

DC to AC Power Adapter Volts, Amps, Watts Data for Common Small Electrical Devices

Notes to the table above

1. Generally, without considering more accurate & technical power factors, we can use three trivial formulas to convert between amps, volts & watts

• Amps = Watts/Volts
• Watts = Amps x Volts
• Volts = Watts/Amps

also

• Volts = Amps * Resistance (Ohms Law)

Details are at

DEFINITIONS of ELECTRICAL TERMS

AMPS VOLTS DETERMINATION

DMM DIGITAL MULTIMETER HOW TO USE

How to Connect a 12-volt to 120-volt DC to AC power converter / inverter (a power transverter) to the vehicle's utility outlet

A 12-V power inverter (also called a power transverter, power adapter, or DC to AC power converter) is a small device designed to be connected to a vehicle's 12-V utility outlet (cigarette lighter outlet).

The power inverter or "transverter" converts 12-V DC current to 120-V AC current and includes one or more 120-V electrical outlets to which you can connect a 120-V device. However unless you've purchased and installed a high-capacity transverter, most likely the unit can not drive higher-wattage electrical devices, tools, or other appliances that draw high wattage (or high current - amperage).

A "DC to AC" power inverter electronically converts DC power from a car battery to 60 hertz AC power at 120 volts like in your home. These inverters have standard household AC grounded power outlets. [6]

We have successfully used a small 12-V power transverter/adapter to drive and re-charge a laptop computer and to operate the recharging station for battery-operated electrical drills and saws - very useful at a jobsite or in a disaster area where conventional electrical power sources are not available.

Typically a 150-watt rated DC to AC power converter/inverter connects directly to the 12-volt utility outlet or cigarette lighter socket in a vehicle, while more powerful models such as a 325-watt rated DC to AC power converter/inverter connects to the vehicle battery directly using its own cables and battery terminal clips.

Still larger DC to AC power converter/inverters connect to a vehicle battery by direct wiring or by using automobile jumper cables.

Watch out: if you over-tax a power converter it will probably shut off, either using an automatic internal overload safety switch or by blowing a fuse. And while power convert/transverter prices vary over a large range, so do their capacities and features, including not only the actual wattage delivered, but the consistency of their power output.

A converter that overheats and shuts off or that drops its voltage level too low after 1/2 hour of laptop computer use may make you wish you'd purchased a different model. Wagan provides this interesting technical detail about the sustained power output of typical DC to AC power Inverters.

All Wagan Tech® inverters feature True-rated Power™. That simply means power tested and rated at a period of 24 hours continuous usage under full load. The competition claims “continuous”, when in fact, they are often only 30 minutes “continuous”. Afterwards, the competition’s output wattage will drop down as much as 30% of the claimed wattage. [8]

How to use (& limits of) vehicles with built-in 120-V electrical power outlets as backup electrical generators

In an emergency you can use the 12-volt electrical system, battery, or generator/alternator found in just about any car, truck, boat or other vehicle as a source of low-capacity electrical power suitable for charging a cellphone or even operating light 120 V electrical tools such as a drill, saw, or lighting.

Some vehicles including most recreational vehicles (RVs) and motor homes, and some cars or light trucks (such as our Toyota FJ Cruiser) already include one or more 120-V electrical power outlets.

In this case plugging in a small (low amperage draw) tool, light, even appliance is simple. Turn on the 120-V outlet using a rocker switch on the car's dashboard, and plug in the appliance. Some vehicles such as the FJ Cruiser provide two different power levels depending on whether or not the vehicle's engine is operating.

Obviously, running a car or truck motor continuously just to operate its electrical system is not practical for more than a brief use, and in some circumstances operating the vehicle engine may be impossible or even dangerous.

Watch out: do not operate a vehicle in dangerous conditions nor in an enclosed space - doing so risks death by carbon monoxide poisoning just as we warn above when we discuss where to locate a gas or diesel fuel operated backup electrical generator.

Watch out: using the vehicle's built-in 120-V power outlet for protracted intervals will run down the vehicle battery making it impossible to re-start the engine.

How to Salvage a 12-Volt battery from a Car or other Vehicle to use as a temporary power source

A third method can be used to provide 12-V electrical power to operate a USB adapter plug or a 12-V DC to 120-V AC electrical power transverter to make use of the battery from a car or truck even if the vehicle itself is not operable. For example if a vehicle has been flooded so that its engine cannot be operated, you may be able to salvage the vehicle battery.

Remove the 12-V battery from the car, truck, van, boat etc.

Connect the input positive and negative terminals (using any makeshift means) from the USB adapter or the 12V to 120V transverter power cord to the corresponding positive and negative terminals on the battery.

Watch out: connect negative to negative (black to black or - to - ) and positive to positive (red to red or + to +) when hooking up an adapter directly to a car battery. If you reverse polarity you will damage the devices or adapter you are attaching, probably blowing a fuse or burning up the device.

Can You Use a Vehicle 12-Volt System for Emergency Survival Heat?

While a vehicle parked safely outdoors in open air and that has an operable engine can be run for a while (fuel runs out) to heat the engine and thus the vehicle heater, some readers have asked about using the vehicle's electric circuit as an alternative heating source, perhaps thinking that they can run the vehicle as a stationary generator and operate an electric heater in a nearby shelter. This approach is not likely to work and is likely to be dangerous.

Watch out: do not try to operate a conventional 120V electric heater (nor other high-current or high wattage devices) from a typical car cigarette lighter DC to AC adapter: The high wattage used by the electric heater and high current draw (amps) will most likely blow any fuses in the vehicle's wiring system if it does not melt the wiring itself, and there is a real risk that you will overheat the vehicle wiring inviting a short circuit or fire.

The maximum electricity usage from a typical car cigarette lighter circuit is about 240 Watts at 12-volts DC, protected usually by a 20Amp 12-V DC fuse. Note that that's 20 Amps at 12-volts, not 20-Amps at 120-volts. Very roughly, because there are other factors, a 12-V 20A electrical circuit in a vehicle has just about one tenth of the wattage capacity of a 120-V 10A circuit in a building.

There are 12-volt operated vehicle seating pads intended to give limited warmth to the driver or occupant (just as some vehicles have electric seats) though that approach means people have to sit in the vehicle and of course run the engine.

Watch out: as we warned earlier, do not operate a car, RV nor other vehicle in dangerous conditions (vehicle was flooded, wiring is unsafe, etc), nor in an enclosed space - doing so risks death by carbon monoxide poisoning just as we warn above when we discuss where to locate a gas or diesel fuel operated backup electrical generator.

Where to Buy 12-volt to 120-volt DC to AC power converters & inverters (power transverters)

• Duracell power converters, Duracell Corporation, 1380 Flynn Road Camarillo, CA 93012 USA, Tel: 800.300.1857, Email: info@duracellpower.com, Website: http://www.duracellpower.com
• Maplin power converters, a U.K. supplier of power converters of varying capacity, Tel: 0844-557-6000, Website: http://www.maplin.co.uk/
• Ring Automotive, a U.K. supplier of power converters of a range of capacities, provides the Ring PowerSource 75-Watt Power Inverter, plugs into the vehicle cigarette lighter, outputs 230V AC power, larger wattage inverter models are also available. The company provides both 12V and 24V power converters. Ring Automotive Limited Gelderd Road, Leeds, LS12 6NA United Kingdom, Tel: +44 (0)113 2132000, Email: autosales@ringautomotive.co.uk, Website: http://www.ringautomotive.co.uk/
• Stanley power converters, (distributed at WalMart stores) include the little Stanley 100W inverter that plugs directly into a vehicle cigarette lighter socket and provides a 120V AC electrical receptacle, the larger Stanley XO Vision DC to AC 300W Power Inverter and other higher wattage models.
• Sima DC to AC power converter/inverters, distributed widely including online via TheEpicenter.com. Epicenter Supplies, LLC 384 Wallis Street #2, Eugene, OR 97402, Tel: 541-684-0717, Email: info@theepicenter.com Website: http://theepicenter.com/dc_to_ac_power_converters_and_inverters.html
• Sumas power inverters provides their Sumas 200 watts Power Inverter with 2 USB charging port - SM-2011US that plugs into the vehicle cigarette lighter. Sumas Media 19575 E. Walnut Dr. South City Of Industry, CA 91748, Tel: 1-877-447-8627, Email: customerservice@sumasmedia.com, Website: http://www.sumasmedia.com/
• Wagan DC to AC power converter/inverters, including the tiny Wagan - 2348-6 • Smart AC™ 100 USB Power Inverter that includes both a USB adapter (for your cellphone, tablet computer) and a 120V electrical outlet capable of powering a laptop computer, as well as higher capacity power inverters ranging from 100W to 5000W - distributed widely including online via BestBuy.com. WAGAN Corporation, 31088 San Clemente Street, Hayward, CA 94544, USA, Tel: U.S. & Canada Toll Free: +1.800.231.5806, Email: sales@wagan.com, Website: http://www.wagan.com/
• Xantrex™ Power Inverters & Converters (and other products), Xantrex USA, 541 Roske Drive, Suite A Elkhart, Indiana USA 46516, Tel: 1-800-670-0707, Xantrex Canada, 3700 Gilmore Way Burnaby, BC Canada V5G 4M1, Tel: 1-800-670-0707, (The company also sells world wide), Website http://www.xantrex.com

 

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