In days gone by, home comforts were hard to find in a truckstop parking lot or a
terminal yard. You made do with take-out coffee and maybe endless peanut-butter-and-jam sandwiches. Maybe you once tried doing bacon and eggs on the hot turbo. Even the biggest sleeper on the road couldn’t really be a home.
No more. If you want to watch the Oilers smother the Flames – or vice versa for
our friends in Calgary – while making a proper dinner in a microwave and brewing a pot of coffee at the same time, you can. Thanks to industrial-grade power inverters, you can really live in that big truck – and easily save $50 or more
every week in restaurant meals.
That’s the obvious benefit, but these high-end inverters are also a great way to
limit idling a diesel engine, and the saving there is counted in both fuel and engine wear.
All in all, depending on your highway lifestyle, not a bad investment at not much more than $1000. And now that they’re available from most truck makers as factory options or as relatively simple to install aftermarket kits, serious power inverters are easy to come by.
What’s the Deal?
Inverters, many of which have battery chargers built in, convert the DC electrical
power coming from the truck’s batteries to ordinary 120-volt alternating current,
just like in your home. Depending on the model you choose, you can run just about any appliance from a simple cell-phone charger to a combination of toasters and
computers and refrigerators – you name it – at the same time. Yes, many of these things can be had in DC form, but for price and selection you really need to think AC.
The smallest inverters, and thus the least capable, can be plugged into the truck’s
cigarette lighter. They’re the kind you’ll find at truckstops for $75 or so, but they’ll do little more than run a laptop computer. And if the wiring behind the dash is too light to carry the big surge of power at start-up, they may have trouble doing even that. We’ve heard stories of people who watched their trucks burn to the ground because they tried to run a microwave oven off one of these little inverters. Horses for courses.
The bigger and better power inverters – and you really don’t want anything less –
are hard-wired into the truck’s electrical system and incorporate a charger that
provides the truck’s batteries with a fast, accurate and complete recharge when the inverter/charger is connected to 120-volt shore power. They also know when your batteries are running low and will simply cut out at some point to save them.
The idea of shore power is the subject of much discussion these days, and there’s a U.S. lobby trying hard to get truckstops to provide AC plug-ins for their clientele.
If some truckstops are resisting this, it’s not hard to see why. It would be
enormously expensive to retrofit a truckstop with electrical outlets in the parking area, so if it’s going to happen, it will almost definitely be at new facilities only. Unless governments step in to help, with a view to cutting down on idling diesels.
Some jurisdictions are actively considering it, on a trial basis at maybe just one
truckstop, but it’s a slow process. Nonetheless, it’s starting to happen, and in the long run it has the potential to change the very nature of the truckstop.
How to Choose
Led by Western Star and then Volvo, Freightliner, Sterling and International, with
other OEMs soon to follow, power inverters are now being offered as factory options in the US$800 range. That’s the easiest way to choose the right one, but retrofit is straightforward – at something like US$1200 and up plus installation for the kind worth having. Do-it-yourselfers can handle the installation with just basic
mechanical skills, we’re told, but remember you’ll be dealing with household-quality wiring and 120 volts.
The first step is to decide what you want to power. A good-quality 1100-watt model, for example, can handle the big surge when appliances are first turned on, and simultaneously run a 900-watt microwave oven, an 800-watt toaster, and a 900-watt coffee maker long enough to make breakfast (about five minutes) without fear of running batteries down.
At the other extreme, with that same 1100-watt inverter, low-wattage things like a
75-watt laptop computer or a 100-watt TV would run for 48 and 24 hours respectively. In the middle, you’d have four hours with a halogen worklight, six hours with an electric drill. Combine a shaver, TV, and 1500-watt hair dryer, and you’re good for 20 minutes.
Look for an inverter/charger that’s rated on continuous output power, not a five-minute rating. You want to know about its surge power too. A good 1100-watt unit might have a surge rating of 3000 watts, and be able to hold it for 10 minutes to get difficult loads started, for example. Not all inverters have safety code ratings
such as ‘UL’, the main American testing lab, or ‘CSA’, the Canadian equivalent. You want one that does.
You also have to ask what happens when the inverter is not working. Lesser, consumer-grade inverters might actually soak up 30 watts or so, enough to drain your batteries in a weekend. Look for a ‘sleep’ feature that drops the power consumption way down – to maybe one watt – if no AC is needed.
Look as well for low-voltage cutout protection in which the AC draw is shut off if
your batteries are sinking fast. That’s essential if you want to avoid the drama of
If you have access to AC power and can plug your truck in you can operate your
appliances indefinitely. With the inverter/charger connected to shore AC power
the unit passes AC to your appliances and automatically starts charging your
batteries. There are things a power inverter won’t do. If you’re looking to operate
high-power loads like a rooftop air conditioner for extended periods of time you
might want to consider an onboard generator.
Now Fuel Cells?
There’s a new twist on all of this from Freightliner, which recently unveiled a concept truck that uses small fuel cells to generate electrical power for on-board appliances. They’re an alternative to gen sets and power inverters dependent on
Developed by Freightliner and XCELLSIS, a joint-venture company partly owned by DaimlerChrysler, the concept truck uses two Ballard fuel-cell ‘stacks’ operating
in series as an auxiliary power unit (APU). Fed with hydrogen from a 52-gal liquid
tank, the fuel cell produces 1.4 kilowatts of 120-volt AC or 12-volt DC power. It’s
connected to the truck’s electrical system by an 1800-watt inverter, which takes
electricity from the fuel cells, batteries, and alternator, and feeds it to accessories or back to the batteries.
The demo truck is fitted with an 8000-BTU/hour air conditioning unit to show its
ability to cool the truck without idling the engine. A fuel cell creates no harmful
emissions, its only byproduct being pure water.
Freightliner says it’s working to make these fuel cell APUs commercially viable
within three to five years. Issues to be resolved include cost, integration with other
truck systems, and availability of suitable fuel for the fuel cell.
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