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14 .ESCAPEES |May/June 2015 |
Getting AC Power out of DC
Batteries—Inverters
Getting AC power into an RV does not
involve solar power. One way is to use
a generator, either a built-in or a por-
table one. Generators create AC power
using fuel. However, you can also get
AC power from the batteries using an
inverter. This is an electrical device
that converts the DC power from the
batteries into AC power.
Inverters come in all sizes and
prices. The smallest ones (around
$20) plug into a cigarette lighter-style
DC outlet and have one or two of the
familiar three-prong A/C outlets that
you can plug a small appliance into.
Plug the inverter into a DC outlet in
your RV (or toad), plug the phone into
the inverter, turn the inverter on and
the phone will begin charging. Invert-
ers can be found at auto parts stores,
Walmart and truck stops.
Many motorhomes come with a big
factory-installed inverter (most trailers
don’t). If your RV has one already,
turn it on while your RV is unplugged
from shore power, and see what goes
“live” in the rig. Plug a cell phone
charger or other small device into all
the wall outlets to find out which ones
your inverter powers. For those out-
lets, you don’t need shore power, just
the inverter. Check the entertainment
system, microwave and other appli-
ances to see which ones turn on. If the
RV has a residential fridge, the invert-
er may be dedicated to the refrigerator
and nothing else.
If your rig doesn’t have a factory-
installed inverter, you will need to use
either a portable inverter (for small
appliances) and/or you will need to
install a big inverter for things like the
microwave, hair dryer and toaster. In-
verters over 350 watts must be wired
directly to the batteries and can’t use a
cigarette lighter-style DC outlet.
Inverters can be either modified
sine wave, meaning that they generate
an adequate electrical signal that may
or may not work for the most sensitive
appliances. Or they can be pure sine
wave, meaning that they generate an
electrical signal that mimics house-
hold electricity very well and can be
used by all appliances.
Beefing Up the Battery Bank
Batteries are just a storage place for
electricity. Think of the batteries as
a big tub, and think of electricity as
water flowing in and out of the tub.
When you charge the batteries, water
is flowing into the tub. When you turn
on the lights and watch TV, water is
flowing out, draining the tub. The big-
ger the tub, the longer it takes to drain
it. Turning on the faucet full blast (like
having lots of current flowing into the
batteries) will fill the tub quicker.
To live without electrical hookups
Solar power may sound a little mysterious, but it isn’t complicated to under-
stand. It all boils down to two basic systems: one to charge the batteries from
the sun, and another to convert the battery power so household appliances like
the TV can use it. This article describes the components that make up a solar
power system and discusses a few elements of system design.
Batteries—the Heart of an RV’s
Stand-alone Electrical System
The difference between a house and
an RV is that a house runs on 110-
volt AC electricity, while an RV is
designed to run (in part) on 12-volt
DC electricity. The heart of this 12-
volt DC power system is the “house
bank” of batteries. These batteries
supply power to “the house” when the
shore-power cord isn’t plugged in.
What Can Your RV Do Now With-
out Hookups?
Before diving into a big solar pow-
er upgrade, it is worthwhile to get a
baseline understanding of how your
rig functions without electrical hook-
ups right now.
Begin by unplugging your rig’s
shore-power cord. If your RV has a
house battery bank switch, turn it on
(most trailers don’t, so you can skip
that part). Then go inside the RV and
see which electrical switches work. If
a light or fan comes on, it’s a DC light
or fan. If it doesn’t, then it requires
AC power. If the refrigerator can run
on propane, then it will be function-
ing, and when you open the fridge
door, the DC light inside will come
on. The microwave, TV and AC wall
outlets won’t work.
“Inverters come in all sizes
and prices. The smallest ones
(around $20) plug into a cigarette
lighter-style DC outlet and have one
or two of the familiar three-prong A/C outlets
that you can plug a small appliance into.”