 A
115 vac inverter can be permanently installed in an RV, and connected
through
an automatic change-over relay. The relay is wired in such a way
that the normally closed contacts are used for the inverter output, and
the normally open contacts are used when external power is
available.
By connecting this way, inverter power is not used to energize the
relay
coil, saving battery power. You will most likely need to do
some re-wiring in the RV to
isolate
the wall receptacles that will be powered by the inverter from built-in
appliances that require external power.
Schematic
of automatic change-over relay installation (including ATS-30
Installation Instructions).
Notes:
- Camping World sells a
30
amp automatic change-over relay for generator use that can be used
as an inverter change-over relay. The relay is the ATS-30 from
Parallax Power Components.
- The 12 VDC converter must not be powered from the inverter
because it
will
just burn up energy trying to charge the battery while running on the
battery.
- Unless you are installing a very substantial solar electric
system in
the
RV, you do not want to run high power appliances like the microwave,
air
conditioning, etc. from the inverter. Therefore, those appliances
must be isolated from the inverter output, and powered directly from
the
115 vac external power bus (see
schematic).
- There is no point in running appliances from the inverter
that can be
run
from propane. Examples are the water heater, refrigerator, and
electric
space heaters.
- It is not necessary to connect the 115 vac inverter output
through a
circuit
breaker because modern inverters have overload protection built into
them.
The inverter will shut down if overloaded.
- If the inverter is more than 150 watts or so, the inverter
should be
installed
as close to the battery as practical.
- Connect the inverter to the battery and RV ground with
adequate gauge
wire.
DC current draw by the inverter will be approximately 10 times the AC
current
it is delivering. A 1000 watt inverter will require 4 - 6
gauge
wire.
- Power from the battery to the inverter should be fused if
possible.
A 1000 watt inverter can draw close to 100 amps, so do the math when
selecting
wire gauge and fuse size.
- If it is not practical to install a fuse, be very careful
that the
wiring
cannot short to ground or chafe. RV batteries can deliver
hundreds
of amps of current through a 6 gauge wire shorted to ground. Fire
or battery explosion could result.
- The Xantrex RS-400 inverter that I
installed in
my RV has provisions for a remote on-off switch, allowing the inverter
to be turned off when not being used. If the inverter you select
does not have this option, you can: leave the inverter running all the
time as the idle current is less than 300 ma, install the inverter in a
location where you can access the on-off switch on the inverter, or
finally,
install a relay in the 12 VDC power wire to the inverter. The
last
option is not very desirable since the relay will need to handle high
DC
currents, and DC power is required to energize the relay when in use,
thereby
using more of the power you are trying to conserve.
- Warning:
Installing an AC inverter must be performed carefully as connections
are
made to high current DC sources and high voltage AC systems. Be
sure
to comply with all electrical codes and utilize high quality
workmanship.
If you are not sure if you are qualified to perform this installation,
seek professional assistance.
Back to klenger.net RV page |