Page last updated Oct 20, 2021 @ 10:10pm
Configuration A
Configuration A involves the use of an inverter in conjunction with a
vehicle electrical system connected to the electrical loads by various means. These
are described below using a number of sub-configurations, depending on the connection
arrangement.
- Configuration A1 - extension
cords only, open
window/door
- Configuration A2 - small multicircuit transfer switch,
open window/door
Configuration A1 is usually the least
cost arrangement for providing backup power during an outage. It relies on a vehicle
generator to provide 12 volts dc to operate an inverter which converts this dc to 110-120
volt ac. The smaller inverters come with a plug which fits into your vehicle lighter
socket. Larger units require a more solid connection directly to the vehicle
battery. The ac power can be fed to electrical loads and small appliances using one
or more plug-in extension cords through any convenient window or door.

Click on thumbnail
image to enlarge
Advantages of this configuration include:
- simplicity
- economy
- if the vehicle is used regularly, no exercising of the engine is needed (unlike other
Configurations that rely on engines not in normal use). Thus, there is a high degree
of certainty that the engine will run when needed.
- transfer switches not required since no connection to the building electrical system is
made
- running a vehicle engine is usually more friendly to the environment than using a small
engine generator. This is because most vehicles have pollution controls to control
exhaust emissions while small engines do not
- no fuel transfers as with portable generators are required as long as adequate fuel is
in vehicle tank
- in contrast to portable generators, virtually no maintenance is required for the
inverter
Some limitations of this arrangement are:
- the vehicle engine should be running whenever inverter is providing power to prevent
discharging battery
- an open window or door to the outside is required which allows possible entry of
weather, insects, rodents and engine noise
- there is a practical limit to the size and the amount of power the vehicle electrical
system and generator can provide. A test on one compact car showed that loading
above about 500 watts would begin to discharge the battery with the car idling.
- all appliances must be connected using multiple extension cords
- time is required to run and connect all the necessary extension cords before power can
be made available
- it is impractical to power larger 240 volt loads such as well pumps, water heaters,
ranges, heat pumps, air conditioners, etc.
- precautions need be taken to minimize chances for theft of the vehicle and/or the
inverter
- bad weather can be a problem if no garage or car port is available since inverters are
NOT weather resistant
Configuration A2 is also a low cost
arrangement for providing backup power during an outage. It relies on a vehicle
generator to provide 12 volts dc to operate an inverter which converts this dc to 110-120
volt ac. Larger inverters require a connection directly to the vehicle
battery. In this configuration the ac power is fed to electrical loads and
appliances using a manual transfer switch. This type of transfer switch is easily
installed by any electrician without pulling the electric meter. The transfer switch
unit has single pole two position switches permanently wired to the preselected building
circuits that require backup power. The cord between the inverter and the transfer
switch is routed through any convenient window or door.

Click on thumbnail
image to enlarge
Advantages of this configuration include:
- simplicity
- economy
- only one heavy duty extension cord required
- backup power is available relatively quickly since there is no need for multiple
extension cords
- if the vehicle is used regularly, no exercising of the engine is needed (unlike other
Configurations that rely on engines not in normal use). Thus, there is a high degree
of certainty that the engine will run when needed.
- running a vehicle engine is usually more friendly to the environment than using a small
engine generator. This is because most vehicles have pollution controls to control
exhaust emissions while small engines do not
- no fuel transfers as with portable generators are required as long as adequate fuel is
in vehicle tank
- in contrast to portable generators, virtually no maintenance is required for the
inverter
- the transfer switch in this configuration can also accept power from a generator
Some limitations of this arrangement are:
- the vehicle engine should be running whenever inverter is providing power to prevent
discharging battery
- an open window or door to the outside is required which allows possible entry of
weather, insects, rodents and engine noise
- there is a practical limit to the size and the amount of power the vehicle electrical
system and generator can provide. A test on one compact car showed that loading
above about 500 watts would begin to discharge the battery with the car idling.
- it is impractical to power larger 240 volt loads such as well pumps, water heaters,
ranges, heat pumps, air conditioners, etc.
- precautions need be taken to minimize chances for theft of the vehicle and/or the
inverter
- bad weather can be a problem if no garage or car port is available since inverters are
NOT weather resistant
Note inverters that have GFI protection may shut down when
connected in this configuration. This is because the inverter senses the
neutral-to-ground bond in the building load center panel as a ground
fault. To eliminate this use an inverter without GFI protection or lift
the ground connection in the cable between the inverter and the transfer
switch. Also, many low cost inverters are not designed to have their ac
neutral tied to ground. Doing so will blow the inverter input fuses and
usually fry the internal field effect transistors (FETs). Using an isolation
transformer at the inverter output will eliminate both of these issues. BEFORE
PURCHASING AN INVERTER THAT WILL BE USED IN THIS CONFIGURATION (A2) PLEASE
CONTACT US AND WE CAN OFFER YOU A SOLUTION.
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