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Last Changed 9/7/2007
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We chose an Inverter/Charger to provide for battery charging while
on shore power (plugged into electricity). A side benefit is that
the AC wiring is simplified.
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We chose a Tripp-Lite APS2012 2000watts Inverter/Charger. It can
supply up to 2000 watts continuously with a burst mode up to 4000
watts.
As a battery charger. it can charge at 25 amps or 100 amps. This is
a microprocessor controlled charger that rapidly but safely charges
the batteries to top off and holds them there with overcharging.
This charging power has been useful to recovery the truck batteries
when I accidently had let them run down.
Cost was one of the driving factors for choosing the Tripp-Lite. It
was a couple of hundred dollars less than the traditional RV
Inverter/Chargers. |
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Note - while I feel that the TrippLite APS2012 Inverter/Charger is a
fine unit, I cannot say the same for TrippLite support. I managed
to damage the remote control for the Inverter/Charger. When I asked
for assistance from TrippLite via email, the responses ran from no
response to some of the inquiries to a useless response that ignored
all the information submitted describing the problem. perhaps the
TrippLite telephone support is better. Too bad because it is a good
unit.
With a plain inverter, we would have had to make some arrangement to
connect the outlets within the cab to the inverter or the shore
power receptacle, but not both at the same time. If both the shore
power receptacle and the inverter were connected to the outlets at
the same time, two problems could occur. First, if there was no
shore power cable in the receptacle, the receptacle would be live
with 110 volts from the inverter, a serious hazard. Second, if the
shore power cable in in the receptacle, then the inverter would be
contending with the shore power and that could be disastrous to the
inverter. The normal solution for this is a switch that swings the
outlets to one power source to the other.
The TrippLite APS2012 Inverter/Charger does the switching
automatically. If the shore power cable is live, then the
Inverter/Charger feeds the AC power through to the outlets and puts
DC power to the batteries to charge them. In the absence of shore
power AC, the inverter creates AC power from DC power from the
batteries. The process is automatic
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One of the advantages of the TrippLite APS2012 Inverter/Charger is
the availability of a Remote Control. The APSRM4 is usable with
several models of TrippLite Inverter/Chargers.
We mounted the APSRM4 Remote Control for the Tripp Inverter under
the shelf holding the microwave. This put the control in an easy
location to see and operate.
The APSRM4 Remote Control allow the APS2012 Inverter/Charger to be
mounted in the
Electrical Compartment and still be controlled.
The APSRM4 also has a capability to connect a control cable from the
ignition switch that either turns the Inverter function with the
ignition on, or disables the Inverter function when the ignition is
on. We did not use this function at first but we added it later to
turn the Inverter function on and off with the ignition because we
forgot to turn the Inverter off too many times.
By experience, we found that we had to connect the input AC circuit
to the truck only to the Inverter through the circuit breakers. We
had connected the neutral wire to the neutral bus but that would
cause GFCI breakers to pop when we plugged in the truck. We had
bypassed the in-built neutral connection mode. |
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There are some excellent write-ups on RV Genset and Inverter wiring
on
Jack Mayer's website.
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We used a double pole circuit breaker on the shore power AC feed to
the inverter. This is a practice we learned from our boating days.
By having a circuit breaker on the hot and the neutral lead, you
protect the AC wiring from having the possible hazard of a crossed
wired outlet that you plug the shore power cable into. This is an
extremely rare situation but the cost is high if it happens. Having
the hot lead connected to the neutral lead of the power cord will
result in the hot lead also being connected to ground, a direct
short circuit. The circuit breaker on the neutral lead will prevent
internal wiring taking the brunt of the short circuit. |
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There is an advantage to using an inverter/charger over just an
inverter and connecting shore power to the output of the inverter.
If you use a plain inverter and connect the shore power to the
output of the inverter, you will have a live input outlet when you
are running on the inverter. This is a very hazardous situation.
The inverter/charger with automatically connect the internal AC
wiring to shore power when it is present and disconnect the shore
power inlet when running on the inverter function. This is far
safer.
Some will try to use a circuit breaker to manually disconnect the
shore power inlet when running on the inverter. This relies on
human memory to flip this breaker when the inverter is turned on, a
risky proposition. If this route is attempted, then a dual pole
breaker should be used as described above.
There is another problem with the manual disconnect method. The
proper place to tie the AC neutral to ground is as close to the
power source as possible. When running on the inverter, the
inverter is the power source and the neutral should be tied to
ground at the inverter. When running on shore power, the source is
the power plant and neutral should be tied to ground at least as far
back as the main power distribution panel for the park or house.
Within the truck, AC neutral should not be tied to ground. By
nature, the inverter will have its neutral tied to ground. To
prevent the incorrect tying of neutral and ground , the inverter
needs to isolated from the truck AC wiring. So now you need a set
of breakers for the invert and a set of breakers for the shore power
and you have to remember only to have one set of breakers closed at
a time.
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If you want to use a plain inverter, the next best thing is to use a
transfer switch. These are typically found on boats to transfer the
boat's AC wiring from shore power to an onboard generator. The
advantage of the transfer switch is that only one source (shore
power or inverter) can be connected through mechanical separation.
These transfer switches can be wiring to solve the neutral to ground
wiring. These switches are not low cost but safety should always be
considered. |
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