ProfilersWhat your RV CONVERTER does.
The converters job is to convert 120v campground AC current into 12v DC
current.
Twelve volt current is used to charge the battery, operate lights, fans
(both heating and ventilating), the electronic controls for appliances
and the lifting mechanisms.
One hundred twenty volt current is used for air conditioning, TVs, VCRs
microwave, coffee maker, etc. Everything you usually plug into an
outlet. Normally the campground 30 amp current is plenty to operate
whatever you need to be using.
Now comes the math part; Volts × Amps = Watts and, of course, Watts ÷
Volts = Amps. Most HI-LOs have either a 30 or 45 amp converter. Let’s
use the 30 for ease of computing. 30 Amps is the DC output thus 12 volts
times 30 amps gives us 360 watts of power. Prior to converting, the 120
volts divided by 360 watts gives us just 3 amps drawn from the
campground supply. (Leaving 27 to make your coffee with.)
Most of the time you will not be using the full 30 amps. A couple of
lights (2 amps) and an exhaust fan (4 amps) with the insignificant
milliamps for control circuits, will not tax your converter.
While dry camping, the same few devices totaling 72 watts could take
over 100 hours to drain a 600 amp-hour battery. Your water pump draws
about 4 amps but operates only intermittently. The big culprit is the
furnace which draws 10 to 14 amps and can do a battery in in just a day
or two.
Now let’s look at INVERTERS.
Many of us carry an inverter with us. This device does just the reverse
of a converter. That is, it accepts 12v DC input and outputs 120v AC
current to run your TV, VCR, DVD, Phone battery charger etc. Invertors
are pretty straight forward. Their limitation is marked clearly on the
front or top. If the capacity is 400 watts there is usually an
additional “momentary” or “surge” limit also posted. This momentary
limit is for the starting current needed to start a motor or initially
charge a fluorescent light. This momentary limit is just that. More than
a few seconds of this high current can damage the inverter.
The same formula rules apply to invertors. 400 watts at 120 v AC equals
about 3 1/3 amps. When running through the inverter this would draw 33
1/3 amps from your battery. A TV at 60 watts plus a VCR at 75 watts
would draw 12 amps from the battery.
Take your battery storage capacity, split it in half, to have enough
charge to prevent battery damage, and you now have the amount of usable
power that you can safely use before recharging.
Most invertors have a low voltage safety feature that will shut down the
inverter before you reach a battery damaging point. So go ahead. Plug in
that appliance and enjoy all the frills of civilization way out there in
the country.
Until next time,
Hatti wishes you “Happy Camping”.