Escapees May June 2015 Demo

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| May/June 2015 |ESCAPEES .15
for extended periods of time, the bigger
the battery bank, the better. The limit-
ing factor is the weight of the batteries
and the space they require, so you don’t
want too big a battery bank. On the
other hand, almost all RVs are shipped
with house batteries that are too small
for extended living off the grid.
The flow of electricity, or current,
is measured in amps, and an amp-hour
is one amp of current flowing for one
hour. Battery ratings are given in amp-
hours, and more amp-hours means the
battery can store more electricity.
A good size for a battery bank on
an RV used for weekends and vaca-
tions is 220 amp-hours or more. A
good size for a full-time RV home off
the grid is 440 amp-hours or more. A
general rule of thumb is for the battery
bank to store three to four times your
maximum daily requirement. So, if
you will generally be using 100 to
150 amp-hours of stored power every
24 hours (fairly typical for full-time
RVers), the house battery bank should
be roughly 450 amp-hours or more.
Batteries are designed either to give
a big punch of power to start an en-
gine or to provide a long, steady flow
of power to keep systems running.
RV manufacturers often use Group
24 12-volt start batteries as house
batteries, so it is common for RVers
to upgrade to at least two six-volt golf
cart deep-cycle batteries. Golf cart
batteries have the same footprint as
Group 24 batteries but are one to two
inches taller.
There are many other sizes and
types of batteries. Wet cell batteries
contain liquid that must be topped
off periodically with distilled water
and metal plates that must be cleaned
periodically through a process called
equalizing. More expensive AGM,
gel, and lithium ion batteries don’t
have those requirements, and they
don’t have to be installed upright ei-
ther since there is no liquid that might
spill out.
Charging the Batteries—
Solar Panels
So far, we have discussed making
your RV’s batteries capable of running
your AC and DC household applianc-
es. This is all on the “drain” side of
the tub that is using up the electricity
that the batteries have stored in them.
That is only one-half of the “solar”
equation, even though there is nothing
solar about it.
Now let’s look at how to replenish
the electricity stored in the batteries.
RVs are built to charge the batter-
ies whenever they are plugged into
shore power. Most trailers have an
inexpensive converter to do this job.
Higher-end motorhomes have a more
complex inverter/charger that acts
as both an inverter when the RV is
not plugged into hookups and as a
charging system for the batteries when
the RV is plugged in.
Solar panels make it possible
to charge the batteries without
shore-power electrical hookups. Solar
panels are rated in terms of “watts.”
More total watts from all the panels
equates to faster battery charging
(filling the tub more quickly).
A good size for a weekend/vacation
RV used mostly in the non-winter
months, when the sun is high in the
sky and the days are long, is 100 watts
Continued ›››
13.4
Charge Controller
dc/ac
inverter
Generator
ac
Charger/
Converter
Shore
Power
“Solar panels make it possible
to charge the batteries without
shore-power electrical hookups.”