RV TECHNICAL |
A microwave oven has the highest
power and energy load in an RV.
Land Cruiser several times,
even when cold. That limited
energy, however, precludes
it from running (say) an RV’s
microwave oven for more
than a few minutes.
RVs NEED ENERGY
AND POWER
Motorhomes and 4WDs
have power-hungry starters.
A 4WD may also have a
power and energy hungry
winch. That winch is typically
run from the starter battery
(plus alternator back-up) –
but not for long.
For winch-like needs, pick
a starter battery that has
only the ‘CCA’ (Cold Cranking
Amps) the vehicle maker
recommends. However,
choose one that has high
reserve capacity (CCA
reflects its power, the latter
its energy capacity).
AUXILIARY BATTERIES
For RVs, the highest
power and energy load is a
microwave oven. Its wattage
rating reflects only its heat
equivalent. The actual draw
of an ‘800 watt’ microwave
is 1200 watts. That, via an
inverter, is about 1350 watts:
about 112 amps at 12 volts.
Such loads are borderline
starter motor power, but
starter batteries dislike more
than a few seconds of such
discharge. A 100 amp hour
deep-cycle battery will run
it briefly, but is wrecked if
done often. A 200 amp hour
version works better, but still
has a shortened life. A similar
capacity AGM is borderline,
but less knocked around. A
300 amp hour AGM does it
with ease.
LiFePO4s are ideal for
loads like this. High capacity
versions are available, but
ultra-costly. LiFePO4batteries
are about 40% of the size
and weight of an AGM
battery but a LiFeP04
withstands discharging to
about 20% remaining with
less degradation. Further,
(in RV use) it stays
within
about 13.1 to 12.9 volts across
most of its range. An AGM’s
life is shortened if discharged
frequently below 50%.
CRYSTAL BATTERIES
This one is curious. There are
two types, but one cannot
possibly be taken seriously.
It is another one of the
perpetual motion devices (but
with a power take-off) that
surface from time to time,
mainly from the USA.
The other is for real. It has
thick plates of lead calcium
selenium and a special
electrolyte that transforms
into a crystal-like state.
Enerdrive’s new
B-Tec battery.
gorv.com.au
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