STAY IN CHARGE
TO GET THE MOST OUT OF YOUR RV’S BATTERY, YOU FIRST NEED TO
UNDERSTAND THE DIFFERENCE BETWEEN ENERGY AND POWER.
| WORDS: COLLYN RIVERS
With batteries and associated
matters, ‘energy’ and ‘power’
are constantly confused.
Energy is the ability to perform
work. Power relates to how
fast that energy is used.
Olga can heave a 200 kg
barbell overhead. Doing so
needs a lot of power. She
cannot do it many times.
Fred re-stacks supermarkets,
typically stacking two hundred
1 kg cans two metres high
every fifteen minutes. In
addition, he does it for hours.
In lifting 200 kg through two
metres, each does the same
amount of work and expends
the same energy. The power
Olga requires, however, is
huge. Fred needs far less.
However, by doing so much
longer his energy capacity and
usage is far greater.
A 4WD starter
motor is
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gorv.com.au
a battery-powered Olga.
It needs a lot of power for
only a second or two, but
surprisingly little energy.
Supplying 500 amps for (say)
three seconds is about that
drawn by a six watt LED for
one hour. It depletes the
starter battery less than 2%.
The alternator replaces that
within a minute or two.
Running an RV’s lights and
TV, etc., however needs a
battery that is more Fred-like
than (powerful) Olga. Deep-
cycle batteries traditionally
fill that role.
OLD TECHNOLOGY
The first rechargeable battery
surfaced around 1860. It had
surprisingly high power, but
limited energy storage.
Batteries then remained
much the same until recently.
Power was rarely an issue but
energy storage (per volume
and weight) increased by only
50% or so.
The later AGM batteries are
mostly Fred-like, but rugged
and a tad more powerful.
LiFePO4 batteries store
about three times the energy
for the same size and weight
lead acid batteries.
NEWISH TECHNOLOGY
Early lithium-ion batteries
proved fire-prone but the
later LiFePO4 variant less
so. Most are Olga-like but
(depending on capacity)
double as Freds.
Their ability to provide high
power enables book-sized
18 amp hour versions to
start a diesel