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So ALWAYS charge up your batteries
EVERY NIGHT without fail! If you are not using your
powerchair at all, and it is just stored you should still charge it at least every
seven days without fail overnight. This is because an
"unused" battery has a "self discharge rate" of a few
percent per day even when you are NOT using it. Keeping it topped up electrically
ensures it will stay in good healthy condition for many
years. Failing to do this will definitely cause it to
fail sooner.
So NEVER put off charging
for even a few days. A battery that is discharged even
slightly, starts to chemically "sulphate" internally. This
reduces its capacity (size) and its performance. Keeping it
fully charged prevents this happening at all.
If you plan to store your
Powerchair for more than 7 days you must disconnect one
battery terminal completely! This is because even when
your powerchair is switched off, the control system is still
active, and taking power out of your batteries. This is only
a small amount but after a few days it can cause your
batteries to become discharged...
Obviously you have no choice but
to discharge the
batteries when you actually use your powerchair, but as soon as
possible plug the charger straight back in the same day,
preferably overnight.
More people murder their
batteries because they were either told to "run them flat"
and charge them fully, by some dummy salesman or because they
don't realise that the batteries age or are damaged when not fully
kept fully charged... So they leave them for months and wonder why they
are then useless...
Obviously then, the less you
"deep cycle" your batteries (or the less miles you do each
day) the MORE total days or "cycles" you will get from your
batteries. Because then the average depth of discharge
will be lower.
I used to get 270 days use from
each set of new Sonnenchien Deep Cycle Gel batteries (Fitted as
standard to my F55s and many other chairs) in my powerchair.
Some people get two or three years! Depends how deeply you
are discharging them...
If you get chance, say while sat
at the computer for a couple of hours, plug the charger in! It will keep your batteries from being so deeply discharged
during the days use. This is very beneficial to the
longevity of your Batteries! Its called "Opportunistic
Charging" You may not need to do this to get you through the
day, but it will save your batteries from unnecessary depth
of discharge and prolong their service life. In all cases FULLY recharge overnight
too!
Modern chargers use microchips
to give a good controlled charge, and also to "equalise" the
cells (there are 6 to each battery) so that some of the cells do
not get "out of step" and become more discharged that their
neighbours! You can leave the modern Gel chargers
connected permanently, even after the "ready or charged"
light comes on. They are STILL maintaining your batteries,
the actual charging process continues. They also work as low current voltage
controlled battery "maintainers". This way you will be
helping your battery. So do not be so keen to unplug
it when it says its done!
Most "cheaper" powerchair
batteries are what's known as GEL batteries. These
use GELLED ACID, (by adding silica gel crystals to
the acid) so it cant spill. These are now "old technology"
and inferior in, both number of charge/discharge cycles,
current producing capability, and efficiency because they
have a relatively high internal resistance compared to the
more modern AGM or ABSORBED GLASS MAT
batteries.
These include the OPTIMA'S,
(see above) and the HAWKER ODYSSEY batteries. These
are typically more expensive, but offer more range, better
performance, and importantly longer life!
There may not be a size
available that fits all chairs though yet.
For those that are interested,
(not important really!) here are the differences between
deep cycle and starter batteries. Starter batteries
typically are discharged for a few seconds only, but need to
provide HUGE (hundreds of amps) current. They do this by
having a lot of very thin battery plates to give a bigger
surface area, and these are covered in a kind of lead
"sponge" that increases surface area further still. This means a
small light automotive battery that can start a car in the
middle of winter! But if you deep cycle one of these in a powerchair,
all the lead sponge plate coating is shed and falls into the bottom as
sediment! Giving far less cycles... (typically 25 to 35 at
80 percent depth of discharge) So after a month or so
they are useless.
A deep cycle battery is the
opposite. It uses less but solid lead plates. Has lower
surface area, can make far less peak currents, but can
withstand many more deep cycles (typically 300 cycles to 350
cycles at 80 percent depth of discharge)
OPTIMAS on the other hand
use pure lead plates but have huge plate area as well because they
can make the plates very thin. The do not need to be thick,
for strength, because they are tightly wound in a spiral,
much like a Ni-cad or a capacitor is. So these deep cycle
batteries can be both deep cycled, AND start your car
because of the increased plate area... This
construction makes for less
voltage drop under heavy loads too. (like when I am doing
wheelies in my powerchair! - So now you know why I use
these Optima batteries!)
None of this page applies to Ni-Cad
batteries that you may have in other equipment!
If you want to know more about
batteries still then head on over to my
Optima
Batteries site, as there is a wealth of
information!
OK that's the lecture over!
BURGERMAN
An
email about storing wheelchair batteries when new
HERE
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