Charging Power Wheelchair & Vehicle
Batteries & what you need to know.
See related:
Inverters and Chargers &
All about Powerchair and vehicle batteries
and Which
batteries to buy
Charging
a motor vehicle battery
If
your Disabled Modified Vehicle is driven daily then there is no need
bother.
Unless you left it unused for too long or left something turned on. The cars alternator charges
it at 14.4v (or close) as soon as you start it up and
charges the battery fast at up to around 100 amps at a fixed 14.4v. This is
ideal for a starter battery.
The danger is if its left unused for say a week or
longer. All modern cars have such things as immobilisers, remote locking, engine
management computers, alarms, various radio memory and other electronics that
drain the battery as the car just sits there. In some cases pretty quickly
over a week or so. With extra electronics such
as remote start, or say the computer in the boot of my wheelchair adapted minivan that controls the
ramp, electric doors, suspension lowering and more the battery has double the drain on
it while I get out and then again whilst it is sat unused on my drive!
This damages
ordinary Car Starter Batteries through sulphation fast even if there is enough energy
left in it to
start the engine later on most of the time. So you will necessarily not know
anything is wrong. You battery will just suffer an early expiry. See
All about Powerchair and vehicle batteries for
more info.
Every time you
switch off and get out, the ramp and suspension lowering (on mine) as well as
the door opening and closing motors all use a lot of power. Your battery is then
already in a slightly discharged condition even after you just exited it after a
long drive. Batteries store or age well in a fully charged state.. But they
all sulphate internally if left in even a slightly discharged
state for very long.
So
that's now happening. In a relatively short time the batteries capacity or starting capability is
reduced.
Compounded by
the fact that all those electrical systems mentioned above are gradually taking
more power out over time as it sits there.. So if you leave your car or van for more than a few days or a week
its a good idea to charge it. Or more accurately to "maintain" it in a
healthy charged state.
Buy a battery optimiser or
battery tender or battery maintainer as soon as possible if this sounds like
you!
Your battery
will love you and it will stay healthy much longer. It doesn't actually need a full charge (although
that wont hurt) but it needs a maintenance charger like this Optimate above (or
something similar)
connecting and leaving connected while you are not regularly using your car.
It may well still start
if you don't bother but your battery is suffering and will sooner or
later let you down. Another alternative is a good solar charger of 2 to 5 watts.
It wont "charge" your battery but it will keep it topped up hopefully
and prevent it going flat or sulphating. Less than 2 watts is a complete waste
of time unless you live in Arizona! I leave a 5 watt one above plugged into the cigarette lighter socket
and sat on my
dashboard when I am not using my van. It keeps my battery fully charged up and
healthy if the vehicle is unused for long periods. (a week or more)!
An Example with actual measured
figures...
See larger image of the
Hawker Odyssey battery under test.
Here is an example. My
Disabled adapted Rollx Van. Has all kinds
of immobilisers, sat nav, engine management, alarm and an extra computer in the
boot to control the ramp/door/lowering etc. Here it is with the vehicle
all locked up and the engine stopped. After 30 mins. The Clamp Ammeter shows a
0.2 amp (200m/amp) drain on the battery. This is quite high but similar figures may
be typical for some other modified
vehicles of this kind. 20 to 50 m/amp is more normal.
It initially starts as 10 amps plus after switching off getting
out and locking the van! 10 Amps! But gradually all the various electronics go to
"sleep" and it settles at this relatively low value. The voltmeter shows the
brand new Hawker Odyssey battery is fully charged at 12.8v. Now 200ma at
12v is 2.4 watts. Or about 0.2 amps lost per hour while parked or 4.8 amps per
day. This looks abnormally high but it always seems to settle at that figure.
50ma is probably closer for most vehicles.
That means that in ten days time if I don't drive it or charge
it the battery will be 2/3rds drained! that's right 2/3rds!!! It will have
suffered some sulphation and had its service life shortened. It will also probably
still start the Van - Just! After two weeks? Doubtful if it would. Now you
see why I use Optima or Hawker Odyssey batteries? They are both dual purpose
Deep Cycle and Starting Batteries. This way the slowly discharging battery
is much less damaged than an ordinary starter battery would be. Most modern vehicles are like this.
Have yours tested. A deep Cycle and Starter battery is often a much better
option in most modern vehicles even standard non adapted ones..
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Remember ALL lead acid
batteries HATE BEING DISCHARGED!
You may like to consider fitting a dual purpose battery to a
mobility vehicle if it has extra equipment like a powered ramp or wheelchair
lift etc. Because these are a special "breed" of battery that can both start a
car as well as being Deep Cycled like a powerchair or scooter battery.
So all
those times when the battery gets a bit low due to the extra drain after the
engine is stopped will do much less damage to your battery.
Examples of these include the
Optima, Hawker Odyssey. and a few others.
Not cheap but being disabled seldom
is. And we need the security of a good battery more than anyone else. See
All about Powerchair and vehicle batteries
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Charging a PowerChair or Scooter battery.
All Powerchairs and Scooters use Deep Cycle Batteries. These, despite their name,
DO NOT LIKE BEING DISCHARGED! All lead based batteries hate it, but deep cycle
batteries suffer less damage when doing so.
With this in mind its best to ALWAYS charge them fully every
single night in a powerchair or scooter if used and once a week even
if NOT used at all. With the manufacturers charger or something equivalent
with the correct charging profile for whatever batteries you have fitted.
A good Deep Cycle 3 or 4 stage logic controlled
charger (switch mode or transformer) designed for the type of battery that you use is essential. Even if you
only used your Power Chair or Scooter for ten minutes you must do a complete
charge every
night. Don't Forget. If you do and you continue to use it you will
discharge your batteries much deeper than needed and no lead based batteries really like
that. Regardless of what any "expert" may tell you!
REMEMBER!!! Weekly if you don't use it.
Nightly if you do use it. Overnight.
If you have not used it at all then charge it once
every week fully over night. Once a week will help prevent the batteries becoming
slightly discharged and internally sulphated which ultimately is what kills them
if just left and allowed to become discharged. Never discharge Lead Acid Deep
Cycle batteries on purpose to get rid of any memory effect! They don't have a
memory! Even the original rumour that NiCad batteries has a "memory"
that came from NASA was
not actually true in any normal use. All deep discharge does is damage your
wheelchairs batteries.
If you get chance during the day it IS BENEFICIAL
to plug in the charger to lower the average daily discharge level. This is
called opportunity charging. Or opportunistic charging. Contrary to what you may read elsewhere it
is definitely
beneficial. Anything that lowers the average discharge level each day helps your
batteries live longer. It still needs
the full overnight charge however every night just the same. The FULL charge
cycle doesn't just "charge" but it equalises all the cells in each battery
bringing them all up to the same voltage level. So Plug it in for a while if you
get chance while sat at a computer for watching TV if you get chance.. But
also do the full overnight charge too. Opportunistic charging does NOT replace
it.
Are you fed up with waiting hours for your chair or scooter to charge? Well
depending on your battery type you CAN fast charge them. I use Optima Deep Cycle
and Starting batteries (Yellow Top ones) or Hawker Odyssey AGM batteries partly because it allows me to charge them up in the
middle of the day up to a 95 percent full charge in around one hour. Go
from all but exhausted, to ready
to go again while you check your email... See
here.
It still needs the full overnight
charge while you sleep from the normal slow 8 amp (or about 20 percent of battery capacity) charger
however every night just the same or your batteries never get properly equalised
and will become unbalanced.
Contrary to what you are told on certain other websites fast charging or
opportunity charging your deep
cycle batteries isn't harmful and can lower the average depth of discharge
meaning longer service life. But you do need to connect directly to the
batteries and not try to put extra current through the normal charging socket...
See
here
Normal overnight (slow) charger size? Its NOT at all critical unlike what
some so called experts would tell you. The sizes below will get your heavily
used scooter or powerchair fully charged and ready to go while you sleep.
Smaller wont hurt the batteries at all. Even a 1 amp multi stage charger will
safely charge your batteries. But it will take way too long!
3 amp for 25 amp hour batteries.
5 amp for 35 to 45 amp hour batteries.
7 to 8 amp for batteries 50 to 75 amp hour.
If you try to charge with a bigger charger
but still of the correct multi stage deep cycle type then several things can
happen.
(a) Depending on battery type you may have no problem at all. Your batteries
will just charge faster. These chargers are voltage controlled so even a big
charger should not hurt a good deep cycle battery unless it gets too hot. Too hot
means about 50 degrees centigrade. I charge mine regularly at 30 amps. My
batteries (Optima) show no sign of stress and the manufacturers suggest that
there is no limit to the current at all. Not only is my 30 amp charger OK its
fine to use a 200 amp one. However charging faster
MAY shorten battery life if they get hot (50+ centigrade). But even at a 100 amp
rate they only get vaguely luke warm so its just not a problem.
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b) If your batteries are less good quality you may find acid or gelled acid all over the
place! Check the manufacturers website for fast charge current limits. Optima's
for e.g. say no problem at all...
Hawker, (+
Sonnenschein I think too) also say its not a problem other than watch the
temperature. And after talking to the MK guys they also say no inrush current
limit is applicable.
So its safe to fast charge all of my batteries at least!
And probably all the others too. But don't blame me if yours fry!
c) don't ever put more than the standard chargers output (5 or 8 amps) through the
stock charging socket!
Connect your own cables and connector directly to the
batteries
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See also:
Inverters and Chargers &
All about Powerchair and vehicle batteries
and Which
batteries to buy
Related Pages
Detailed PowerChair Only Menu
Inverters and chargers for powerchairs
Fast charge your
powerchair or scooter
Lithium Ion Batteries for
Powerchairs and Scooters
