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The iBOT 4000 Powerchair review, last
page! Batteries and conclusion.
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11. batteries
The IBOT 3 and 4000 uses slightly different battery
technology from most powerchairs on the market.
Conventional powerchairs use a pair of heavy Lead Acid Gel
batteries that are called Deep Cycle batteries. This
is old technology. Typically they use a pair of 40, to
75amp/hour 12v batteries. These are actually bigger
and heavier than we really need purely because they cannot
be run down "really flat" without shortening their lives
drastically.
A conventional
PowerChair battery will give 350 use and recharge cycles if
discharged by 80% on average. Or less than half that
if discharged 90 percent! On the other hand, if you
never go far and only discharge your chair by say 30 percent
per day, you will typically get 800 cycles or more from your
batteries. So knowing this the manufacturers try to
fit batteries that are larger than we really need to give
good battery longevity for the average user. Just make
sure you fully charge them as often as possible!
The IBOT uses
Ni-Cad (Nickel Cadmium) batteries instead. The reason
is both efficiency, and weight. Advantages are:
1. They can be
discharged almost completely without the damage this would
cause a lead acid type battery and still give 500 plus
cycles. Contrary to popular belief Ni-Cad batteries do
NOT suffer from the "well known" memory effect.
2. They can give
huge currents needed for stair climbing even though small
and light due to extremely low internal resistance.
3. They can be
configured into higher voltage "battery packs" in series,
without the cell balancing problems that this would cause
during charging if the same thing was tried with lead acid
batteries. The higher voltage (67v in this case) has
many advantages in efficiency. Smaller currents are
required, less power is wasted as heat in the wiring
resistance, motors, extending range further.
In the iBOT two
67v 7.2 amp hour battery packs are used. This is
equivalent to using two 12v normal batteries of approx 40
amp hour. That may not seem large enough, but they
will give as great a range because they can be safely
discharged further, and because of the efficiency gained by
using a higher voltage. In addition, balance mode
wastes less power steering than a normal PowerChair so this
too will give increased range.
In summary then
the iBOT batteries are lighter, and should give about the
same range as we get from standard PowerChair batteries with
the advantage of longer service life, and faster constant
current charging. But they cost £500 each!
12. conclusion
Would I buy one??? Difficult question. My
current (modified) PowerChair is both more manoeuvrable and
better / faster / more comfortable on the street and in the
house.
In the normal
configuration where you are going to use the iBOT most of
the time its simply not ANYTHING LIKE as good or capable as
my current chair.
But only for one
or two minor reasons! I simply cannot believe that the
company that designed this expensive piece of technology
would allow a few minor issues as discussed here in this 6
page test from ruining a perfectly good chair.
It seems to me
that the core technology and idea is great! Ruined by the
implementation.
One look at the
pictures on the CD told me to expect the castor problem, the
C of G and wheelbase length problem, as well as the
footplate / transfer issues. And the tyres... If I can
see that from a photo even before I saw the new PowerChair
why the hell cant they???
In many ways they
have gone backwards, square castors, weak armrests, swing
away footrests***, too wide a seat back (difficult to reach
behind if you are skinny!) etc. None of these were
evident in the original.
But it DOES allow
you to go to places and across terrain that my current chair
wont allow. So for 90 percent of the time its worse.
(normal mode) and for the rest its far better when you need
it! (stairs / off road)
Since the steering
in 4 wheel drive, and the daft footrest and armrest issues
are easily solved even by me, (I have a workshop!) then I
would buy one if they would allow me to buy parts / spares.
But they wont. So I have no choice, because I couldn't
use it in normal mode as it stands - too many problems.
So would I buy it?
Still depends on the answers I get when they get back to me.
Meanwhile I am still on a huge diet.
*** The
footplate swing away problem will only effect people that
need to transfer with a board. Most likely the
majority of their buyers!
-----------------------------------
LATEST
NEWS!
The
iBOT 4000 is not to be sold in Great Britain from the end of
this year...
Today I received
this letter.
It says...
I am writing to
let you know that, with considerable regret, Independence
Technology has decided to cease selling and marketing of the
iBOT 4000 Mobility system in the UK. We have made the
difficult decision after extensive review and consideration
of the UK market.
We want to
assure you that we will continue to offer assessments until
19th December and will honour all sales agreements signed by
16th Jan 06. If you proceed with the purchase of the
Independence iBOT 4000 Mobility system, we will honour all
product warranties per your user manual and continue to
service all existing products. Your product consultant
will follow up with you to discuss the next steps. Etc...
Make of the
above whatever you will. But since they will not fix
it, will not allow me to fix it, then it really makes no
difference to me in the end... What a waste of
an excellent and extremely expensive project.
Latest
>>>
MORE! <<<
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