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Now, an engine is not a
generator... But they don't make generators this small,
because most generators need to run at 3000 rpm to give the
50 cycles per second required for the UK power supply, or
3600 to give 60 cycles in the USA. Now small engine do
not make any noticeable power at these revs! And the smaller the engine
the more they like to rev...
But I want 24v DC (no AC so the
"frequency" it runs at does not matter to me, so it can rev
freely. So now it
makes no difference to me that this little engine want to go
7000 rpm all day. It effectively means it can make as
much power as a much "BIGGER" mains type generator, 1hp (this
engine) is 740 watts. So allowing for some inefficiency it will
give me about 500 watts out at 24volts DC.
The actual generator is a
motorcycle 3 phase field coil from a Ducati motorbike. It is
new, and was never fitted so going "spare" as such...
It also happens to have the part that goes in the middle
with the magnets in it too... I will need to make a
neat case, and mount the rotor on the engine. Then I
will have about 80v AC 3 phase or single phase depending on
how it is wound. (Not actually seen this bit yet)
Now I have! Its not
Ducati! It does not use a centre rotor with magnets...
Its an indeterminate 3 phase, 450 watt Japanese bike one.
I don't know which exactly.
The output
from this (about 80v AC between any two phases) will go to either a stock "pair" of motorcycle
regulator/rectifier units with each one feeding a separate
12v battery, (if they are isolated electrically and I think
they will be). Shown below... These two are actually
from a Honda VFR800 motorcycle, but each one is capable of
charging a Gel type wheelchair battery, as they are 14.4v
regulated output.
If you look at the picture you see 3 yellow
wires. One for each phase of the generator shown higher up!
That's the power in sorted! The other green and
red 4 wires are just 14.v DC output, and are actually only
two wires, connected internally to carry more power while
still being flexible. This goes to a powerchair
battery in each case. The Three phase inputs are
electrically isolated from the outputs (I hope!) so they can
feed the two regulators at the same time. The two
regulators outputs "should" according to my calculations be
"floating" electrically speaking, and can be safely
connected to two individual batteries whilst they are still
wired in series! We will see. I visualise smoke!
Then every time I go outdoors I
can start that little Honda engine and it charges my
batteries at up to 20 Amps! So as I travel it will be
adding energy at a faster rate than I can use it. It will
not overcharge though as the regulators are set to
14.4 v on most bikes, so it will not damage sealed gel or AGM
batteries.
Still not sure if I should fit
the little motor and generator inside the battery box and
use half sized batteries to make room. If it will not fit
easily (it will be tight!) I may just keep existing
batteries and fit the generator under the wheelchairs seat
at the front. But then you can see it...
So stay tuned MUCH more to come!
What I want
to know is this... If I can do this at home as a
paraplegic user, why can't they??? Think about the
long term battery benefits alone. Even if you do not
need the extra range (I do!!!) then you will not be "deep
cycling" your batteries as much or as deeply. A deep
cycle battery that is deep cycled to 80 percent will DIE in
10 months because they give 300 cycles at best like this! I
have had 2 very expensive deep cycle batteries every ten
months for 4 and a half years. After this mod, they
should last 5 years with the same distance covered.
It is NOT a
weight issue, this motor weighs 7lb only. The generator
still to be fitted adds another 8lb. I have already
removed MORE than this by removing all the iron brackets,
footrests, etc. And since much smaller & LIGHTER and
CHEAPER (deep cycle not required!) batteries could now be
used it would not add a lot to the total cost. The motor and
bike generator cost me 100 UK Pounds, but I didn't pay for
the Bike bits. They may be a few hundred. On a £5000
chair it is not important. It adds flexibility!
OK then I need to
machine stuff bigger than my toy Myford ML7 Lathe can cope
with so the generator is on hold until the local college
re-opens in a few weeks time! Bugger!!!
Never mind, I can
finish the footplate in the manner that the manufacturers
should have done in the beginning.
So on to the next
page because this one will take an age to download as it is!
Go to part 3 below...
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Start
(looking at the mess! And sorting it all out
starts) |
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Part 2
(On board four stroke petrol power begins!) |
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Part
3 (The modified smaller lighter
footplate design continued) |
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GETS
A 4 STROKE HONDA ENGINE! (and a few other bits)