Thoughts regarding our "Stromvelo"
(current bicycle) as we also call our Muscle Power Generator, is a machine,
with which electric current can be produced for charging the solar batteries
by pedalling on the spot, as this is done with a hometrainer.
Too often it has been observed that young people light up the whole house,
even if they are only in one room. While this is in houses with mains connection
only a waste of energy, it leads in a mountain building with a solar electric
supply to the early exhaustion of the batteries. Then with genuine need
of battery power, there is possibly no reserve available. If the sun shines
daily, this is probably no great problem; however, during rainy days or
scarce radiation due to overcast skies, there will be no supply of electrical
energy and the batteries will stay empty.
Surely we could have made another energy source available (e.g. a gasoline
engine with generator operating a battery charger). We prefer however an
educational source, which our Muscle Power Generator truly is. - So, if
the batteries are empty (or already if the control unit of the solar electic
plant indicates low reserve), the youngsters should (preferably in groups)
descend to the basement and push the pedals strongly. They are to feel in
their muscles, what effort it takes, in order to produce only e.g. 100 Watts,
which normal bulbs or the PC use in the minimum.
We do hope that this instructive experience leads to more conscious and
responsible handling of electrical energy.
The idea for this construction
I have received from my engineering colleague Rudolf Bertschi in Zürich,
who has built a similar machine for himself and his children. - For our application
we have designed a rather complicated electronic control network, which
provides a number of features that are described further down in this description.
Basically the machine consists of an old bicycle, an old alternator of
a scrap car and a long V-belt, which runs in the rear wheel rim. A sturdy,
welded construction holds the whole device together (see pictures). Everything
(machine and electronics) was assembled in the cooperation of my older son
Matthias (technician), who also serves as webmaster for this homepage, and
me (electrical engineer) during the winter 2002/03.
For the purpose of illustration the operating instructions for the Muscle
Power Generator are copied here, as they are fastened to the wall next
to the machine.
Operating instructions for
the muscle power generator
The BSOP Muscle Power Generator
is an emergency power generator, which enables us to charge the solar batteries
by means of muscle power, should there charge level have dropped too low
due to lack of sunshine or high consumption. The pedals' torque that corresponds
with the slope of the road and the choosen gear on the regular bicycle, can
be adjusted step-free with a control knob, so that the favorite torque can
be chosen exactly at the best r.p.m. for each individual (the chain gears
The following is to be considered: The max. permitted current (equivalent
to the max. pedal torque) is limited by the electronic control circuitry
to 15Amps (to protect the mechanical construction against excessive wear
If the battery voltage reaches 15Volt (battery fully charged), the electronic
controls reduce the current likewise (reducing also the pedal torque),
so that the voltage cannot rise more (for the protection of the battery).
The electronic control circuitry also permits an energy measurement,
in other words different pedallors can involve in a competition, e.g. who
can work the most (or put most energy into the batteries) within e.g. 15
minutes. The built in bicycle tachometer indicates in the position KMH
the charging current in Amps, in the position TRIP the executed work (or
gained energy) in ah (amp-hours) and in position DIST the total of all
to this date executed work in ah. If a competition is to be started, the
TRIP indication should be reset to 0.0 before each start of a fresh person.
DIST cannot be reset by the user.
A person, who would like to carry out maximum work, should not pedal
real hard from the beginning (no short sprint), which leads to rapid fatigue.
In contrary we must give time to our body, so that it can make its stored
energy available. This is different depending upon age and physical condition
and requires at first low pedal torque at the most pleasant pedal r.p.m.
in the beginning. During the following approx. 5 minutes then the pedal torque
can be continously increased, until the power level is reached, which can
be held for a longer duration. - 7Amps correspond to approx. 100Watt electrically;
due to the efficiency of the entire set-up of approx. 50 percent this corresponds
to an effort of about 200Watt, which is really good exercise!
And this is what you have to do:
- Put the plug into the
- Reset at the energy gauge
the TRIP indication to 0.0.
- Start with easy pedalling
during approx. one minute for loosening of muscles and joints.
- Press button labeled
- Within the next 20 seconds
a minimal current must be produced (red LED off, green LED below this lit),
since otherwise the control circuit switches itself off again.
- As described above increase
the pedal torque continuously to a comfortable level and adjust it for the
entire performance so that it feels good.
- Once the goal is reached,
slowly reduce the pedalling torque, until the machine switches itself off.
- Now the performed work
can be read from the TRIP display; it is to be said that it is a good achievement,
if e.g. 7Amps have been held for half an hour, which corresponds to a TRIP
indication of approximately 3.5 (3.5Amphours).
- At last before leaving
the Muscle Power Generator pull the plug out of the socket (fire protection,
in case there would go something wrong with the insulation of the generator).