T
The Dougster
- Jan 1, 1970
- 0
Hello, sci.electronics.design readers.
I have been working on an "electric flywheel bicycle" for five years
now. In various versions, a road-wheel or crank-coupled brushed DC
electric motor/generator is always coupled to an ultracapacitor pack.
Energy stored is proportional to voltage squared, and voltage a linear
function of speed, so it acts like a massive flywheel with fluid
clutch.
I have 6 Maxwell Technologies manufacture PC 2500 model 2700 F, 2.5
WVDC rated ultracapacitors on the current bike, which can source 4500
amps into a short. I'd like to fuse the voltmeter with fusible link
wire. The last time I had a voltmeter short I was using 24 gage solid
wire and it didn't open. It smoked the nylon fabric capacitor pack. I'd
like to avoid damage to the surrounding equipment.
Where do I get flat cable, 24 conductors, that will fuse and part on a
short? Would ribbon cable for computer equipment do the job?
I don't want to just fuse the return wire; I will be metering 12 caps
soon to establish the standard deviation of voltage and so the
capacitance distribution, with an eye to avoiding cell overcharge by an
appropriate pack charge limit. A DMM with serial comm gets the measured
values into a spreadsheet to do the standard deviation.
I have some 12-contact rotary switches to monitor cell or pack
voltages. One will be wired to 12 negative terminals, one to 12
positive terminals, and a mis-switch would short a cell. Right now
that's the way to do it. In the future, an NI.com USB DAQ with auto
range will monitor 12 voltages above ground with no short potential.
The onboard voltmeter is a 15 V analog panel meter with 50 mv internal
full scale capacity. Two bannana/probe jacks interface the DMM when
balancing is undertaken.
The 12 caps will be in two banks of 6, series within packs,
series/parallel pack by pack, to give regeneration (parallel) and boost
(series) modes of propulsion. Power is also taken out by an inverter,
but when the packs are in parallel, this imbalance is rebalanced..
It's not a problem to replace all the wires right now if one opens
under a short.
There is a 100 ohm, 1/4 watt resistor across each cell to establish and
maintain balance by voltage division. I will go to 1/2 watt soon for
more durable lead wires.
When the characteristics of the cells are known, the whole tap system
will be pulled and replced with clip leads for use only when parked.
Doug Goncz
Replikon Research
Seven Corners, VA 22044-0394
I have been working on an "electric flywheel bicycle" for five years
now. In various versions, a road-wheel or crank-coupled brushed DC
electric motor/generator is always coupled to an ultracapacitor pack.
Energy stored is proportional to voltage squared, and voltage a linear
function of speed, so it acts like a massive flywheel with fluid
clutch.
I have 6 Maxwell Technologies manufacture PC 2500 model 2700 F, 2.5
WVDC rated ultracapacitors on the current bike, which can source 4500
amps into a short. I'd like to fuse the voltmeter with fusible link
wire. The last time I had a voltmeter short I was using 24 gage solid
wire and it didn't open. It smoked the nylon fabric capacitor pack. I'd
like to avoid damage to the surrounding equipment.
Where do I get flat cable, 24 conductors, that will fuse and part on a
short? Would ribbon cable for computer equipment do the job?
I don't want to just fuse the return wire; I will be metering 12 caps
soon to establish the standard deviation of voltage and so the
capacitance distribution, with an eye to avoiding cell overcharge by an
appropriate pack charge limit. A DMM with serial comm gets the measured
values into a spreadsheet to do the standard deviation.
I have some 12-contact rotary switches to monitor cell or pack
voltages. One will be wired to 12 negative terminals, one to 12
positive terminals, and a mis-switch would short a cell. Right now
that's the way to do it. In the future, an NI.com USB DAQ with auto
range will monitor 12 voltages above ground with no short potential.
The onboard voltmeter is a 15 V analog panel meter with 50 mv internal
full scale capacity. Two bannana/probe jacks interface the DMM when
balancing is undertaken.
The 12 caps will be in two banks of 6, series within packs,
series/parallel pack by pack, to give regeneration (parallel) and boost
(series) modes of propulsion. Power is also taken out by an inverter,
but when the packs are in parallel, this imbalance is rebalanced..
It's not a problem to replace all the wires right now if one opens
under a short.
There is a 100 ohm, 1/4 watt resistor across each cell to establish and
maintain balance by voltage division. I will go to 1/2 watt soon for
more durable lead wires.
When the characteristics of the cells are known, the whole tap system
will be pulled and replced with clip leads for use only when parked.
Doug Goncz
Replikon Research
Seven Corners, VA 22044-0394