Wednesday, 23 March 2011

Cell #2 Endurance test (Oct. 7 update)

the graph below shows the cell's on-load terminal voltage and temperature for the latest 5200 hours of operation (ie. seven months, since Mar 5th) 
 (click image to enlarge
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the Cell #2 experiment settled into an apparent self-sustaining state approx. 400 hours after construction

the cell-stack (2 cells in series) has been under continuous load by a very low-powered LED flasher circuit since the cell was constructed on Feb 17th (ie. 7.5 months continuous operation, so far)

the trend of the on-load terminal voltage shows a slight increase since the start of the experiment whilst the trend of the ambient temperature has decreased over the same period, showing a net charge effect is occurring on the cell stack

to compare the self-sustaining action of these cells with conventional cell behaviour, see the post "Comparison test using NiMH cell"

since the average terminal voltage has slightly increased whilst the average ambient temperature has decreased, it appears that the self-sustaining behaviour is not directly temperature-related and therefore neither is the system gaining its external energy just from ambient heat

the ambient temperature is approx. 20 degC; the mean on-load terminal voltage of this type #2 cell-stack is approx 1.2V

Tuesday, 15 March 2011

DIY Voltage Cell #2

Cell-stack #2 was constructed on Feb 17th 2011, using a similar construction to Cell-stack #1, with just a few differences:-

- there was no paper separator layer glued 
  with Starch to the Zinc sheet;
- the cotton layer was sprinkled with undiluted honey
  (ie. no added water);
- the cells were not initially heated at higher than ambient;

the circuit also was mostly the same, the main differences were:

- a multi-toroid transformer was used in place of the inductor;
- the buffer capacitor was doubled in capacity to 4700uF;
- the leakage current feed to the 'relaxation oscillator' 
  sub-circuit was repositioned at the Collector of the 2N2222
  to allow any residual coil-collapse current in the primary
  to flow back into the cell-stack 

(the 'relaxation oscillator' sub-circuit is shown as a generic oscillator here - it's the same component configuration as for the Cell #1 schematic)

the initial o/c terminal voltage was approx 1.75V, ie. higher than cell-stack #1 o/c voltage, but it decreased after connecting the load circuit (instead of increasing steadily, like cell-stack #1)

the voltage/temperature readings gave a slight indication that this system had inverse temperature characteristics compared to the Cell #1 system

after a few days the in-circuit terminal voltage started to level-out around 1.6V and, after about a week, the LCD clock was moved from cell-stack #1 to cell-stack #2 as an additional load with the LED flasher

within a few days, the terminal voltage of cell-stack #2 decreased to approx 1.2V and the LCD was removed

after approx 400 hours of continuous operation from construction, the in-circuit terminal voltage was centred around 1.2V and the voltage/temperature characteristic of the system became very clear - the terminal voltage was a remarkably close inverse-correlation with the ambient temperature (the opposite of the Cell #1 system, which showed a positive correlation)

since passing the 400 hours on-load point, the system appears now to be in a self-sustaining stage of operation (which has persisted for an additional 400 hours, so far):

  - the trend line for the cell voltage is the inverse of the trend line for the
    temperature readings

  - the 'crossover' points of the two sets of graphical data have kept level
    (see the 21 degC ruled line in the DIY Cell #2 graph,
    immediately below this text)

(blue = Vnimh;  red = Tnimh)                   

compare the graph data for the DIY Cell type #2 with the graph data for a system with a commercial rechargeable NiMH** cell type
(the graph immediately above this text) powering a similar LED flasher circuit

the NiMH powered system shows a positive correlation with temperature (similar to DIY Cell #1) but the trend of the in-circuit terminal voltage is decreasing steadily whilst the trend for the temperature is rising

therefore the graph data shows that the NiMH powered system is steadily discharging

(** the 1000mAh NiMH cell was used with a low state of charge to bring it closer to the very low energy capacity of the DIY cell and make it easier to see how the NiMH terminal voltage varied with continuous operation of a similar load circuit)

DIY Voltage Cell #1

the first of these Copper/Zinc voltage cells (Cell type #1) was constructed 8th Dec 2010

each cell was formed from 1 layer of copper foil (Cu) and 1 layer of Zinc sheet (Zn), each approx 10cms square

a sheet of non-coloured, acid-free tissue paper was glued to the Zinc sheet using starch glue (eg. sold as 'Pritt Stick', in the UK)

a layer of non-coloured cotton was used as an additional separator; it was impregnated with approx. 0.5 cc of a 50:50 mix of honey and tap-water

two cells were used, connected in series by a small piece of folder copper foil held between the centre of the two cells

the initial o/c voltage of this cell-stack was 1.6V

two 10mm x 10mm diam rod Neodymium magnets were located adjacent to the outer flat surface of the top cell, with both fields aligned in the same sense, across the surface

the cells were connected to a very low-powered LED flasher circuit which drew a current of a few uA

the cells were heated (in circuit) for over a week at around 35 deg. C; then the heat was removed and the complete system was contained inside a mild-steel case with a lid

for a period of over 1 month the in-circuit terminal voltage of the cell-stack rose from 1.6V to 1.9V, showing a daily variation which corresponded with the changes in ambient temperature 

an unused cell, made at the same time with the same materials, showed a steady self-discharge and little or no correlation with the ambient temperature

an additional load was then added to the cell-stack + LED flasher: an LCD clock module was connected across the buffer capacitor C1

this extra load caused a steady decrease in terminal voltage of the cell-stack until the clock stopped operating and displaying correctly at around 1V, and later the LED stopped flashing around 0.85V

towards the end of operation of Cell #1, a second cell-stack (Cell type #2) was made with slight differences of construction and preparation (details to follow soon, in the next entry)

Sunday, 13 March 2011

Charge Anomaly confirmed

The results below, from the switched-charge experiment (
12 May 2008), show that the total value of charge-separation in the isolated test circuit increased by approximately 25% from the initial state of the circuit, after the switched transfer of charge from the input capacitor to the output capacitor

0.299 Coulombs of charge-separation were removed from the input capacitor, C1  

0.913 Coulombs of charge-separation were added to the output capacitor, C3

(any charge on the only other two capacitors in the circuit - 500uF and 0.1uF - was small enough to ignore by comparison with that on C1 & C3)

 the final state of charge in the circuit was significantly different from that expected by conventional circuit analysis - the circuit had gained an anomalous excess of charge-separation!

Charge Results:
Input cap, C1: 0.299F
Start volts: 8.0V
Start charge: 2.392Coulombs

Final volts: 7.0V
Final charge: 2.093C

Output cap, C3: 0.342F
Output volts: 2.67V
Output charge: 0.913C

charge switched from input to output capacitor, then discharged by S2

Total start charge: 2.392C
Total end charge: 2.093 + 0.913 = 3.006C

(ignoring charge on switching cap, C2, 500uF)

Switched-charge test period: 45.8s
cycle period: 0.85ms
charge period: 0.17ms
charge/cycle duty: 0.17/0.85 = 20%

Stand-alone switched-charge experiment setup:-
(12 May 2008 )

the circuit was constructed to transfer charge from an input capacitor to an output capacitor, via a switching capacitor and inductor, using a number of repeated cycles to switch a small amount of charge in each cycle

the switching was achieved using MOSFET devices driven by a free-running oscillator constructed using NAND gates from a CMOS logic device

the entire circuit was powered solely by the initial charge in the input capacitor

the only external connection was to a DVM, used to monitor the voltage on the input capacitor

the test achieved the same results, regardless of whether the DVM was connected for the full duration of the test or if it was disconnected at the start and only reconnected a few seconds before the end

Open switch S1, close switch S2;
Monitor C1 volts with DVM;
Charge C1 to approx 9V;
When C1 voltage approaches 8V then open S2;
As Voltage on C1 measures 8V, start timer &
  Close S1, to connect C1 into circuit;
When voltage on C1 reaches 7V, stop timer &
open S1;
  measure voltage on C3 with DVM;

Switched-charge experiment schematic

Parts list:
R1: 12K 0.25W
R2: 100K 0.25W variable
R3: 100K 0.25W variable
C1: 0.299F (4x1F, 2.3V series)
C2: 500uF 16V
C3: 0.342F (4x1F, 2.3V series)
C4: 0.1uF ceramic
D1: OA93
D2: 1N914
D3: 1N914
Q1: FDN304P
Q2: IRF540N
L1: 2.5mH
U1-U4: 4093B Quad Schmitt NAND