I realize that we may have a different power versus resistance profile, but I prefer to keep my experiment under control and a constant current system does a great job of achieving that.
My latest experiment has been running for about 5 hours now and I can list a few of my observations: 1) I initially connected the wires backwards so that the copper plumbing joint was attached to the positive supply and nickel to negative. The copper part immediately began to be coated with a bright green deposit. At the same time, the voltage was climbing rapidly in order to deliver the 1 amp of current required. I realized my error after a few minutes and found that the copper coupler was quite a bit warmer than the electrolyte. The nickel was clean and not noticeably effected or warmer than the bath. 2) I cleaned up the copper coupler to remove the green scales and connected the circuit properly. At this time, the copper item is connected to the negative supply terminal and the nickel is attached to the positive one per Chucks design. 3) Power was applied and I noticed that green scales were now accumulating on the nickel while at the same time the voltage required to deliver the 1 amp of current was climbing. It took approximately 50 volts to get the desired current with my electrodes and the spacing, etc. This 50 volt reading was the maximum required throughout the test and began to drop soon after achieving it. 4) I decided to search for the reason and measured the voltage drop across each electrode. It appears that the green scale deposit on the nickel was highly resistive and caused a large voltage drop to appear across that path. The minimum voltage across the copper electrode to a point nearby within the electrolyte was about .8 volts although it is difficult to get a good reading due to critical probe placement. 5) I left and returned to find that the voltage of the supply had dropped to around 20 volts. I noticed that most of the green scale had dropped off of the nickel and now it had a dark deposit visible on its surface. 6) This new material deposited seems to have much lower resistance than the green one and I took time to measure the voltage drop from the positive supply terminal to the electrolyte very close to the nickel. It is difficult to get an accurate measurement, but it is in the vicinity of 7 volts while the comparable difference across the nickel-electrolyte junction is in the range of .8 volts. 7) Now the nickel is clearly warmer than the electrolyte. When I observe that there is 7 watts of power being dissipated in the nickel-electrolyte junction I suspect that a lot of the energy is due to joule heating of the deposit appearing upon the nickel. 8) The experiment is continuing and I will add additional water and borax as they become depleted due to evaporation and electrolysis. These results are very preliminary and the voltage measurements are difficult to verify. Perhaps the system will settle down after it has been active for a adequate period of time so that I can make more accurate measurements. Dave Recap of setup: Copper plumbing coupler connected to the negative supply terminal, standard nickel connected to the positive supply line, current set to 1 amp, borax electrolyte with crystals remaining on the bottom of the test fixture un dissolved, spacing approximately 1.5 inches between nickel and copper electrodes, gator clips located above the electrolyte. My supply can deliver up to 60 volts DC at 1 ampere of current. More current is available if the output voltage is reduced reaching a maximum of 5 amps on a sliding scale. I am using a sears craftsman digital multi meter to measure the voltages. Terry, this is not a scientific quality measurement, but a quick dirty amateur test so settle down. -----Original Message----- From: David L Babcock <[email protected]> To: vortex-l <[email protected]> Sent: Fri, Sep 28, 2012 12:06 pm Subject: Re: [Vo]:Good Alloy for Celani type reaction costs 5 cents : Chuck Sites Comment below On 9/28/2012 2:39 AM, David Roberson wrote: Hi Chuck, [snip] My supply is current limited and will not increase beyond what it is set for. I would see my supply voltage drop toward zero if the system resistance were to head in that direction. I am positive that I am reading the voltage and current across and through the cell. On occasions I have recorded the open circuit cell output voltage as a function of time immediately after disconnect and it has interesting behavior. This appears to be a quick way to test the electrolyte condition, but I have not put much effort into performing calibration. [snip] Dave -----Original Message----- From: Chuck Sites <[email protected]> [snip] I hope your measuring the voltage and amperage going into the cell(s). When I saw the heat, the current would shoot through the roof, just like somehow the resistance drops toward zero. Best Regards, Chuck Chuck and Dave: BIG difference right there in front. One of you is running the supply in constant current mode, and one in constant voltage. If the resistance decreases, the first setup's input power will decrease in proportion (I^2*R); and the second, the input power will increase inversely (V^2/R). So the question might be, does the temperature rise only because the input power rose, or did it start to rise before the power rose? My apologies if this was already obvious. Also, it strikes me that a sudden big resistance drop is sort of unthinkable if occurring in the bulk of the electrolyte. A flood of new ions zipping out from some small source (or if an area source, weirdly synchronized)? But likewise with an interface change: If small, little effect; if big then weirdly synchronized. But I never did any chemistry. Dave B.
