Hi,
You're receiving this newsletter because youasked to hear of updates or news of my "green" energyprojects in Victoria BC (ocean wave power, a motor system to make"any old car" into a plug-in hybrid, and better largebatteries) or because I thought you'd be interested. If you don't wantany more, please reply and let me know. It isn't my intent to sendunwanted "spam".
Regards, Craig
Turquoise EnergyLtd. News #9
Craig Carmichael November 1st 2008
Contents:
The Month in Brief(overview... summary... the short version!)
<>Or, here's the Super Shortversion!
<>
<>* Electric Hubcap Motor Moves Car!
<>
* Batteries start to Charge!
* Promising New Battery Chemicals!
BC's Goals? - aneditorial comment
<>Proposed First Electric HubcapMotor Making Class/Workshop
<>
<>(...January?)
Electric Hubcap Car DriveProject, Long, Detailed Report
Turquoise Battery Project, Long,Detailed Report
The Month inBrief
Everything seemedclose to fruitition at the end of September and yet nothing much couldbe claimed for results. October got better!
Car pulling out on 36 volts ElectricHubcaptm power
(movie URL below)
On the 6th, aftersending the September newsletter, I glued six more magnets onto thecar wheel rotor. It look quite impressive -"industrial".
But it didn'tseem to increase the propulsion at 24 volts. Worse, the motorcontroller burned up - again - when I tried to roll the car. That wasa bad moment.
I made a new motorcontroller and a couple of mechanical improvements and on the 20th Itried it out with 36 volts. The car moved on level pavement, ifonly slowly.
MovieClips
At perhaps1500-2000 RPM, this wheel has never before turned thisfast!
The pivotalevent!
(extrafootage - the remote's "Stop" didn't turn the camera off.)
The torque and power can andwill be improved, but it looks like "all wheel drive", fourmotors, will probably be needed rather than just two, to havesatisfactory power for highway speeds and hills. The essential planfor making "any old car" into a plug-in hybrid stillworks.
Having recentlylocated pre-made parts for most items, the motors will be amazinglyeasy to make! Most of the effort will instead be installing them,including mounting brackets, wiring and controls.
The directdrive concept, now shown to work, is easily the lightest and mostefficient possible means to propel a vehicle: 2/3 as much horsepoweris required and it'll have half again the electric range per batteryof everything else. That's better than anything you can buy today atany price. It's the future of vehicle propulsion.
Also on the evening ofOctober 6th, I finally tried some things that worked - not exactly asI'd envisioned them - and got a battery to charge.
Then on the 9th, Itried making a "Ni-Ni" battery[1.1v] as an experiment. That charged too! That chemistry would bequite a simple battery to make at home, with energy density similar toNi-Cd or Ni-MH. Then I found calcined zincoxide. With a higher voltage than the others [1.6v+], Ni-CaZn cells are almost equally simple,promise considerably better energy density, and will cost less. La-CaZn holds considerable promise for evenbetter density, but is more complex to make.
My batteries stillneed much work.
BC'sGoals?
What does it say aboutthe effectiveness of our society if the will to go to sustainableelectric power runs from the premier on down, and yet there seems tobe provided no channel for action or practical support to nurture andsustain vital breakthroughs in furtherance of our goals when once theymake their appearance? It seems the province is now offering"savings of over $6000 on the purchase of a new fuel efficientcar", but not $6 assistance to develop a means for eliminatingthe bulk of the fossil fuel usage of the entire province over the nextfew years.
Most talented butunpaid innovators give up and get a job. When by some miracle theymanage to develop a valuable product on their own puny resources, itis grabbed and used by industry, usually without recompense. (Lessthan 1% of inventors make good money off their inventions. Musicianswith original work are much better protected.) Is that the process ofenergy innovation the premier is trying to promote?
The whole face oftransportation will be changed forever by better batteries, and by theElectric Hubcap type of drive motor and what automakers willeventually turn it into.
I put the wave poweron hold because it doesn't look like anybody will make the slightestuse of even a superb, practical demonstrated working unit - or evenpermit it to be deployed and connected - even though west coast wavepower would be 1/2 the price of the Site C dam, environmentallybenign, and could be phased in incrementally.
Here are newindustries, new Boeings or Microsofts in potential. Who will grab themand take the lead: BC where they were invented, or Europe or China? Itseems to me that currently we drift with no plan while everybody -government, business, investors, and the public - waits for somebodyelse to do everything for them.
FirstProposed Class - Workshop
When is a good time to offer workshops?...
The batteries are certainly not ready. On the otherhand, the prototype Electric Hubcaptm works,the design will now have improvements based on the deficiencies andstrengths revealed in the tests, and it will be a very easymotor to construct and to duplicate.
On balance I think it would be a good idea to holdan Electric Hubcap making and installing workshop/class with a numberof sessions in the upcoming months, perhaps starting in January.
The Electric Hubcap is not a finished product. Morefabrication and trial of design variants would be of value. Themicroprocessor controls aren't ready and motor operation will be quitebasic (drive power and forward/reverse, no regenerative braking ordisplays...) until they are.
On the other hand, it would seem enough is known nowto make reliable, workable motors and run cars with them, and if I onmy own very meager resources try to get all the desired things testedalone, it could take a year or more and meanwhile nobody's driving onelectricity, whereas if workshop participants each try a variant ortwo, much would be learned before the sessions end, the participantswould have electric drive cars and know how to make them, and I wouldhave some funds to continue the R & D for the batteries and thecomputer controls, which is otherwise about to go into very low gear.(When ready the computer controls would be provided at cost toworkshop alumni.)
So if anyone is eager to electrify their vehicle,please let me know! I'd be very pleased to run an early workshopseries when about 4 or 5 people are signed up. The motors made at theworkshop will certainly be better than my prototype, which has atleast moved the car!
Here is a description of the proposed program as I currently seeit, details subject to change:
CourseOverview
* Instruction session:working principles of the Turquoise Energy Electric Hubcaptmvehicle drive motor and its ancillary components, as applied tocreating a plug-in hybrid car and other usefulapplications.
* Motor making workshops as required toassemble the motors.
* Instruction session: motor controllerdetails; simple controls details.
* Workshops: assembling the motor controllersand wiring boxes, and the simple controls.
* Instruction session: various aspects ofinstalling the motors, and the computer controls.
* Motor installing workshops as required toget the cars going.
* Additional instruction and workshops asrequired to complete projects.
* Followup session(s) when computer controlsare complete: install computer controls.
Participants should bemechanically inclined. Experience with design, fabrication andinstallation in any fields of metal working, mechanical, automechanics, electrical and electronics are assets. Participants areencouraged learn principles of construction during the workshops anddo work on their own if and as convenient. Work will be inspected anddiscussed by me and by the other participants. Creative thought inadaptation to specific vehicles and improvements to systems isencouraged.
The object of this course istwofold:
(a) to have the participantcreate his or her own Electric Hubcap equipped superefficient plug-in hybrid vehicle or other similar motor installationof choice, and
(b) without obligation, toprovide a trained nucleus of people to who are familiar with thisexciting and promising new technology, the future ofpropulsion. They'll not only save on gas,they'll be engaged with the cutting edge of electric transportationtechnology.
I haven't specified the number of workshops for each phase:there's lots of new things here and it's hard to quantify how long thejobs will take. We'll continue for one or as many sessions as it takesto satisfy the class. Installating things in the car is the most timeconsuming part, and is likely to vary considerably by vehicle.
There'll be three instructional manuals (or subjectsin one large manual) to accompany the workshop: Making the ElectricHubcaptm Motor, Making the ElectricHubcaptm Motor Controller, andInstalling the Electric Hubcaptm Drive Systemin a Vehicle. Writing of these proceeds apace.
The tuition fee for the workshop program will be$2000, and the parts cost will be $900 per motor. That includes mosteverything: the motor, controller, wiring box, and cables. But (whatelse is new?): batteries not included.
Unless they can be scaled up in diameter, magnetsand coils, four motors would seem the necessary number tosatisfactorily propel a typical smallish car.
I think I should order/buy the parts, paid for inadvance by the participants (at cost - but see below). That shouldbring some quantity discounts, and the materials would all be on handwhen the workshop sessions commence. Perhaps the money for materials(as well as the tuition fee of course) can be made tax deductable andPST exempt - that would lower the costs for participants.
I was surprised the materials for each complete motorinstallation cost so much when I added them all up. Anyone who wishesto provide some of the supplies themself is certainly welcome to doso. I will of course need to know what you are bringing before I orderthe parts. Particular items to provide that can save money are listedbelow.
Particular items to provide that can save money:
* car disk brake rotors - Honda Civic(?) rotors (10.25"diameter with a hub of 5.5" inside diameter) appear to beideal for typical 4 lug bolt wheels. As rotors are perhaps $40 and twoare used per motor, that's $320 for four motors. Anywhere that doesauto brake repairs should have used rotors going into the garbage can.They don't have to be in great condition, though a pretty flat face tomount the magnets on is desirable.
* winding and casting or varnishing/baking your own coils. If thecoils are $20 (though that price is not ascertained yet) and you canwind your own for $8, at 9 coils per motor that saves $432 for fourmotors. It is however quite a time consuming operation that would haveto be mostly done outside workshop time after initial guidance andpractice.
* Finding your own heavy copper wire, 200 amp circuit breakers,capacitors, wiring boxes and other electrical parts. Heavy #4 batterycables and #6 or #4 "cab tire" cables to the motor cost inthe upper tens of dollars per motor. 200 amp breakers for the motorcontroller boxes (preferably aluminum boxes for heat dissipation) alladd up.
The ElectricHubcapTM Vehicle Drive Motor
October GoryDetails
The first thing to try to get more torque wasobviously to fill the rotor with magnets. It had twelve, and I'dspaced them so six more could be added between. The rotor stuffed withmagnets had a really "industrial" look that said "partof a Motor"!
But then I tried it out. At 24 volts, the jacked upcar wheel spun vigorously up to 680 RPM, the same speed as before andwith about the same amps, and on the ground the car again didn't seemto quite want to move. I started it slowly down the street with thegas engine and turned on the juice, using a potentiometer on thepassenger seat instead of the one on the gas pedal. At"max", one could feel vibration from the magnetic thrust,creating a bit of propulsion, but after a few seconds at "max"a transistor blew and burned the circuit board. Lots of smoke andflame. There seems to be nothing to tell you when you're crossing intothe red zone until that sudden "BANG".
I must say that was a bad moment. I reflected thatperhaps after all I'd simply made everything just a bit too small andunderpowered to succeed, and that maybe I should just abandon thewhole motor project and leave the future of vehicle propulsion tosomebody with more resources.
But the motor was undamaged, I hadn't tried 36 voltsyet (it would have been the next test), and I had one more motorcontroller circuit board and could soon rebuild the controller with afew more transistors and (doubtless) a new MOSFET driver chip.
I had to give it a shot with 36 volts. If that wouldat least budge the car on flat ground and not burn out, a second motorshould bring the power up to "driveable".
I limited the PWM duty cycle to 80% max hoping to preventanother controller burn-out and made a couple of needed mechanicalimprovements. I finally spun the jacked up car wheel on October 20thafter previous testing on the bench. With 36 volts, it spun up to whatseemed like 1500-2000 RPM. 2000 RPM would be 200 Km/Hr, though ofcourse the only load was the wheel. Accelerating, the motor may havedrawn 60-80 or more amps, and it seemed to drop to around 40 amps onceit was up to speed. (I suspect it was more on startup, probably wellover 100, but the meter was too slow responding to catch it.)
Then I took the car to a level cul-de-sac and trieddriving it. On level pavement there were a couple of non-starters -until I remembered first to take the car out of gear... and then toturn off the parking brake.
Then the car moved, though only slowly. One couldhear the coils buzzing with the PWM and feel the push and the suddensmall changes of force as the wheels turned and different groups ofcoils turned on and off.
After driving just 3 or 4 car lengths (twice), I went outside andfelt the coils. They were very hot, some notably hotter than others.Not smoking - yet - but obviously the wiring is too light. (#10 feedwires & #14 coil windings - should increase those to about #6  or #11.) Then I felt the heat sink and the transistors in themotor controller, but they were only warm. The new MOSFETs certainlyseem to generate less heat. The car moved, nothing blew up or burned,and I got a bit of footage! That was enough for one day!
What factors might have limited the performance?
1. the 80% PWM duty cycle.
2. a 6mm or so air gap. (It was supposed to have been 3mm -something must have changed with the last ball bearing changes!)
3. The timing might not have been optimum. A bearing seal(previously mutilated) fell out and ravaged the optics just at the endof the spin-up tests. I had to replace a phototransistor and justguessed at the timing/rotation when I replaced the optics board. Poortiming makes higher currents and less effective force.
4. The light wiring cable to the motor (#10) probably hadsignificant voltage drop.
What might improve things in a notable way?
1. A thinner air gap between the magnets and coils. That may makeconsiderable improvement. I've heard you can run PMSM motors withquite wide air gaps, but no doubt that really means 1/16th or 1/8th ofan inch instead of 5/1000ths, not the 1/4 inch the car moved with.With the new trailer axle hardware for the future models, it will bepossible to set the gap very thin without danger of things hittingeach other, but a certain amount of gap improves electrical efficiencyand prevents the coils from gradually weakening thesupermagnets.
2. The computer controls, when they're done, will be set tosafely limit the maximum PRM duty cycle at the low RPMs that burnthings out, and allow 100% at higher speeds, so the power willincrease somewhat with speed.
3. Larger rotors. The rotor diameter provides the leverage radiusfrom the center of the wheel that the magnetic forces push from. Vis:if you have a ten foot pole attached to the wheel, you can easily pushthe end of the pole to turn the wheel and move the car. With a teninch pole instead, you may not be able to turn the wheel at all.
The rotor size is the biggest advantage of the axialflux design - the effective magnetic diameter is almost three timesthat of a comparable radial flux motor.
The new rotors for the "production" modelare 10-1/4" instead of the prototype's 9-1/2", for about aten percent torque increase.
A 12 inch or even larger diameter would provide roomfor more sets of coils and magnets, acting at again a larger radiusfrom the center of the wheel. I would imagine this variant would be agood size for a heavier vehicle -- or if one perhaps hopes to outfit asmaller car with just two motors instead of four.
4. Electromagnet coils with larger iron cores, eg, 2" rounddonut cores instead of 1" x 2" almost rectangular ones:three square inches of iron facing the magnets instead of the two ofthe prototype. With the marginally bigger new rotors there should beenough room. Bigger cores should broaden the magnetic field to therotor magnets for more torque.
And one might perhaps deepen the coil coresfrom 1 to 1.25 or 1.5 inches if it seems useful, to fit even heavierwire (eg #10), for more magnetism with less heat.
I think the basis for optimum performance lies inthese details.
I didn't like the fact that the transistor hadburned a hole right through the circuit board in the 24 volt test. SoI started to rethink the layout. Again, why mount these high poweredcomponents on a printed circuit board at all? I did it because theoriginal direct wiring was messy with six transistors, and would havebeen a hodge-podge with 12. I cleared off the old heat sink, dumpedsome of my new batch of MOSFETs on it, and started looking for anintrinsically neater wiring layout. After some moving things around,and finally bending and chopping leads to better visualize things, Ifound one. The five heavy leads and connections (battery +, -, and thethree phase motor outputs) are short and direct. It's so simple you'dthink it was a natural, and indeed once I'd found it it was obvious,but actually it took a lot of puzzling out. The backing insulation is(ready for this?)... tarpaper. Cheap, takes heat, and makes goodcontact without messy silicone heat conducting grease. How well doesit conduct heat? The most I can say so far is that thetransistors didn't feel warmer than the heatsink fairly soon aftermoving the car.
The new MOSFETs are rated at 60 volts instead of 100(still 120 amps) and have half the internal ON resistance (.0024ohms). This means they generate half the heat.
The new rendition of the motor controller powersection. This moved the car.
The motor controller transistors are now doubled up,which should theoretically be good for up to 240 amps and the circuitbreaker is 200 amps. But another transistor blowout attempting a teston Halloween indicates the need either to further limit the maximumpower at low RPMs or else to at least triple the transistors. (or tostay indoors on Halloween!) Since triple transistors and the samepower would probably result in soon blowing the breaker instead, thefirst choice is probably the better.
I phoned an old electronics friend on the mainlandand I said I was doing a car motor. His first reaction was, "Oh,popping MOSFETs, are you?" It would seem it's a given for thissort of project.
Things will be eased when there's more than onemotor. Then the car should accelerate smoothly with moderate powerfrom each one, instead of painfully starting to roll slowly at fullpower.
Also in one recent test, the three black filtercapacitors between the wires (photo above) popped, and have beenreplaced by much heftier units from a motor shop. Across supposedlysteady DC lines, the transient spikes from the motor - which are afterall what the capacitors are there to filter - must have made enoughtransient currents to blow the small ones.
Someone has an interesting idea for an all-electricvan: turf the gas engine, transmission et al, and mount the motors onthe inner ends of the CV axles. This has all the electromechanicaladvantages of the direct drive approach, and it would have space formultiple rotors and stators to gain any desired amount of power andtorque. In that case, the rotor and stator I made would be one ofperhaps two or even three for each wheel, essentially multiple motorson one shaft. (One could perhaps even "stack" multiplerotors and stators with no iron backing except at the end rotors, tomake a very light high powered motor: see my Turquoise EnergyMPMG generator stacked rotor-stator machine idea on the web athttp://www.sears.com/~craig .)
I'd visited Canadian Tire, Lordco and other autoparts stores many times, and it's very frustrating. You know they havelots of stuff, but it's in boxes in the back, and if you don't givethem a make and model of car, they have no way of looking it up, andare mostly unwilling to even open any boxes. I was lucky to find thebrake rotors I did for the stator and rotor. Then, in the middle ofOctober, I found Thomcat Trailers in Langford, where there are variousaxles, hubs, rotors and bearings right there where you can piecethings together. After some puzzling with what could work with what, Iworked out an excellent looking set of standard parts to make thehubcap motors from.
A week later I was walking by an auto service centerand looked at disk brake rotors in their garbage drums. (dumpsterdiving for R & D!) There were some four stud rotors that were avirtually perfect size, much better than the ones I'd been buying.They're 10.25" diameter instead of 9.5" (a better fit forthe magnets and a bit more leverage radius for the magnetic torque),and the center hub is bigger, in fact a perfect fit for the traileraxles.
The motors don't need perfect new rotors. Themechanics thought these were probably from a Honda Civic... now weknow what to look for at Midas!
And, seeing some trailer electric brake coils atThomcat gave me the idea of looking for pre-made electromagnets forthe motor instead of having participants wind them during workshops.Though these seemed a good size and shape, the wire was too fine withtoo many turns. But that started a search for them. A hundred dollarsextra for coils is cheap if it saves you from winding your own! Ididn't find anything suitable "off the shelf", but it may bethat a local motor shop will be able to wind them in quantity for areasonable price per coil.
With fine pre-made parts, the motor itself willpretty much bolt together like a mechano set, including securelyfixing the entire motor right onto the wheel, dead center, by an axleand bearings. This is a great improvement! As far as mounting themotor, that just leaves fitting the two brackets that bolt to thebrake drum housing and come around the wheel, ahead and behind, upperand lower. These meet the arms on the stator, now merely to hold it soit can't spin.
The other major parts of the installation aremounting the motor controller, driver controls, batteries, and doingthe wiring.
Fuzzy Logic
Somewhere earlier there was some mental lapse in mylogic. 100 amps feeding three parallel coils splits into 33 amps percoil, not 100 amps each, where 33 amps through series coils is again33 amps per coil. Thus, the motor with the coils wired in seriesshould in fact have performed about the same at 108 volts as it nowdoes at 36 volts with parallel coils. Operation-wise, there was nogood reason to switch. It should have moved the car about the same.The question is academic first because I never got up past 60 volts (5batteries), and second because it's changed and I won't go back.
Safety alone is worth $100 and a few extra pounds ofcopper in the car for fat low voltage wiring. It's much harder to beelectrocuted on a damp day by 36 volts than by 108 or 120 volts, and Iexpect lots of people to be making and installing their own motors. (Iunthinkingly grabbed that 60 volt connection just once to disconnectit. Nothing happened. At a higher voltage, or in the rain, one mightnot get a second chance.)
But there's more: the low voltage MOSFETs generatemuch less heat, and the minimum number of 12 volt batteries needed todrive electrically goes from 9 to 3, an economical figure and asmaller weight and bulk to put into the car. Having even 6 batteriesinstead of 9 far more than makes up for the extra weight of copperwire.
Electric Hubcap Motor Factoids:
* Two small but powerful hubcap motors supplied with 36volts should have the power to drive a motor vehicle to city drivingspeeds (up to 60-70 Km/H or so on level ground) instead of using thecar's engine. Four are needed for highway travel and steephills.
* The motors weigh about 50 pounds each.
* They are very easy to make.
* Most installations are expected to use two or four, evennumbers providing for left-right wheel balance and better, balanced,regenerative braking.
* Only the car's wheel turns. The only moving part in themotor is an extended axle that ties the stator firmly to the wheel.Brackets extending around the wheel from behind prevent the statorfrom spinning.
* The virtually frictionless magnetic link to the wheelmagnifies useful power by transmitting it all directly to the wheel.There's no losses from a transmission or gears. It requires no gearshifting or other attention by the driver, and it'squiet.
* Permanent magnet synchronous motors also have thehighest intrinsic efficiency of all electric motor families, furtherleveraging the efficient power transfer. Roughly, one might perhapsexpect up to 50% greater range than other (geared induction motor)electric motor systems from the same energy, and correspondinglybetter performance for the same kilowatts of electricity used by themotor.
* Installation requires no connections with or changes tothe car's existing mechanical components and systems.
* When not in use, the motor has no more effect on the carthan any other 35 pounds of luggage.
* The motor sticks out just 4" from the wheel or acouple of inches past the fender, less protrusion than the outsiderear view mirror.
* The RPM with 13 inch wheels is about 10 per onekilometer per hour of speed, that is, 450 RPM at 45 Km/Hour. Mostelectric motors prefer much higher speeds, but the "Hubcap"has good low RPM torque and power. 120 Km/hour is just 1200 RPM, astately pace for most electric motors but a good upper range for the"Hubcap".
* The rotor is a 10 inch steel disk brake disk mounted onthe wheel lug bolts, 6 poles using 6, 12 or 18, .5" x 1" x2" NIB supermagnets, glued and-or bolted on.
* The stator is a similar 10 inch brake disk (but withcooling vanes), with 9 epoxy cast coils bolted to it, each of 60 turnsof #14 wire, in 3 phase "Y" configuration. Magnetic flux isaxial.
* A unique design breakthrough is that the stator coiliron is strips of regular nail gun finishing nails in the coil coresinstead of custom die cut iron laminate sheets. With this and no axleor other moving parts, the motor is simple enough to make at home, orthe coils could be wound by machine and cast, for super economicalmass production. Individual coils can be easily replaced.
* The motors dissipate their waste heat via air cooling,avoiding the complexity of liquid cooling systems. There's maximalcoil air exposure and heat sinking with the magnets blowing air infront of them, an air scoop on the front of the fairing and air guidevanes, plus a temperature actuated electric fan in case all else isinsufficient at low motor RPMs that don't move much air and high power(eg, climbing hills and mountains).
Motor Controller Factoids:
* The controller switches the DC power from the batteryonto three power wires that go to the motor's stationary magnet coils,in a six state drive sequence timed to continually push/pull thesupermagnets on the rotor around in one direction.
* Three optical sensors looking through slots on the rotortell the controller the rotor magnet positions, to time theswitching.
* The amount of torque is controlled by pulse widthmodulation of the power, proportional to depression of the acceleratorpedal beyond "neutral". Reverse torque to slow the motor(regenerative braking) is provided by differently timed pulsesproportional to the release of the accelerator pedal above its"neutral point".
* A reverse switch switches the signals to reverse thepush on the magnets.
* In accelerating, the motor uses energy from the battery.In decelerating, the motor generates energy, which goes back into thebatteries.
* The individual motors and controllers have minimaldigital logic and will run connected to controls having nothing morethan a 555 timer to generate the PWM signal (connected to the gaspedal) and a forward/reverse switch, though connection to amicrocontroller "brain" at the front of the car is needed toprovide the more sophisticated features such as dynamicbraking.
* The microcontroller chip in the motor controller is the"brains" of the switching system, reading also motortemperature, car speed and direction, and batteryvoltage.
TurquoiseBattery Project
October GoryDetails
I started this project in January knowing no moreelectrochemistry than most people. But in the endeavor one learns, andI'm gradually catching on and finding some very good ideas andsubstances.
A Better Positive Electrode Material
The challenge: the low energy density of nickeloxyhydroxide as a positive electrode limits the energy density of thewhole family of Ni-xx rechargeable alkaline batteries. Finding abetter oxidizing electrode material seems to need going beyond thesimplest reactions and the commonest elements.
I got enthusiastic about using lanthanum hydroxideas a reducing (negative) electrode, as it wasn't too expensive and hada -2.80 volts potential (or -2.90 depending where you look) and moves3 electrons per molecule, promising higher voltage and higheramp-hours cells. What I didn't know then was that water startsseparating into ions (H+ & OH-) and even into H2 and O2 gas atthis voltage level, so you can't use it in a water based electrolyte.About two volts is the effective limit.
Then I thought I could separate the cell into twohalves with a graduated "voltage ramp" (dope the electrodeseparator sheet with ferric oxide or osmium powder) so the water neversees the whole voltage at any given point, but I finally realized thateach half still has to be under two volts. The ramp idea may reduceself-discharge, and may provide the potential for cells up to fourvolts instead of two, but under two volts on each side. Barringfiguring out some strange non-water based electrolyte, the energeticlanthanum hydroxide to lanthanum reduction would seem to be out.:(
But perhaps the lanthanum could instead be used inan oxidizing (+) electrode.
I found many of the "rare earths" willform a tetravalent oxide, LxO2, instead of Lx2O3. A lanthanumhydroxide to this "overcharged" oxide should have a goodenergy.
But this reaction wasn't listed for lanthanumitself. Another reaction is lanthanum chloride to lanthanumperchlorate, which should have very good energy. Complications arisein that perchlorate is more reactive towards organic substances thaninorganics, so some organic catalysts are called for.
The first battery made up with this, with thesintered monel-lanthanum powder gelled with agar agar in acetal estersolution does seem to charge, but even with all the trouble I've goneto the case has a leak, so the (promising) results are inconclusive sofar.
(Dysprosium should probably be better at oxidizingthan lanthanum, but I have the lanthanum.)
TheNickel-Nickel Battery
andNickel-Calcium Zincate Battery
OctoberExperiments
In the process of working on the Ni-La battery, Idecided to discharge the cell by reversing the polarity. It charged upbackwards as La-Ni to over a volt, and supplied some useful current toa load. That's when I started clueing in to lanthanum as a positiveelectrode - and nickel hydroxide as a negative one. I looked up thereduction reaction of nickel hydroxide and noticed it looked quitesimilar to cadmium:
Ni(OH)2 + 2H+ + 2e- <==> Ni + 2H2O [-0.72V]
This of course complements the nickel oxidationreaction usually used:
Ni(OH)2 + 2OH- <==> NiO(OH) + 2H2O [+0.52V]
Total would be 1.24 volts - call it 1.1 volts underload.
Cadmium [hydroxide] is -0.824V, but cadmium is moreexpensive than nickel and otherwise objectionable for such a smallgain.
Why, then, had no one made a nickel-nickel batterysimply using nickel hydroxide for both electrodes? It would seem anobvious thing to try, but I couldn't find any mention of such a thingon the web, including nothing explaining why it wouldn't work.
Perhaps companies start with the idea of replacement"AA" and "D" cells, and decided 1.1 volts justdidn't quite cut it? Then because it wasn't mentioned anywhere, no onethought of it for big batteries?
Having the chemicals et al on hand, I decided to tryit.
It started charging fine! But the usual bubbles onmy open experiment indicate the cell has to be sealed.
What would it cost? To make a long list ofcalculations short, around 150 $/Kg for materials. That's not too muchmore than for lead-acid, and (probably) would last for ages.
That was in early October. Then I found calcinedzinc oxide! Zinc has a higher voltage than nickel, 1.2v instead of.72, and "calcium zincate" may be even higher. And, it'shalf the price of nickel hydroxide!
1.6 volt Nickel-Zinc batteries have been made, butwhen recharged, the zinc crystals tend to grow through the electrodeseparator sheet and short out the battery, limiting the cycle life.(This seems to be the usual fate of Ni-Cd's too, in my electronicsexperience.)
I can see several ways or potential ways to preventthis, and the calcium may possibly mitigate the process regardless.Worst case, one makes the batteries so they can be dismantled andserviced, eg, replacing the separator sheet with a clean one. Thiswould obviously be impractical for AA cells, but perhaps not for bigelectric car batteries. But, I don't really expect that none ofthe possible methods to avoid the problem in the first place willwork!
Even with a nickel positive electrode, the zincateoffers better energy density than Ni-MH and Ni-Cd owing to the highervoltage of the reaction, and the cells are still under the two voltceiling even if the "voltage ramp" should proveineffective.
Again, the nickel-zincate battery should be an easyone to make at home.
Now all we need are leak proof containers. The thinkI may have the ansswer: I'm going to try stuffing the batteries intosmall salad dressing or similar bottles, using rubber test tubestoppers to seal the tops. These would have two holes, one for eachelectrode terminal. The original caps will have the middles cut outand will be screwed back on as compression rings to prevent thestopper from working its way out or popping out under pressure. If thebatteries become very pressurized, or if they freeze, the sides willsimply bulge out.
And, they should certainly be cheap! (I can seemyself now, digging through blue boxes on the boulevards!)
http://www.turquoiseenergy.com
Craig Carmichael
250 384 2626
Victoria BC
