Batteries for Electric Car

[CraigCarmichael]

Hi,

Having invented the Turquoise Energy MPMG (see my post under mechanical), a few tests would seem to indicate it would make a great direct drive electric car motor mounted in the wheels (13"-14" wheels), which would stick out an extra 2-5/8" if flat plate magnet rotors are used.

I haven't looked into electronic power controls, but I can't see they'd prove a serious problem to an electronics engineering technologist like me. Likewise for a battery charging system.

So the question is batteries, and I didn't see what I wanted at anything like a reasonable price. So I'm thinking maybe I should make flat plate cell NiMH batteries of some sort and wondering if anybody here knows much about batteries & battery making - especially anode materials.

It's nothing I ever wanted to get into - not my field at all. My high school chemistry (1972) is a little rusty. But surely it can't be that hard!

It would seem the cathodes are usually sintered nickel oxyhydroxide, and the electrolyte is always potasium hydroxide. The anode seems to be the wild card: Ni-Fe, Ni-Cd, Ni-metal hydride - what actually gives good power storage, zillions of rechages, and is relatively cheap? (LaNi5? Without looking up the price of lanthanum... I doubt it's very economical.)

There are actually several subjects battery making needs to be broken down into.

1. Sources of materials (nickel powders, potasium hydroxide...)
   
2. Making the sintered nickel cathode.
   
3. Turning the nickel into NiOOH for the cathode. (Awg, Chemistry!)
   
4. The electrolyte (Can that be just a piece of flannel soaked in potasium hydroxide? or craft paper or cardboard? or else what?)
   
5. The anodes: alloys... making...
   
6. sealing the cells. My idea is to just use that gooey putty-like stuff that's sold as a "tape" with paper backing for sealing windows into a frame.
   
   

Bull in china shop,

dangerous with just a little knowledge,

Craig

[Bruce S]

CC;

  I will help with a little of this, but not in the making of batteries, but how hrad it may turn out to be.

Here in St. Louis, we have both Excide batteries and energizer. Excide used to put out a kit where you could go there and buy a Lead acid battery kit and build it yourself and would come out with a pretty heafty car battery or marine battery. Because of the lead going into ground water problems , they don't offer that anymore.

Energizer has a "speciality" battery plant close to the house, and when we were talking to them about powering our companies velomoblie, they let two of us tour the plant. WAY COOL too:-))

I certainly don't want to be the one to stop some one from trying something or learning. BUT this one may be on that edge.

The main reason for NiCd, NiMh and such are round are for consistant voltage across the widest surface are possible within the given size. Rectangle isn't used for this reason except in wet batteries were they can. Li-On batteries use rectangle for the wide flat surface area, much like Lead acid batteries.

Back a short time ago, while building and testing battery banks made from NiCds (sub-c) the charger blewup some that I hadn't connected the thermal sensor. Being the curious type, I put on several gloves( Cadmimum is dangerous/poison and will absorb through the skin, not just in a cut) eyes glasses and took one apart. The way these are built to very tight tolerances , explains why the equipment the different companies use are so darned expensive.

I would say to try some of what you're wanting to do with the good starting point of rolling your own with the lemon juice that was taught in Chemistry class first. From there get better and better

What are the electrical requirements of your electrical car? voltage, amperage, distance. There may already be an close answer to your needs

Good luck with your endeavors:-)

Bruce S

 

[CraigCarmichael]

Hi Bruce,

Thanks for your thoughts.

I think making flat plate NiMH batteries is worth trying just to prove (if) it can be done at home, given what's (not) available for sale.

And, if one experiments a bit, one never knows but that they may find something nobody else has tried that works even better.

But it looks like there aren't a bunch of metalurgists and chemists with vast experience and novel ideas chomping at the bit to post here!

Main reason for not making flat plate batteries has been leakage around the edges. I think this can be overcome - how about some plastic strips and superglue? the other ways (prism & round batteries) are more complex and I understand bulkier.

18" x 18" plates (324 square inches) should solve your valid concern about small contact area. (But I'll experiment with 6" x 12" or smaller until I'm satisfied.)

Final product: 18" x 18" x ~10", 144V, perhaps ~100 amp hours (if no improvements to regular NiMH), hundreds of amps . Actually it'll be about 13" not 10", as I'll put a 1/4" gap with some aluminum heat sink fins in between every 10 cells or so, and then it'll actually be 12 separate 12V batteries around an inch thick.

...admittedly much lies in the realm of dogged persistence with trying out techniques that probably won't all work as first envisioned to get everything working - and learning more... and "luck".

But I've found a source for the powdered alloy anode material with lanthanum. That's the material I was most worried about locating. (Is there a common source for nickel powder?)

Sintering: oxyacetylene torch and a fire brick enclosure on the patio?

--Craig

[spinningmagnets]

Edisons Nickel-Iron (NiFe) batteries failed in their original design application of an electric car battery. The chemistry was more benign than lead/acid, and they lasted a very long time with many deep cycles, but the bulk per Voltage/Amp/Hour was poor. This led to very short range when configured for adequate voltage.

For a short time, some New York electric taxis had several NiFe packs per taxi. While one pack was running, several others were charging, and the pack would physically be replaced with a forklift several times a day. Didn't last long, Edison lost a lot of money.

I thought NiFe's may be useful for an RE battery pack, as an RE battery could be very large. I think every part could be figured out by the garage enthusiast, and the only expensive part is getting Nickel. (you said you're interested in Nickel-Metal-Hydride batteries)

I found out that 1981 and older Canadian nickels are 99% Nickel, also Nickel brazing rod should be available at most large welding suppliers. The rod with the highest percentage of Nickel is (of course) the most expensive. Getting pure enough Nickel as a base for NiMH battery construction may require some smelting. I am unfamiliar with the proper processes or the probable dangers.

Whether smelting Lead or Nickel, use too much protection. Gloves, eye goggles plus a face splatter shield, and NEVER breathe the fumes. You MUST have forced ventilation. You might consider using a wet/dry vac on top of a 55-gallon drum full of water as an exhaust bubbler "filter". Look up any bong website for proper configuration ideas. I'm sure you would never vent to your neighbors house, but I'm compelled to add that.

I don't want to sound as if I'm encouraging you to do any of this, but you sound like you're going to try no matter what anyone says. So, hopefully, my input will encourage you to be more cautious than you had previously planned on.

[CraigCarmichael]

Hi Spinningmagnets,

Thanks for the comments.

Well, you pretty much have me figured out! I'm somewhat more cautious than you suppose.

I've learned much about NiMH batteries in the last 3 days. Seems there's little nasty chemistry involved after all.

The nickel-iron probably would be pretty similar to make to the nickel-metal hydride.

I'm not going to smelt down nickels. I've found at least one source for the exact chemical, Ni(OH)2 or nickel hydroxide salt. It's probably about $10-$15 Kg in any quantity. And I've found powder for the hydride end also I think, but I won't get more info and a price back until tomorrow.

And I think I have the cell edge sealing solved: polyamide heat glue. It really bonds.

I think the biggest questions now are:

 (a) the formulation of the electrodes. There are many options and 'minor' additives, and it's a matter of picking out the most promising sounding one(s) from the glowing patent claims, maybe experimenting with 2 or 3.

 (b) formation of the electrodes. Currently I plan to mix the Ni(OH)2 (or the metal hydride) in a flour paste and roll it out thin, then cut the dough into electrode size flat squares and let it dry.

 (c) sintering of the electrodes - especially as I hope to do one on each side of each plate: half the plates and superb intercell connection. I'm pretty sure it'll work out somehow and I'll just have to try things until something works out. I hope the flour or other paste should keep the powder from blowing away while torching it, so hopefully I can just torch it, without a special furnace.

 (d) what to use for the electrolyte sheet. Fabric? Paper? Maybe polyamide fiber sheet.

 (e) whether nickel silver is a good plate material. (It's readily available.) A bit of copper might actually be an advantage to the hydride, it would seem. Otherwise I'll need to find pure nickel sheet.

 (f) How big should I - or can I - really make it? At the moment I haven't found NS sheets bigger than 6" x 18". (or thinner than #28 - a bit heavy I think.) The 18" x 18" idea might be out. So then I might well want to make 2 or 3 - not Less work than one big one.

Aside from precautions with the caustic electrolyte and fumes while sintering (outdoors), I've just given a bit of thought to the potential for trouble working on a heavy 144 V battery to be assembled from 12 12 volt cells that are too skinny to stand up reliably, with electrified metal exposed everywhere and capable of hundreds of amps - now that's starting to sound a little scary!

--Craig

[spinningmagnets]

I'd recommend starting small. Make up a couple of plates to test your plate and electrolyte chemistries. Ten square inches is a handy number for the math, then check the volts and amps, fiddle with it until your happy before scaling up.

Its my understanding that at around 50 volts and rising (DC or AC) the "bell curve" kicks in. Any higher and some people will die while others will just be severely burned (externally AND internally). I understand the need for 144 volts to run an EV, but you might consider making 6 X 24-volts, or 4 X 36, or 3 X 48. At least then if there's an "incident" with the battery manufacturing, only the battery will be fried.

Be cautious and keep everyone posted!

[Jeff]

Craig,

You may want to see if there is a machine shop nearby (for sintering of the electrodes). Most machine shops I've worked in had a heat-treating furnace that should do the trick. There's even a couple nearby now that have atmosphere-controlled heat-treat furnaces.

[CraigCarmichael]

Thanks, I may just check that out!

...materials are currently on order. So far I have 2Kg of lanthanum.

--Craig

[CraigCarmichael]

I've been working away steadily on the batteries, keeping good ideas and finding more of them, and discarding inferior things. And trying things out and assembling pieces.

Sintering the electrodes into coherent sheets wasn't working out for me, so I looked up "powder electrodes" and found a writeup detailing some techniques and extolling their virtues. They're actually better: 600+ mAH/cc (considering the positive electrode only) where sintered are maybe 400+. And making the batteries with the flat plate design really makes them more practical. And instead of 1 or 1.5mm sintered plate thickness I can do 6mm thick powders, thus magnifying the cc's at the small added cost of needing to add cobalt trioxide to the nickel hydroxide powder to make the thick, lower connectivity positive electrode more conductive. So I'm doing 4" x 6" plates instead of 6" x 12" - 1/3 the size and sheet metal cost, though 1/3 the max amps capacity. (and since I've already bought the plates, I have enough extra nickel-silver sheet metal for 240 more cells or 24 "extra" 12V batteries.)

I've just put together a cell and am giving it a week before I try and charge it, for some internal "electrophoresis" chemistry to set itself up. I've put up a preliminary writeup on my new Turquoise Energy Ltd. web page. Frames and case are ABS flat plates. I started "glueing" the cell divider sheets in with acetone (there's probably some better solvent or glue though), and window glazing silicone or something along those lines might make a better metal to ABS sealer.

www.turquoiseenergy.com/batteries.html

www.turquoiseenergy.com

My first model with the 4" x 6" plates should yield something like these rough specs:

Size: 4.3" x 6.3" x ~5.7" (~1/3 size of lead-acid car battery)

Weight: about 9 pounds

Cells: 10

Nominal Volts: 12.5

Nominal Amps Max Current Capacity (the vaguest spec): 400

Nominal Amp Hours: 50

Nominal Watt-Hours of Energy: 625

Recharges: theoretically indefinite

Note that with the high current, really fast charges should be possible as well as discharges. Not only from grid or car engine power, but they'll hopefully take whatever high currents dynamic braking deals out, without having any use for "supercapacitors".

When I've got them working well, I might produce and sell them. I haven't really priced things out very well yet. (a couple of "bottlenecks" like grinding monel into fine powder have really slowed things down, but buying monel powder would be almost 1/2 the total materials cost.) If anyone is interested in buying one/some instead of making them, price might be anywhere from about $250 to $375 per 12V battery. Sincere expressions of interest (not to say actual orders) should be really helpful if I look for a loan to set up better equipment and to buy raw materials in small production quantities.

Cheers,

Craig