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From what I remember NiCad batteries can't reach capacities as high as NiMH, so to get a 13 AH pack would require a lot of NiCad batteries. The pack might end up being too big to be practical. The biggest Cell I remember was 900 mAH or 0.9 AH. So if you wanted a 13 AH pack, you would first need to put 13 Cells in parallel just to get 1.2 Volts @ 13 AH, then multiply that to get 36 volts and now it's 36 / 1.2 = 30 of the (13 in parrallel) in series would mean you need 390 NiCad batteries to make a 13 AH pack. Those would be about "D" size as well, so imagine trying to fit 390 NiCad "D" size batteries into a pack. That and the weight problems with that many.

I believe NiCad patents are owned by big oil. they won't allow large scale batteries to be manufactured.

My understanding is that NiCad has better power/weight ratio then lead, but is quite expensive. NiMH are cheaper per capacity, and lighter too.

Lessss said:

I believe NiCad patents are owned by big oil. they won't allow large scale batteries to be manufactured.

Click to expand...

That sounds mythical. After all, NiCad technology and perfected NiCads are over a half century old. The patents are long expired on that stuff.
NiCads are gradually disappearing for several reasons. But they do and did last longer and handle abuse somewhat better than NiMh, yes?

Needing a link to that guy who is -the- battery info doctor of letters.

(looking for it now)

http://www.batteryuniversity.com/partone.htm

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Mr. Buchman is regarded as a straight-talker.
I don't see conspiracy here.

The fact is that NiMh is not as cycle-durable nor as current-capable as NiCad.
OTOH, NiMH is more enviro-friendly, and is of higher energy density.

The day is not long-off when the A123 sort of LI technology supplants and replaces both of the above (my inexpert opinion). Yet the cycle life of these phosphate-base LI batteries does no admit of as great cycle life as other LI chemistries, nor does it have the energy density (see battery university link up above)

The technology is growing and things are changing.
There's no monopoly holding back battery makers nor allowing them to cartel
costly or high-tech stuff from the market, nor to overcharge for the goods once manufacturing and distribution kinks are worked out.

In the end, cheap-enough batteries are available.

Look, for instance, at SLA batteries: there's no cartel and no collusion there. A great deal of pressure is always on the makers to keep things
competitive. In reality, it is the consumer who holds the market; not the makers.

That's my opinion. I've never gone big for conspiracy theories about carburators giving 200mpg, nor batteries for pennies, etc.

Most conspiracies are about human affairs rather than... oh wait.
Never mind... the auto makers DID kill the electric car. I forgot that!

It's true though; GM did that deed and Oil applauded.

I just don't smell smoke around batteries.
And I'm not yet ready to trust LI batteries, though the A123-type is getting attractive.

These are mostly only my opinions--and not anything more than that.

Justin's 8ah nicads got good reviews from a couple people at the old V. He recently received a new shipment of 8ah nicads not yet listed at his store.
http://www.ebikes.ca/store.shtml
Twenty years ago I used them for my RC car. Only recent experience is with powertools where nicad, due to longevity/cycle life, still rules over NiMH. Nicad is banned in the UK due to cadmium toxicity concerns. If I ever do go with nickel batteries for my ev's, I'd definitely choose nicad over nimh.

xyster's right about Nicads trumping NIMH for cordless power tool applications. DeWalt still uses Nicads in all of their cordless tools except for their new 36V lithium line. I have used their 18V drills for years as a contractor and will attest to their power and durability.

It is my understanding that Nicads also see a lot of use in the two way radio market. I worked this summer for a fellow who manufactures very expensive radio equipment for the military and security organizations, and was told by him that virtually all his equipment runs on Nicads. Apparently a lot of it had to do with superior cold weather performance.

But in the end I agree with the fellow who posted that lithium will eventually eclipse both these other chemistries as almost all the major automakers have announced a switch to lithium in their hybrids within 3-5 years, and technological advances seem to be occuring at a very rapid pace: A123, altairnano, and many others have already scored significant breakthroughs in improving both the safety and discharge/recharge capabilities of lithium-based cells.

Hi Xyster

I think NICAD is still a good buy as well, it tends to be heavier and bigger but its cheaper than NIMH and dishes out big amp surges better, however it is not very earth friendly, it isnt banned here in the UK its just harder to dispose of legally.

NIMH seems Like Larry said to be on its way out, they seem to be using LION packs more and more and I am sure Lipo will finally find its way in, both me and Larry can testify that Lipo is certainly the way to go.

Any more videos yet? I have some work to do in the garage before I shoot any more videos, should have some fun stuff coming up like a winter KMX run and testing of those new Lipos, I would like to run a Puma at 100V, I think I will rest then!!

All the best

Knoxie

Hi Knoxie,
Thanks for the clarification on the UK nicad possession situation. If I remember right, isn't it the sale of nicad batteries that's banned within the EU? But you can still import them OK?

I'll shoot another vid just as soon as I can squirt some emoli boost-pack juice into the ol' x5 ebike. As soon as I recover the money I lost to airfreetires.com and robotcombat's business incompetence, I'm going to DIY either a 4s2p or a 3s3p emoli pack connected to an 80amp relay and switch. Right now the bike's still 18s15p -- about 8 volts less than two of your 10-cell lipoly's in series.

I'm very interested to see the Puma running at 100v. In the past, didn't you say you didn't think it could take it? How are those nylon gears holding up?

We still need to do our virtual video comparison testing...All else being about equal, I have little doubt the much lighter, geared Puma will beat the X5 off the line. I suspect the X5 will catch up and win the race from 10-35mph, or up long, steep inclines -- which would be good, else I'm going to be super-tempted to buy a Puma too.

Hi Xyster

Yes I stripped one of the pumas down after about 500 miles of abuse and its perfect inside and out, the nylon gears look a1 no problems, the only bit to wear is my home made torque arm that has taken a battering, it shows you how much torque the thing is putting out if it can bend 4 pieces of 3mm mild steel plate pressed together.

I am working on a new design for the front and rear and will get them samples on the road soon. A friend has donated a really nice GT mountain bike, one of those I drive bikes with top spec gear on it, I am going to use that as the Puma 26 inch test bed machine, another ride to the collection.

Very busy with things still here but as soon as it dies down a little I will get a do that comparison video and the hill climb video.

After inspecting the Puma at 72V I am happy the motor will run ok at 100V but I wont do it until I have the new torque arm in place, I will also put better quality fets and gate resistors in on the controller as an upgrade.

Hope you sort the problem with your lost money, its horrible when that happens!! Happy New Year to you anyway!

Knoxie

Cheaper Nicads in pretested packs:
http://www.ebikes.ca/store/

Gots to figure total cost of ownership: nicad reasonably lasts about 2-3x as long as NiMH
http://www.batteryuniversity.com/parttwo-36.htm
and is only slightly heavier.

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I think the early NiMh had some flaws but they have improved them recently. They are now claiming a full 1000 charges. (unless they are simply lying)

Lithium is nice because the weight is so low. In cases where weight is the primary issue the only way to go is Lithium. NiMh makes more sense if you are willing to accept higher weight but you want more power per penny than with Lithium.

and large, surplus flooded nicads:
http://www.sg-photo.com/nicad_batteries.htm

I've had good luck with sub-C and C size nicads, but I've been very disappointed with the larger sizes. The 10000mah ones say only 16 amps discharge? I can get more than that from a good sub-C.

Too bad it's so hard to make them behave in parallel. I suppose one could make some kind of BMS that isolated them during charge and put them together during discharge. Otherwise you need a big plug or a big switch with lots of pins and separate chargers.

Why wouldn't diodes, one per string, work to isolate the parallel strings during charge but not discharge?

Diodes would work, but have a voltage drop (loss) that's nice to avoid. Low loss schottky diodes might drop almost 0.5v at high load.
FETs might work better, but would be more complicated to use. Most of the lithium BMS circuts use FETs.

I would like to know 1000 cycles under what conditions, that would tell the whole story.


Joe