When will batteries grow beyond sub-C?

Sub-C cells are the standard for NiCd and NiMH power tool battery packs. As voltages grow, so does pack size.
At some point, the pack size curve will reach a point where the tool will be
too heavy for all but the most macho professional construction / repair / assembly worker to hoist.
Is LIon the next-highest-density rechargeable cell on the horizon for such applications? Are there others that hold promise but have yet to hit the market?
Thanks,
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I have implied, but should explicitly ask my question: when will the densities grow such that cell size shrinks?
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DaveC wrote:

You have at least two problems Internal resistance is a killer. Smaller batteries have higher internal resistance...sometimes... As do lithiums...sometimes... mike
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In 2002, Toshiba announced a prototype run of 18650 lithium-ion cells that could do 6C, with a 1600mAh cell. As I can find no mention of them more recently, I can only assume that nobody expressed an interest in buying a few million, to make it worth their while setting up to make them.
The third problem is that even if you've got a smaller cell with an identical thermal resistance, it's going to get hotter, due to the lower surface area to dump the heat.
Lithium-ion is not very much better than NiMH, in terms of energy density. However, it's lots better in terms of weight per unit mass.
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Ian Stirling wrote:

Whoa! Equivalence Principle violation!
Events are unfolding faster than I had anticipated.
--- Graham Cowan http://www.eagle.ca/~gcowan/Paper_for_11th_CHC.doc
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[...]

I think the problem with the hydrogen fuel cell based tools is that they are so light the stores just can't keep them on the shelves.
I have, also, noticed that a battery powered drill gets heavier as you use it.
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Ken Smith wrote:

That's because the weight per unit mass keeps increasing. ;-)
Ted
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I read in sci.electronics.design that Ted Edwards
'When will batteries grow beyond sub-C?', on Mon, 19 Jul 2004:

It's due to the build-up of entropy in the battery as it discharges.
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John Woodgate wrote:

Yes. An entropy weighs a lot more than a regular trophy. They even spell it differently to emphasisze the point. It's a probelm with the internal energy => mass converter which they haven't yet solved.
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I read in sci.electronics.design that Ian Stirling
reader01.plus.net>) about 'When will batteries grow beyond sub-C?', on Sun, 18 Jul 2004:

It isn't subject to normal gravity?
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wrote:

I suppose I could argue that I was talking about the weight due of the extra energy storage per unit mass of battery, but of course I meant energy per unit mass, and it was a typo.
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DaveC wrote:

Why should cell size shrink?
Do you want to make everything that uses C,D,etc. cells obsolete?
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DaveC wrote:

Actually the battery makers have been fighting *against* this for a couple decades now. Witness the consumer C cells and D cells that are really sub-C's or even AA-sized batteries in a hollow shell.
Tim.
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DaveC wrote:

I don't know if that's going to happen. Cell capacity (energy density) is increasing all the time. Cells are getting better all the time. If they're still putting in more cells, then the tools are getting more powerful all the time.
When it gets to the stage that the battery powered tools reach the power of mains powered tools, you'll be paying many more times for the same thing, just cordless and very much heavier.
That's when they'll start using portable generators and normal mains powered tools. Oh look, they're already doing that.
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As
will be

/
is
they're
the time.

of
just
powered
<http://counter.li.org
Try dragging that corded 1/2" drill (or sometimes sawzall) into the deepest, darkest, hottest, tightest, itchiest part of the attic with you to drill down into the wall for fishing wire. Your partner on the floor couldn't hear you screaming at him to unsnag your cord with the roar of the generator either. I'll stick to my DeWalt 18v XRP.
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[...]

I have a *slightly* modified electric drill. It has a cable and connector where the battery used to be and plugs onto a battery belt. That way, you've got about 10 times as much energy and about 1/2 the weight in your hand.
Its really too bad they don't make electric tools with a standard connector you can either plug a battery or a cable into.
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Ken Smith wrote:

Then they couldn't charge the truly outrageous prices for their propritary battery packs. I have a cordless phone that uses five AA NiCds for which the manufacturer wants $85. Needless to say, I intend to rebuild it myself.
Ted
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vincee wrote:

You gonna drive a 3/4" Greenlee through a 12" rim joist with that?
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packs.
density)
all
power
thing,
deepest,
hear
I assume you mean 12" thick. Answer = Yes. In low gear(3 speed) I can turn a 7/8" Lennox ship auger (Greenlees don't stand up to the nails as well I have found) through just about anything (with a reasonably fresh battery and I do have to clear the hole a couple of times and it does bog a little on the thick hard stuff but it will do it). It really does have an enormous amount of torque for a cordless. If it snags on something and your not braced for it it can hurt you. I wouln't want to use it up drilling out entire houses with it (that is hole hawg territory-much faster) but as I said before it is an excellent tool for attic or basement crawls.
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I read in sci.electronics.design that vincee
com>) about 'When will batteries grow beyond sub-C?', on Thu, 22 Jul 2004:

I didn't realise that there are still cave-dwellers in USA. Still, I suppose I shouldn't be surprised. I was a part-time cave dweller in 1941.
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