OT: cordless screwdriver

Is anyone familiar with the cordless screwdriver in the link or a similar one? I'd like to know if using rechargeable 1.2V NiCd or NiMH cells instead of the specified 1.5V alkalines will result in a severely reduced torque.

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Reply to
Pimpom
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"Pimpom"

** The torque may well be better with rechargeable cells in use.

Under heavy load, the voltage from alkalines drops significantly while the others hold up.

.... Phil

Reply to
Phil Allison

Thanks, Phil. I need a handy cordless screwdriver, not the bulky heavy-duty drill-cum-screwdriver type. The one I had died some time ago and I'm weighing a built-in battery type against one using AAs - the convenience of the built-in type against the fact that the battery's likely to degrade in a few years and a replacement is not likely to be available to me.

Reply to
Pimpom

Not sure if the small difference in voltage would affect its operation but NiCd batteries would give much more torque than NiMh ones due to their lower internal resistance.

Reply to
asdf

"asdf"

** There is simply no difference.

NiMh cells matched NiCd in that respect long ago - but with much greater mAh.

... Phil

Reply to
Phil Allison

Pimpom Inscribed thus:

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I've got one very similar that I put MiMH cells into. I've not noticed any slowdown. It does seem to weed out a poor cell very quickly, one getting discharged far faster than the others.

--
Best Regards: 
                        Baron.
Reply to
Baron

I experienced this difference myself years ago when swapping my mini kitchen vacuum cleaner old 1.6 Ah NiCd battery pack with a 2.1 NiMh one made with fresh store bought branded cells. The NiMh pack let the motor run a lot slower, albeit lasting much longer than the old NiCd cells, which is what one would expect by a fresh and more powerful current source having a higher internal resistance. Those NiMh cells once put back in other appliances worked fine for years, I still have most of them operating after about 10 years.

Some searches brought similar results from other people along with the explanation: for power hungry devices NiCd cells are preferable due to lower internal resistance. I'm not aware of new developments in the field though, or about industrial grade batteries, only speaking of commonly available NiMh cells.

Reply to
asdf

A while ago the NiCd cells in my shaver died and I couldn't find anywhere that still sells NiCd. While the NiMh cells I tried have about double the Ah capacity, they only ran the shaver about 1/4 - 1/3 of the length of time.

It was fairly noticeable that the NiMh cells were getting fairly warm under load - so that's where all the energy was going!

Unfortunately I'd bought a lot of early NiMh cells at good prices some time ago - apparently more modern ones have lower internal resistance.

Reply to
Ian Field

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http://www.batterybob.com/googlesearchresults.asp?cx=002871419911360800563%3A7eqzgsumivs&cof=FORID%3A11&ie=UTF-8&q=NiCd&sa=Google+Search
Reply to
John Fields

NiCds are still easily available here in India - one of the "advantages" of being not as advanced as the West. If I decide to use NiMH types, they'll be Eneloops although, Ah for Ah, an eneloop costs twice as much as a NiCd.

Can anyone point to a reliable comparison between Eneloops and NiCds regarding performance under load? Phil?

Reply to
Pimpom

"Pimpom"

** There will be no difference in terminal voltage with any load that takes an hour or more to consume the cell's charge.

RC models are pretty much the only things that devour cells faster than hat - and they have gone over to NiMH almost entirely.

FYI:

The internal resistance of good quality AA size NiCd OR NiMH cells is less than 20mohms.

... Phil

Reply to
Phil Allison

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Go away you confused boring old druggie.

Reply to
Ian Field

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Perhaps, but only because we'd have your ever-receptive quivering bum 
in common.
Reply to
John Fields

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