phil@amdcad.UUCP (Phil Ngai) (11/25/85)
It seems that Radio Shack sells AA NiCads for about $2 each while GE
sells them for twice as much, about $4 each. They are both the same
size, AA, same voltage, 1.2 V, and the same capacity, about 450 mA-Hr.
(the capacity is roughly ten times the recommended charging current
which is 45 mA) Finally, they are both made in Mexico. The obvious
choice seems to be Radio Shack. Have I overlooked anything?
--
The INS arrested the Rajneesh for trying to leave the country and
then deported him.
Phil Ngai +1 408 749-5720
UUCP: {ucbvax,decwrl,ihnp4,allegra}!amdcad!phil
ARPA: amdcad!phil@decwrl.dec.comdss00@amdahl.UUCP (dss00) (11/26/85)
> -- > The INS arrested the Rajneesh for trying to leave the country and > then deported him. > > Phil Ngai +1 408 749-5720 Aren't the condemned prisoners saved from death due to natural causes (sickness etc.) and prevented from committing suicide, so they could be put to death in accordance with the LAW ? -- Deepak S. Sabnis ...!{ihnp4,hplabs,amd,nsc}!amdahl!dss00 (408) 746-6058 (Usual Disclaimer Here)
ray@othervax.UUCP (Raymond D. Dunn) (11/28/85)
In article <6871@amdcad.UUCP> phil@amdcad.UUCP (Phil Ngai) writes: >It seems that Radio Shack sells AA NiCads for about $2 each while GE >sells them for twice as much, about $4 each. They are both the same >size, AA, same voltage, 1.2 V, and the same capacity, about 450 mA-Hr. >(the capacity is roughly ten times the recommended charging current >which is 45 mA) Finally, they are both made in Mexico. The obvious >choice seems to be Radio Shack. Have I overlooked anything? >-- Dont think so. I investigated this a couple of years ago, and came to the conclusion they were all coming out of the same factory, and were identical, I bought some Radio Shaft, then additional GE's (they were on *very* good special, with a charger thrown in). One thing to watch however, is 'D' cells. Both the (consumer retail variety) GE and Radio Shaft products are again identical, but have the same milli-amp-hour rating as the 'C' cells! If you open one up, it is only about 1/3 full of "electrolyte" (probably the wrong term for the contents of a Ni-Cad). They both feel about the same weight. Much higher capacities can be found in GE's catalogue, at much higher $$$'s. BTW folks, a caveat since Ni-Cads are being hyped at the moment: You have no guarantee that Ni-Cads will work satisfactorily in any given piece of equipment unless they are specifically mentioned in the "user-manual". This is due to the fact that a Ni-Cad has a fully charged voltage of ~1.25 (~1.22v during 90%+ of its discharge cycle), while carbon-zink, and alkalines are closer to 1.5volts (which does though decay during use). In particular, "Walkman" type cassette players (no specific brand implied) often are problematic. 9volt battery applications show the problem up worst (a Ni-Cad "9volt" is actually ~7.3volt). Ni-Cads also do not have nearly the same capacity as alkalines (e.g. less time per Ni-Cad charge, than from an alkaline cell in a given piece of equipment). Modern Ni-Cads can however supply much higher currents than other cell types (an ordinary 'AA' Ni-Cad can supply >10amps for short periods - they get *hot*). In addition, for ecology worriers, cadmium is a serious heavy-metal pollutant (Ni-Cad's are banned in some European countries). For the technically minded (sorry, just press 'n' if I'm going on too much, I know a little about Ni-Cads 'cos I fly model Radio Control, the batteries are a weak link): There are two things to watch out for when using Ni-Cads: 1) Discharge Memory. For some strange reason, if you *repeatedly* discharge a Ni-Cad by say 20%, then fully re-charge it, it "remembers" this, and when you now try to discharge it by more than 20%, it wont (actually it will - wow - contradiction within 5 words! - eventually, at the low almost discharged voltage). You should thus nearly fully discharge them before re-charging (but see below). As an example of what is bad, the Ni-Cads in an electric shaver will appear dead fairly soon if you just shave for 5-minutes every day, then shove it back in the charger. (I almost fully discharge mine every couple of weeks, and still get over 45mins of use when travelling after 7 years on the same cells). The memory can even show if you leave the cells *fully charged* for long periods. A rechargable calculator should not be left plugged in - use it off-line until it is just discharged, then re-charge it over-night. For serious applications (i.e. radio control), the cells are continuously cycled when not in use (or at least several times immediately before use), from fully charged to almost discharged. 2) Deep Discharge and Reversed polarity. Unfortunately, the capacities of Ni-Cads vary cell to cell, and when used together, e.g. in a 9volt pack, or 4 AA's together, one of the cells will become discharged before the others, which continue to supply current. This is forced through the dead cell, and, to cut a long story medium length, horrors, IT DOESN'T LIKE IT (would you?). In short, this cell expires rapidly (pushing-up-the-daisies-type-expire). Even with single cells, leaving the equipment "switched-on" after the cells are discharged, is bad news. The solution is to not *completely* discharge, and to match your cells, but that is another story more suitable for net.consumers.tech (as if the above wasn't)! If anyone is interested out there, I can also give some info on "fast-charge" types & etc. Ray Dunn. ..philabs!micomvax!othervax!ray
john@hp-pcd.UUCP (john) (12/02/85)
>>>>>> > -- > The INS arrested the Rajneesh for trying to leave the country and > then deported him. > > Phil Ngai +1 408 749-5720 > Between the arrest and the deportation they did extract a 1/2 megabuck fine and the promise not to return for five years. John Eaton !hplabs!hp-pcd!john
smh@mhuxl.UUCP (henning) (12/02/85)
**** **** From the keys of Steve Henning, AT&T Bell Labs, Reading, PA mhuxl!smh > One thing to watch however, is 'D' cells. Both the (consumer retail > variety) GE and Radio Shaft products are again identical, but have the same > milli-amp-hour rating as the 'C' cells! If you open one up, it is only > about 1/3 full of "electrolyte" (probably the wrong term for the contents of > a Ni-Cad). They both feel about the same weight. You are partially right. I opened a GE 'D' cell up and it had a 'C' cell inside. I have some real 'D' cells with 4 ampere-hour ratings that were made by Gould and Marathon. I needed to draw nearly an amp for 4 hours and the GE batteries were a joke for that application.
copp@petrus.UUCP (12/05/85)
Not only do ni-cads not work in some equipment (due to the lower voltage per cell), they can actually DAMAGE some items. The classic example is cheapo electronic flash units. Some designs rely upon the internal resistance of conventional cells to provide a current limit; the ni-cads have a lower internal resistance and permit current levels high enough to fry the electronics. The moral: don't put ni-cads in your toy unless the owner manual says it is OK.