tag@garfield.UUCP (Terry Greening) (11/02/84)
[gobble gobble munch munch]
I have recently bought a set of GE size 'D' rechargeable
batteries and have had to recharge them twice in the past month
and a half. When I first bought them, I charged them up, used
them in my flashlight for probably less than an hour, and they
died. I figured that it was because they were new so I recharged
them. I then "tested" them a few times over the next few weeks
and they seemed to be doing good. Last night, I left the flash-
light out in the cold for a few hours and when I went to use it,
the batteries were just about dead. I wonder if the cold has
this effect on the batteries or do Ni-cad batteries die this fast
anyways. By the way, I also have a set of 'AA' batteries by Ra-
dio Shack which I am not totally satisfied with. A friend of
mine says that she has to recharge her GE 'AA' batteries, which
she uses in her walkman, every night.
--
Terry Greening
{akgua, allegra, dalcs!dreacad, ihnp4, utcsrgv}!garfield!tag
Memorial University of Newfoundland2141smh@aluxe.UUCP (henning) (11/06/84)
**** **** From the keys of Steve Henning, AT&T Bell Labs, Reading, PA aluxe!2141smh The GE nicad D-cells contain a nicad C-cell, at least the last time I checked. You can tell by picking the up, the C and D cells weigh the same. Nicads are not too swift when they get cold. Also they have a memory effect. If you only discharge them 10% before you charge them several times, they will only hold about 10% charge. By the way, a nicad D-cell should be a 4 ampere battery. If treated properly, nicads only last about 3 years typically. If after using nicads several months and you notice that they do not hold a full charge, they have developed a memory for the use and recharge cycle. You can recover the nicads by leaving the appliance on for about 12 hours to get a deep discharge. Charge the batteries for 24 hours. You should do a deep drain and recharge every 3 months.
parnass@ihu1h.UUCP (Bob Parnass, AJ9S) (11/06/84)
There are differences among brands of NiCd batteries, for instance: -The Radio Shack AA NiCd batteries are marked as having a capacity of 450 milliampere-hours. -The GE AA NiCd batteries are marked as having a capacity of 500 milliampere-hours. Also, some brands cannot be fast charged, due to the inability of the cell structure to withstand the high temperatures and pressures developed during fast charge. Although they have 10% less capacity, the Radio Shack batteries are usually a few dollars cheaper. I've used both with good success (although Radio Shack once had a bad batch of AA NiCd's). -- =============================================================================== Bob Parnass, Bell Telephone Laboratories - ihnp4!ihu1h!parnass - (312)979-5414
dmmartindale@watcgl.UUCP (Dave Martindale) (11/06/84)
More info on nicads: Real "D" cell nicads are made, and can be found at large electronic distributors. They cost a lot though, and require a different charger, since a charger that puts out an appropriate charge rate for C cells will not fully charge a real D cell. Nicad batteries are used in some business jets as the main battery. They put out more current than a lead-acid battery, which translates into a faster rate of acceleration of the turbine when starting a jet engine, which results in less wear to the engine. In this use, the "memory" effect is well known, and after the battery has been used for a certain number of engine starts it is serviced. It is fully discharged to see how much power it can still deliver; if that is less than some high percentage of the original output, it is recharged and discharged again to see if its capacity has improved. When it can't be rejuvenated, it will be replaced. One potential problem with discharging by leaving a battery-powered appliance on for a long time: If some cells hold a bit more charge than others (due to production non-uniformities or age) then when you do this, one cell will reach zero output first, and then start reverse-charging as the other cells continue forcing current through it. This is a good way of developing a short in the cell. You probably want to discharge the cells to the point where output drops drastically - the cells are almost discharged at that point.
karsh@geowhiz.UUCP (Bruce Karsh) (11/09/84)
> [gobble gobble munch munch] > > I have recently bought a set of GE size 'D' rechargeable > batteries and have had to recharge them twice in the past month > and a half. When I first bought them, I charged them up, used I just bought a 9 volt nicad battery and found out that 9 volt nicads really only produce 7.2 volts. Thats fine for my application, but are there some common appliances which won't work with 7.2 volt nicads, but will work with regular 9 volt transistor batteries. -- Bruce Karsh --------------------------- Univ. Wisconsin Dept. of Geology and Geophysics | | 1215 W Dayton, Madison, WI 53706 | THIS SPACE FOR RENT | (608) 262-1697 | | {ihnp4,seismo}!uwvax!geowhiz!karsh ---------------------------
ron@brl-tgr.ARPA (Ron Natalie <ron>) (11/09/84)
> A friend of > mine says that she has to recharge her GE 'AA' batteries, which > she uses in her walkman, every night. Portable tape recorders consume the batteries. Regular carbon batteries last for about 3 runs of a C-90 tape. Nicads are not likely to be as good. -Ron
keithd@cadovax.UUCP (Keith Doyle) (11/12/84)
>> I have recently bought a set of GE size 'D' rechargeable >> batteries and have had to recharge them twice in the past month >> and a half. When I first bought them, I charged them up, used > I just bought a 9 volt nicad battery and found out that 9 volt >nicads really only produce 7.2 volts. Thats fine for my application, >but are there some common appliances which won't work with 7.2 volt >nicads, but will work with regular 9 volt transistor batteries. It's obvious that the battery manufacturers just can't bring themselves to produce a product that would effectively obsolete their disposable battery products. I remember some battery packs in some of the Tektronix scopes that seemed to last for years. Thinking that rechargables were practical because of this, I bought some Eveready rechargeables, AA, C, D, and 9 volt. The 9 volt is of course only 7.2 and won't work in some applications. I found that these batteries would recharge about 5 or 6 times before they wouldn't hold a charge. On the other hand, a friend of mine found some 9 volt type batteries some time ago that were made in Europe somewhere, that were actually 9.6 volts (or thereabouts) and held a charge much better then the Evereadys. I tried G.E's and Radio Shack (ugh!) out of desperation, but still found no success. My old T.I. calculator batteries hold up better than these. I've since resorted to building power supplies for many of my battery operated gizmos ( particularly musical instrument black boxes ), as I don't like to patronize these battery manufacturers. I've also heard that light bulbs that last forever can be made, but you can't buy them, because G.E. (etc.) would lose money. Keith Doyle {ucbvax,decvax}!trwrb!cadovax!keithd
woods@hao.UUCP (Greg "Bucket" Woods) (11/15/84)
> A friend of > mine says that she has to recharge her GE 'AA' batteries, which > she uses in her walkman, every night. > That's funny. I have an AIWA (competing brand, same product) and I cannot use the GE NiCad batteries in mine because they are the WRONG VOLTAGE!!! People should be aware that the NiCad batteries will not work in any appliance that depends on the voltage being correct. --Greg -- {ucbvax!hplabs | allegra!nbires | decvax!stcvax | harpo!seismo | ihnp4!stcvax} !hao!woods "...once in a while you can get shown the light in the strangest of places if you look at it right..."
klein@ucbcad.UUCP (11/16/84)
--------- [] About 5 years ago I bought some AA nicads for a Vivitar flash unit. They are still in the flash, although they now discharge themselves within a few days even when not used. For the first 3 years they performed superbly, requiring recharging only every month or two or after some large (> 100) number of flashes. Does anyone else have an experience like this, or has the quality gone way down? -- -Mike Klein ...!ucbvax!ucbmerlin:klein (UUCP) klein%ucbmerlin@berkeley (ARPA)
greenber@acf4.UUCP (11/19/84)
<> Now the rumor that I hear is that if you let a nicad discharge totally, you get to buy a new one. This seems to hold true on my trusty HP-65...howzabout it, oh knowledgable ones??? Ross M. Greenberg @ NYU ----> allegra!cmcl2!acf4!greenber <----
keithd@cadovax.UUCP (Keith Doyle) (11/21/84)
>So stop assuming bad karma from the battery makers until you understand >the technicals. I suppose they could stick in 7 cells ( 7 x 1.2 = 8.4 ) >but that's hard to do in two stacks. (There would have to be an odd cell >somewhere. Sometime pry apart a dead 9-volter to see what I mean...) >If they went to 8 cells ( 8 x 1.2 = 9.6 ) the OVERvoltage might burn out >something... I have no particular problem with the different VOLTAGE output of ni-cads, 9.6 volts (or even 8.4) is FINE as far as I'm concerned. Even 7.2 is better than nothing. I'm talking about the apparent (note: apparent) SHORT recharge life of average consumer ni-cads (I've experienced about a half dozen recharges and then they no longer hold a charge). I say apparent because I've yet to try the 10 ohm discharge trick. (But I will! I promise!) Keith Doyle {ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd "You'll PAY to know what you REALLY think!"
crandell@ut-sally.UUCP (Jim Crandell) (11/22/84)
> Now the rumor that I hear is that if you let a nicad discharge totally, you > get to buy a new one. If you mean a battery of several cells connected in series rather than a single-cell ``battery'', then you're right. Problem is that it's generally impossible to get two cells with exactly the same amount of charge in them, so if you wire them in series and, say, put a load resistor across the combination, all goes as expected until the one with the lesser charge completely discharges. After that, the one with the greater charge continues to discharge by ``charging'' the discharged cell. You'll notice, however, that the polarity of the voltage that the discharging cell applies to the discharged cell is incorrect for charging. The damage caused by allowing this condition to persist for several minutes (to say nothing of hours) is usually not reversible by electro-chemical means; hence you're out the cost of at least one cell, if you're lucky enough to be able to replace them separately. -- Jim Crandell, C. S. Dept., The University of Texas at Austin {ihnp4,seismo,ctvax}!ut-sally!crandell
palisano@sunybcs.UUCP (Tom Palisano) (11/28/84)
> >> I have recently bought a set of GE size 'D' rechargeable > >> batteries and have had to recharge them twice in the past month > >> and a half. When I first bought them, I charged them up, used > > > I just bought a 9 volt nicad battery and found out that 9 volt > >nicads really only produce 7.2 volts. Thats fine for my application, > >but are there some common appliances which won't work with 7.2 volt > >nicads, but will work with regular 9 volt transistor batteries. > > It's obvious that the battery manufacturers just can't bring themselves > to produce a product that would effectively obsolete their disposable > battery products. I remember some battery packs in some of the Tektronix > scopes that seemed to last for years. The problem with NiCads is that by nature they only produce ~1.25 volts/cell as opposed to carbon cells @ 1.5 V/cell. NiCads also tend to have 'memory' with regard to how they were/are used. A battery that is recharged before it is fully exhausted will remember this and give limited service once charged. In addition NiCads are not ment to be used in a parallel combination due to their low internal resistance. These factors lead to problems when batteries of this type are used as replacements for standard non-rechargeable cells. Perhaps a better solution would be to use Lead-Acid cells that produce about 1.7-2.0 V/cell and have none of the quirks that a NiCad exhibits. Tom Palisano -- -- Tom Palisano uucp:[bbncca,decvax,dual,rocksanne,watmath]!sunybcs!palisano csnet:palisano@buffalo arpanet:palisano.buffalo@csnet-relay -- --