km@emory.uucp (Ken Mandelberg) (12/28/87)
I have a Sony D7 portable CD player that comes with
a rechargeable battery pack.When I first got the player
the batteries would run it for about 4 hours. Now its
down to a little over an hour.
I'm certainly guilty of abusing it. I have both overcharged
it and run it to empty several times, contrary to the
instructions. The only thing I haven't done is used it
to often. I probably have only used it on batteries 25
times.
The battery pack is unique to this player, and costs about
$60 from Sony to replace. Given that the state of the art
has advanced in CD players, and costs have come down on new
ones its probably not worth replacing the battery pack.
I'm wondering if there is some way to rejuvinate them.
I've heard that the batteries "learn" some bad habits
and can be retrained with the right charge.
Any advise?
--
Ken Mandelberg | {decvax,sun!sunatl,gatech}!emory!km UUCP
Emory University | km@emory BITNET
Dept of Math and CS | km@emory.ARPA ARPA,CSNET
Atlanta, GA 30322 | Phone: (404) 727-7963wtm@neoucom.UUCP (Bill Mayhew) (12/29/87)
<<bad battery pack on a Sony D7>> I'm not sure about the D7, but the hard case for the D5 used a battery pack that was identical to one of the camcorders that Sony makes, but the battery is kind of expensive. One might be able to obtain an equivalent battery from 47th St. photo or a similar source, though. Also Spiratone has many such A/V accessories. Genrally, running a battery down to empy is a good thing in the case of NiCd cells, as it ensures that all cells are fully depleted and thus all cells will take a full charge. This, of course, doesn't mean leaving it on for days. If a NiCd cell is completely discharged, it will short out thus rendering it potentially useless. Over charging a NiCd battery is bad for it because the heat build-up can kill the cells. Only partially discharging a NiCd battery can cause some cells to become more depleted than others in the battery, due to normal statistical variation of the real world. Subsequent partial use and recharges causes the bad cell to get more out of sync, until it is fully depleted and shorts out. Sometimes a shorted cell can be rejuvenated by charging up a 40,000 uF or so capacitor to around 20 volts, removing said cap from power supply and applying it + to +, - to - on the shorted cell. Sometimes, you'll get lucky and break the short. Often several current pulses need be applied to clear the short. Such rejuvenated cells are seldom as good as fresh cell, but the technique is useful to get a piece of gear back on line quickly when a replacement cell is not available. The Sony battery packs are usually pretty well sealed, so you'd have to do some work with an X-acto knife to get at the individual cell of the battery. --Bill
perseus@nvuxk.UUCP (A D Domaratius) (12/30/87)
In article <2428@emory.uucp>, km@emory.uucp (Ken Mandelberg) writes: > I'm wondering if there is some way to rejuvinate them. > I've heard that the batteries "learn" some bad habits > and can be retrained with the right charge. > > Ken Mandelberg Rechargeable batteries can develope a "memory". To erase this memory you must run the batteries down completely. Then hook up the charger and let it charge the full time as indicated in the insructions that came with the Diskman. I had a similar problem occur with a portable phone that would stay operational for shorter periods of time as the unit was used. By following the method I just outlined. Al Domaratius
cs211s40@uhccux.UUCP (Taro Nobusawa) (12/31/87)
In article <897@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: > ><<bad battery pack on a Sony D7>> > >I'm not sure about the D7, but the hard case for the D5 used a >battery pack that was identical to one of the camcorders that Sony >makes, but the battery is kind of expensive. One might be able to >Genrally, running a battery down to empy is a good thing in the >case of NiCd cells, as it ensures that all cells are fully depleted >and thus all cells will take a full charge. This, of course, >doesn't mean leaving it on for days. One thing, the newer Sony portable CD players, like the D-10 I own, have lead acid batteries, and the D-7 might be one of these. Anyone know for sure? Do the same rules apply to these? I seem recalling hearing that it's slightly different for lead-acid batteries. Well, ciao All. It's been a blast! My student account gets zapped in a few days. ___ |n| -- "who ever said the human race was logical?" ST-IV Taro Nobusawa cs211s40@uhccux.BITNET cs211s40@uhccux.uhcc.hawaii.edu Compu$erve: 71071,322
neal@weitek.UUCP (Neal Bedard) (12/31/87)
In article <897@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: ><<bad battery pack on a Sony D7>> > >I'm not sure about the D7, but the hard case for the D5 used a battery pack >that was identical to one of the camcorders that Sony makes, but the battery >is kind of expensive. [...] > >Genrally, running a battery down to empy is a good thing in the case >of NiCd cells, [...] ^^^^ The battery pack for the D7 and D10 is called a "BP-100", and it's a *lead- acid* battery, not NiCad. It seems pretty specific to the application, too, as it "mates" to the Discman itself (I doubt that it would fit any camcorder.) I don't know of any way of "recovering" lead-acid battery. It is possible to take apart a BP-100, but I'd have serious doubts about being able to put it back together again and have it fit and function correctly (the screwed-on cover seems to be glued in place.) I suppose an alternative to the BP-100 would be to use the 9-volt plug in back and kludge up some NiCad pack to slip onto it, but that seems like more work than it's worth. -Neal
dave@onfcanim.UUCP (Dave Martindale) (01/07/88)
In article <897@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: > >Genrally, running a battery down to empy is a good thing in the >case of NiCd cells, as it ensures that all cells are fully depleted >and thus all cells will take a full charge. This, of course, >doesn't mean leaving it on for days. More precisely, it is a *good* thing to use the battery-powered device until its low-battery warning comes on, at least once or twice a month. As Bill notes, this prevents NiCd cell "memory effect". However, it is a very *bad* thing to leave the power switch on beyond the low-battery warning point, particularly after the device stops functioning. Since the actual capacity of each cell in the battery pack differs, one of them will eventually reach zero charge while the others still have some remaining charge. At this point, if current is still flowing, the discharged cell begins charging in *reverse* - a good way to destroy it rapidly. If you want to completely discharge each cell in the pack, you have to discharge each cell individually (through a resistor) - just connecting a resistor across the pack as a whole will probably reverse-charge one or more cells. Yours for longer nicad life, Dave Martindale