From: Donald MacQueen (dmacq_at_erols.com)
Date: Wed Mar 21 2001 - 22:05:05 EST
Tim,
Wednesday, March 21, 2001, 8:49:32 PM, you wrote:
why do they put counters on batteries? planned obsolescence?
> Hello Sven:
> [...]
> I wrote:
>>> Meanwhile, I'm dissecting the old, dead battery pack and trying to
>>> figure out if a NiCad battery case can be safely rebuilt with NiMH
>>> batteries (the only problem I can see is if the temperature sensing
>>> unit the in pack is specific for the battery type).
> Sven:
>>I'm afraid things aren't as simple as that. The Battery sensing unit
>>is a lot smarter than that, and for all I know implemets a counter
>>which, after loading the battery N times, will declare the battery
>>dead, even though it might still be in perfect working condition. I
>>own such a battery, which can only be charged externally and will only
>>work in the TP 701 if all battery-sensing functions are disabled, but
>>will then work perfectly. The only Problem with this is that
>>switching the computer on has to be done on mains, as this tries to
>>talk to the battery...
> That's somewhat annoying. I just peeled up the three-wire chip that
> came inside my old NiCad battery to read the markings. It's a Dallas
> chip. The markings are: DS2434 9447C4 0190AA
> Now I've looked it up: It's a battery identification and temperature
> sensing chip. The chip has memory to store charge/discharge cycles
> and other information (and, of course, it's now considered obsolyte).
> There is something in the refs about non-volatile storage as well.
> http://www.dalsemi.com/datasheets/pdfs/2434.pdf
> The good news is that it should be re-programmable through the
> Dallas one-wire interface. However, there are three downsides to
> the problem: 1) One is that I'd need to steal the information off a
> working battery pack (but no disassembly is required & I've got
> a spare pack), 2) The chip comes with lockable non-volatile
> memory that may be essential to battery pack identification.
> (Worst case: Replace with a new chip and start from scratch),
> and 3) I've got to piece together a one-wire interface (Sounds
> like Basic Stamp time...).
>>But please, report any success with this should you succeed.
> I'll keep digging. Now I've got an incentive to learn the one-
> wire device interface. And thanks, without that warning I might
> never have bothered checking out the chip before rebuilding
> the pack.
> Regards,
> Tim Ikeda (tikeda_at_sprintmail.com)
-- DonaldDonald M. MacQueen Registered Smalltalk Bigot, [Esq.]
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