-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Thanks for the pointers.
How would you suggest I go about using a power supply to zap the individual cells? I'll use my fog lamp connectors on my car as a last resort only, so I'm curious about trying the other methods first. Cheers - -Andy On Wednesday, February 27, 2002, at 07:57 AM, [EMAIL PROTECTED] wrote: > > In a message dated 2/27/02 7:32:56 AM, [EMAIL PROTECTED] writes: > >> Perhaps your 1 amp supply connected for a longer period >> would stir things up enough. > > NO!!!!!! DO NOT DO THIS!!! I've been following the thread....lemme > get on > my soapbox quickly. > > Dendritic growth int the chemical medium of nickel cadmium batteries is > well > documented. Some success with a REVERSE "tap" of 2x/3x cell voltage @ > 5x > rated max amperage has been reported. Please note we're talking > milliseconds > here....NOT minutes. The high amperage reverse "burst" seems to "snip" > the > dendrites. They will eventually regrow, but for the moment.....the > cell will > hold a usable charge. > > The forward (standard "charge" position") connection is more commonly > attempted, as it is easier to do with a quantity of cells. Voltage > needs to > be around 2-3x and amperage in the 10A+ range (you're looking for a > quick > "pop" instead of a hard minutes-long connection). It is less > successful but > does work. > > The problems. Well, where do I start? Fire/damage/injury from a burst > cell. > Burns from the cabling (you DON'T use light wire for this trick). > Damage to > the other cells when trying this with a multicell pack. If there is an > internal ROM for S/N, the possiblilty of damage to it (i.e., don't try > this > on the "intelligent batteries" from the 520/540 series unless you're > right on > the individual cell). ALSO.....Apple batteries have (as do most packs) > an > overload sensor which will sense a short circuit and open. Multiple > hits can > burn this out and totally kill your battery (as it will be an open in > the > middle of the battery connections internal to the pack). > > Plus side? If if works, you've just resuscitated an expensive battery! > > Tricks. First, I prefer to do a cell by cell reverse "hit," followed > by a > 300 mA charge for 12 hrs. Obviously, this involves opening the battery. > I've had good success with this on Duo batts. I use a 6V 17 Ah battery > (well > charged) to "hit" each cell quickly (reverse polarity), then charge the > pack > as mentioned. The problem with this is the possibility of killing a > cell > completely. On the assembled pack, the forward "pop" works fairly > well, just > with less success. Remember, you want just a quick "hit" to pop the > dendrites. > > If you'd like to try this, do the following: Using a car battery (be > CAREFUL!!!) or a "gel-cell" type unit, "pop" the pack in > reverse.....wait > about 10-20 seconds for the overload sensor to reset...."pop" it again. > Next, charge the battery (in the normal way, not reverse, of course) > using an > EXTERNAL source for 10-20 hrs. You will need 15-16 VDC at 200 to 300 > mAh (a > "wall wart" type power supply is perfect for this....I have a 15VDC lab > supply which I use...overkill). DON'T PUT THE BATTERY BACK INTO THE > COMPUTER > TO CHARGE! The possible current draw can be excessive. Charge > externally > first...at least for a couple of hours before putting it back into the > PowerBook. > > WARNINGS: If you use a car battery, use ALL precautions, 'cuz if you > short > circuit a lead-acid battery, you will have a high generation rate of > hydrogen > as well as heat/sparks etc, resulting in a neat chemical reaction known > as an > explosion. I've seen several....not any fun. Remember, it is a > lead-ACID > battery....sulfuric acid hurts, esp. in the eyes. > > If you play with radios, as do I, you may have a regulated power supply > which > outputs in the 13-14 VDC range. If it is a nice, regulated > supply.....don't > use it. Short circuits (i.e., high drain overamperage connections) can > kill > such a supply. The thing to use is a standard 6/12V battery charger. > No > chance of blowing up your $100 radio power supply and the battery > charger is > designed for high instantaneous outputs. This is the best thing to > use, as > it also should not explode <<grin>>. > > I used to keep the remains of a Gates lead acid cell in the lab to > remind > techs what can happen when you screw around with the laws of physics. > Why? > Think "hand grenade." The tech that was screwing around with it had to > pick > out several bits of casing from his hand and chest, as well as a few > from the > walls. Don't want that in your Duo or 2400! > > <<Off soapbox>> > > OK, real world. I've done LOTS of cells...probably 60 to 70% success. > However, I have the burn scars from wires and have ducked shrapnel from > exploding batts....one of the hazards of being a "hands-on" engineer. > DO BE > CAREFUL!!! I hate attending funerals. <<grin>> > > Andrew > > ---------- > Duo/2400 List, The friendliest place on the Net! > A listserv for users and fans of Mac subportables. > FAQ at <http://www.themacintoshguy.com/lists/DuoListFAQ.shtml> > Be sure to visit Mac2400! <http://www.sineware.com/mac2400> > > To unsubscribe, E-mail to: <[EMAIL PROTECTED]> > To switch to the DIGEST mode, E-mail to <DuoList- > [EMAIL PROTECTED]> > Need help from a real person? Try. <DuoList- > [EMAIL PROTECTED]> > > ---------- > Dr. Bott | 10/100 Ethernet for your 2400 is finally here! > MPC-100 | <http://www.drbott.com/prod/mpc100.html> > > RoadTools $30 PodiumPad available at Apple retail stores, $20 Traveler > CoolPad at Staples. Both in white for iBooks at <http://roadtools.com> > > Midwest Mac Parts ][ <http://www.midwestmac.com> > After-market parts for Macs. ][ 888-356-1104 ][ > > MacResQ Specials: LaCie SCSI CDR From $99! PowerBook 3400/200 Only $879! > Norton AntiVirus 6 Only $19! We Stock PARTS! <http://www.macresq.com> > - ----- "... I realized that when they [random people pulled from the streets] used the mouse, they were pointing. Pointing, and tapping the button with the finger they were pointing with ... there was no mental model for pointing with more than one finger. So we got rid of the two-button mouse ..." Larry Tesler of Apple Computer on the Lisa (and later Macintosh) mouse. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (Darwin) Comment: For info see http://www.gnupg.org iD8DBQE8fUxi6akgVXVbCzMRAgADAKCJRrKoDfxBua3unYQi6f42uILgAgCgk1lT F5uiX5vPVklSEZWpqxyu3cg= =ZRiK -----END PGP SIGNATURE----- ---------- Duo/2400 List, The friendliest place on the Net! A listserv for users and fans of Mac subportables. FAQ at <http://www.themacintoshguy.com/lists/DuoListFAQ.shtml> Be sure to visit Mac2400! <http://www.sineware.com/mac2400> To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> Need help from a real person? Try. <[EMAIL PROTECTED]> ---------- Dr. Bott | 10/100 Ethernet for your 2400 is finally here! MPC-100 | <http://www.drbott.com/prod/mpc100.html> RoadTools $30 PodiumPad available at Apple retail stores, $20 Traveler CoolPad at Staples. Both in white for iBooks at <http://roadtools.com> Midwest Mac Parts ][ <http://www.midwestmac.com> After-market parts for Macs. ][ 888-356-1104 ][ MacResQ Specials: LaCie SCSI CDR From $99! PowerBook 3400/200 Only $879! Norton AntiVirus 6 Only $19! We Stock PARTS! <http://www.macresq.com>
