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 <[EMAIL PROTECTED]> Need help from a real person? Try. <[EMAIL PROTECTED]> ---------- Dr. Bott | 10/100 Ethernet for your 2400 is finally here! 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