> > Here's James Garry's really great page with pictures of how to do this: > > http://www.fastlight.demon.co.uk/jg/duobatt.html > > Does anyone have a real schematic for these batteries, or know the part > number of what James calls the "Q1 Transistor-like thing"? I assume it's > just a serial number chip, but I need a part number to buy one so I can > rebuild a BTI Type 4 that has a PIC microcontroller where that Q1 device > should be.
It's a Dallas 64 bit electronic serial number register. Basically it's what gives each batteries it's own ID number. The first 8 bit IDs the type (it's probably used to distinguish between Type 1, Type 2, etc) then the next 48 bits are the actual serial number. The last 8 is used for parity checking to ensure the Duo loaded the entire 64 bits correctly. When facing the contact with the negative pad on the left side, the pad #2 is the signal from Dallas DS2400 or DS2401. The DS2400 I saw were only in Type 1 while DS2401 were in 2 and 3 and possibly 4 as well. The link for DS2401 specs is http://dbserv.maxim-ic.com/quick_view2.cfm?qv_pk=2903 and it's a direct replacement for DS2400. PDF file of the data sheet is available for download from the above link. Next is pad #3 which is the common ground for both the DS240x and the thermistor. Then the Thermistor is connected to pad 4. It's what provides the Duo with the battery temp reading. And lastly there's a positive pad. Pad 2, 3, and 4 are not connected with the battery at all, it's just housed inside the battery case. Now for the 2 fuses inside the battery, they are there to prevent overload due to a short. Should you accidently short the - and + pad, the thermal fuse will blow from either the current load or heat. The first fuse is between 3rd and 4th battery, and the second one between 6th and 7th battery. While you could probably leave them out, I do suggest them anyway because they do get really hot if there's a short and probably would leak or even explode. Word of caution when soldering in replacement thermal fuse, the heat may blow the fuse so try to keep it short or use low temp soldering iron. > BTW, the BTI Type 4 sticks out the front of the Duo about 1/2" more than > a regular battery. I had some suspicions that the larger size was because > BTI originally used A cells instead of 4/5 A to save cost or get more > capacity, and when I opened it up sure enough - there were popsicle stick > spacers in there to keep the 4/5 A cells from rattling around. It looks > like there actually is enough room for 10 A cells. Finally, the mythical > 2700 mAH Duo battery is in sight! I don't know what the Type 4 is supposed to have but if you put your mind to it you wouldn't be limited to the battery case. You could cannibalize a dead Type 1 battery, install cables and make a big battery case out of rechargeable "D" batteries. Now that would outlast anything else unless you count on a car battery >=) True it wouldn't be portable but it would be really useful if you live in a power failure prone area and frequently suffers from computer withdrawal, email withdrawal, and/or email withdrawal effect. An easy way to do this would be to leave in the dead cells to hold the circuits and pads in place. Do cut out the + and - and run a set of wires to an external source. Also I'd recommend you also strech the themristor so the Duo can monitor the temp of the new battery pack. The 64 bit electronic serial number chip can stay in. A D battery pack can easily be made to sit under the Duo if you arrainge them in 3 rows x 3 per row layout plus one more somewhere (along side?) to round out out 10 batteries, 12v total. (typical rechargeable batteries are only 1.2v each rather than 1.5v with disposable batteries.) If anyone actually tries this with D batteries, I'd like a screen shot of Battery Amnesia working on a fully charged set. I wouldn't be surprised if the discharge rate is off the chart. IIRC "D" sized NiMH can hold upward of 6 or 7000mAh, possibly more as I'm tooo tired for a through research on this. I might do this as well as I've been in one power failure too many as of late. :-p ---------- 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> NineWire | If they are cool enough to host this list... Digital Solutions | ...you should check them out! http://www.NineWire.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>
